Simultaneous Chemical Oxygen Demand Removal Research Articles

Efficient simultaneous removal of nickel, phosphorus and COD from electroless nickel plating wastewater by three dimensional electrodialytic system

The simultaneous removal of nickel (Ni), phosphorus (P) and chemical oxygen demand (COD) from electroless Ni plating (ENP) wastewater by a three-dimensional electrodialysis (3D ED) system with graphite as the third electrode was investigated in this study. Compared to conventional two-dimensional electrodialysis (2D ED) system a significantly higher removal efficiency of complexed Ni, P and COD was achieved. The optimal process conditions were determined as dilution factor of 20, voltage of 20 V, treatment time of 10 h and particle electrode addition of 3 %, with removal rates of 95.8 %, 97.7 %, and 91.8 % for Ni2+, total phosphorus (TP) and COD, respectively. The decomplexed Ni2+ was recovered in the form of Ni(OH)2. Additionally, the mechanisms of enhanced ENP wastewater treatment was discussed and analyzed through SEM-EDS and XPS on solid and liquid products prior to and after treatment. This study provides crucial theoretical and practical support for the application of electrochemical technology in the treatment of ENP wastewater. It also offers new insights for achieving resource-efficient wastewater treatment and environmentally friendly electroplating industries.

Optimisation of electrochemical oxidation process with boron doped diamond (BDD) for removing COD, colour, ammonium, and phosphate in landfill leachate

ABSTRACT This study investigated the electrooxidation (EO) of mature landfill leachate from the Brady Road Resource Management Facility, Winnipeg (Canada). EO using boron-doped diamond (BDD) electrodes were applied to treat real landfill leachate using a batch reactor. Response surface methodology (RSM) was used to determine the optimum process parameter levels. This research mainly focused on how different current densities (64, 95, and 125 mA/cm2) and operational time (30 min, 1, 1.5, 2, 2.5, and 3 hr.) influenced the optimisation of parameters such as chemical oxygen demand (COD), colour, ammonium, and phosphate removal in mature landfill leachate at varied pH. To attain a high percentage of removal for the parameters mentioned above, the optimal conditions were found to be a current density (J) of 125 mA/cm2 and a pH of 8. The optimum conditions resulted in removal percentages of 95.47%, 80.27%, 71.15%, and 47.15% for colour, NH4 +, COD, and PO4 3- respectively, with an energy consumption of 0.05 kWh/dm3. The removal is related to a mechanism of the decomposition of water molecules to hydroxyl radicals and by direct anodic oxidation where the pollutants are transformed to CO2 and H2O. The novelty of this research lies in the optimisation of BDD electrode-based treatment for the simultaneous removal of COD, ammonium, phosphate, and colour from mature leachate collected from a severely cold climatic region of Canada. The BDD electrode showed excellent removal efficiencies for the targeted contaminants with lower energy consumption, making it a feasible method for on-site landfill leachate treatment.

Optimization of Simultaneous Nutrients and Chemical Oxygen Demand Removal from Anaerobically Digested Liquid Dairy Manure in a Two-Step Fed Sequencing Batch Reactor System Using Taguchi Method and Grey Relational Analysis.

The technological development for efficient nutrient removal from liquid dairy manure is critical to a sustainable dairy industry. A nutrient removal process using a two-step fed sequencing batch reactor (SBR) system was developed in this study to achieve the applicability of simultaneous removal of phosphorus, nitrogen, and chemical oxygen demand from anaerobically digested liquid dairy manure (ADLDM). Three operating parameters, namely anaerobic time:aerobic time (min), anaerobic DO:aerobic DO (mg L-1), and hydraulic retention time (days), were systematically investigated and optimized using the Taguchi method and grey relational analysis for maximum removal efficiencies of total phosphorus (TP), ortho-phosphate (OP), ammonia-nitrogen (NH3-N), total nitrogen (TN), and chemical oxygen demand (COD) simultaneously. The results demonstrated that the optimal mean removal efficiencies of 91.21%, 92.63%, 91.82%, 88.61%, and 90.21% were achieved for TP, OP, NH3-N, TN, and COD at operating conditions, i.e., anaerobic:aerobic time of 90:90 min, anaerobic DO:aerobic DO of 0.4:2.4 mg L-1, and HRT of 3 days. Based on analysis of variance, the percentage contributions of these operating parameters towards the mean removal efficiencies of TP and COD were ranked in the order of anaerobic DO:aerobic DO > HRT > anaerobic time:aerobic time, while HRT was the most influential parameter for the mean removal efficiencies of OP, NH3-N, and TN followed by anaerobic time:aerobic time and anaerobic DO:aerobic DO. The optimal conditions obtained in this study are beneficial to the development of pilot and full-scale systems for simultaneous biological removal of phosphorus, nitrogen, and COD from ADLDM.

