Article

Domestic sewage treatment in a sequencing batch biofilm reactor (SBBR) with an intelligent controlling system

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The sequencing batch biofilm reactor (SBBR) system, one type of biofilm technology, has attracted much attention because of its ability to take advantage of being both a biofilm reactor and a sequencing batch reactor ( Wilderer et al., 1993;Ding et al., 2011). The SBBR system shows greater biomass concentration in the reactor, with corresponding higher specific removal rates and less sludge product, greater volumetric loads, increased process stability towards shock loadings and biomass enrichment of slow growing organisms such as nitrifiers ( Wilderer et al., 1993;Arnold et al., 2000;Tan et al., 2013;Li et al., 2015) than competing technologies. ...
... The SBBR system shows greater biomass concentration in the reactor, with corresponding higher specific removal rates and less sludge product, greater volumetric loads, increased process stability towards shock loadings and biomass enrichment of slow growing organisms such as nitrifiers ( Wilderer et al., 1993;Arnold et al., 2000;Tan et al., 2013;Li et al., 2015) than competing technologies. Furthermore, compared to the activated sludge process, simultaneous nitrification-denitrification (SND) can be achieved much more easily in biofilm reactors such as the SBBR (Ding et al., 2011;Tan et al., 2013). During the aeration phase, nitrification occurs on the surface of the biofilm, whereas denitrification occurs in the inner layers due to the inherent dissolved oxygen (DO) gradient within the biofilm ( Matsumoto et al., 2007;Zou et al., 2015). ...
... Protecting the raw carbon source in the influent is critically important to promote the efficiency of SND economically, especially when treating wastewater with low COD/TN ratio. Some studies have been conducted for SBBR to investigate the effects of the COD/TN ratio on nutrient removal (Ding et al., 2011;Jin et al., 2012;Tan et al., 2013;. However, enhancing the SND in raw domestic wastewater treatment via upgrading the structure and oper- ational process of the SBBR is rarely reported. ...
Article
Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen (COD/TN) ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor (NSBBR) was developed to enhance the nitrogen removal from wastewater with low COD/TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration were performed in the two units, which created an anoxic unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR (CSBBR) operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios (9.0, 4.8 and 2.5). In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low COD/TN ratios (4.8 and 2.5). Furthermore, it is easy to upgrade the CSBBR into an NSBBR in practice.
... The SBR systems have many advantages such as lower operational cost, less bulking and higher flexibility to combine nitrification and denitrification phases into one reactor and subsequently into a small treatment plant [8]. This process has a good performance for nitrogen, phosphorus and COD removal [9]. Since nutrient removal in a SBR takes place through alternating anaerobic and anoxic/aerobic periods, nitrification, denitrification and phosphorous removal, all happens during the reaction period of SBR within on/off cycles of air/mixers [9]. ...
... This process has a good performance for nitrogen, phosphorus and COD removal [9]. Since nutrient removal in a SBR takes place through alternating anaerobic and anoxic/aerobic periods, nitrification, denitrification and phosphorous removal, all happens during the reaction period of SBR within on/off cycles of air/mixers [9]. ...
Article
Full-text available
Simultaneous nitrogen, phosphorous and COD removal in a pilot-scale enhanced Sequencing Batch Reactor (eSBR) was investigated. The reactor consisted of a pre-anoxic zone and internal recycle and was fed with synthetic wastewater. The study was performed by operating the reactor in 6-hour cycles in three different operational modes during a time frame of 279 days. Under the best operational conditions, the average removal rate of COD, TN, and TP were obtained as 93.52, 88.31, and 97.56%, respectively. A significant denitrifying phosphorus removal (more than 80%) occurred at run1 and 3 which started the cycle under anoxic condition.
... The one-stage autotrophic nitrogen removal process has been used for sequencing batch biofilm reactor (SBBR) systems, which have attracted considerable attention for their ability to simultaneously utilise a biofilm reactor and a sequencing batch reactor (SBR) [10][11][12][13]. Compared with SBR systems, SBBRs show higher biomass concentration and removal efficiencies, greater volumetric loads and more stability towards shock loadings [14,15]. ...
... To identify the species of microorganisms in SBBR, PCR-DGGE was conducted to analyse biofilm and activated sludge ( All of the sequences were identified in GenBank, with high homology ranging from 92% to 100% ( M a n u s c r i p t 13 in biological nitrogen removal systems [30][31][32]. ...
Article
Full-text available
Abstract Wastewater with C/N ratios ranging from 1.00 to 0.33 caused by gradual increase in influent NH4(+)-N concentration was used to evaluate performance of the one-stage nitrogen removal process in a biofilm reactor. The system was operated for 197 days under COD concentration of 250 mg L(-1) and influent NH4(+)-N concentrations ranging from 250 mg L(-1) to 750 mg L(-1). The effects of C/N ratio and DO on nitrogen removal were evaluated at different influent C/N ratios and DO concentrations, respectively. The microbial composition of the system was examined by SEM and PCR-DGGE, and the relative contribution of ANAMMOX to nitrogen removal was assessed by calculating the average rates of ANAMMOX and denitrification in batch experiments. Results showed that the removal efficiencies of TN, NH4(+)-N and COD were 74% to 97%, 75% to 99% and 64% to 97%, respectively. C/N ratio had significant influence on nitrogen removal efficiency when it was decreased from 1.00 to 0.70, but no significant change was observed when it was reduced from 0.70 to 0.33. DO also correlated with NH4(+)-N concentration in the influent, and 3.0 mg L(-1) was found to be a suitable concentration for influent NH4(+)-N concentration of 450±5 mg L(-1). Analysis of microbial composition of the system revealed that biofilm and activated sludge were mainly composed of aerobic ammonium oxidising bacteria, anaerobic ammonium oxidation bacteria (AnAOB) and denitrifying bacteria. Activity tests suggested that AnAOB played an important role in the one-stage autotrophic nitrogen removal process, contributing about 52.7% of total TN removal via ANAMMOX.
... Atıksuyun C/N oranının azot giderimine etkisi birlikte nitrifikasyon denitrifikasyona dayalı ardışık kesikli reaktör [7,10], ardışık kesikli biyofilm reaktör [11], biyolojik havalandırmalı filtre [12], akışkan yataklı reaktör [13] gibi biyoreaktörlerde çalışılmıştır. Ardışık kesikli reaktör, bir tank içerisinde KOİ, azot ve fosforun birlikte gideriminde iyi bir performansa sahip olduğundan dolayı oldukça dikkat çeken bir prosestir. ...
... Ardışık kesikli reaktör, bir tank içerisinde KOİ, azot ve fosforun birlikte gideriminde iyi bir performansa sahip olduğundan dolayı oldukça dikkat çeken bir prosestir. Son yıllarda ise, ardışık kesikli biyofilm reaktör hem biyofilm hem de ardışık kesikli reaktörün avantajlarını bir araya getirdiğinden dolayı cazip bir proses haline gelmiştir [11]. ...
Article
In this study, the effect of different carbon to nitrogen (C/N) ratios (5, 10 and 15) on simultaneous nitrification and denitrification (SND) in sequencing batch reactor (SBR) and sequencing batch biofilm reactor (SBBR) was compared. The COD removal efficiencies in both reactor were above 90 % suggesting that it was irrespective of C/N ratios. The C/N ratios has little effect on NH4+-N removal, while they had greater effect on the removal of TN. The TN removal efficiency and simultaneous nitrification denitrification efficiency in both reactors increased with increases in C/N ratios. The simultaneous nitrification denitrification efficiency inSBBR is higher than SBR. The results showed that the effect of different carbon to nitrogen (C/N) ratios in both reactors was similar and SBBR had higher nitrogen removal and simultaneous nitrification denitrification
... Sequencing batch reactor (SBR) as compared to traditional or conventional treatments is an easily obtainable, on timescale, highly operational, flexible technology for newer and varied pollutants (Popple et al. 2016;Dutta and Sarkar 2015); Kulkarni 2013). The SBR systems have many advantages such as lower operational cost, less bulking and higher flexibility to combine nitrification and denitrification phases into one reactor (Lim et al. 2011) with good removal efficiency for nitrogen, phosphorus and chemical oxygen demand (Khan et al. 2017;Ding et al. 2011). ...
... Higher levels of COD in wastewater lead to drastic oxygen depletion once discharged into water body and adversely effect the biota. The decrease may be linked to the aeration and digestion processes, which has also been confirmed by Tian et al. (2011), Ghehi et al. (2014), Johal et al. (2014 and Ding et al. (2011) by 90% 94%, 98% and 99%, respectively. Highly significant positive correlation (r = 0.728; P < 0.01) of COD with TSS shows that increase in TSS increases the COD and TSS is composed of both organic and inorganic substances. ...
Article
Full-text available
The present study was carried out to evaluate the performance of 16.1 MLD sewage treatment plant (STP) located at Brari Nambal (J&K), India. The STP is based on sequential batch reactor (SBR) technology. Wastewater (influent and effluent) samples were analyzed for 14 different physicochemical parameters. Significant variation (P < 0.05) was recorded within and among the wastewaters in pH (F11,1 = 7.49, 26), electrical conductivity (F11,1 = 12.13, 49.94), calcium (F11,1 = 8.58, 91.66), magnesium (F11,1 = 4.68, 132.37), chloride (F11,1 = 10.18, 74.85), sodium (F11,1 = 11.31, 192.64), potassium (F11,1 = 5.98, 52.22) and chemical oxygen demand (F11,1 = 4.16, 267.65), whereas among the wastewaters in total suspended solids (F1 = 165.21), total dissolved solids (F1 = 150.40), biological oxygen demand (F1 = 307.89), ortho-phosphate (F1 = 624.54), total phosphorous (F1 = 336.85) and nitrate nitrogen (F1 = 68.10). Significant negative correlation exists between TSS and EC (r = − 0.796; P < 0.01) and Cl and Ca (r = − 0.646; P < 0.05), whereas significant positive correlation between BOD5 and Ca (r = 0.579; P < 0.05), COD and TSS (r = 0.728; P < 0.01) and ortho-phosphate and pH (r = 0.791; P < 0.01). Maximum decrease was recorded in TP (68.37%) followed by NO3-N (64.88%), COD (63.79%), BOD (59.38%), OP (55.94%), TDS (44.82%) and least in TSS (38%) among parameters which are of prime concern. Six principal components (PCs) have been identified by factor analysis which explained 90.30% of total variance, representing alkaline factor, salts/ions factor, household/water usage factor, dissolved salts factor, soaps/detergents factor and catchment factor. Thus, least reduction in concentration of ortho-phosphate, TDS and TSS is concern when the effluent is disposed off in a water body which is already under the stress of nutrient enrichment/pollution.
... Although the removal of TP (less than 60%) was inhibited by the salinity more than 7.5 g/L of NaCl, stable removal efficiency of COD (92%), TN (80%), and NH 4 + -N (82%) could be obtained from 0.0 to 10.0 g/L salt concentration. This SBBR is compared with previous SBBRs in Table 2. Some researchers [14,32,43] investigated the behavior of pollutants removal in an intelligent, controlled SBBR on salt-free condition for municipal wastewater treatment, and high removal efficiency of TP was achieved. Although a stable and persistent partial nitrification was observed in an SBBR when the salinity was gradually increased to 6.5 g/L of NaCl by Zhang et al. [13], the start-up period for Canon process was about 37 days. ...
Article
Full-text available
Differing from municipal wastewater, rural wastewater in salinization areas is characterized with arbitrary discharge and high concentration of salt, COD, nitrogen and phosphorus, which would cause severe deterioration of rivers and lakes. To overcome the limits of traditional biological processes, a spiral fiber based salinity-persistent Sequencing Biofilm Batch Reactor (SBBR) was developed and investigated with synthetic rural wastewater (COD = 500 mg/L, NH4+-N = 50 mg/L, TP = 6 mg/L) under different salinity (0.0–10.0 g/L of NaCl). Results indicated that a quick start-up could be achieved in 15 days, along with sufficient biomass up to 7275 mg/L. During operating period, the removal of COD, NH4+-N, TN was almost not disturbed by salt varying from 0.0 to 10.0 g/L with stable efficiency reaching 92%, 82% and 80%, respectively. Although TP could be removed at high efficiency of 90% in low salinity conditions (from 0.0 to 5.0 g/L of NaCl), it was seriously inhibited due to nitrite accumulation and reduction of Phosphorus Accumulating Organisms (PAOs) after addition of 10.0 g/L of salt. The behavior proposed in this study will provide theoretical foundation and guidance for application of SBBR in saline rural wastewater treatment.
