[Show abstract][Hide abstract] ABSTRACT: We investigated the decolorization of Orange II with and without the addition of co-substrates and nutrients under an anaerobic sequencing batch reactor (ASBR). The increase in COD concentrations from 900 to 1750 to 3730 mg/L in the system treating 100 mg/L of Orange II-containing wastewater enhanced color removal from 27% to 81% to 89%, respectively. In the absence of co-substrates and nutrients, more than 95% of decolorization was achieved by the acclimatized anaerobic microbes in the bioreactor treating 600 mg/L of Orange II. The decrease in mixed liquor suspended solids concentration by endogenous lysis of biomass preserved a high reducing environment in the ASBR, which was important for the reduction of the Orange II azo bond that caused decolorization. The maximum decolorization rate in the ASBR was approximately 0.17 g/hr in the absence of co-substrates and nutrients.
Journal of Environmental Sciences 01/2012; 24(2):291-6. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The study involved investigating the effects of Cr(III) and the efficacy of powdered activated carbon (PAC) in reducing the inhibitory effects of Cr(III) on activated sludge under sequencing batch reactor (SBR) operation. The addition of Cr(III) into SBR system caused significant inhibitory effects on the activity of activated sludge as indicated by drastic drop in specific oxygen uptake rate (SOUR). The increase of Cr(III) concentration from 5 to 10 mg/L further deteriorated the treatment performance of SBR system in terms of the total organic carbon (TOC), suspended solids (SS) and Cr(III) removal efficiencies. With 0.167 g/L PAC (0.5 g PAC/cycle) addition into the SBR reactor influent wastewater, the TOC and Cr(III) removal efficiencies were improved from 88 to 94% and 82 to 90%, respectively. Coupled with the increasing mixed liquor biomass suspended solids concentration after PAC addition, the biomass apparently played the key role in the uptake of Cr(III) and kept the effluent Cr(III) concentration low. The addition of PAC was an effective way to allow continuous operation of the biological process in the presence of Cr(III) as indicated by increased SOUR as well as Cr(III) and TOC removal efficiencies.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this research was to investigate the effects of Ni(II), Cr(III), and Zn(II) on the treatment performance of sequencing batch reactor (SBR) system. The kinetics of adsorption study showed that the pseudo second-order reaction model provided the best description of the data obtained. From the Langmuir isotherm, the maximum adsorption capacities of Ni(II), Cr(III), and Zn(II) were 30 mg/g, 23 mg/g, and 18 mg/g, respectively. Cr(III) and Ni(II) were found to exert a more pronounced inhibitory effect on the bioactivity of the microorganisms compare to Zn(II). The increase of Cr(III) and Ni(II) concentration from 5 to 10 mg/L caused significant effect on the suspended solids (SS) and total organic carbon (TOC) removal efficiency in SBR system but vice versa in the case of Zn(II). The addition of powdered activated carbon (PAC) and termination of metal ions addition into SBR systems were carried out to investigate the capability of system recovery from the toxic effects of metal.
Acta Hydrochimica et Hydrobiologica 09/2010; 36(3):204-209. · 0.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The adsorption of Cu, Cd, Ni, Zn, and Cr from synthetic solutions on powdered activated carbon (PAC), activated sludge, and dried sludge were investigated under laboratory conditions to assess its ability to remove heavy metals. The adsorption efficiency increased rapidly within the first 30 min and then slowed down as it approached a steady state after 5 h of contact time. The results showed that activated sludge and PAC had a higher adsorption capacity than dried sludge. However, PAC showed a better adsorption capacity for Cu, Zn, and Ni than activated sludge. The maximum adsorption capacity, as quantified by the Langmuir parameter Q for activated sludge was 44, 30, 24, 23, and 18 mg/g for Cu, Ni, Cd, Cr, and Zn, respectively. In the case of dried sludge, the respective values of Q were 20, 13, 11,3, and 10 mg/g. The acute toxicity of these five heavy metals to the activated sludge microorganisms was determined on the basis of the reduction in the specific oxygen uptake rate (SOUR). The results obtained from the SOUR measurements indicated a decreasing toxicity scale, Cu > Cd > Ni ∼ Cr > Zn on activated sludge microorganisms.