Simultaneous removal of COD and NH4+-N from domestic sewage by a single-stage up-flow anaerobic biological filter based on Feammox

In recent years, Feammox has made it possible to remove NH4+-N under anaerobic conditions; however, its application in practical wastewater treatment processes has not been extensively reported. In this study, an up-flow anaerobic biological filter based on limonite (Lim-UAF) was developed to facilitate long-term and stable treatment of domestic sewage. Lim-UAF achieved the highest removal efficiency of chemical oxygen demand (COD) and NH4+-N at a hydraulic retention time (HRT) of 24 h (Stage II). Specifically, the COD and NH4+-N content decreased from 240.8 and 30.0 mg/L to about 7.5 and 0.35 mg/L, respectively. To analyze the potential nitrogen removal mechanism, the Lim-UAF was divided into three layers according to the height of the reactor. The results showed that COD and NH4+-N removal had remarkable characteristics in Lim-UAF. More than 55.0% of influent COD was removed in the lower layer (0–30 cm) of Lim-UAF, while 60.2% of NH4+-N was removed in the middle layer (30–60 cm). Microbial community analysis showed that the community structure in the middle and upper layers (60–90 cm) was relatively similar, but quite different from that of the lower layer. Heterotrophic bacteria were dominant in the lower layer, whereas iron-reducing and iron-oxidizing bacteria were enriched in the upper and middle layers. The formation of secondary minerals (siderite and Fe(OH)3) indicated that the Fe(III)/Fe(II) redox cycle occurred in Lim-UAF, which was triggered by the Feammox and NDFO processes. In summary, limonite was used to develop a single-stage wastewater treatment process for simultaneously removing organic matter and NH4+-N, which has excellent application prospects in domestic sewage treatment.

Evaluation of Contemporary Computational Techniques to Optimize Adsorption Process for Simultaneous Removal of COD and TOC in Wastewater

This study was aimed at evaluating the artificial neural network (ANN), genetic algorithm (GA), adaptive neurofuzzy interference (ANFIS), and the response surface methodology (RSM) approaches for modeling and optimizing the simultaneous adsorptive removal of chemical oxygen demand (COD) and total organic carbon (TOC) in produced water (PW) using tea waste biochar (TWBC). Comparative analysis of RSM, ANN, and ANFIS models showed mean square error (MSE) as 5.29809, 1.49937, and 0.24164 for adsorption of COD and MSE of 0.11726, 0.10241, and 0.08747 for prediction of TOC adsorption, respectively. The study showed that ANFIS outperformed the ANN and RSM in terms of fast convergence, minimum MSE, and sum of square error for prediction of adsorption data. The adsorption parameters were optimized using ANFIS-surface plots, ANN-GA hybrid, RSM-GA hybrid, and RSM optimization tool in design expert (DE) software. Maximum COD (88.9%) and TOC (98.8%) removal were predicted at pH of 7, a dosage of 300 mg/L, and contact time of 60 mins using ANFIS-surface plots. The optimization approaches showed the performance in the following order: ANFIS-surface plots>ANN-GA>RSM-GA>RSM.

Simultaneous Desalination and Removal of Recalcitrant Organics from Reverse Osmosis Leachate Concentrate by Electrochemical Oxidation.

