Simultaneous Organic Matter Removal Research Articles

Performance of micro-pressure double-cycle coupled membrane integrated bioreactor for the treatment of urban sewage.

Based on the theory of nitrogen and phosphorus removal and technical requirements, a micro-pressure double-cycle bioreactor coupled with membrane components was used to treat municipal wastewater. The method realized the simultaneous removal of organic matter, nitrogen, and phosphorus in the same reactor and had the characteristics of membrane bioreactor process. Results showed that the average removal efficiency of COD, NH+4-N, TN, and TP were 93.74%, 95.1%, 71.85%, and 81.03%, respectively. During operation, Proteobacteria and Bacteroidetes were the main dominant bacteria, and they had complete nitrogen and phosphorus metabolic pathways. Owing to the low protein content in the mixture, the design of film placement in the micro-precipitation zone was conducive to alleviating the membrane pollution caused by the accumulation of protein, thereby improving the effluent quality and extending the service life of the membrane components.

Biodegradation and sorption of nutrients and endocrine disruptors in a novel concrete-based substrate in vertical-flow constructed wetlands

Removing phosphorus and endocrine-disruptors (EDC) is still challenging for low-cost sewage treatment systems. This study investigated the efficiency of three vertical-flow constructed wetlands (VFCW) vegetated with Eichhornia crassipes onto red clay (CW-RC), autoclaved aerated concrete (CW-AC), and composite from the chemical activation of autoclaved aerated concrete with white cement (CW-AAC) in the removal of organic matter, nutrients, and estrone, 17β-estradiol, and 17α-ethinylestradiol. The novelty aspect of this study is related to selecting these clay and cementitious-based materials in removing endocrine disruptors and nutrients in VFCW. The subsurface VFCW were operated in sequencing-batch mode (cycles of 48-48-72 h), treating synthetic wastewater for 308 days. The operation consisted of Stages I and II, different by adding EDC in Stage II. The presence of EDC increased the competition for dissolved oxygen (DO) and reduced the active sites available for adsorption, diminishing the removal efficiencies of TKN and TAN and total phosphorus in the systems. CW-RC showed a significant increase in COD removal from 65% to 91%, while CW-AC and CW-AAC maintained stable COD removal (84%–82% and 78%–81%, respectively). Overall, the substrates proved effective in removing EDC, with CW-AC and CW-AAC achieving >60% of removal. Bacteria Candidatus Brocadia and Candidatus Jettenia, responsible for carrying out the Anammox process, were identified in assessing the microbial community structure. According to the mass balance analysis, adsorption is the main mechanism for removing TP in CW-AC and CW-AAC, while other losses were predominant in CW-RC. Conversely, for TN removal, the adsorption is more representative in CW-RC, and the different metabolic routes of microorganisms, biofilm assimilation, and partial ammonia volatilization in CW-AC and CW-AAC. The results suggest that the composite AAC is the most suitable material for enhancing the simultaneous removal of organic matter, nutrients, and EDC in VFCW under the evaluated operational conditions.

Modeling of simultaneous carbon and nitrogen removal (SCNR) in an anaerobic/anoxic reactor treating salmon fishery wastewater