[Show abstract][Hide abstract] ABSTRACT: This study is an effort to develop an efficient process for low-cost production of calcium-l-lactate (CaL2). CaL2 showed higher inhibitory effect on lactate production than ammonium-l-lactate (NH4) at lactate concentration lower than 100 g/L, but it showed lower inhibitory effect at higher lactate concentration. The strain Lactobacillus rhamnosus (NBRC 3863) was resistant to glucose inhibition and final CaL2 concentration increased with initial glucose concentration increasing up to 190 g/L. High-concentration CaL2 induced, however, flocculation of fermentation broth, causing incomplete fermentation. It was confirmed that stirring speed markedly influenced flocculation, an increase of the stirring speed leading to an earlier flocculation. Formation of colloidal CaL2 during fermentation was considered to be the cause of flocculation in this study. Addition of YE raised fermentation efficiency and made complete fermentation feasible. In the fermentation with 25 g/L YE, glucose was completely consumed and final CaL2 concentration of 220 g/L was obtained, when flocculation did not yet occur. In this study, CaL2 crystals and activated carbon powder were added as nucleation sites to get earlier crystallization of colloids and to decrease the inhibitory effect of CaL2, and so to increase productivity. Of the two nucleation sites, activated carbon powder showed higher performance in CaL2 production. Finally, the feasibility of crystallization-based recovery without concentration step was discussed.
Chemical Engineering and Processing: Process Intensification. 01/2009; 48(1):464–469.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study is to investigate the mineralization of C.I. Acid Orange 7 (AO7) by biological process in oxygen limited condition under GAC-biofilm configured sequencing batch reactor (SBCR) operation. The granular activated carbon (GAC) used was immobilized with azo dye-degrading microbes through attachment by immersing the GAC into anaerobic bioreactor treating dye-containing wastewater for more than 200 days. The SBCR system was fed with 2 l of AO7-containing wastewater and was operated in FILL, REACT, DRAW and IDLE periods in a time ratio of 3:20:0.45:0.15 for a cycle time of 24 h. Nearly complete mineralization of AO7 was achieved with the biological system working at initial AO7 concentration of 625 mg/l, dissolved oxygen (DO) below 0.25 mg/l and without the presence of external carbon sources. Reductive environment was well developed in the phases with the addition of external carbon sources, and this had improved the decolorization rate but deteriorated chemical oxygen demand (COD) removal efficiency.
[Show abstract][Hide abstract] ABSTRACT: To reduce nutrient cost for lactic acid production, rice bran, one of agricultural wastes, was chosen as a nutrient source in this study. Although rice bran is rich in protein and vitamins, the use of rice bran without any treatment was inefficient in lactic acid production. Rice bran was treated by acid-hydrolysis before it was put in experiment, when it was hydrolyzed at initial pH 1, 30 g/L rice bran could provide a productivity to that degree of about 8 g/L YE, showing such a desirable result that the use of rice bran as nutrient source would be a solution for reducing nutrient cost. However, the addition of hydrolyzed rice bran prolonged lag phase of fermentation, especially, in the fermentation with rice bran hydrolyzed at initial pH 0.5, a prolonged lag phase of about 40 h was observed. According to the quantitative determination of thiamine, pyridoxine, organic nitrogen and carbon, the prolongation of lag phase might be the result from the destruction of B vitamins and excessive hydrolysis of protein. To shorten the lag phase, combining hydrolyzed rice bran with yeast extract (YE) of small amount was considered to be a solution. When 3g/L YE was combined with 30 g/L rice bran hydrolyzed at initial pH 1, obtained was a productivity 1.6 times higher than that of the control fermentation with 15 g/L YE.
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to investigate the feasibility of using a granular activated carbon-biofilm configured packed column system in the decolorization of azo dye Acid Orange 7-containing wastewater. The Acid Orange 7-degrading microbial from anaerobic sequencing batch reactor which treating the azo dye-containing wastewater for more than 200 d was immobilized on spent granular activated carbon (GAC) through attachment. The GAC-biofilm configured packed column system showed the ability to decolorize 100% of the azo dye when working at high loading rate of Acid Orange 7 at 2.1 g/(L x d) with treatment time of 24 h. It was observed that the decolorization rate increased along with the increasing of initial Acid Orange 7 concentrations, until it reached an optimum point at about 0.38 g/h with initial Acid Orange 7 concentrations of 1,150 mg/L and the decolorization rate tend to be declined beyond this concentration.