Reverse osmosis (RO) concentrate produced in the municipal solid waste (MSW) leachate treatment process is extremely hard to be treated because of its high color, high salt content, and high concentration of recalcitrant organic compounds. A new multichannel flow reactor with electrode gaps of 5 mm was designed to desalinate and remove organics simultaneously from the RO leachate concentrate (ROLC) by electrochemical oxidation process using the RuO2/IrO2-coated titanium plate (RuO2/IrO2-Ti) as the anodes. The effects of the process parameters of current density (IA), superficial circulating velocity (UL), etc. on the removal efficiency (RE) of the chemical oxygen demand (COD) and average energy consumption () were investigated. The results illustrated that after 3 h of treatment, the RE of COD, Cl–, and color could reach as high as 96.5, 96.7, and 99.6%, respectively. Besides, the of the electrochemical oxidation treatment process is as low as 40.98 kWh/(kg COD), and a new mechanism of the simultaneous removal of COD and desalination has been proposed. This work provides an alternative technology for the treatment of MSW leachate RO concentrate.

Stepping Control of Electrochemical Process for Simultaneous Removal of COD and Ammonia with High Efficiency and Energy Saving

To maximize pollutant removal efficiency with minimal energy consumption, electrochemical process for wastewater treatment should be further conducted. The stepping control of electrochemical process for simultaneous removal of chemical oxygen demand (COD) and ammonia from simulated and actual wastewater with high efficiency and energy saving was studied in this work. Flow rate, initial pH value, Cl− concentration, and applied current density were determined to be the influencing factors for the degradation performance, and analyses of pollutant removal efficiency further revealed that applied current density was the significant parameter in this case. A stepping control system by operating applied current density timely based on the degradation pathway of organic matter and variation of anodic working potential was then proposed; results indicated that 90.9% COD and 100% ammonia could be removed, and energy consumption of 7.6 kWh m−3 was calculated, which was substantially lower than that of the traditional electro-oxidation system (11.7 kWh m−3). Additionally, the developed stepping control system was validated by treating an actual pharmaceutical wastewater, results for which showed that removal efficiencies of 81.7% and 100% were achieved for COD and ammonia, respectively, and energy saving could be up to 37.2%.

Treatment of coking wastewater in biofilm-based bioaugmentation process: Biofilm formation and microbial community analysis

Coking wastewater (CWW) containing complicated organic compositions and strong toxicity cause potential hazards to natural water bodies as well as human health. The aim of this study was integrating newly isolated Comamonas sp. ZF-3, biofilm-based bioaugmentation and fluidized bed reactor into an anoxic filter-fluidized bed reactor (AF-FBR) system to treat actual CWW. The results showed that 93 % of chemical oxygen demand (COD) and 97 % of ammonia nitrogen (NH4+-N) removal efficiency were achieved with hydraulic retention time of 70 h. The main pollutants including phenolic compounds, heterocyclic compounds and polycyclic aromatic hydrocarbons could be removed via biofilm-based process in AF-FBR. The formation of carrier biofilm was consistent with the system performance as well as the biofilm community evolution, during which the microbial community was gradually dominated by some functional genus (e.g., Comamonas, Thiobacillus, Pseudomonas and Thauera), meanwhile, ammonium-oxidizing bacteria Nitrosomonas, nitrite-oxidizing bacteria Nitrospira and denitrifiers (e.g., Pseudomonas, Thiobacillus and Bacillus) coexisted in biofilm to form a microbial community for biological nitrogen removal. Such microbial community structure explained the observed simultaneous removal of COD and NH4+-N in the AF-FBR.

