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Infrastructure configurations for wastewater treatment and reuse: a simulation based study of membrane bioreactors
Abstract
Recent research on advanced wastewater treatment methods and techniques has generated a new set of technologies developed for use at anything from the household to the city scale. However, one of the central issues in the application of new technologies is the relevant scale at which to design and implement physical systems. This contribution reports the design and use of a demand based simulation model to study issues of appropriate scale and connectivity for a wastewater reuse system. The particular case of membrane bioreactors as treatment units to supply sub-potable demand is considered in detail. Results identify optimum levels of system connectivity and size with regard to both the cost of distributing recycled water and savings in potable quality resources.
... Can become complicated and expensive to control in hybrid arrangements Lihua et al. (2010), Yuasa (1998) , Ramli and Williams (2012), Jeffrey et al. 1998) Cost-effective option for water treatment, with low operating costs and minimal maintenance requirements May require pre-treatment of the feed water to remove larger particles, which can add to the overall cost of the treatment process Wang and Li (2018) Energy-efficient and do not require the use of chemicals, making them an environmentally friendly option Prone to membrane fouling, which can reduce the system's effectiveness and require additional maintenance Bhattacharya et al. (2013) Have a small footprint and require less space compared to other water treatment technologies, making it useful in areas with limited space May be prone to bacterial growth and contamination, which can lead to water quality issues if the system is not properly maintained Zhou and Smith (2002) Are user-friendly as they require minimal training to maintain and operate effectively. This makes them a convenient option for water treatment Although are highly effective at removing many types of contaminants from water, they may not be capable of removing certain dissolved gases that can significantly impact water's taste and odor Alexakis and Tsakiris (2013) Effective in removing turbidity and color from water, improving the aesthetic quality of the water May not be suitable for treating water with high levels of organic matter, which can lead to fouling and reduced effectiveness Mokhtar and Naoyuki (2012) Can be utilized in a range of applications, including treating drinking water, wastewater, and for various industrial processes May not be the best option for removing certain types of contaminants like minerals or dissolved solids from water. ...
The purification of water is not only essential for human consumption but is becoming a necessity considering the limited freshwater reserves of the planet. Over the last few decades advancements in material sciences and technology have paved the way for the development of novel purification techniques. Amongst these techniques membrane-based filtration is considered as the least expensive and most effective. These membrane-based filtration techniques can be broadly categorized into reverse osmosis (RO), ultrafiltration, microfiltration and activated carbon filters (ACF). The mode of operation, research evolution and practical applications of each technique are compared in this holistic analysis. Although RO is the oldest and most established membrane-based filtration technique in the literature, it is ACF that is ranked as the most promising new technique with much simplicity and effectiveness.
... Effluent of MBRs is normally free of bacteria [9,10] as the use of membranes retains almost all microorganisms (MO) in the bioreactor and the HRT, therefore, becomes completely independent on the sludge retention time [11] and can recover reusable water from permeate stream, thus reducing water consumption and minimizing effluent discharge [12][13][14]. With the high sludge concentration obtained and the retention of other macromolecules in the bioreactor, contact time of the activated sludge and pollutants is elongated, increasing the possibility and the efficiency of degrading the none-biodegradable pollutants [15], giving good conditions for the treatment of textile wastewater; that is high in color and low in BOD5/COD and one of the most difficult wastewaters to be treated [16]. ...
A laboratory scale aerobic membrane bioreactor (MBR) using a submerged microfiltration (MF); hollow-fiber membrane was used for treating wastewater polluted with azo dye acid orange 7 (AO7). Initial dye concentrations studied were from 50 to 400mg/l with a COD ranging from 95 to 550mg O2/l and hydraulic retention times (HRT) 4, 6, 8 and 24h. Results showed that the biological process was responsible for almost 60–80% of COD removal and almost all the removal of AO7 color. Membrane microfiltration merely balanced the unstable biological treatment of COD and demonstrated almost no contribution to AO7 color removal. Trans-membrane pressure (TMP) increased with time, and with the increase of dye concentration reaching a maximum of 4.175psi. Scanning electron microscope (SEM) images of the membrane’s filament were taken and compared with a SEM image of a virgin membrane; clear deformation in membrane’s pore structure could be noticed as well as scale formation on the outer surface of filaments, foulants were determined using the energy dispersive X-ray analysis (EDX).
The microbiological quality of water from a wastewater treatment plant that uses sodium hypochlorite as a disinfectant was assessed. Mesophilic aerobic bacteria were not removed efficiently. This fact allowed for the isolation of several bacterial strains from the effluents. Molecular identification indicated that the strains were related to Aeromonas hydrophila, Escherichia coli (three strains), Enterobacter cloacae, Kluyvera cryocrescens (three strains), Kluyvera intermedia, Citrobacter freundii (two strains), Bacillus sp. and Enterobacter sp. The first five strains, which were isolated from the non-chlorinated effluent, were used to test resistance to chlorine disinfection using three sets of variables: disinfectant concentration (8, 20 and 30 mg·L−1), contact time (0, 15 and 30 min) and water temperature (20, 25 and 30 °C). The results demonstrated that the strains have independent responses to experimental conditions and that the most efficient treatment was an 8 mg·L−1 dose of disinfectant at a temperature of 20 °C for 30 min. The other eight strains, which were isolated from the chlorinated effluent, were used to analyze inactivation kinetics using the disinfectant at a dose of 15 mg·L−1 with various retention times (0, 10, 20, 30, 60 and 90 min). The results indicated that during the inactivation process, there was no relationship between removal percentage and retention time and that the strains have no common response to the treatments.
In the present paper, we developed an accurate method for the analysis of alcohol sulfates (AS) in wastewater samples from wastewater treatment plant (WWTP) influents and effluents. Although many methodologies have been published in the literature concerning the study of anionic surfactants in environmental samples, at present, the number of analytical methodologies that focus in the determination of AS by gas chromatography in the different environmental compartments is limited. The reason for this is that gas chromatography-mass spectrometry (GC-MS) technique requires a previous hydrolysis reaction followed by derivatization reactions. In the present work, we proposed a new procedure in which the hydrolysis and derivatization reactions take place in one single step and AS are directly converted to trimethylsilyl derivatives. The main factors affecting solid-phase extraction (SPE), hydrolysis/derivatization and GC-MS procedures were accurately optimised. Quantification of the target compounds was performed by using GC-MS in selected ion monitoring (SIM) mode. The limits of detection (LOD) obtained ranged from 0.2 to 0.3 μg L(-1), and limits of quantification (LOQ) from 0.5 to 1.0 μg L(-1), while inter- and intra-day variability was under 5%. A recovery assay was also carried out. Recovery rates for homologues in spiked samples ranged from 96 to 103%. The proposed method was successfully applied for the determination of anionic surfactants in wastewater samples from one WWTP located in Granada (Spain). Concentration levels for the homologues up to 39.4 μg L(-1) in influent and up to 8.1 μg L(-1) in effluent wastewater samples.
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