Mathematical modeling can help to clarify some aspects of the process that promote the simultaneous removal of organic matter and nitrogen (SCNR) from the fish processing industry wastewater that still require elucidation, such as the competition between methanogenic and denitrifying microorganisms for the substrate, for example. Therefore, the aim of this paper is to present the application of the Anaerobic Digestion Model No. 1 (ADM1) for modeling the SCNR process in a single stage anaerobic/anoxic reactor fed with a mix of a synthetic substrate and a saline protein-rich salmon processing industry. The ADM1 was not specifically developed for the treatment of this wastewater, therefore, initially, a parametric sensitivity analysis was performed to define the most sensitive parameters. The sensitivities were quantified in terms of the variation of measurable process variables under the perturbation of model parameters in their neighborhood domain. After this analysis, the model was calibrated and validated using previously published experimental data. Based on a sensitivity analysis, five parameters of the original ADM1 and of the denitrification processes were estimated using iterative methods, which optimized the parameters with experimental results. Namely: proteins hydrolysis constant (khyd,pr = 0.05 h−1); Monod maximum specific uptake rate for amino acids utilizers (km,aa = 1.87 h−1); half saturation value for amino acids utilizers (KS,aa = 0.23 kg COD m−3); Monod maximum specific uptake rate for acetate utilization rates by the denitrifiers (kno3,ac = 0.09 h−1) and half saturation value for the utilization of the acetate by the denitrifiers (KS,no3,ac = 0.38 kg COD m−3). Simulation with calibrated parameters indicated good agreement with experimental data, with the mean absolute error below 40 %. Considering these optimal values, the complete reduction of the oxidized forms of nitrogen occurred up to 11 h of reaction time. Cross-validation results indicated that the calibrated model was able to predict the experimental results of effluent COD, acetate, propionate, butyrate, nitrate and nitrite flows with good accuracy showing a mean absolute error below 40 % (19 %–36 %).

Scaling up 3D-printed urine microbial fuel cells with the membrane electrode assembly

Urine microbial fuel cells (MFCs) show potential for urine treatment to achieve simultaneous organic matter removal and electricity production. However, factors affecting the performance of urine MFCs during scaling up remain unclear. This study develops a 3D-printed air-cathode urine MFC with the membrane electrode assembly (MEA). After scale-up in parallel, unstable anode potential is responsible for the open circuit voltage (OCV) difference among various units, which leads to the energy loss in the system. For systems connected in series, unstable cathode potential mainly contributes to the voltage reversal, resulting in large power loss. Electrochemical impedance spectroscopy analysis indicates dramatically increased ohmic and polarization resistance in both serial and parallel systems. Bode plot further demonstrates after parallel connection, an obvious capacitance effect is observed, which provides evidence to illustrate the phenomenon of non-Faradaic current. Compared to serially connected systems, the capacitor of power management system can harvest more energy from systems connected in parallel. The microbial community analysis demonstrates Geobacter is the most dominant anodic electroactive bacteria both before and after scale-up. Overall, these results show the different strategic improvement should be executed while utilizing parallel connection (focusing on anode) or serial connection (focusing on cathode) to scale up urine MFCs.

Sustainable wastewater treatment using a new combined hybrid digester – Constructed wetland system

Constructed wetlands are one of the most promising decentralised wastewater treatment technologies for single-family homes, rural or peri-urban areas as well as for low-income areas. The present work reports for the first time the combination of a new hybrid anaerobic/anoxic digester (HD) as pre-treatment for a vertical subsurface constructed wetland (VF). Part of the nitrified VF effluent was recirculated to the HD to favour the simultaneous removal of organic matter and nitrogen, intensifying both the HD denitrification and VF nitrification processes. The results indicate that HD was the main responsible for the removal of suspended solids and organic matter, which was completed in the VF up to values always below the discharge limits. Nitrate removal ranged from 64 % to 94 % and ammonium removal from 64 % to 89 %, the former occurring mainly in the HD and the latter in the VF. The combined HD-VF system achieved high overall removal efficiency, reaching 98 % TSS, 94 % COD, 97 % BOD5, 86 % NH4+-N and 43 % TIN on average. Methane emissions were lower than those reported in the literature for CWs. The VF showed no signs of clogging. The system was operated in a sustained manner during a continuous period of 266 days with an average overall surface loading rate of 43.6 g BOD5 m−2 d−1 (range of 29–83 g BOD5 m−2 d−1). The total surface area required was 1.4 m2·equivalent inhabitant−1.