The Evaluation of Simultaneous COD and Sulfate Removal at High COD/SO42− Ratio and Haloalkaline Condition

The effects of different electron donors on sulfate reduction at high COD/SO42− and haloalkaline conditions were investigated. For this purpose, the anaerobic submerged membrane reactor, fed with acetate and ethanol as an electron donor, was operated at a salinity of 10 g NaCl/L and a high pH (about 9.5) for 210 days. The bioreactor was inoculated with a mixed haloalkaliphilic culture and was enriched with saline soda from Lake Van, Turkey. The bioreactor’s performance was mainly evaluated with the removal of chemical oxygen demand (COD) and sulfate and changes in microbial community. A significant increase for both COD and sulfate removal was simultaneously achieved in the ethanol-fed bioreactor. The highest removal efficiency of COD and sulfate was about 70% and 80%, respectively, once the ratio of COD/SO42− was 6. The effect of hydraulic retention time on treatment performance of the bioreactor was inconsiderable as a result of the low flux during the whole operation time. There was no biogas production throughout the experiment due to the haloalkaline condition in reactor medium. From DGGE analysis, it was postulated that ethanol usage can cause bacterial abundance and diversity in bioreactor medium with no detection of sulfate-reducing bacteria.

Treatment of industrial effluents and assessment of their impact on the structure and function of microbial diversity in a unique Anoxic-Aerobic sequential batch reactor (AnASBR)

A novel Anoxic-Aerobic Process (AnAP) that eliminated the anaerobic process was optimized and operated for the simultaneous remediation of phosphate, nitrate, and chemical oxygen demand (COD) from industrial effluents. Two sequential batch reactors (SBR) with AnAP were established for the treatment of effluent from two industries; phosphate fertilizer (AnASBR_PPL) and dairy industry (AnASBR_DW). The adaptability of the bacterial consortium in the SBRs, dominated by denitrifying phosphate accumulating organisms (DNPAOs), facilitates the stable performance of AnAP for simultaneous nutrient and COD removal. Up to 90% and ~80% of COD removal were achieved in AnASBR_PPL and AnASBR_DW, respectively. Nearly complete denitrification was observed along with phosphate removal accounted for ~90% in both the reactors. Granulation of sludge has been widely reported in aerobic reactors; however, interestingly, in this study, partial granulation of the sludge was observed in both the AnASBRs which facilitated the microorganisms to uptake a minimal amount of phosphate and nitrate even under the aerobic condition. The underlying mechanism of DNPAOs and other associated microbes in the consortium were investigated for microbial diversity by 16S rDNA based targeted amplicon sequencing using the Illumina platform and imputed metagenomic analysis. The dominance of Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria, and Bacteroidia was observed in AnASBRs. At steady-state operation, the identity of the core community members remained largly stable, but their relative abundances changed considerably in both the reactors as a function of varying industrial effluent. However, population of few strains such as Lactobacteriales, Enterobacteriales changed drastically with respect to the influent, as these strains were predominat in AnASBR_DW but not present in AnASBR_PPL. The dominant strains were the vital contributor to the gene pool encoding for denitrification, dephosphatation, TCA cycle, glycolysis, EPS production, and polyhydroxyalkanoate (PHA) storage, etc. Few less abundant but persistent species were also detected as contributors to these functional groups. It unveiled the TCA cycle remains preferable over conventional glycolysis in both the SBR irrespective of carbon source. The new AnASBR was proved to be an efficient alternative system that is energy efficient with higher ease of operation for the treatment of different industrial effluents without fail.

Synergistic removal of cadmium and organic matter by a microalgae-endophyte symbiotic system (MESS): An approach to improve the application potential of plant-derived biosorbents

Plant-derived materials as environmentally friendly biosorbents to remove heavy metals from wastewater have been extensively studied. However, the chemical oxygen demand (COD) increase caused by the plant-derived biosorbent has not been considered previously. In this study, water hyacinth was used as biosorbent to remove Cd(II) from wastewater. About 66% of Cd(II) was removed by the biosorbent with a maximum biosorption capacity (qmax) of 21.6 mg g−1. However, the COD of the filtrate increased from 0 to 292 mg L−1 during this process. Subsequently, endophytes, microalgae and the microalgae-endophyte symbiotic system (MESS) were assessed for the simultaneous Cd(II) and COD removal. Among these three systems, the MESS achieved the best performance. After 3 d of inoculation, the extent of total Cd(II) removal increased to 99.2% while COD decreased to 77 mg L−1. This study provides a new insight into the application of a plant-derived biosorbent in combination with microalgae and endophytes for the effective treatment of heavy metal-bearing wastewater.