... The former system was able to obtain setting optimizing input values for feedback control system, then the latter one could ensure the stable qualified effluent through precise real-time control of DO concentration, exhibiting the feasibility of intelligent control system for wastewater treat plants (WWTPs). Ding et al. (2011) adopted a novel intelligent control system (ICS) to optimize the operation of conventional sequencing batch biofilm reactor (SBBR) in terms of the aeration process. With regard to the effects on the activity of the microorganisms, three key variables (DO, temperature and intermittent aeration) were selected as controlling factors in this proposed SBBR with ICS. ...
... The functioning of SBBR systems and their pollutant removal efficiency is attracting ever-increasing interest from scientists around the world [21,[33][34][35][36][37][38]. Still, few publications report full technical scale tests of the reliability of these systems during long-term operation. ...
... The effluent of SBR introduced into the SBBR operated under a limited oxygen concentration. SND could be achieved at a dissolved oxygen (DO) concentration of 3-4 mg/l during SBBR process (Zhang et al. 2009) .The researchers reported that the required DO concentration to achieve SND in SBBR is between 0.6 and 2.5 mg/l (Do Canto et al. 2008;Ding et al. 2011;Xiao et al. 2009). The required DO concentration to achieve SND in SBBR was reported between 0.1 and 0.45 mg/l during another study (Hou et al. 2015). ...
Article
Full-text available
A series of reactors including a sequencing batch reactor (SBR) and a sequencing batch biofilm reactor (SBBR) were used for nitrogen removal. The aim of this study was simultaneous removal of NH 4⁺ -N and NO x– -N from synthetic wastewater. In the novel proposed method, the effluent from SBR was sequentially introduced into SBBR, which contained 0.030 m ³ biofilm carriers, so the system operated under a paired sequence of aerobic-anoxic conditions. The effects of different carbon sources and aeration conditions were investigated. A low dissolved oxygen (DO) level in the biofilm depth of the fixed-bed process (SBBR) simulated the anoxic phase conditions. Accordingly, a portion of NH 4⁺ -N that was not converted to NO 3– -N by the SBR process was converted to NO 3– -N in the outer layer of the biofilm in the SBBR process. Further, simultaneous nitrification and denitrification (SND) was achieved in the SBBR where NO 2– -N was converted to N 2 directly, before NO 3– -N conversion (partial nitrification). The level of mixed liquid suspended solids (MLSS) was 2740 mg/l at the start of the experiments. The required carbon source (C: N ratio of 4) was provided by adding an internal carbon source (through step feeding) or ethanol. Firstly, as part of the system (SBR and SBBR), SBR operated at a DO level of 1 mg/l while SBBR operated at a DO concentration of 0.3 mg/l during Run-1. During Run-2, the system operated at the low DO concentration of 0.3 mg/l. When the source of carbon was ethanol, the nitrogen removal rate (R N ) was higher than the operation with an internal carbon source. When the reactors were operated at the same DO concentration of 0.3 mg/l, 99.1 % of the ammonium was removed. The NO 3– -N produced during the aerobic SBR operation of the novel method was removed in SBBR reactor by 8.3 %. The concentrations of NO 3⁻ -N and NO 2– -N in the SBBR effluent were reduced to 2.5 and 5.5 mg/l, respectively. Also, the total nitrogen (TN) removal efficiency was 97.5 % by adding ethanol at the DO level of 0.3 mg/l. When C:N adjustment was carried out SND efficiency at C:N ratio of 6.5 reached to 99 %. The increasing nitrogen loading rate (NLR) to 0.554 kg N/m ³ d decreased SND efficiency to 80.7 %.
... A balanced simultaneous nitrification and denitrification (SND) could prevent lots NO 2 emission because of low accumulation of nitrite. The optimal C/N ratio for SND in SBBR was reported to be 12.5, and no accumulation of nitrite was found (Ding et al. 2011). N 2 O emission increased with the addition of biofilm density in the experiment could be explained as a result of relatively weak SND at low C/D ratio. ...
Article
Full-text available
The reduction of nitrous oxide (N2O) emission during nitrogen removal process in municipal wastewater treatment is of great urgency. Sequencing batch biofilm reactor (SBBR) system could be a promising and efficient way to solve the problem. In order to get the high chemical oxygen demand (COD) and nitrogen removal efficiency and low nitrous oxide emission, the influence of biofilm density on SBBR was investigated. When the biofilm density changed from 15 to 30 %, the effluent COD, total nitrogen (TN) and ammonia nitrogen decreased, but the effluent TN concentration did not meet the class I-B standard of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant in China. COD, TN, and ammonia nitrogen concentration was 42.34, 19.14 and 2.97 mg/L at 50 % biofilm density. When the density turned from 50 to 70 %, although the effluent COD, TN, and ammonia nitrogen were still decreased, N2O emission increased from 0.45 to 0.77 %. Considering the effluent quality and N2O emission, the optimal biofilm density in SBBR was 50 %.
... It is also noticeable that the process of the complete nitrification and denitrification could not be Fig. 4 Microbial activities for the S-sludge and biofilm at different salinities eliminated in terms of the existence of nitrate. The presence of an anoxic microzone in the biofilm could be an explanation for the high SND efficiency (90.1%) attained at this salinity, as microzone was favorable to the development of SND [18]. ...
Article
Full-text available
The effect of increasing salinity on nitrogen removal via simultaneous nitrification and denitrification, microbial activities and extracellular polymeric substances (EPS) were investigated in a hybrid sequencing batch biofilm reactor filled with soft combination carriers. In the influent salinity range from 1.0 to 2.0%, average COD, NH4(+)-N and TN removal efficiencies were higher than 97.1, 97.8 and 86.4% at the steady state. When salinity was increased to 2.5 and 3.0%, ammonium oxidation was obviously inhibited in the reactor. For both suspended sludge (S-sludge) and biofilm, specific ammonium oxidation rate, specific nitrite oxidation rate, specific oxygen uptake rate and dehydrogenase activity reduced with the increase of salinity. The quantity of total EPS increased with the increase of salinity from 1.0 to 2.0%. Generally, humic substances were the dominant composition of EPS in both S-sludge and biofilm, with the percentages of 43.9-54.0 and 43.8-64.6% in total EPS.
... Among others, Ganesh et al. (2014), and Mathioudakis & Aivasidis (2009) studied how nitrogen sources were removed from wastewater, and investigated nitrifying and denitrifying conditions. Simultaneous nitrification and denitrification (SND) is a newly identified biological removal method for nitrogen compounds, and a number of researchers have shown that some processes are capable of SND in reactors (Ding et al. 2011;Vijayalayan et al. 2014). Nitrification takes place in the outer layers and denitrification in the inner layers of biofilms (Ganesh et al. 2014). ...
Article
This study evaluates the removal of nitrogen compounds from wastewater in modified, small diameter gravity slope (SDGS) pipes during its conveyance. A 13-meter long, closed loop, wastewater collection network was designed and built at laboratory scale. The modified SDGS consists of Polyvinyl Chloride (PVC) tubes with perforated plastic netting fixed to the inner surfaces, to enhance biofilm attachment and growth under gravity flow. The system was operated at constant temperature using synthetic wastewater similar to municipal wastewater. The efficiency of ammoniacal nitrogen (NH3-N) removal at initial chemical oxygen demand (COD) concentrations of 340, 570, and 860 mg/L was studied. The NH3-N batch concentrations tested were 4.58, 6.32, and 9.48 mg/L, respectively. The results showed that nitrogen loss under aerobic conditions may have been due to simultaneous nitrification and denitrification, which began to operate when the biofilm was between 2.5 and 5.5 mm thick. A maximum NH3-N removal efficiency of 75% was achieved following 10 hours’ circulation period, at a COD concentration of 570 mg/L.
... The functioning of SBBR systems and their pollutant removal efficiency is attracting ever-increasing interest from scientists around the world [21,[33][34][35][36][37][38]. Still, few publications report full technical scale tests of the reliability of these systems during long-term operation. ...
Article
The aim of this work was to determine the technological reliability of pollutions removal in different seasons in one-stage constructed wetland system with horizontal flow operating in the conditions of moderate climate. In the above-mentioned system, willow (Salix Viminalis L.) was planted and the average flow of domestic sewage were 1.2 m³/d. The analyzed system is located in south-eastern Poland, where the climate is moderate transitional. The tests were carried out during the 14-year exploitation of the wastewater treatment plant (1997–2010). During this period, sewage samples were collected in 4 seasons (winter – February, spring – may, summer – August and autumn – November) to be analyzed. The average long-term air temperatures in these months were respectively: −1.8; 13.8; 18.3 and 3.5 °C. Altogether 56 series of analyzes were carried out during the research and 112 samples of the sewage, both from the inflow and the outflow of the wastewater treatment plant, were collected. The measured parameters were: BOD5, COD, total nitrogen, total phosphorus. On the grounds of the reliability analysis performed on the basis of the Weibull probability model, it was found that the reliability of pollutions removal in the tested constructed wetland system are higher in summer and autumn (August, November) than in winter and in spring (February, May). It was shown that exceedance of the admissible values of pollutant indicators in treated wastewater is dependent on the season (air temperature) and it occurred mainly in the winter period (February). It was proved that the tested CW does not provide effective elimination of biogenic indicators (nitrogen and phosphorus), as evidenced by small values of reliability. To increase the technological reliability of the tested treatment plant, it is proposed to expand the existing system and create a hybrid system consisting of two beds with vertical and horizontal flow and a special P-filter.
... Recently, the sequencing batch bio-film reactor (SBBR) system has attracted a great deal of attention due to its ability to take advantages of both a bio-film reactor and a SBR (Ding et al. 2011). Specifically, SBBR systems show improved biomass concentration in reactors with corresponding higher specific removal efficiencies, greater volumetric loads, increased process stability toward shock loadings, and are capable of covering small areas (Wilderer et al. 1993;Arnold et al. 2000). ...
Article
Full-text available
Water pollution in India is primarily associated with unmanaged urbanization, population explosion, inadequate capacity of sewage treatment, and its disposal, which lead to unhygienic and insanitary conditions. This paper gives an overview on sewage treatment plants (STPs) in Goa—a coastal state in India. Being a famous tourist destination, it is important to monitor and control water pollution levels in Goa state, so as to safeguard the health of tourists and thereby the economy of the region. The capacity-wise distribution of STPs was mapped against regional population distribution and drainage system of Goa using ArcGIS. This information will be very useful for further analysis of the allocation of STPs and its adequacy with regard to the population. A majority of STPs at Goa are managed by private authorities like hotels and resorts. Four municipal plants under Goa Public Works Department were evaluated.
... Therefore, the inner regions of the biological flocs probably did not receive oxygen and transformed to anoxic zones, thus providing favorable conditions for denitrification [49,50]. In such cases, nitrification occurs on the surface of the flocs, whereas denitrification occurs in the internal layers of the flocs due to a dissolved oxygen gradient, therefore simultaneous nitrification and denitrification (SND) take place in the reactor even during aeration [51,52]. Due to sludge concentration was high; part of the total nitrogen removal may be result from a higher nutrient uptake. ...
Article
This study was performed to investigate effect of different concentrations of graphene oxide (GO)nanoplates on fouling mitigation of polyethersulfone (PES) membranes applied in membrane bioreactor(MBR) to treatment milk processing wastewater. The GO was prepared from graphite and characterizedby FTIR, SEM and XRD. The mixed matrix membranes were prepared in three concentrations of 13, 15 and17 wt% of PES polymer. Static contact angle of the membranes were decreased significantly with additionof the GO nanosheets caused to increasing of pure water flux and MWCO. Cross sectional SEM imagesshowed that the finger-like pores for all of the GO embedded membranes were slightly wider than thatof the unfilled PES membrane. Ultrafiltration performance and fouling resistance of the membranes weretested by filtration of activated sludge. With addition of GO nanoplates, fouling resistance ratio (FRR) ofthe nanocomposite membranes was improved. AFM images and FRR results presented that a membranewith smoother surface has greater fouling resistance ability. Based on antifouling and water flux results,the PES/GO membrane with 15 wt% of PES and GO content of 0.5 wt%, was selected as an optimal mem-brane and tested in MBR system. The MBR showed an increased capacity for removal of organic matter,both in terms of COD and BOD5of milk processing wastewater. With increasing of MLSS concentration,flux of the membrane was increased due to a decrease in soluble microbial products and extracellularpolymeric substance from the bacterial cells in the lower food to microorganism ratio (F/M).