Enhanced Simultaneous Nitrogen and Phosphorus Removal Performance of the AGS-SBR Reactor Based on the Effects of the C/N Ratio and Microbial Community Change

In recent years, the development of AGS technology will likely lead to a new direction in wastewater treatment development in the future. Traditional sewage treatment technology has been unable to meet the increasingly strict quality standards of wastewater treatment and limited land requirements. AGS technology may be a new method to replace traditional sewage treatment technology. However, the stable operation of AGS technology is a major obstacle to the popularization and development of this technology. The C/N ratio is an important parameter affecting the stability and simultaneous nitrogen and phosphorus removal of AGS technology. In order to enhance the nitrogen and phosphorus removal capacity of a low-load aerobic granular sludge SBR (AGS-SBR) system, changes in the morphology, EPS, and simultaneous removal of organic matter, nitrogen, and phosphorus in the AGS system were studied by regulating different C/N ratios (20, 15, 10, 5). The changes in the microbial community in the system were deeply analyzed by high-throughput sequencing technology. The results showed that different C/N ratios have a significant effect on the nitrogen removal rate of AGS but have little effect on the removal rate of organic matter and phosphorus. When the C/N ratio was reduced to 10, it was conducive to the stability of the low-load AGS-SBR system. An effective C/N ratio promoted the secretion of EPS by microorganisms, and the increase in the PN value contributed to the stability of the granular sludge, which became smooth and compact. The main functional genus in the system were norank_f__Saprospiraceae, Tetrasphaera, Ellin6067, and Pseudomonas. In addition, the simultaneous nitrogen removal performance of the system was significantly improved.

Composite Polysilicate Metal Coagulants for Simultaneous Removal of Organic Matter, Phosphorus, and Ammonium-Nitrogen: Effects of Metal/Silicate Molar Ratio and Basicity

Coagulation can effectively recover substances from wastewater; however, there is a lack of efficient coagulants for simultaneous recovery of organic matter, nitrogen, and phosphorus. We prepared a composite polysilicate metal (CSM) flocculant by combining Fe3+ and Mg2+ ions in polysilicic acid (PSiA). According to the results of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), the CSM exhibited a larger amorphous phase along with new compounds, including Mg3Fe2(SiO4)3 and hydroxyl metals. The CSM demonstrated a higher coagulation efficiency than PSiA and polymeric ferric sulfate, particularly for PO43−-P and NH4+-N removal. The metal/silicate molar ratio substantially influenced the structure and composition of the CSM, along with the coagulation efficiency, with an optimal ratio of 3:1. Additionally, we proposed a novel preparation strategy to achieve an optimum CSM basicity (B*) for coagulation by adjusting the initial pH of PSiA (pHInitial) without adding an alkali agent. The results demonstrated that the optimum B* can be obtained by adjusting pHInitial to 0.5 or 1. The overall optimum coagulation performance for the simultaneous removal of organic matter, PO43−P, and NH4+-N from wastewater was 68.5%, 99%, and 17.5%, respectively. This study provides a feasible approach for synchronous pollutant recovery from wastewater.

Simultaneous methanogenesis and denitrification coupled with nitrifying biofilm for high-strength wastewater treatment: Performance and microbial mechanisms

A combined system consisting of an upflow blanket filter (UBF) and a moving-bed biofilm reactor (MBBR) was developed for the simultaneous removal of organic matters and ammonia from high-strength wastewater. With a constant COD of approximately 2000 mg/L and ammonium nitrogen in a series of concentrations (e.g., 50, 200 and 400 mg/L in stages I to III) of the influent wastewater, the removal efficiencies of COD, ammonium nitrogen and total nitrogen reached 96.10%-98.19%, 100%, and 79.12%-82.15%, respectively. With the increase of influent ammonia nitrogen concentration, the specific methanogenic activity of the UBF granules decreased significantly, while the specific denitrification rates of the UBF granules and specific nitrification rates of the MBBR biofilms increased significantly. Microbial community analysis showed that Methanobacterium and Methanosaeta were the dominant methanogens in the UBF granules, while Candidatus Competibacter, Thauera and Acinetobacter were identified as dominant denitrifiers. In addition, nitrifiers were enriched in MBBR biofilms at 11.33% and 13.87% of the average abundance of Nitrosomonas and Nitrospira, respectively, at stage III (influent ammonium at 400 mg/L, COD/NH4+-N = 5). The ecological network analysis, including full-networks and sub-networks, indicated that the interactions between methanogens and denitrifiers in the UBF granules were strong when the influent ammonium concentration reached 400 mg/L. No intensive interactions were observed among the functional bacteria in the MBBR biofilms over the entire operation. Overall, this study provides a new strategy for the application and construction of efficient biological processes to achieve simultaneous removal of organic matter and nitrogen for high-strength wastewater treatment.