Simultaneous removal of COD and Ammoniacal Nitrogen from dye intermediate manufacturing Industrial Wastewater using Fenton oxidation method

The untreated wastewater from the dye industry having high ammoniacal nitrogen and chemical oxygen demand (COD) significantly pollutes the receiving water, such as a river, having major ill implications on the aquatic environment. The present study is undertaken to address this problem. It investigates the effectiveness of Fenton reagent in simultaneous treatment (removal) of ammoniacal nitrogen and COD present in the wastewater by varying the parameters like pH, concentration of Fe 2+ and H2O2 and their molar ratio. The reaction time for all the experiments was kept 60 min. The experimental analysis in terms of calculating the residual % of ammoniacal nitrogen and COD revealed that the maximum reduction occurred at pH 3. At this pH, further set of experiments were performed by varying the molar doses of Fe2+/H2O2 as 1:1, 3:3 and 5:5, and the results reveal that the maximum reduction in both ammoniacal nitrogen and COD happens at molar dose of 3:3. To understand the effect of the concentration of Fe2+ and H2O2 on the respective removal efficiency, set of experiments were performed by taking the molar ratio of Fe2+/H2O2 as 2:1, 3:1, 5:1, 1:2, 1:3 and 1:5. The experimental analysis reveals that the maximum reduction happened at molar ratio 1:3. Fenton process can mineralize the pollutants up to 75.8% and 78.6% for ammoniacal nitrogen and COD removal. The findings of the study would be of great use for planning and optimizing the wastewater treatment facility for the dye intermediate industry.

Electricity generation in fuel cell with light and without light and decomposition of tetracycline hydrochloride using g-C3N4/Fe0(1%)/TiO2 anode and WO3 cathode.

Visible-light-driven photocatalytic Fuel Cell (PFC) is of great interest in the environmental pollutant remediation with energy recovering. Herein, enhancement in photocatalytic degradation of Tetracycline Hydrochloride (TC) with electricity generation was achieved in a single reactor of PFC with paired stainless-steel mesh electrode loaded with anodic g-C3N4/Fe0(1%)/TiO2 and cathodic WO3 catalyst (at various pH, 0.05M Na2SO4, 10Ω external resistance) with visible light and without light. With light, TC molecules were successfully removed (97.3% in 90min, at initial and optimal pH 5), while generating 0.98V cell voltage and 24Wm-2 power density, simultaneous removal of COD (chemical oxygen demand) and TOC (total organic carbon) was 91.3% and 95%, respectively, suggesting superior mineralization that can be explained by the excitation of the anodic triple component g-C3N4/Fe0(1%)/TiO2. In contrast, without light, the removal of COD, TOC and the cell voltage were much lower (48.8%, 65.3%, 0.78V). In dark, the fuel cell is self-driven and self-biased, forming potential gradient and degrading pollutants. The effects of solution pH, initial TC concentration on degradation and power generation were evaluated. This PFC degrading TC can maintain high photocatalytic activity and high power output capacity after 5 cycles with light. Without light, the electricity generation capacity was 50-70% that in visible light PFC. These features reveal that fuel cell with g-C3N4/Fe0(1%)/TiO2 photo anode and WO3 photocathode has great application potential for removing refractory pollutants from wastewater.

Potential use of aquatic plants in constructed wetlands for simultaneous removal of Phosphate and COD from laundry wastewater

One component of household wastewater that has a bad impact on the environment is waste that comes from washing which uses detergent, due to a fairly high phosphate and chemical oxygen demand (COD) concentration. The purpose of this study was to determine the potential of using aquatic plants to reduce phosphate and COD levels from laundry waste. This research was carried out using constructed wetlands model of laboratory scale using the combination of flow types of subsurface flow systems (SFS) and the type of vertical flow system (VFS) with a waste residence time of 5 days and 10 days. Based on the results, for model I, the average percentage of COD levels reduction is 67.62% and phosphate is 13.89%, while in model II, the average percentage of COD reduction is 59.93% and phosphate is 14.36%, after 10 days of waste residence time. Aquatic plants used in the modeling of constructed wetland can grow and reproduce well, this can be indicated by the growth of new shoots and flowers of these plants.