... The SEM images of the biofilm show that the microorganisms adhere densely on the carriers which proved that the carrier was good in forming biofilm. Ding et al. [44] found that bacteria adhere densely on the sponge carriers, similarly. A higher biomass concentration resulted in the SBBRs to achieve better performance at removing COD. ...
Article
Full-text available
The operational performance of the sequencing batch reactor (SBR) and sequencing batch biofilm reactor (SBBR) for treating the university campus wastewater was evaluated. The effects of power failure on performance of processes were investigated by comparing chemical oxygen demand (COD) and total suspended solids (TSS) removal, sludge settling properties and microorganism’s morphological properties by using SEM photos. The experiments were carried out at four 2-L reactors made from plexiglas. Three in four reactors were operated as SBBR. SBBRs were filled with the kaldnes biomedia K1 to 40, 50 and 60% of the volume of empty reactor. SBR and SBBRs were operated at 6/24 h cycling periods on a day that consisted of wastewater fill (30 min), reaction (4 h), settling (1 h) and draw (30 min), summed up to 6 h with the hydraulic residence time of 7.5 h. The effect of filling ratio on SBBR performance was also determined. In normal operation, average COD removal rates were calculated as 86, 88.5, 90.6 and 94.2% for SBR, SBBR1, SBBR2 and SBBR3, respectively. Power failure is one of the most encountered problems in the small wastewater treatment plants. Its effect was observed at 1 cycle as short term and 4 cycles as long term. Besides the negative effects of the power failure on COD and TSS removal, it also affects sludge settling properties. While interruption time is increased, recovery took much more time than expected to reach steady state conditions for all the reactors. However, the presence of biofilm restricted the adverse effect of power failure. SEM photos and better effluent quality supported these findings.
... Removal of Chemical Oxygen DemandIn the present study, the highest and lowest COD removal was noted as 68.74% and 34.98% during the months of March and May respectively. The reduction in COD is attributed to aeration and digestion processes, which are confirmed by previous studies showing 99%, 90%, 98% and 94% removal respectively[36][37][38]. As per the report of USEPA, SBR is effective in removal of COD and BOD along with nitrification, denitrification and suspended solids [39]. ...
Article
Full-text available
Treatment of pharmaceutical wastewaters is a challenging task owing to their complexity and pollution load, variability in strength of waste streams accompanied with shock loads. Since no single treatment system is a viable option, integration of existing systems with advanced physical/chemical processes has been gaining attention for treatment of pharmaceutical wastewater. In the present study, two biological treatment methods were evaluated for their efficiency as pre-treatment system for RO which are sequencing batch reactor and membrane bioreactor. Efficiency of biological treatments tested SBR and MBR was pre-sented in terms of percentage removal of physico-chemical parameters. Total dissolved solids removal by SBR was 31.82% while MBR showed 29.25% reduction. Chemical oxygen demand removal by SBR was 69.54% while MBR showed 30.35% removal. Efficiency of combined treatments SBR-RO and MBR-RO was presented in terms of removal of total dissolved solids, COD and ammonia. TDS removal was the highest in the combination of SBR-RO with 95.94% removal, while MBR-RO combination resulted in 87.29% removal. Chemical oxygen demand was achieved maximum with the combination of MBR-RO 92.33% while competitive results were achieved with the combination SBR-RO also with 88.62% removal. Removal of ammonia was maximum with the combination SBR-RO 87.5%, while competitive results were obtained with MBR-RO 85.51%. From the results, it can be understood that SBR was efficient in removing ammonia, total dissolved solids and was equally competent in removing chemical oxygen demand. This study concludes that combined treatment of SBR-RO proves to be promising in treating pharmaceutical wastewaters.
... Greater fluctuations were observed on the denitrification rate than the nitrification rate when the A 2 O was subjected to shock loadings. It was reported that the COD/N ratio of 5-15 in the bioreactor was suitable for nitrification and denitrification reaction (Ding et al., 2011). The deficiency of carbon substrate resulted in the unbalance of nitrification and denitrification reactions and finally led to low overall nitrogen removal. ...
Article
Sudden changes in influent organic carbon (OC) and ammonia nitrogen (AN) concentrations were performed to evaluate the resistance of A²O process against shock loadings. The influent organic loading rate was increased from 11 gCOD/(gMLSS·d) to 48 gCOD/(gMLSS·d) with low OC shocking loading and to 125 g COD/(gMLSS·d) with high OC shock loading. The influent NH4⁺-N was increased from 55 mg/L to 110 mg/L as AN shock loading. The results showed that the augmented OC concentration was beneficial for nitrogen removal and high AN concentration had slight influences on COD removal, but was detrimental to nitrogen removal in the A²O system. The performance of the A²O system restored rapidly from the shock loadings once the normal influent conditions were provided. The loosely bound extracellular polymeric substances (LB-EPS) and total extracellular polymeric substances (EPS) increased at the initial stage of shock loadings and then declined with the prolonged shock loading, whereas the tightly bound EPS (TB-EPS) experienced smaller variations. The SVI value varied in a similar trend with LB-EPS and total EPS and their low values indicated a good settleability of the activated sludge. In conclusion, the A²O process produced high-quality effluents once the shock loading ceased.
... In addition, SBBRs have been combined with other mechanisms for higher effectiveness. For example, the use of an intelligent controlling system (ICS) in a SBBR was studied by Ding et al. (2011). It turns out that the use of this ICS provides 99% ammonia removal, 100% total phosphorus removal, and 96% COD removal. ...
Article
Extensive growth of industries leads to uncontrolled ammonia releases to environment. This can result in significant degradation of the aquatic ecology as well as significant health concerns for humans. Knowing the mechanism of ammonia elimination is the simplest approach to comprehending it. Ammonia has been commonly converted to less hazardous substances either in the form of nitrate or nitrogen gas. Ammonia has been converted into nitrite by ammonia-oxidizing bacteria and further reduced to nitrate by nitrite-oxidizing bacteria in aerobic conditions. Denitrification takes place in an anoxic phase and nitrate is converted into nitrogen gas. It is challenging to remove ammonia by employing technologies that do not incur particularly high costs. Thus, this review paper is focused on biofilm reactors that utilize the nitrification process. Many research publications and patents on biofilm wastewater treatment have been published. However, only a tiny percentage of these projects are for full-scale applications, and the majority of the work was completed within the last few decades. The physicochemical approaches such as ammonia adsorption, coagulation-flocculation, and membrane separation, as well as conventional biological treatments including activated sludge, microalgae, and bacteria biofilm, are briefly addressed in this review paper. The effectiveness of biofilm reactors in removing ammonia was compared, and the microbes that effectively remove ammonia were thoroughly discussed. Overall, biofilm reactors can remove up to 99.7% ammonia from streams with a concentration in range of 16–900 mg/L. As many challenges were identified for ammonia removal using biofilm at a commercial scale, this study offers future perspectives on how to address the most pressing biofilm issues. This review may also improve our understanding of biofilm technologies for the removal of ammonia as well as polishing unit in wastewater treatment plants for the water reuse and recycling, supporting the circular economy concept.
... As the compounds which in the liquid phase in the reactor were gradually consumed, the desorption process began, providing substrates for microbial growth and metabolism. Therefore, SBBR can use internal equalization to control fluctuations in biomass load and provides a stable living environment for microorganisms maintain the biological activity of microorganisms (Gieseke et al. 2002;Ding et al. 2011;Jin et al. 2012;Wilderer and McSwain 2004). ...
Article
Anaerobic-oxic (AO) systems have been extensively adopted for the biological treatment of wastewater from recycled paper mills, which is characterized by high chemical oxygen demand (COD) concentrations and contains hundreds of organic compounds. In this study, an up-flow anaerobic sludge blanket (UASB) served as the anaerobic treatment of recycled paper mill wastewater. Then, either a sequential batch reactor (SBR) or a sequential batch biofilm reactor (SBBR) were adopted as aerobic treatment to treat the UASB effluent respectively. Parameters such as COD, BOD5, and TSS were measured to compare the treatment performance of SBR and the SBBR. After 80 days’ operation, COD removal efficiency of SBR and SBBR were 21.79 ± 3.4% and 38.38 ± 2.69% respectively; TSS removal efficiencies were 20.84 ± 5.15% and 47.02 ± 5.84% respectively. The results indicated that SBR was effective for removing residual organic matter in UASB effluent. However, SBBR showed significant advantages for the removal of COD and total suspended solids (TSS), which are ascribed to the effective biomass retention and biofiltration of SBBR.
... Compared to traditional treatments, SBRs are characterized by highly operational, flexible technology for various pollutants. They have the advantages of lower operational cost, less bulking, high removal efficiency for nitrogen, phosphorus, and chemical oxygen demand (Ding et al., 2011;Dutta and Sarkar, 2015;Khan et al., 2017;Kulkarni, 2013;Showkat and Najar, 2019). ...
Article
Given that water scarcity is a big issue nowadays, wastewater treatment is necessary for the future water use and the prevention of environmental contamination. In this context, this study presents the results of the statistical analysis of ten water parameters before and after the water cleaning in a wastewater treatment plant (WWTP). The influent biodegradability is assessed by computing the BOD5/COD ratio. New momentary and global efficiency indices are introduced for the evaluation of the pollutants' removal efficiency. Five classes of efficiencies (excellent, good, fair, marginal, and poor) are also proposed for the evaluation of WWTP's performances. The study shows that the WWTP's efficiency is good - when working with six water parameters – and marginal - when working with ten parameters. Small efficiencies of nitrates, total dissolved solids, and chlorine removal are noticed. Statistical distributions of ten water parameters in the influent and effluent are fitted and tested by the Kolmogorov-Smirnov and Chi-squared tests. They are used for computing the probability of exceeding the admissible limits of water parameters in the effluent, which can be used as a warning tool for improving the WWTP's performance.
... The measured NO 3 concentrations in the initial stage were 112 ± 10, 166 ± 10 and 218 ± 10 mg/L. In this lab-scale experimental investigation, an attempt has been made to explore the performance of SBBR technology for simultaneous removal of COD, NH 4 , NO 3 and PO 4 from SWW under 3 levels of the Design of Experiments (DoE) combination of reacting periods (oxic/anoxic) (Ding et al., 2011). In order to describe the reduction patterns of COD a quadratic polynomial model was used with estimated coefficients as described elsewhere (Ismail et al., 2018). ...
Article
Full-text available
Slaughterhouse wastewater (SWW) contains a significant volume of highly polluted organic wastes. These include blood, fat, soluble proteins, colloidal particles, suspended materials, meat particles, and intestinal undigested food that consists of higher concentrations of organics such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrogen and phosphorus hence an efficient treatment is required before discharging into the water bodies. The effluent concentrations and performance of simultaneous sequential batch biofilm reactor (SBBR) with recycled plastic carrier media support are better than the local single-stage sequential batch reactor (SBR), which is lacking in the literature in terms of COD, NH3, NO3, and PO4 treatment efficiency. The present study reports a novel strategy to remove the above mentioned contaminants using an intermittently aerated SBBR with recycled plastic carrier media support along with simultaneous nitrification and denitrification. The central composite design was evaluated to optimize the treatment performance of seven different process variables including; different alternating conditions (Oxic/anoxic) for aeration cycles (3/2 h in a 6 h cycle, 6/5 h in a 12 h cycle and 9/8 h in an 18 h cycle) and hydraulic retention time (6, 12 and 18 h). The average removal efficiencies are 94.5% for NH3, 93% for NO3 and 90.1% for PO4, and 99% for COD. The study reveals that the denitrification in the post-anoxic phase was more efficient than the pre-anoxic phase for pollutant removal and maintaining higher quality effluent. The effluent concentrations and performance of simultaneous SBBR with recycled polyethylene carrier support media were better than local SBR system in terms of COD, NH3, NO3 and PO4 treatment efficiency. Results stipulated the suitability of SBBR for wastewater treatment and reusability as a sustainable approach for wastewater management under optimum conditions.