Simultaneous Removal of Organic Matter and Nutrients from High Strength Organic Wastewater Using Sequencing Batch Reactor (SBR)

Industrial wastewater discharges often contain high levels of organic matter and nutrients, which can lead to eutrophication and constitute a serious hazard to receiving waters and aquatic life. The purpose of this study was to examine the efficacy of using a sequencing batch reactor (SBR) to treat high-strength organic wastewater for the removal of both chemical oxygen demand (COD) and nutrients (nitrogen and phosphorus). At a constant COD concentration of approximately 1000 mg/L, the effects of cycle time (3 and 9 h) and various C:N:P ratios (100:5:2, 100:5:1, 100:10:1, and 100:10:2) were investigated using four identical SBRs (R1, R2, R3, and R4). According to experimental data, a significant high removal, i.e., 90%, 98.5%, and 84.8%, was observed for COD, NH3-N, and PO43−-P, respectively, when C:N:P was 100:5:1, at a cycle time of 3 h. Additionally, when cycle time was increased to 9 h, the highest levels of COD removal (95.7%), NH3-N removal (99.6%), and PO43−-P removal (90.31%) were accomplished. Also, in order to comprehend the primary impacts and interactions among the various process variables, the data was statistically examined using analysis of variance (ANOVA) at a 95% confidence level, which revealed that the interaction of cycle time and C/N ratio, cycle time and C/P ratio is significant for COD and NH3-N removal. However, the same interaction was found to be insignificant for PO43−-P removal. Sludge volume index (SVI30 and SVI10) and sludge settleability were studied, and the best settling was found in R3 with SVI30 of 55 mL/g after 9 h. Further evidence that flocs were present in reactors came from an average ratio of SVI 30/SVI 10 = 0.70 after 9 h and 0.60 after 3 h.

Simultaneous removal of organic matter and nitrogen by heterotrophic nitrification–aerobic denitrification bacteria in an air-lift multi-stage circulating integrated bioreactor

This study aimed to propose a novel air-lift multi-stage circulating integrated bioreactor (AMCIB) to treat urban sewage. The AMCIB combined the reaction zone and sedimentation zone, the alternating circulation of activated sludge in separate aerobic and anaerobic environments facilitates the enrichment of HN-AD bacteria. The preliminary study showed that AMCIB had high removal efficiencies for COD, NH4+-N, TN and TP under high dissolved oxygen (DO) concentration conditions, with average removal rates of 93.21 %, 96.04 %, 75.06 % and 94.30 %, respectively. IlluminaMiSeq sequencing results showed that the system successfully cultured heterotrophic nitrification-aerobic denitrification (HN-AD) functional bacteria (Pseudomonas, Acinetobacter, Aeromonas) that played a crucial role in sewage treatment, and Tetrasphaera was the central phosphorus removing bacteria in the system. Functional gene predictions showed that the HN-AD played a dominant role in the system.

Formation and stability of aerobic granular sludge in a sequential batch reactor for the simultaneous removal of organic matter and nutrients from low-strength domestic wastewater