Anaerobic treatment of blended sugar industry and ethanol distillery wastewater through biphasic high rate reactor

ABSTRACTThis study aimed to investigate the physicochemical properties of sugar industry and ethanol distillery wastewater and the treatment of the blended wastewater through a two-stage anaerobic reactor. For this treatment, different initial chemical oxygen demand (COD) concentrations (5–20 g/L) and hydraulic retention times (HRTs) (2–10 days) were applied. The sugar industry effluent characteristics obtained in terms of organic matter (mg/L) were as follows: 5 days biochemical oxygen demand (BOD5): 654.5–1,968; COD: 1,100–2,148.9; total solids (TS): 2,467–4,012 mg/L; and pH: 6.93–8.43. The ethanol distillery spent wash strengths obtained were: BOD5: 27,600–42,921 mg/L; COD: 126,000–167,534 mg/L; TS: 140,160–170,000 mg/L; and pH: 3.9–4.2. Maximum COD removal of 65% was obtained at optimum condition (initial COD concentration of 10 g/L and HRT of 10 days), and maximum color removal of 79% was recorded under similar treatment conditions. Hence, the performance of the two-stage anaerobic reactor for simultaneous removal of COD and color from high-strength blended wastewater is promising for scaling up in order to mitigate environmental problems of untreated effluent discharge.

COD and colour removal from molasses spent wash using activated carbon produced from bagasse fly ash of Matahara sugar factory, Oromiya region, Ethiopia

The aim of this study was to investigate the removal of chemical oxygen demand (COD) and colour from a melanoidin solution using activated carbon produced from bagasse fly ash (BFA). Melanoidins are heterogeneous polymers and major contributors to the dark brown colour of molasses spent wash, which is an extensive cause of environment pollution. The surface area of the BFA was determined as 160.9 ± 2.8m²/g with 90% of particle less than 156.8 μm in size. Characterization of the BFA by Fourier transform infrared spectroscopy (FTIR) showed the presence of hydroxyl and carbonyl functional groups, whereas X-ray diffraction analysis indicated its amorphous nature. Moreover, scanning electron microscopy analysis showed a heterogeneous and irregular shape of pores. Among the adsorption isotherm models analysed, the Freundlich model fitted best to the experimental data, indicating a maximum adsorptive capacity of 124.80 mg/g. The removal of COD and colour from a melanoidin solution with this activated carbon was carried out using an experimental design taking 4 factors into account. These were adsorbent dose, contact time, pH and initial COD concentration, with removal of COD and colour as response variables. COD reduction was influenced by initial COD concentration whereas colour removal was dominated by contact time, which was in line with the findings of principal component analysis . The maximum COD removal recorded was 61.6% at the optimum condition of adsorbent dose of 4 g in 100 mL, contact time of 4 h, pH 8 and initial COD concentration 6 000 mg/L, whereas the decolourization of melanoidin solution was 64% at adsorbent dose of 4 g, contact time 4 h, pH 3 and initial COD concentration 6 000 mg/L. Hence, activated BFA is a promising option for simultaneous removal of COD and colour from molasses spent wash under the stated conditions.Keywords: adsorption; factorial design; distillery spent wash; melanoidins; optimization; COD and colour removal

Simultaneous chemical oxygen demand removal, methane production and heavy metal precipitation in the biological treatment of landfill leachate using acid mine drainage as sulfate resource