... There can be listed numerous papers on the effi ciency of activated sludge wastewater treatment plants in the world [Di Trapani et al. 2011, Ding et al. 2011, Mansouri and Zinatizadeh 2017, Marques et al. 2008, Podedworna et al. 2016]. However, the issue of the reliability of the system is still not commonly developed and there is not much research carried out on it [Marzec 2017, Jucherski et al. 2019. ...
Article
Full-text available
The aim of the work was to analyze the efficiency and reliability of pollutants removal (total suspended solids – TSS, BOD5, COD) in a collective wastewater treatment plant with activated sludge and hydroponic lagoon during its long term operation. The tested object was designed to treat wastewater inflowing through the sewerage system and wastewater delivered by the septic truck. The projected capacity of the treatment plant was 1200 m3∙d-1. The technological system for wastewater treatment consisted of a mechanical part, a flowing biological reactor working according to the BARDENPHO process, a secondary settling tank and a hydroponic lagoon. The efficiency and reliability of pollutants removal in the analyzed treatment plant were assessed on the basis of the data concerning influent and effluent wastewater collected during the years 2011–2018. On the basis of the measurements results, there were determined characteristic values of the selected pollution indicators in wastewater and the average efficiency of pollutants removal. The technological reliability of the wastewater treatment plant was assessed for the basic pollution parameters (BOD5, COD, TSS) in accordance with the elements of the Weibull’s reliability theory, with regard to normative values of the indicators specified in the Regulation of the Minister of Environment. The analysis was carried out using the Statistica 13.1 software. It was proved that in the wastewater treatment plant with an activated sludge and hydroponic lagoon the level of organic pollutants removal expressed by BOD5 was on average 99.5%, COD – 98.1% and TSS – 99.4%. The technological reliability of the system was 100% in terms of the removal of pollutants from the basic group, which means that during the long term operation (8 years) it provided failure-free operation and guaranteed the fulfillment of the requirements that can be found in the Polish law regulations concerning the analyzed pollutants.
... Nevertheless, other factors as the COD/N ratio and the metabolisms involved in nitrogen transformation could change this optimal value. COD/N ratio of 9.0-12.5 were related to higher nitrogen removal efficiencies (76.8-98%) for SND process [26][27][28]. In the present study, the COD/N ratio was 8.2. ...
Article
The Structured Bed Reactor with Recirculation and Intermittent Aeration (SBRRIA) is a reactor configuration that presents high efficiency of organic matter and nitrogen removal, besides low sludge production. However, operational parameters, as the recirculation rate, aeration time, and airflow, are not fully established. A bench-scale structured bed reactor with intermittent aeration was fed with synthetic effluent simulating the characteristics of sanitary sewage. The reactor was operated for 280 days with an operational hydraulic retention time (HRT) of 10 h. The reactor was operated without effluent recirculation for the first time since this approach was not yet reported, and was named Structured Bed Reactor with Intermittent Aeration (SBRIA). The COD removal was higher than 81% for all operational conditions, and the total nitrogen removal ranged from 10 to 80%. The highest efficiencies were obtained with an aeration time of 1 h 45 min (total cycle of 3 h) and an airflow rate of 4.5 L.min⁻¹. Different nitrification and denitrification behaviors were observed, resulting in nitrification efficiencies over 90% when the reactor was submitted to higher aeration times and denitrification efficiencies above 90% when the reactor was submitted to low aeration times. The airflow ranges tested in this study affected the nitrification and the total nitrogen efficiencies. Even without effluent recirculation, the temporal profile showed that there were no peaks in the concentration of the nitrogen forms in the reactor effluent, saving electrical energy up to 75% due to pumping.
... And the shape of pellets was naturally spherical, smooth and elastic. To obtain immobilized microbial activated pellets whose particle size 5.0 mm, it was placed at 6-8℃ in the freezer for the cross-linking for 0, 8 The optimization conditions are set as follows using one-variable-at-a-time approach, various immobilization parameters were optimized by maintaining all factors at a constant level, except the variable under study. To determine the optimum addition amount of PVA, various concentrations of 0%, 2%, 3%, 4% and 5% (w/v) were added to prepare the pellets, respectively, when the amount of SA is fixed at 2%. ...
... Deng et al. (2016) indicated that biocarrier systems facilitate better organic compound removal than conventional bioreactor systems. Dahu et al. (2011) studied sewage wastewater treatment using a sequencing batch biofilm reactor (SBBR). This resulted in a nitrification and denitrification efficiency of 98.0%, although this level of efficiency did not exist for the nitrate (NO 3 − -N) and nitrite (NO 2 − -N) conversion processes. ...
Article
Landfill leachate contains many pollutants that have a negative effect on the environment when improperly discharged. Thus the treatment of landfill leachate is a crucial issue, especially in the bigger cities in developing countries. In this study, landfill leachate is treated using a continuous flow sequencing biofilm batch reactor (CF-SBBR) with different biocarriers (non-carrier (NC), kaldness K1 (K1), mutag biochip 30TM (MB), and sponge polyurethane (SP)). The results show that the best COD, TOC, and NH4⁺-N removal efficiencies were 79.6 ± 0.8%, 78.1 ± 1.9% and 77.5 ± 3.9% in the MB biocarriers tank with an aeration/mixing ratio of 1.3, a cycle time of 9 h and an organic loading rate (OLR) of 1.74 kgCOD/m³.d. The TN removal efficiencies was decreased when there was an increase in the biocarrier’s surface area (NC > K1 > MB > SP). At the highest it was 46.1 ± 6.4%, where the aeration/mixing ratio was 1.3, the cycle time was 9 h, and the OLR was 1.52 kgCOD/m³.d. The higher the surface area of the biocarriers, the greater the anti-shock organic loading capacity of the biocarriers due to the formation of biofilm layers. The microbial communities in the CF-SBBR tanks were abundant with common phylum bacteria as in a conventional activated sludge system. Anammox candidatus bacteria was found to total 0.5%. This study concluded that CF-SBBR is an efficient method to treat landfill leachate.
... In the other cycles, which had shorter aeration times, a competition for oxygen was initiated, damaging the conversion of nitrogen. The good nitrogen removal rates in the experiments, and the balance between the reactions (even if the COD/N ratio was high) occurred because there was no deficit in the supply of the carbon source for nitrogen removal by the SND process [38][39][40]. ...
Article
Full-text available
Abstract This study evaluated an intermittently aerated, fixed-bed, single-batch reactor, with mini BioBob© as biofilm media support, as an alternative treatment of craft brewery wastewater. In order to remove chemical oxygen demand (COD) and total nitrogen (TN), seven conditions were performed in a central composite experimental design (CCD) with different aeration times (1, 2 and 3 h in a 4 h cycle) and hydraulic retention times (HRT) (12, 16 and 20 h). The results showed that the removal of COD and TN were positively affected by increased aeration time and HRT. The condition that presented the best quality effluent was Condition No. 1 (20 h HRT and 3 h aeration), with 209 ± 28 mg COD L-1; 3.00 ± 0.15 mg TKN L-1 ; and 0.67 ± 0.11 mg NO3-N L-1. Kinetic assays showed that the highest values for the substrate removal rate constant, kCOD = 0.1774 h-1 were obtained with the longest aeration time (3 h). The most probable number (MPN) test showed a higher concentration of denitrifying bacteria (heterotrophic), 3.3 x 106, than for AOB and NOB bacteria (autotrophic), which were 4.9 x 103 and 2.7 x 103, respectively. Moreover, it was possible to verify that correcting the influent alkalinity with 7.14 mg CaCO3 for each 1 mg of TKN resulted in better process efficiency. It was concluded that COD and TN can be removed from craft brewery wastewater using an intermittently aerated, fixed-bed, single-batch reactor with mini Biobob© as biofilm media support.
Conference Paper
KEYWORD: sequencing batch biofilm reactor (SBBR); aeration amount; simultaneous nitrification and denitrification (SND) ABSTRACT: A pilot scale sequencing batch biofilm reactor (SBBR) for treating wastewater was used for the purpose of investigating treatment performance under different aeration flows(10m3/h 、 12m3/h、14m3/h、16m3/h、18m3/h、20m3/h、22m3/h、24m3/h),by analyzing the changeable concentration of COD、NH4+-N、NH3--N NH2--N and TN both influent and effluent. To find the optimum condition of aeration, provide a reference for practical engineering application. The exper- imental results showed that, the amount of aeration have less effect on COD removal efficiency but on nitrogen removal. The SBBR could achieve a higher degree of SND, and TN removal could maintain around 62% , the quality of effluent meet level 1B standard of 《Discharge standard of pollutants for municipal wastewater treatment plant 》When the aeration flow was controlled the range of 16~18mg/L.
Article
Two kinds of materials, filamentous bamboo and hollow plastic ball, were employed as biofilm carrier for bioremediation of river water with micro-contamination. The experiments were carried out in sequencing batch bioreactor (SBBR) with (19.0±1.5)°C, and dissolved oxygen (DO)≥4.5 mg/L to compare the two materials for potassium permanganate index (CODMn), total nitrogen (TN) and total phosphor (TP) removal. Experimental results demonstrate that CODMn and TN removal rates reached at 17.5%~48.8% and 49.38%~70.93%, respectively based on the biofilm on filamentous bamboo, and TP removal rate was little; while CODMn removal rate was only 2.4%~42% based on the biofilm on hollow plastic ball, and both TN and TP removal were little. By means of microscopic examination, microbial quantities and series on filamentous bamboo were found to be more than that on hollow plastic ball.
Article
Full-text available
An innovative hybrid process was designed using an integrated bio-reactor based on an anoxic / aerobic process that combined a fixed bed and a fluidized-moving bed with a constructed wetland (A/OFMCW) to enhance the removal of organic material and nitrogen. The goal was to achieve stringent discharge standards for rural domestic wastewater treatment. A preliminary lab-scale investigation of about 130 days obtained an average COD (Chemical Oxygen Demand) removal rate as high as 92.2% at an average influent concentration of 319.5 mg/L. The average TN (Total Nitrogen) removal efficiency positively correlated with the attached-growth biofilm as observed by SEM (Scanning Electron Microscope), and declined from 79.1% to 53.2%. The was accompanied by a gradual increase in the average influent concentration from 16.73 to 52.01 mg/L despite the relative nitrification rate fluctuating between 92.5% and 97.9%. The entire integrated system improved the COD removal efficiency by nearly 36% and the TN by 14–28%. Classical autotrophic nitrification and heterotrophic denitrification were the main mechanisms responsible for the elimination of pollutants, and the latter was determined to be the limiting step. Overall, this study provides an effective and less expensive alternative method to apply or upgrade DWWT (Decentralized Wastewater Treatment).
Chapter
Full-text available
Since the 21st century, the use of artificial intelligence (AI) has accelerated data driven innovations that are adaptable and undoubtedly efficient in today’s digital world. This technology complements human intelligence by creating the enabling environment that delivers the will power to handle environmental issues such as water pollution. Polluted water can cause life-threatening diseases such as cholera, dysentery and diarrhoea, hence, the need to harness data from water sources for use in developing useful algorithms that can accurately predict the influx of pollutants in waters. The recent application of High-Performance Data Centric Systems (HPDCS)/AI in water pollution control, has resulted in apt human-machine based expedient solutions that help to harness the potentials offered by these technologies in tackling issues that compromise water standards and thus improve the quality of aquatic life and human existence. In oceanography, machine learning is being exploited as a way of monitoring marine litters via feedback-enabled algorithms. Considering the prospects underlying life sciences (robotics, machine learning, drones and internet of things), these tools can help monitor and understand the origin, physical chemistry and nature of water pollutants/stressors. In the proposed chapter, topics to be covered include: deep and machine learning applications in water quality management, modelling and prediction of surface/groundwater contamination, rainwater quality prediction using data-centric and intelligent systems, deep learning and machine learning strategies in contaminant hydrology, deep/machine learning methods in emerging contaminants and micro-pollutants research, and a review of recent advances and applications of data-centric systems in water pollution monitoring, assessment and control. Keywords: Artificial Intelligence; Data-centric systems; Feedback enabled-algorithms; Machine Learning Technology; Predictive Modelling; Wastewater Management
Article
Atenolol, a widely used drug with an aromatic structure and amino groups, is one of the resistant compounds to biological degradation. In this study, the sequencing batch biofilm reactor (SBBR) was used for the biodegradation of atenolol and removing its nitrogenous compounds. Under optimal operating conditions, SBBR removed atenolol and its associated COD and total nitrogen by 93%, 87%, and 92%, respectively. SBBR has a higher ability in biodegradation, mineralization, and simultaneous removal of nitrogen compounds from atenolol than the previously studied processes. For the first time in this study, Hydrogenophaga palleronii, Corynebacterium sp., Staphylococcus hominis strain EFS, and Microbacterium paraoxydans in biofilm and Bacillus aquimaris, Hydrogenophaga palleronii, and Hydrogenophaga palleronii strain MC11 in biomass were identified as atenolol-biodegrading bacteria. Phenol, 5-methyl-2-(1-methylethyl), 2-Hexen-4-ol,5-methyl-, Docosane, Tricosane, Eicosane, (2 -ethylhexyl) phthalate, and Squalene were identified as the main intermediates resulting from the biodegradation of atenolol under optimal operating conditions by GC–MS.