Journal of Environmental Sciences 02/2008; 20(8):952-6. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Biological treatment of selenium-containing wastewater was investigated using the selenium-reducing sludge acclimatized from denitrifying sludge. The kinetic behavior of selenium reduction was evaluated for both selenate- and selenite-acclimatized sludge using methanol as an electron donor in batch and continuous runs. Selenate and selenite concentrations decreased linearly till the end of reaction, indicating the zero-order kinetics of the consecutive reduction paths. The temperature dependency was satisfactorily expressed by the Arrhenius type equation with different activation energy in selenate and selenite reduction. The pH dependency was quite different, too. The inhibitory effects of nitrate coexistence in reacting fluid were different depending on the type of selenium and sludge employed. The continuous runs with actual industrial wastewater could be performed satisfactorily resulting in full reduction of the aqueous selenium species to native Se, which was reflected in quite low selenium concentration of the effluent.
Process Biochemistry - PROCESS BIOCHEM. 01/2008; 43(11):1304-1307.
[Show abstract][Hide abstract] ABSTRACT: We studied the feasibility of using biological granular activated carbon-packed column in treating methylene blue-containing wastewater. The granular activated carbon with immobilized microbes was packed into a column and fed with 3 liter methylene blue-containing wastewater daily. With initial 1350 mg/l of methylene blue and 1550 mg/l of chemical oxygen demand, it was observed that the colour and chemical oxygen demand removal efficiencies were 99 and 78%, respectively. The high treatment performance of the system could be due to the simultaneous adsorption and biodegradation processes and advantages of immobilized microbes compare to suspended cell system.
[Show abstract][Hide abstract] ABSTRACT: Extraction and stripping kinetics of lactic acid in extractive fermentation were studied using tri-n-octylmethylammonium chloride, a quaternary ammonium salt, as an extractant and oleyl alcohol as a diluent. The kinetic analysis was performed through simulated time course studies of lactate concentration in both the extraction and stripping phases. Dependences of extraction rate on initial lactate and extractant concentrations and those of stripping rate on initial chloride and extractant-lactate complex concentrations were examined. Because diffusion through the organic film was a rate-controlling step, the experimental results of both extraction and stripping could be explained well by a simple equation.
[Show abstract][Hide abstract] ABSTRACT: Taken impurities in fermentation broth into account, effect of concentration of fish waste hydrolyzate (FWH) on lactic acid production was investigated in this study. The efficiency of the fermentation using 6.8% FWH as a nutrient source was competitive to that using 1.5% yeast extract (YE), however, with a result of much higher impurities in the fermentation broth due to the much larger amount of addition of FWH. Reducing the amount of FWH reduced the amount of impurities in fermentation broth, but the fermentation efficiency dropped significantly. In order not to make fermentation efficiency drop, spent cells obtained after each fermentation were combined with FWH and their joint effect on lactic acid production was investigated. Spent cells as sole nutrient source did not show good performance in lactic acid production. Contrarily, the combination of the two nutrient sources showed complementary effect and the fermentation with the combination had much higher efficiency than that of either of the two nutrient sources. When 1.7% FWH was combined with spent cells, the fermentation efficiency was similar to that using 1.5% YE and the impurities were also in appropriate values. Finally, the feasibility of the fermentation process with the combination was determined.
Biochemical Engineering Journal - BIOCHEM ENG J. 01/2007; 36(3):276-280.
[Show abstract][Hide abstract] ABSTRACT: In this study, two acid-hydrolysis processes, process A and process B, were proposed to produce low-cost nutrients for the production of lactic acid. Process A was a direct way to hydrolyze protein with diluted acid while process B was process A plus fish wastes pretreatment (an extraction by water). The two methods could both treat fish wastes to be suitable nutrient sources for promoting lactic acid production. As the pretreatment indicated some favorable effect on fish waste hydrolyzate (FWH), process B increased lactic acid productivity by 22%. Compared with 20 g/L yeast extract (YE), 6.8% FWH hydrolyzed by process B had more efficiency in lactic acid production, indicating that process B was suitable to produce high performance nutrients for lactic acid production and FWH hydrolyzed by process B would be an substitute for YE.