Simultaneous removal of organic matter, nitrogen, and phosphorus, via simultaneous nitrification and denitrification (SND) and enhanced biological phosphorus removal processes, was evaluated in a pilot-scale sequential batch reactor. The focus was on granule's morphology, stability, microbiological composition, and reactor performance while treating diluted domestic wastewater with total chemical oxygen demand (CODt) of ≈ 200 mg.L-1. The applied organic loading rate was 0.9 ± 0.3 kg CODt.m−3.d−1 in the experiment. Aerobic granular sludge developed gradually. After 87-day operation, granules (diameter ≥ 0.2 mm) were ≥ 50 % of the biomass, and after 168 days, complete granulation was obtained (≥ 80 % of biomass). In the third period (days 168–247, complete granulation), mixed liquor biomass reached a volatile suspended solids (VSS) concentration of 1.2 ± 0.3 g VSS.L−1, with the granules remaining stable until the experimental end. In this period, low effluent concentrations of COD, nitrogen (NH4+-N, NO2−-N and NO3−-N) and phosphate (PO43—P) were obtained (mg.L−1): 36 ± 11; 4 ± 5; 3 ± 3, 4 ± 5; and 0.9 ± 0.4, respectively. COD, NH4+-N, and PO43−-P removal efficiencies (%) were 80 ± 11; 83 ± 20; and 55 ± 24, respectively. Heterotrophic nitrification and SND were observed, resulting in a process efficiency of 31 % even with dissolved oxygen applied to saturation. The phosphate removal was mainly attributed to denitrifying phosphorus accumulating organisms. Pseudomonas, the dominant genus found, acted in nitrogen and phosphorus removal. Pseudoxanthomonas also assisted in phosphorus removal. Bacterial communities in the flocs (≈ 20 % of biomass) during the last period were similar to those in the granules; therefore, they constituted the basis for granule formation, directly contributed to the simultaneous good removal of organic matter and nutrients.

Coke-oven wastewater treatment in a dual-chamber microbial fuel cell with thiocyanate-degrading biofilm enriched at the air cathode

Abstract Coke-oven wastewater is usually treated with the activated sludge process, which requires large amounts of electrical energy for aeration and sludge disposal. A more sustainable treatment is strongly required. Recently, microbial fuel cells (MFCs) are focused as a technology for the production of electricity from wastewaters with simultaneous removal of organic matter. However, no MFC has been reported that can remove phenol, thiosulfate and thiocyanate simultaneously without aeration. Phenol can generally be removed well, whereas thiocyanate is relatively difficult to degrade. In this study, a dual-chamber MFC (D-MFC) was designed and equipped with a thiocyanate-degrading biofilm enriched on an air cathode. The D-MFC degraded phenol and thiosulfate in the anode chamber at the rate of 104 and 331 mg/L/day, respectively and subsequently degraded thiocyanate in the cathode chamber at the rate of 250 mg/L/day. The D-MFC showed high thiocyanate degradation rate. This suggests that pre-enrichment could accelerate thiocyanate degradation in MFC. In addition, thiocyanate degradation was not inhibited by phenol as thiocyanate was removed in the cathode chamber after phenol was removed in the anode chamber. This study demonstrated the feasibility of treating coke-oven wastewater by a D-MFC with a thiocyanate-degrading biofilm enriched at the air cathode.

Simultaneous removal of organic matter and nitrogen compounds by partitioned aeration in a 226 L-scale microbial fuel cell.

Although microbial fuel cells (MFCs) have been widely studied as wastewater treatment technologies that convert organic matter to electricity, there are few reports of large-scale MFCs that treat both organic matter and nitrogen compounds. In this study, a 226 L reactor equipped with 27 MFC units was partially aerated at 10% of its total volume. The MFC unit consists of a cylindrical air core covered with a carbon-based air cathode, an anion exchange membrane, and a graphite non-woven fabric anode. The air-cathode MFC with 13 L min−1 aeration rate produced a current density of 0.0012–0.15 A m−2 with 40 to >93% biological oxygen demand (BOD) removal to have an effluent BOD of <5–36 mg L−1 at a hydraulic retention time (HRT) of 12–47 h. Meanwhile, 55 ± 17% of the total nitrogen (TN) was removed, resulting in 9.7 ± 3.8 mg L−1 TN in the effluent, although the TN removal was limited at ≥20 °C. The mono-exponential regression for BOD and TN (≥20 °C) estimated that an HRT of 21 h could meet the Japanese effluent quality standards of BOD and TN. Calculation of the total energy recovered via current generation and energy consumed by aeration suggested an energy consumption of 0.22 kW h m−3. Decreasing the aeration rate and HRT in the reactor would further reduce energy consumption and increase energy production.