Article
A sequencing batch biofilm reactor (SBBR) was operated at different salinities with focus on reactor performance and nitrogen removal by simultaneous nitrification and denitrification (SND). The SBBR contained suspended-growth sludge and biofilm attached to synthetic fibrous carriers. When salinity increased from 1.4 to 4.2 g NaCl/L, it increased the -N and total nitrogen removal efficiencies, the nitrification rate (NR), and denitrification rate (DNR). A slight drop in nitrogen removal, NR, and DNR was observed, when the salinity was increased from 4.2 to 9.8 g NaCl/L. Efficient SND occurred in the reactor and the SND efficiency was above 90.7%. Nitrification was the main contribution of the suspended sludge, while the major role of biofilm was denitrification in the SBBR at the salinity of 9.8 g NaCl/L.
Article
Full-text available
This research investigated the effect of changing media filling rates, various cycles duration in the SBR process and changing the organic loading rates on the removal of organic and nutrients from a medium strength synthetic wastewater (COD 420 mg/l.). A laboratory-scale bioreactor has been fabricated and installed in Imyay W.W.T.P. The experiment was performed at three phases; the first phase was to investigate the effects of changing the media filling rates, the second phase was to study the effects at various cycles duration and the third phase was to investigate the treatment efficiency at different organic loading rates. The solid retention time (SRT) was 11 days and flow rate of (1.70 L/Hr.). Complete cycle duration was 12 hours and MLVSS was adapted to be 1200 mg/l by letting the excess sludge to be removed from the reactor. The biological oxygen demand (BOD) removal was 91.2, 93.6 and 94.0% for media filling rate of 0, 50 and 25% respectively. Also, the removal rates for the same test was 94.0, 93.5 and 92.2% for aeration-settling cycle duration (8-2), (7-3) and (6-4) hours respectively. Finally, the removal rates at this test was 94.0 and 95.6% for OLR of 0.84 and 1.44 (Kg COD/m3.day). The chemical oxygen demand (COD) removal was 89.1, 91.7 and 92.7% for media filling rate of 0, 50 and 25% respectively. Also, the removal rates for the same test was 92.7, 91.7 and 90.6% for aeration-settling cycle duration (8-2), (7-3) and (6-4) hours respectively. Finally, the removal rates at this test was 92.7 and 94.8% for OLR of 0.84 and 1.44 (Kg COD/m3.day). Total nitrogen (TN) removal was 39.2, 50.9 and 53.2% for media filling rate of 0, 50 and 25% respectively. Also, the removal rates for the same test was 53.2, 55.5 and 57.5% for aeration-settling cycle duration (8-2), (7-3) and (6-4) hours respectively. Finally, the removal rates at this test was 53.2 and 49.5% for OLR of 0.84 and 1.44 (Kg COD/m3.day). Total phosphorus (TP) removal was 63.5, 71.8 and 72.3% for media filling rate of 0, 50 and 25% respectively. Also, the removal rates for the same test was 72.3, 73.3 and 76.4% for aeration-settling cycle duration (8-2), (7-3) and (6-4) hours respectively. Finally, the removal rates at this test was 72.3 and 83.4% for OLR of 0.84 and 1.44 (Kg COD/m3.day).
Article
In this study, a synthetic nanocomposite ultrafiltration membrane (prepared by blending polyvinylidene fluoride (PVDF) and hydrophilic O-carboxymethyl chitosan modified Fe3O4 (OCMCS-Fe3O4) nanoparticle) was applied in a bioreactor to treat milk processing wastewater (MPW). Experiments were carried out with two independent operating variables, mixed liquor suspended solids (MLSS) and hydraulic retention time (HRT). The region of exploration for the variables was taken as the area enclosed by MLSS (6000–14,000 mg/L) and HRT (8–44 h) boundaries. Throughout the experiments, high COD removal efficiency (92–99%) was obtained. The MLSS had an increasing impact on the removal efficiency of nitrogen, total phosphorous (TP), and flux. HRT also showed an increasing effect on the removal efficiency of nitrogen and flux while had a reverse impact on the TP removal efficiency. The optimal membrane performance was compared to commercial microfiltration (MF) membrane and the results showed that the blended membrane with modified nanoparticles leads to a high flux ultrafiltration membrane comparable with microfiltration while remaining its separation properties as much as UF membrane.
Conference Paper
Water is an exhaustible worldwide common resource and the future of all humankind depends on availability of this unique source of life for all ecosystems. Due to the continuous growth of the world population, development of agriculture and industry in the emerging countries as well as climate change, the insufficiency of water has become in the past few years an increasingly important issue. In this context, it was necessary the orientation of the community towards an eco–sustainable lifestyle and techniques to conserve and reuse development, especially reusing of treated water. This study analyses the result of a combined air-ozone aeration and ultrafiltration with PP hollow fibre membrane MBR in a domestic WWTP for 2 years, for the purpose of effluent reuse for irrigation. It was examined the efficiency of the pollutants degradation by analysing the parameters concentration of the usual contained organic compounds in effluents: chemical oxygen demand (COD), ammonia, nitrites, nitrates, surfactants, which have been 15-20% extra degraded using mixed aeration. COD value decrease in the integrated air-ozone aeration process up to 90% compared to only 75% that occurs in a conventional biological activated sludge process. Further membrane MBR ultrafiltration entailed a values reduction from another 10 -15%.
Article
In this paper, for the first time, sodium alginate gel spheres prepared by N, N-methylene bisacrylamide cross-linking method were used as immobilized microorganism carriers. And they were combined with sequencing batch biofilm reactor to obtain sodium alginate -SBBR, used to treat simulated urban domestic sewage. After 52 days of start-up, the removal rate of chemical oxygen demand and ammonia nitrogen could reach 87% and 97%, respectively. The abundance of denitrifying bacteria and anaerobic bacteria on sodium alginate gel particles increased, including Dokdonella and Aridibacter, whose abundances were 11.12% and 15.20%, respectively. It proved that the carrier provided a partial hypoxic and anaerobic environment for microorganisms. When dissolved oxygen concentration was 2.5 mg/L, the average removal rates of oxygen demand and ammonia nitrogen were both above 88%. Under three modes, the average removal rates of total nitrogen were 70.98%, 80.04%, 72.38%, respectively. Dissolved oxygen concentrations were both uneven in a single particle and entire reactor, which was conducive to the occurrence of SND.
Article
Moving-bed biofilm reactor (MBBR) and integrated floating-film activated sludge (IFFAS) are considered as well-established technologies for simultaneous nitrification and denitrification (SND). However, SND biofilm formation and nutrient removal performance are generally limited by the innate physico-chemical properties of conventional suspended carriers and/or insufficient carbon source available for denitrification. In this study, novel surface-modified carriers were developed via introducing mixed functional materials (natural zeolite, cationic polyquaternium-10, insoluble biodegradable organic polybutylene succinate/bamboo powder) into polyethylene. The modified carrier revealed enhanced hydrophilicity, positive surface charge, higher surface free energy and carbon source slow release capacity. Biofilm growth feature showed that the surface-modification resulted in more biofilm formation and more polysaccharide and protein in extracellular polymeric substances (EPS), which was structural and functional beneficial for substrate capture, transfer and intercellular interactions between nitrifiers and denitrifiers. IFFAS reactor filled with novel modified carriers was upgraded by dividing into two vertical units, where alternate feeding and aeration was conducted to create an anoxic unit to enhance the utilization of influent carbon source for denitrification as well as an aerobic unit to strengthen nitrification. The two-units IFFAS reactor exhibited highly efficient SND performance with TN removal efficiency of 59.9-65.9%, increased by 12.3-13.5% compared with control group. This study proposed an approach towards enhancement of functional biofilm formation and SND performance, and had fascinating potential in actual applications.
Article
Full-text available
Optimized methods for simultaneous removal of nitrate, nitrite and ammonium are important features of nutrient removal. Nitrogen removal efficiency in an intermittently aerated sequencing batch reactor (IA-SBR) with multiple filling events was studied. No external carbon source was added and three filling events were considered. Oxidationreduction potential (ORP) and pH curve at solids retention time (SRT) of 20 d were analyzed. Effects of three organic loading rates (OLR), 0.67, 1.0 and 1.5 kgCOD/m
In this study, strain CC76, identified as Enterobacter sp., was tested for the reduction of Fe³⁺ and denitrification using immobilized pellets with strain CC76 as experimental group (IP) and immobilized pellets with strain CC76 and magnetite powder as experimental group (IPM) in the autotrophic denitrification immobilized systems (ADIS). Compared with IP, a higher nitrate removal rate was obtained with IPM by using three levels of influent Fe³⁺ (0, 5, and 10 mg/L), four levels of pH (5.0, 6.0, 7.0, and 8.0), and three levels of hydraulic retention time (HRT) (12, 14, and 16 h), respectively. Furthermore, response surface methodology (RSM) analysis demonstrated that the optimum removal ratios of nitrate of 87.21% (IP) and 96.27% (IPM) were observed under the following conditions: HRT of 12 h, pH of 7.0 and influent Fe³⁺ concentration of 5 mg/L (IP) and 1 mg/L (IPM).
Article
Sequential batch reactors (SBR) are widely used in waste water treatment due to flexibility in operation and low investment costs. However, the main drawback of this technology is the large energy requirements for its operation. In addition, SBR performance is mostly determined by the quality of treated water, which is affected by model uncertainty. Efficient control systems that can meet the operational goals for this process under uncertainty is therefore desired. In this work, we propose an efficient control approach for composition control of organic matter and nitrogen in SBR systems in presence of model uncertainty. A local sensitivity analysis was performed to identify the variables that have a major impact on SBR behavior. Robust and stochastic model predictive controllers were designed to effectively control the SBR process under uncertainty. Our results indicate that water quality requirements can be achieved even in presence of uncertainty without sacrificing SBR performance.
Article
Full-text available
To enhance the startup and efficient simultaneous nitrification and denitrification for sewage treatment, sequencing batch biofilm reactors (SBBRs) partially coupled with rice husk were established and operated under various intermittent micro-aeration cycles (IMCs) and COD/N ratios under oxygen-limiting intermittent aeration conditions. Experimental results showed that the increase of IMCs with non-aeration/micro-aeration mode of (8 h/4 h)1 to (2 h/1 h)4 in a 12 h-cycle accelerated the startup performance and improved NH4+-N and COD removal. NH4+-N, TN and COD removal efficiencies were 98.7 ± 0.9, 89.2 ± 5.2 and 82.9 ± 6.7% at COD/N ratio of 7.6 with the highest IMCs in SBBR, respectively. Higher TN removal efficiencies of 87.2 ± 4.0 and 58.1 ± 3.5% were also achieved at lower COD/N ratio of 5.6 and 2.8, respectively. In SBBRs with various IMCs, facultative denitrifier like genus Acinetobacter and solid-phase denitrifier belonging to Comamonadaceae family were enriched. However, aerobic denitrifiers with function of heterotrophic nitrification like Paracoccus were favored to enrich under higher IMCs condition, and more anoxic denitrifiers like sulfur-based autotrophic denitrifier Thiothrix and heterotrophic denitrifiers like Pseudomonas and Methyloversatilis were observed at lower IMCs condition. Autotrophic nitrifier (Nitrosomonas and Nitrosipra) and heterotrophic nitrifiers both contributed to the efficient nitrification.