[Show abstract][Hide abstract] ABSTRACT: To reduce nutrient cost for lactic acid production, spent cells, a by-product in fermentation processes, were used as a nutrient source and the treatments of spent cells were investigated in this study. Untreated spent cells did not show significant effect on lactic acid production. After acid-hydrolysis, spent cells gave an increase in productivity to some extent, but the low glucose consumption indicated a nutrient limitation. The nutrient limitation was overcome easily by supplementing a small amount of yeast extract (YE). The combination of 5 g/L YE and the spent cell hydrolyzate (SCH) had high performance in lactic acid production relative to 15 g/L YE. Moreover, two kind of acid-hydrolysis methods, diluted acid based hydrolysis and concentrated acid based hydrolysis, were also compared. The diluted acid based hydrolysis had the advantages over the concentrated acid based one in lactic acid production due to its less nutrient destruction and lower salt inhibition. When diluted acid based SCH was supplemented, YE supplementation could be cut down to 20% with no significant decrease in productivity and yield.
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to investigate the decolorization behavior of Acid Orange 7 (AO7) with different dosages of co-substrates under granular activated carbon-biofilm configured packed column (BGAC-packed column) operation. The spent granular activated carbon (GAC) was immobilized with azo dye-degrading microbes through attachment and then the GAC-biofilm was packed into a column. The system was fed with 3 l of AO7-containing wastewater for operation time of 24 h/batch. With initial 500mg/l of AO7 concentration, it was observed that complete decolorization was achieved in all runs although the co-substrates added into the BGAC-packed column system reduced until to zero. The kinetic data obtained from the removals of AO7 and COD could be explained by the autocatalytic kinetic model and Monod kinetic model, respectively. INTRODUCTION Removing of dyes is a major concern when treating textile-processing wastewater. The vast majority (60-70 %) of the dyes applied in textile-processing industries are azo compounds, characterized by azo (N=N) bridges linking substituted aromatic structures (Carliell et al., 1995). The electron withdrawing character of the azo bond makes this class of compounds problematic for oxidative strategies of microbial degradation. Some azo dyes and their biotransformation products are toxic and carcinogenic (Brown and DeVito, 1993). Cytoplasmic azo reductases play an important role in the anaerobic biodegradation of azo dyes to produce colorless aromatic amines although complete mineralization is difficult. Once the xenobiotic azo component of the dye molecule has been removed, the resultant amino compounds are good substrates for aerobic biodegradation suggesting a choice of a sequential anaerobic–aerobic system for wastewater treatment (Banat et al., 1996; Robinson et al., 2001; Razo-Flores et al., 1997; Manu and Chaudhari, 2001; Ong et al., 2005a and 2005b). The addition of electron donors such as glucose or acetate ion apparently stimulated the reduction cleavage of azo bonds because the oxidation of these compounds produced electrons used for the formation of reduced cofactors (FAD, FMN and NADH) (Carliell et al., 1995; Bras et al., 2001). It is known that the co-substrate is an alternate growth substrate which when supplied to a bioreactor can enhance the degradation of some wastes or pollutants that cannot alone support the microbial growth (Atlas, 1993). Some researchers had observed that the decolorization of azo dyes follows the first-order kinetic model (Carliell et al., 1995; Van der Zee et al., 2001; Mechsner and Wuhrmann, 1982; Willetts and Ashbolt, 2000) whereas other researchers found zero-order kinetics (Brown et al., 1981; Dubin and Wright, 1975; Harmer and Bishop, 1992). Besides, the autocatalytic behavior was also reported by some researchers in the anaerobic biological degradation and chemical reduction of AO7. The autocatalytic nature is related to the generation of 1-amino-2-naphthol, an intermediate produced after anaerobic breakdown of dye, which acts as a redox mediator favoring the reduction of the dye (Mendez-Paz et al., 2003; Van der Zee et al., 2000). The aim of this study was to investigate the decolorization behavior of AO7 with different dosages of co-substrates under granular activated carbon-biofilm configured packed column (BGAC-packed column) operation. The kinetic models involved in the color and organic matter removals are analyzed with autocatalytic kinetic model and Monod kinetic model, respectively.