Biological treatment played an important role in the treatment of landfill leachate. In the current study, acid mine drainage (AMD) was used as a source of sulfate to strengthen the anaerobic treatment of landfill leachate. Effects of chemical oxygen demand (COD) and SO42- mass concentration ratio on the decomposition of organic matter, methane production and sulfate reduction were investigated and the microbial community was analyzed using the high throughout methods. Results showed that high removal efficiency of COD, methane production and heavy metal removal was achieved when the initial COD/SO42- ratio (based on mass) was set at 3.0. The relative abundance of anaerobic hydrogen-producing bacteria (Candidatus Cloacamonas) in the experimental group with the addition of AMD was significantly increased compared to the control. Abundance of hydrogenotrophic methanogens of Methanosarcina and Methanomassiliicoccus was increased. Results confirmed that AMD could be used as sulfate resource to strengthen the biological treatment of landfill leachate.

Mathematical modeling assisted investigation of forward osmosis as pretreatment for microbial desalination cells to achieve continuous water desalination and wastewater treatment

Coupling forward osmosis (FO) with microbial desalination cells (MDCs) can lead to some synergistic benefits, i.e. simultaneous water recovery, desalination and removal of COD (chemical oxygen demand). Herein, an FO-MDC system was developed and examined in a continuously-operated mode. It achieved 70.6% COD removal from a synthetic wastewater and 94.0% conductivity decrease in a salt solution containing 35gL−1 NaCl. The flow rates of both wastewater and salt water exerted strong effects on the system performance. At a draw flow rate of 0.02mLmin−1, the effluent TDS (total dissolved solids) reached 315mgL−1, lower than the maximum contaminant levels of the National Secondary Drinking Water Regulations. A mathematical model was developed for the first time through integrating FO model with MDC model. This model could well predict the key performance parameters such as current generation and desalination effectiveness and rate. When further tested with actual domestic wastewater amended with glucose and NaHCO3, the FO-MDC system generated a desalinated effluent containing 1130mgTDSL−1. The results of this study suggest that proper coordination of the treatment capacity of the two membrane-based treatment processes could create a potentially effective system for wastewater reuse and seawater desalination.

Granulation of Non-filamentous Bulking Sludge Directed by pH, ORP and DO in an Anaerobic/Aerobic/Anoxic SBR.

In an anaerobic/aerobic/anoxic (A/O/A) sequencing batch reactor (SBR), non-filamentous bulking sludge granulated after the adjustment of cycle duration and influent composition directed by pH, oxidation-reduction potential (ORP) and dissolved oxygen (DO). The turning points and plateaux of pH, ORP and DO profiles indicated the end of biochemical reactions, such as chemical oxygen demand (COD) consumption, P release, ammonium oxidation, P uptake and denitrification. The difference of nutrient concentration between the beginning and turning points represented the actual treatment capability of the sludge. Non-filamentous bulking with SVI30 of 255 mL g(-1) resulted in a huge biomass loss. After regulation, the cycle duration was shortened from 310 to 195 min without unnecessary energy input. In addition, the settling ability was obviously improved as SVI30 reduced to 28 mL g(-1). Moreover, matured granules with an average diameter of 600 μm were obtained after 45 days, and simultaneous COD, ammonium and phosphate (P) removal was also realized after granulation.

Effect of Nitrogen Concentration on the Performance of Single-Chamber Microbial Fuel Cells

The nitrogen removal in wastewater using single chamber microbial fuel cells is an interesting process. The nitrogen removal from nitrogen wastewater was examined using single chamber air cathode microbial fuel cells (SC-MFCs). SC-MFCs were fed with synthetic wastewater containing the initial chemical oxygen demand (COD) 1,000mg L-1 and nitrogen (N) 125, 250, 625, and 875 mg-N L-1, respectively and operated under mesophilic batch mode. Performance of SC-MFCs with external resistances 1,000Ω was based on maximum power density, COD and nitrogen removal. The SC-MFCs with ammonia-N concentration 625 mg-N L-1 gained higher maximum power density by 160 mW m-2.The ammonium removal was 58%. The results suggested that SC-MFCs are potential technology for simultaneous nitrogen and COD removal; and electricity generation.