Article
s Artificial intelligence technologies were confirmed as a useful tool for wastewater treatment, but its application in the electrochemical nitrate removal had less been reported. In this work, the artificial neural network in machine learning was used to construct the model, which combines the methods of electrochemistry and artificial intelligence to achieve the prediction and intelligent control of nitrate removal. The control system consists of a prediction module with an artificial neural network (ANN) algorithm model and a control module. First, initial nitrate concentration, pH, time and current density were considered as input. An ANN algorithm using 7 hidden layers and a negative feedback regulation mechanism was developed to optimize the model and predict the nitrate removal rate. Results indicates that the proposed prediction model (4–7–1) yields a better coefficient of determination and lower root mean square error. The optimal set-points of the current density in the electrochemical process can be obtained according to the water quality change and qualified effluent quality using the ANN model. Also, the proposed intelligent control strategy can eliminate the influence of water quality change on nitrate removal and reduce energy consumption by 15.0 % compared to the post strategy. This work demonstrated the potential of artificial intelligence in the electrochemical process of nitrate removal.
Article
Nitrogen removal performance was investigated in a sequencing batch reactor (SBR) and two moving bed sequencing batch reactors (MBSBRs) containing a given proportion (20% v/v) of various carrier materials. The maximum total nitrogen (TN) removal efficiency (78%) was achieved using an MBSBR packed with luffa sponge (LS) substrate; polyurethane (PU) foam cube-packed MBSBR and SBR systems followed at 71% and 62%, respectively. Suspended-growth biomass played a role in the conversion of ammonium-N to nitrite-N and nitrate-N. Simultaneous nitrification and denitrification (SND) processes enhanced TN removal in the MBSBRs. In addition, LS facilitated denitrification by serving as a carbon source. Pyrosequencing analysis showed that the enhanced nitrate removal rates in Reactor B (RB; MBSBR-PU) and Reactor C (RC; MBSBR-LS) systems may be attributed to Clostridia enrichment; the higher relative abundance of Clostridia in RC may have caused the superior nitrate removal rate therein. Pseudomonas was the dominant genus in denitrification processes in RB and RC. This work demonstrates that MBSBRs are capable of outperforming traditional SBRs and that the choice of carrier material is essential to MBSBR wastewater treatment performance.
Article
A nitrificação e desnitrificação simultânea é um processo biológico inovador que minimiza a energia necessária para fornecimento de oxigênio, reduzindo a adição de fonte de elétrons. Este processo é aplicado a sistemas de biofilme de batelada sequencial e algumas de suas condições operacionais vem sendo testadas para a remoção máxima. Este trabalho avaliou as diferentes combinações de alcalinidade e nitrogênio com testes de 32 ciclos de 6h (com aeração de 4,5h) e nesse período foram realizadas análises para verificação das condições ambientais, das eficiências de remoção de carbono e nitrogênio como também a avaliação de adesão microbiana. As condições ambientais indicadas para o processo foram mantidas durante toda a operação. Com a relação carbono/nitrogênio média de 5,3, obteve-se eficiência de remoção de demanda química de oxigênio entre 62 e 84% e remoção de nitrogênio total de 14 a 34%. As eficiências de nitrificação e desnitrificação obtidas foram baixas, mas indicaram que não houve limitação do processo por indisponibilidade de doadores de elétrons. Por fim, a eficiência de remoção de demanda química de oxigênio mostrou-se, pela regressão múltipla, relacionada com a relação carbono/nitrogênio afluente, enquanto a eficiência de remoção de nitrogênio total sofreu forte influência da demanda química de oxigênio e da alcalinidade.
Article
The study aims to assess the operation efficiency of sequencing batch reactor (SBR) and advanced sequencing batch reactor (ASBR) wastewater treatment plants (WWTPs) in Egypt. After auditing more than 24 SBR and ASBR plants, four plants Al-Maamora [MAAM], Al-Negeela [NEGL], Khorshed No. 1 [KOR#1], Khorshed No. 2 [KOR#2] were selected for the current study according to its virtuous performance, good construction conditions and regulatory workflow. COD, BOD and TSS were measured in the influent and effluent samples according to APHA standard methods. Influent quantities and treatment power consumption were monthly recorded. The power consumed for removing a kilogram of BOD and/or treating a cubic meter of wastewater was taken as a comparative indicator among the included WWTPs and between SBR and ASBR technologies. The monthly average inflows were 427058, 189581, 1019876, and 144937 m³/month for MAAM, KOR#1, KOR#2, and NGEL and the monthly power consumption were 56553, 69763, 178778 and 49545 kW/month respectively. The average removal percentage of the plants reached 92, 91.75, 92.5 % for BOD, COD, and TSS respectively, the effluent concentrations of the intended parameters has met the regulatory standard. The average power consumption for removal of a kilogram BOD by SBR and ASBR was 0.932 and 1.58 kWh respectively. SBR and ASBR plants consumed average of 0.245 and 0.296 kWh to treat one cubic meter of wastewater complying with the Egyptian standard for discharge into the drainage canals as a reference values. The study concluded considering the ASBR technology for building new WWTPs or extending current plants, especially for the crowded cities.
Article
Full-text available
Extracellular polymeric substances are the construction materials for microbial aggregates such as biofilms, flocs ("planktonic biofilms") and sludge. Their major components are not only polysaccharides but also proteins and in some cases lipids, with minor contents of nucleic acids and other biopolymers. In the EPS, biofilm organisms can establish stable arrangements and function multicellularly as synergistic microconsortia. The matrix facilitates the retention of exoenzymes, cellular debris and genetic material; it can be considered as a microbial recycling yard. Gradients can develop due to the physiological activity and the fact that diffusive mass transport prevails over convective transport in the matrix. Biofilm cells tolerate higher concentrations of many biocides. The EPS matrix sequesters nutrients from the water phase. In photosynthetic communities, EPS molecules can function as light transmitters and provide photons to organisms located deeper in a microbial mat. The EPS matrix is a dynamic system, constructed by the organisms and responding to environmental changes. It enables the cells to function in a manner similar to multicellular organisms.
Article
Full-text available
A bioreactor was constructed and used to treat a synthetic wastewater containing ammonium acetate and trace nutrients for about 190 days. The reactor was aerated by means of bundles of gas-permeable hollow-fiber membranes that were installed in the reactor. The membranes provided a specific surface area of 422 m(2)/m(3) and the external surface of the membranes rapidly became covered in an active biofilm. The membrane bundles were agitated by an internal gas recycle. The gas bubbles in the water encouraged fiber-fiber contact and were intended to control biofilm growth. Chemical oxygen demand (COD) removals in excess of 95% were achieved in a 6h nominal detention time. Nitrification developed rapidly and complete oxidation of the influent ammonium was evident within 20 days. Even though the reactor was equipped with a large membrane surface area, the oxygen was consumed within the biofilm growing on the membrane surface. As a result, the external dissolved oxygen (DO) dropped to zero and the reactor was able to support essentially complete denitrification. After about 3 months of operation the reactor showed excellent removals of both COD and inorganic nitrogen but the performance could not be sustained. Excess biofilm accumulation eventually contributed to a deterioration in process performance. This study demonstrates that while membrane aeration can provide simultaneous BOD and N removal in the same reactor, the membrane modules/bioreactor must be designed to allow for the development of thick biofilms. In addition, options for controlling the biofilm thickness need to be investigated.
Article
Full-text available
Biofilm configured system with sequencing/periodic discontinuous batch mode operation was evaluated for the treatment of low-biodegradable composite chemical wastewater (low BOD/COD ratio approximately 0.3, high sulfate content: 1.75 g/l) in aerobic metabolic function. Reactor was operated under anoxic-aerobic-anoxic microenvironment conditions with a total cycle period of 24 h [fill: 15 min; reaction: 23 h (aeration along with recirculation); settle: 30 min; decant: 15 min] and the performance of the system was studied at organic loading rates (OLR) of 0.92, 1.50, 3.07 and 4.76 kg COD/cum-day. Substrate utilization showed a steady increase with increase in OLR and system performance sustained at higher loading rates. Maximum non-cumulative substrate utilization was observed after 4h of the cycle operation. Sulfate removal efficiency of 20% was observed due to the induced anoxic conditions prevailing during the sequence phase operation of the reactor and the existing internal anoxic zones in the biofilm matrix. Biofilm configured sequencing batch reactor (SBR) showed comparatively higher efficiency to the corresponding suspended growth and granular activated carbon (GAC) configured systems studied with same wastewater. Periodic discontinuous batch mode operation of the biofilm reactors results in a more even distribution of the biomass throughout the reactor and was able to treat large shock loads than the continuous flow process. Biofilm configured system coupled with periodic discontinuous batch mode operation imposes regular variations in the substrate concentration on biofilm organisms. As a result, organisms throughout the film achieve maximum growth rates resulting in improved reaction potential leading to stable and robust system which is well suited for treating highly variable wastes.
Article
Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.
Article
Field measurements documented successful one-reactor denitrification with nitrification in single-channel oxidation ditches at one underloaded and one overloaded facility; nitrogen was removed and oxygen requirements were reduced. Results and theoretical considerations indicated that denitrification occurred continuously in anoxic microzones inside the floc. No anoxic zones were detected at one facility. Operation was relatively simple; primary control parameters were oxygen transfer rate and the average DO concentration (0.1 to 0.5 mg/L).
Article
This study investigated the spatial distribution of biofilm extracellular polymeric substances (EPS) with depth in biofilms. Heterotrophic biofilms were grown in a rotating drum biofilm reactor fed with synthetic wastewater with a COD of 150 mg/L. Biofilm was found to be heterogeneously structured, represented not only by the spatial distribution of EPS yields but also by clearly defined aerobic/anoxic zones, increased density, decreased porosity, decreased soluble COD concentrations, and decreased viable biomass concentrations along the biofilm depth. Thicker biofilms exhibited greater soluble COD concentrations, EPS yields, and viable biomass than thinner biofilms. The net EPS yields in the biofilms are proportionally related to the amount of viable biomass present, and viable biomass loses its ability to produce EPS at the deeper sections because of its lower microbial activity resulting from lower nutrient availability. Also, it is possible that the naturally produced EPS was consumed as a substrate in the deeper layers, where more readily degradable organics were absent. The results of the spatial distribution of EPS yields gained in this paper provide helpful information to achieve a more complete description of heterogeneous biofilm structure. New biofilm models need to be developed to incorporate the EPS information to accurately reflect the heterogeneity of biofilms.
Article
Side stream reactors to treat reject water from sludge dewatering facilities may be considered to be small treatment plants embedded in large ones. Combination of main stream and side stream treatment provides a number of advantages. Of major importance is that tailored processes can be employed for the two waste streams very different in composition and concentration. Pilot scale experiments were conducted to study the applicability, and to compare the performance of two types of Sequencing Batch Reactor (SBR) systems, an activated sludge and a biofilm SBR. The reactors were operated to achieve nitrification only. Subsequently, the effluent of the reactors is fed into the anoxic zone of the main stream activated sludge plant to achieve denitrification. In general it can be stated that both, activated sludge and biofilm SBR systems are applicable for treating reject water of high ammonia loading. Nitrogen removal efficiencies of more than 90% could be obtained with both systems. If complete nitrification without denitrification is to be achieved, pH control is necessary. However, the amount of sodium hydroxide required for adjusting the pH during nitrification is significant. Foam development and accumulation caused major problems, especially during the early stage of start up. But the time proceeding, and by changing the type of polyelectrolyte used in the sludge dewatering process foam problems could be kept under control. Keywords nitrification; nitrogen removal; sequencing batch reactor (SBR); sequencing batch biofilm reactor (SBBR); sludge dewatering; process water; reject water
Article
In continuous flow biofilm reactors (CFBR) stratification of the microbial community may develop in the direction of flow. Problems arise when substrate is transported into regions where the population size of the required species such as nitrifiers is underdeveloped. Results of experimental studies support this assumption. Equalisation of the species distribution appears to be necessary to maintain reasonable reactor performance under shock loading conditions. Uniform population size and species distribution was achieved in a sequencing batch biofilm reactor (SBBR), which provided positive results, and stratification of hetero‐trophs and nitrifiers was eliminated. Equalisation of the population size of heterotrophs was less effective because of the apparent acclimatisation potential of the bacteria.