[Show abstract][Hide abstract] ABSTRACT: The objective of this study is to evaluate the decolorization of Methylene Blue (MB) by an up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor was operated under batch condition with total treatment volume of 3l and operation time of 24 h per batch. It was found that the color of MB disappeared within a few minutes after entering into the UASB reactor due to reduction by anaerobic biomass. However, the reduced MB was re-oxidized again by air after discharged from the reactor and thus caused low color removal efficiency. The presence of suitable amount of organic content (sucrose and peptone) as an electron donor played an important factor for color removal. It was observed that more than 90% of color removal efficiency was achieved in the UASB reactor with 0.627 mmoll(-1) of MB concentration and the presence of low amount of organic content (<0.45 g COD/(ld)). Biological dye reduction kinetics depends on the concentration of dye and reducing equivalents. The kinetic behavior of MB biodegradation by microbes was also investigated to determine the model involved in the process.
Journal of Hazardous Materials 10/2005; 124(1-3):88-94. · 3.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The performance of aerobic- and anaerobic-SBR in treating Orange II-containing wastewater was investigated. The result from a specific oxygen uptake rate (SOUR) study showed that the Orange II compound did not exert significant inhibitory effects on the activity of activated sludge microorganisms. It was found that Orange II and organic loading rates affected the treatment performance in terms of COD and Orange II removal efficiencies in the SBR systems. The increase of organic loading rate from 2.66 to 5.32 g COD/l day had slightly improved the COD removal efficiency in aerobic-SBR but deteriorated the COD removal efficiency in anaerobic-SBR. On the other hand, the increase of organic loading rate improved the Orange II removal efficiency in both SBR systems. In the case of 100 mg/l Orange II addition, the average fraction of Orange II removed was 15 and 80% in aerobic- and anaerobic-SBR, respectively. The anaerobic microbes exhibited five times higher Orange II removal rate compared to aerobic microbes.
Process Biochemistry 07/2005; · 2.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Micron-sized inorganic microparticles with hollow insides were prepared by interfacial reaction method, in which an ion exchange reaction between Na(+) and metal cations in internal and external aqueous phases, respectively, proceeded through the oil phase involving a cation carrier. The diameter of microballoons was approximately 10 microm and shell thickness was below 2 microm. The effects of preparation conditions against the formation of microballoons were examined. The factors examined were metal species in the external aqueous phase and the concentrations of metal chloride and cation carrier. The cross-section of microparticles formed was inspected by scanning electron microscope (SEM) and the inner space of some metal silicates was not hollow but filled-up. The increase of internal and external aqueous solution concentrations caused the increase of diameter and shell thickness of microballoons. Since the penetration of metal cation through the oil phase was promoted by the increase of carrier concentration, the formation of microballoons was completed in a short time of less than 30 min.
Journal of Microencapsulation 06/2005; 22(3):291-301. · 1.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The combination of up-flow anaerobic sludge blanket (UASB) and sequencing batch reactor was chosen as an anaerobic and aerobic system, respectively, in the treatment of Orange II-containing wastewater. The Orange II and COD removal efficiencies were improved in the UASB system when the operating temperature and hydraulic retention time were increased up to 30 °C and 48 h, respectively. Nearly complete decolorization (>95%) was accomplished in UASB system when working at 0.3 g/l d of Orange II loading rate at 30 °C with hydraulic retention time of 24 h. The electron-scanning microscope (SEM) photographs showed that there were discrepancies in the microorganism composition of the two systems, which was probably the main reason for different treatment performance in COD and Orange II removals in both systems.
Separation and Purification Technology 04/2005; · 2.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We studied the biodegradation of Orange II in a sequential anaerobic and aerobic-sequencing batch reactor system. Granular activated carbon was used either packed into a column or added directly into the anaerobic reactor to investigate the treatment performance between the two operation conditions. We found that the circulation of mixed liquor between the anaerobic reactor and the carbon-packed column enhanced the chemical oxygen demand from 28 to 52% and Orange II removal efficiencies from 88 to 96%, under simultaneous adsorption and biodegradation process. The morphology of microbes was observed under an electron-scanning microscope