Article
Biofilms, accumulations of microorganisms at interfaces, have been described for every aqueous system supporting life. The structure of these microbial communities ranges from monolayers of scattered single cells to thick, mucous structures of macroscopic dimensions (microbial mats; algal-microbial associations; trickling filter biofilms). During recent years the structure of biofilms from many different environments has been documented and evaluated by use of a broad variety of microscopic, physico-chemical and molecular biological techniques, revealing a generally complex 3D structure. Parallel to these investigations more and more complex mathematical models and simulations were developed to explain the development, structures, and interactions of biofilms. The forces determining the spatial structure of biofilms, including microcolonies, extracellular polymeric substances (EPS), and channels, are still the subject of controversy. To achieve conclusive explanations for the structures observed in biofilms the cooperation of both fields of investigation, modelling and experimental research, is necessary. The expanding field of molecular techniques not only allows more and more detailed documentation of the spatial distribution of species, but also of functional activities of single cells in their biofilm environment. These new methods will certainly reveal new insights in the mechanisms involved in the developmental processes involved in the formation and behavior of biofilms.
Article
Wastewater treatment plants are typically subjected to variable influent loading conditions. Extreme variations of flow, composition and substrate concentration may occur in the influent of industrial wastewater treatment plants, but also at plants serving tourist areas. High rate reactors of low hydraulic buffer capacity are particularly affected. Exploitation of internal equalization capacities are proposed to dampen the fluctuations of biomass loading. In this context, the biomass itself and — in case of biofilm reactors — the biofilm support media may be considered as a sink during peak loading situations, and as a source of substrate as soon as the influent loading drops. Sequencing Batch Biofilm Reactors (SBBR) studies in laboratory and pilot scale were conducted to investigate the capacity of these internal sink and source terms. The reactors were packed with four types of biofilm carrier materials, blasted clay granules, granular activated carbon, zeolite and small size plastic rings (Kaldnes). Temporary storage of substrates was achieved by means of adsorption, ion exchange and absorption processes. As the react phase proceeded, the bulk liquid concentration dropped and desorption processes followed by metabolic reactions became dominant. From the results achieved it can be concluded that thick biofilms, and biofilm support media with sorptive capacities are favorable to counteract peak loading fluctuations, and to keep the effluent concentration from exceeding set discharge levels.
Article
Laboratory scale experiments were conducted to study the deterioration of enhanced biological phosphorus removal (EBPR) due to influent ammonium concentration, and to compare the performance of two types of sequencing batch reactor (SBR) systems, a conventional SBR and sequencing batch biofilm reactor (SBBR). Both in SBR and SBBR, the total nitrogen removal efficiency decreased from 100% to 53% and from 87.5% to 54.4%, respectively, with the increase of influent ammonium concentration from 20 mg/l to 80 mg/l. When the influent ammonium concentration was as low as 20 mg/l (C: N: P=200: 20: 15), denitrifying glycogen-accumulating organisms (DGAOs) were successfully grown and activated by using glucose as a sole carbon source in a lab-scale anaerobic-oxic-anoxic (A2O) SBR. In the SBR, due to the effect of incomplete denitrification and pH drop, the nitrogen and phosphorus removal efficiency decreased from 77% to 33.3% when the influent ammonium concentration increased from 20 mg/l to 80 mg/l. However, in the SBBR, simultaneous nitrification/denitrification (SND) occurred, and the nitrification rate in the aerobic phase did not change remarkably in spite of the increase in influent ammonium concentration. Phosphorus removal was not affected by the increase of influent ammonium concentration.
Article
Two bench-scale sequencing batch reactors were fed with domestic wastewater and operated in an anaerobic-aerobic sequence for 139 d. Denitrification during the aerated react period was observed and the factors influencing the extent of simultaneous nitrification and denitrification were examined. It was found that the influence of DO on the nitrification rate during the aerated react period could be described by a Monod kinetic with a high oxygen half-saturation coefficient for autotrophic nitrifiers (KO.A) of 4.5 mg/l. The dependency of the denitrification rate on DO could be described by a mathematical switching function with a higher switching function constant than expected, meaning that the extent of aerobic denitrification was higher than usual. It was also observed that aerobic denitrification decreased with time over the aerated react period. For most of the time of reactor operation nitrite was the main NOx species in the effluent, instead of the commonly expected nitrate. This led to the conclusion that the activity of Nitrobacter species was probably inhibited in the SBRs studied. It also demonstrated the importance of measuring nitrite in the effluent to ensure that the reactor performance and the extent of aerobic denitrification was not over-estimated.
Article
This study shows how the carbon and nitrogen (C/N) ratio controls the simultaneous occurrence of nitrification and denitrification in a sequencing batch reactor (SBR). Data demonstrated that a low C/N ratio resulted in a rapid carbon deficit, causing an unbalanced simultaneous nitrification–denitrification (SND) process in SBR. When the initial COD/NH4+-N ratio was adjusted to 11.1, the SND-based SBR achieved complete removal of NH4-N and COD without leaving any NO2−-N in the effluent. The nitrogen removal efficiency decreases gradually with increasing ammonium-loading rate to the SND–SBR system. Altogether, data showed that appropriate controls of carbon and nitrogen input are required to achieve an efficient SND–SBR. An established SND technology can save operation time and energy, and might replace the traditional two-stage biological nitrification and denitrification process.
Article
The occurrence of denitrifying phosphate accumulating organisms (DNPAOs) and the contribution of DNPAOs to biological nutrient removal performance were investigated in a bench-scale A2O system. Moreover, the effect of excessive aeration on biological phosphorus removal (BPR) was studied. The experimental results suggested that anoxic phosphorus uptake could occur in the A2O process, as compared with the conventional A2O process. Good COD, phosphorus, ammonia nitrogen and total nitrogen removal efficiency (92.3%, 95.5%, 96% and 79.5% respectively) could be achieved. Furthermore, sludge analysis demonstrated that the ratio of anoxic P uptake rate to aerobic P uptake rate reached 69% in such a system and nitrate concentration in the anoxic phase and different organic substrate introduced into the anaerobic phase had significant effects on the anoxic P uptake. It was also found that if the air supply was not adjusted properly under good anoxic P uptake conditions, excessive aeration of activated sludge at the end of aerobic zone could lead to the deterioration of BPR.
Article
The influence of high biomass concentration on the operating conditions of a newly developed high-performance bioreactor, the impinging-stream loop reactor, combined with membrane filtration is discussed. The efficiency and the advantages of this combination with respect to economy, effluent concentration and operating conditions are shown in comparison to conventional wastewater treatment plants.Finally, a short summary of investigations with a pilot plant for treatment of landfill leachate are given.
Article
A compact suspended carrier biofilm reactor (SCBR) was developed for simultaneous nitrification and denitrification (SND) in a single reactor and the performance of nutrient removal was investigated. Microbial community structure response to different ratio of carbon to nitrogen (C/N) was determined by denaturing gel gradient electrophoresis (DGGE) profiles of 16S rDNA V3 region and amoA gene amplifications. In addition, the population dynamics of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were estimated by fluorescence in situ hybridization (FISH) with 16S rDNA-targeted oligonucleotide probes. Results showed that the compact SCBR was efficient in nutrient removal with CODCr removal efficiency over 90% and SND efficiency (ESND) about 83.3%. The diversity of microbial community structure was positively correlated with C/N ratio, while the three communities of amoA gene were relativity homogenous. The population of nitrifiers was in inverse proportions to C/N ratio with the average fraction of AOB and NOB to all bacteria 5.4, 4.8, 3.1% and 4.6, 3.5, 2.7% respectively as C/N ratio changing from 3:1, 5:1 to 10:1. Therefore we could reach a conclusion that the compact SCBR was practical to treat municipal wastewater and the shift of microbial community monitored by molecular technologies could offer guidance to the process optimization in engineering.
Article
Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.
Article
The study on the operational conditions of simultaneous nitrification and denitrification (SND) in the channel of oxidation ditch (OD) without the need for a special anoxic tank was carried out based on lab-scale and pilot-scale experiments using real domestic wastewater. The influence of sludge loading and component proportion in influent, temperature, hydraulic retention time (HRT), dissolved oxygen (DO) and operational mode on SND was investigated. The result indicated that the optimal DO (ODO) of SND occurrence was confirmed majorly by the sludge loading of influent and temperature, the high TCOD/NH(3)-N and short HRT can enhance the occurrence of SND. A new operational mode was proposed that achieved a higher removal efficiency of 60-70% for total nitrogen by SND with HRT of 4-6h, and the concentrations of NH(3)-N and TN in effluent are less than 5 and 15 mg/L, respectively.
Article
The objective of this study is to evaluate the performance of sequencing batch biofilm reactors (SBBRs) and sequencing batch reactor (SBR) in the simultaneous removal of p-nitrophenol (PNP) and ammoniacal nitrogen. SBBRs involved the use of polyurethane sponge cubes and polyethylene rings, respectively, as carrier materials. The results demonstrate that complete removal of PNP was achievable for the SBR and SBBRs up to the PNP concentration of 350 mg/l (loading rate of 0.368 kg/m3 d). At this loading rate, the average ammoniacal nitrogen removal efficiency for the SBR and SBBR (with polyethylene rings) was reduced to 86% and 96%, respectively. However, the SBBR (with polyurethane sponge cubes) still managed to achieve an almost 100% ammoniacal nitrogen removal. Based on the results, the performance of the SBBRs was better than that of SBR in PNP and ammoniacal nitrogen removal. The results of the gas chromatography mass spectroscopy, high-performance liquid chromatography and ultraviolet-visible analyses indicate that complete mineralization of PNP was achieved in all of the reactors.
Article
In this study, pilot-scale experiments for the removal of nitrogen from sewage obtained from a county Y sewer system were performed using modified A(2)O processes. Using this approach, the total amount of nitrogen discharged during denitrification of the influent was average 38.6 mg/L and a level of average 10.8 mg/L was maintained throughout the denitrification process, which resulted in an average removal efficiency that was greater than 72%. The nitrogen components in the effluent water consisted of 22% ammonia nitrogen, 6% nitrite nitrogen and 72% nitrate nitrogen, reaching a nitrification efficiency of 94%. In conclusion, since these advanced treatment methods, which involve modified A(2)O processes, were successfully employed to remove nitrogen from sewage discharge, they hold promise for wide spread use by treatment plants.
Article
The spatial distributions and activities of ammonia oxidizing bacteria (AOB) and polyphosphate accumulating organisms (PAOs) were investigated for a novel laboratory-scale sequencing batch pumped-flow biofilm reactor (PFBR) system that was operated for carbon, nitrogen and phosphorus removal. The PFBR comprised of two 16.5l tanks (Reactors 1 and 2), each with a biofilm module of 2m(2) surface area. To facilitate the growth of AOB and PAOs in the reactor biofilms, the influent wastewater was held in Reactor 1 under stagnant un-aerated conditions for 6 h after feeding, and was then pumped over and back between Reactors 1 and 2 for 12 h, creating aerobic conditions in the two reactors during this period; as a consequence, the biofilm in Reactor 2 was in an aerobic environment for almost all the 18.2 h operating cycle. A combination of micro-sensor measurements, molecular techniques, batch experiments and reactor studies were carried out to analyse the performance of the PFBR system. After 100 days operation at a filtered chemical oxygen demand (COD(f)) loading rate of 3.46 g/m(2) per day, the removal efficiencies were 95% COD(f), 87% TN(f) and 74% TP(f). While the PFBR microbial community structure and function were found to be highly diversified with substantial AOB and PAO populations, about 70% of the phosphorus release potential and almost 100% of the nitrification potential were located in Reactors 1 and 2, respectively. Co-enrichment of AOB and PAOs was realized in the Reactor 2 biofilm, where molecular analyses revealed unexpected microbial distributions at micro-scale, with population peaks of AOB in a 100-250 microm deep sub-surface zone and of PAOs in the 0-150 microm surface zone. The micro-distribution of AOB coincided with the position of the nitrification peak identified during micro-sensor analyses. The study demonstrates that enrichment of PAOs can be realized in a constant or near constant aerobic biofilm environment. Furthermore, the findings suggest that when successful co-enrichment of AOB and PAOs occur in biofilm environments, such as in the PFBR system, they do so at different zone depths in the biofilm.
Article
A combined strategy of a photo-Fenton pretreatment followed by a Sequencing Batch Biofilm Reactor (SBBR) was evaluated for total C and N removal from a synthetic wastewater containing exclusively 200 mg L(-1) of the antibiotic Sulfamethoxazole (SMX). Photo-Fenton reaction was optimized at the minimum reagent doses in order to improve the biocompatibility of effluents with the subsequent biological reactor. Consequently, the pretreatment was performed with two different initial H(2)O(2) concentrations (300 and 400 mg L(-1)) and 10 mg L(-1) of Fe(2+). The pre-treated effluents with the antibiotic intermediates as sole carbon source were used as feed for the biological reactor. The SBBR was operated under aerobic conditions to mineralize the organic carbon, and the Hydraulic Retention Time (HRT) was optimized down to 8h reaching a removal of 75.7% of the initial Total Organic Carbon (TOC). The total denitrification of the NO(3)(-) generated along the chemical-biological treatment was achieved by means of the inclusion of a 24-h anoxic stage in the SBBR strategy. In addition, the Activated Sludge Model No. 1 (ASM1) was successfully used to complete the N balance determining the N fate in the SBBR. The characterization and the good performance of the SBBR allow presenting the assessed combination as an efficient way for the treatment of wastewaters contaminated with biorecalcitrant pharmaceuticals as the SMX.
Article
Biofilms, accumulations of microorganisms at interfaces, have been described for every aqueous system supporting life. The structure of these microbial communities ranges from monolayers of scattered single cells to thick, mucous structures of macroscopic dimensions (microbial mats; algal-microbial associations; trickling filter biofilms). During recent years the structure of biofilms from many different environments has been documented and evaluated by use of a broad variety of microscopic, physico-chemical and molecular biological techniques, revealing a generally complex 3D structure. Parallel to these investigations more and more complex mathematical models and simulations were developed to explain the development, structures, and interactions of biofilms. The forces determining the spatial structure of biofilms, including microcolonies, extracellular polymeric substances (EPS), and channels, are still the subject of controversy. To achieve conclusive explanations for the structures observed in biofilms the cooperation of both fields of investigation, modelling and experimental research, is necessary. The expanding field of molecular techniques not only allows more and more detailed documentation of the spatial distribution of species, but also of functional activities of single cells in their biofilm environment. These new methods will certainly reveal new insights in the mechanisms involved in the developmental processes involved in the formation and behavior of biofilms.
Article
Experimental investigations were performed to determine the possibility of simultaneous biological nitrogen and phosphorus removal during various biofilm processes in conjunction with biofilm characterisation, especially extracellular polymeric substance (EPS). Since biologial nitrogen removal requires an alternating exposure of anaerobic-anoxic-oxic conditions in the bulk liquid that surrounds the biofilm growth media, a sequencing batch reactor (SBR)-type operation was used. Various materials including expanded clay, polystyrene, polyurethane, and acrylic materials were used as the biofilm growth support medium. Simultaneous nitrogen and phosphorus removal was possible with SBR, but it was postulated that nutrient removal efficiencies varied with film thickness. Thinner biofilm promoted nitrification and phosphorus removal, but thicker biofilm enhanced denitrification and reduced phosphorus removal. EPS contents were similar regardless of support media types or biofilm configuration, but EPS contents gradually increased as the film growth continued after backwashing. EPS contents were increased with increased nitrogen removal, but it was difficult to define its relation with phosphorus removal. In addition, suspended solids removal was correlated well with the EPS content in the biofilms.
Article
A sequencing batch biofilm reactor (SBBR) with well established enhanced biological phosphate removal (EBPR) was subjected to higher ammonium concentrations to stimulate and eventually implement simultaneous nitrification. Changes of activity and populations were investigated by a combination of online monitoring, microsensor measurements and fluorescence in situ hybridisation (FISH) of biofilm sections. Nitrification and nitrifying bacteria were always restricted to the periodically oxic biofilm surface. Both, activity and population size increased significantly with higher ammonium concentrations. Nitrification always showed a delay after the onset of aeration, most likely due to competition for oxygen by coexisting P accumulating and other heterotrophic bacteria during the initial aeration phase. This view is also supported by comparing oxygen penetration and oxygen uptake rates under low and high ammonium conditions. Therefore, simultaneous nitrification and phosphorus removal in a P removing SBBR appears to be only possible with a sufficiently long oxic period to ensure oxygen availability for nitrifiers.
Article
Simultaneous nitrification and denitrification (SND) via the nitrite pathway and anaerobic-anoxic-enhanced biological phosphorus removal (EBPR) are two processes that can significantly reduce the energy and COD demand for nitrogen and phosphorus removal. The combination of these two processes has the potential of achieving simultaneous nitrogen and phosphorus removal with a minimal requirement for COD. A lab-scale sequencing batch reactor (SBR) was operated in alternating anaerobic-aerobic mode with a low dissolved oxygen (DO) concentration (0.5 mg/L) during the aerobic period, and was demonstrated to accomplish nitrification, denitrification, and phosphorus removal. Under anaerobic conditions, COD was taken up and converted to polyhydroxyalkanoates (PHAs), accompanied by phosphorus release. In the subsequent aerobic stage, PHA was oxidized and phosphorus was taken up to <0.5 mg/L by the end of the cycle. Ammonia was also oxidized during the aerobic period, but without accumulation of nitrite or nitrate in the system, indicating the occurrence of simultaneous nitrification and denitrification. However, off-gas analysis showed that the final denitrification product was mainly nitrous oxide (N(2)O), not N(2). Further experimental results demonstrated that nitrogen removal was via nitrite, not nitrate. These experiments also showed that denitrifying glycogen-accumulating organisms (DGAOs), rather than denitrifying polyphosphate-accumulating organisms (DPAOs), were responsible for the denitrification activity.
Article
A novel biofilm reactor-alternating pumped sequencing batch biofilm reactor (APSBBR)-was developed to treat synthetic dairy wastewater at a volumetric chemical oxygen demand (COD) loading rate of 487 g COD m(-3) d(-1) and an areal loading rate of 5.4 g COD m(-2) d(-1). This biofilm reactor comprised two tanks, Tanks 1 and 2, with two identical plastic biofilm modules in each tank. The maximum volume of bulk fluid in the two-tank reactor was the volume of one tank. The APSBBR was operated as a sequencing batch biofilm reactor with five operational phases-fill (25 min), anoxic (9 h), aerobic (9 h), settle (6 h) and draw (5 min). The fill, anoxic, settle and draw phases occurred in Tank 1. In the aerobic phase, the wastewater was circulated between the two tanks with centrifugal pumps and aeration was mainly achieved through oxygen absorption by micro-organisms in the biofilms when they were exposed to the air. In this paper, the biofilm growth and characteristics in the APSBBR were studied in a 98-day laboratory-scale experiment. During the course of the study, it was found that the biofilm thickness (delta) in Tank 1 ranged from 1.2 to 7.2 mm and that in Tank 2 from 0.5 to 2.2 mm; the biofilm growth against time (t) can be simulated as delta=0.07t0.99 (R2 = 0.97, P = 0.002) in Tank 1 and delta = 0.08t0.66 (R2 = 0.81, P = 0.04) in Tank 2. The biomass yield coefficient, Y, was 0.18 g volatile solids (VS) g(-1) COD removal. The biofilm density in both tanks, X, decreased as the biofilm thickness increased and can be correlated to the biofilm thickness, delta .
Article
An investigation was performed on the biological removal of ammonium nitrogen from synthetic wastewater by the simultaneous nitrification/denitrification (SND) process, using a sequencing batch biofilm reactor (SBBR). System behavior was analyzed as to the effects of sludge type used as inoculum (autotrophic/heterotrophic), wastewater feed strategy (batch/fed-batch) and aeration strategy (continuous/intermittent). The presence of an autotrophic aerobic sludge showed to be essential for nitrification startup, despite publications stating the existence of heterotrophic organisms capable of nitrifying organic and inorganic nitrogen compounds at low dissolved oxygen concentrations. As to feed strategy, batch operation (synthetic wastewater containing 100 mg COD/L and 50 mg N-NH(4)(+)/L) followed by fed-batch (synthetic wastewater with 100 mg COD/L) during a whole cycle seemed to be the most adequate, mainly during the denitrification phase. Regarding aeration strategy, an intermittent mode, with dissolved oxygen concentration of 2.0mg/L in the aeration phase, showed the best results. Under these optimal conditions, 97% of influent ammonium nitrogen (80% of total nitrogen) was removed at a rate of 86.5 mg N-NH(4)(+)/Ld. In the treated effluent only 0.2 mg N-NO(2)(-)/L,4.6 mg N-NO(3)(-)/L and 1.0 mg N-NH(4)(+)/L remained, demonstrating the potential viability of this process in post-treatment of wastewaters containing ammonium nitrogen.
Article
The potential for PHB (poly-beta-hydroxybutyrate) to serve as the electron donor for effective simultaneous nitrification and denitrification (SND) was investigated in a 2-L sequencing batch reactor (SBR) using a mixed culture and acetate as the organic substrate. During the feast period (i.e., acetate present), heterotrophic respiration activity was high and nitrification was prevented due to the inability of nitrifying bacteria to compete with heterotrophs for oxygen. Once acetate was depleted the oxidation rate of PHB was up to 6 times slower than that of soluble acetate and nitrification could proceed due to the decreased competition for oxygen. The slow nature of PHB degradation meant that it was an effective substrate for SND, as it was oxidised at a similar rate to ammonium and was therefore available for SND throughout the entire aerobic period. The percentage of nitrogen removed via SND increased at lower DO concentrations during the famine period, with up to 78% SND achieved at a DO concentration of 0.5 mg L(-1). However, the increased percentage of SND at a low DO concentration was compromised by a 2-times slower rate of nitrogen removal. A moderate DO concentration of 1 mg L(-1) was optimal for both SND efficiency (61%) and rate (4.4 mmol N x Cmol x(-1) x h(-1)). Electron flux analysis showed that the period of highest SND activity occurred during the first hour of the aerobic famine period, when the specific oxygen uptake rate (SOUR) was highest. It is postulated that a high SOUR due to NH(4) (+) and PHB oxidation decreases oxygen penetration into the floc, creating larger zones for anoxic denitrification. The accumulation of nitrate towards the end of the SND period showed that SND was finally limited by the rate of denitrification. As PHB degradation was found to follow first-order kinetics (df(PHB)/dt = -0.19 x f(PHB)), higher PHB concentrations would be expected to drive SND faster by increasing the availability rate of reducing power and reducing penetration of oxygen into the floc, due to the corresponding increased SOUR. Process control techniques to accumulate higher internal PHB concentrations to improve PHB-driven SND are discussed.
Article
The aim of this work was to assess the phosphorus storage capability of the polyphosphate (poly-P) accumulating organisms (PAO) in the biofilm using a sequential batch biofilm reactor (SBBR). In the anaerobic phase, the specific COD uptake rates increases from 0.05 to 0.22 (mg-COD/mg-biomass/h) as the initial COD increases and the main COD uptake activity occurs in the initial 30 min. The polyhydroxyalkanoates (PHAs) accumulation from 18 to 38 (mg-PHA/g-biomass) and phosphorus release from 20 to 60 (mg-P/L) share a similar trend. The adsorbed COD cannot be immediately transformed to PHAs. Since the PHAs' demand per released phosphorus is independent of the initial COD, the enhancement of the PHA accumulation would be of benefit to phosphorus release. The only requirement is to have an initial amount of substrate that will result in sufficient PHA accumulation (approximately 20 mg-PHA/g-biomass) for phosphorus release. During the aerobic phase, the aeration should not only provide sufficient dissolved oxygen, but should also enhance the mass transfer and the diffusion. In other words, the limitation to the phosphorus storage capability always occurs during the anaerobic phase, not the aerobic phase.
Start-up and optimization of a sequencing batch biofilm reactor (SBBR) based on an intelligent controlling system
  • D H Ding
  • Y X Jin
  • C P Feng
  • X T Liu
D.H. Ding, Y.X. Jin, C.P. Feng, X.T. Liu, Start-up and optimization of a sequencing batch biofilm reactor (SBBR) based on an intelligent controlling system, Proceedings of 13th World Lake Conference, 2009, pp. 849-853.
Water and Wastewater Monitoring Analysis Method
State Environmental Protection Administration, Water and Wastewater Monitoring Analysis Method, third ed.China Environmental Science Press, Beijing, 1997.
Start-up and optimization of a sequencing batch biofilm reactor (SBBR) based on an intelligent controlling system
  • Ding
Simultaneous P and N removal in a sequencing batch biofilm reactor: insights from reactor- and microscale investigations
  • Gieseke