Model-based analysis of the effect of temperature in biological wastewater treatment plants for simultaneous removal of organic matter, nitrogen, and phosphorous

The effect of temperature on the phosphorous, nitrogen, and organic matter removal in an activated sludge system(ASS) has been assessed in this research. Benchmark Simulation Model No.1 (BSM1-P) with an ASS (ASM3bioP) is used and the temperature is chosen between 10 to 35°C. The kinetic expressions for the maximum growth rate of heterotrophic biomass, autotrophic, and phosphate accumulating organisms and their decay rates are considered. Total ammonia, nitrogen, and phosphorous in the effluent are analysed and when the range of temperature is less than 15°C and greater than 30°C, the effluent quality deviates from the legal requirements.

COD, nitrogen and phosphorus removal from simulated sewage in an aerobic granular sludge in the absence and presence of natural and synthetic estrogens: Performance and biomass physical properties assessment

In this research, the effect of two endocrine-disrupting chemicals (EDCs), namely 17β-estradiol (E2) and 17α-ethinylestradiol (EE2), on the simultaneous removal of organic matter, nitrogen and phosphate in an aerobic granular sludge (AGS) sequencing batch reactor (SBR) was addressed. The reactor operation was divided into Stage I (Control) and Stage II, with E2 and EE2 (20 µg L−1) added to the reactor influent only in the latter. The results showed that ammonium removal substantially dropped from 97% to 58% when the reactor was fed with EDCs. However, gradual recovery of nitrifying activity was observed, and complete ammonium oxidation was re-established. Phosphate removal also became unstable in the presence of EDCs, dropping from 100% to 67%. Nevertheless, the estrogens seemed to have only an initial adverse effect on polyphosphate accumulating bacteria, and P removal capacity was recovered. Regarding the granular biomass physical properties, a decrease in the granules average density was observed at the beginning of Stage II, a result associated with a slight disintegration of the granules surface, affecting their stability. Under these conditions, an increase in total proteins and polysaccharides within the biomass was also noticed. Nevertheless, the density of the granules quickly returned to the original values. These findings suggest an adaptation of the microorganisms harboured in the AGS system to the presence of EDCs.

Treatment of a slaughterhouse wastewater by anoxic-aerobic biological reactors followed by UV-C disinfection and microalgae bioremediation.

In this study, removal of organic matter and nitrogen from a cattle slaughterhouse wastewater was investigated in a two-stage anoxic-aerobic biological system, followed by UV-C disinfection. Ecotoxicity of the raw, biotreated, and disinfected wastewater against the microalgae Scenedesmus sp. was evaluated in short-term tests, while the potential of the microalgae as a nutrient removal step was addressed in long-term experiments. Throughout 5 operational phases, the biological system was subjected to gradual reduction of the hydraulic retention time (8-1.5day), increasing the organic (0.21-1.11kgCOD·m-3 ·day-1 ) and nitrogen (0.05-0.28kgN·m-3 ·day-1 ) loading rates. COD and total ammoniacal nitrogen (TAN) removal ranged within 83%-97% and 83%-99%, respectively. While providing alkalinity source, effluent TAN concentrations were below 5mg·L-1 . Nitrate was the main nitrification product, while nitrite levels remained low (<1mgN·L-1 ). Upon supplementation of external COD as ethanol, total nitrogen removal reached up to 90% at the highest load (0.28kgN·m-3 ·day-1 ). After UV-C treatment, 3-log reduction of total coliforms was attained. The 96-hr ecotoxicity tests showed that all non-diluted samples tested (raw, biologically treated and UV-C irradiated wastewater) were toxic to microalgae. Nevertheless, these organisms were able to acclimate and grow under the imposed conditions, allowing to achieve nitrogen and phosphorous removal up to 99.1% and 43.0%, respectively. PRACTITIONER POINTS: The treatment of a slaughterhouse wastewater in an anoxic-aerobic biological system followed by a UV-C disinfection step was assessed. The pre-denitrification system showed efficient simultaneous removal of organic matter and nitrogen from the wastewater under increasing applied loads. UV-C disinfection worked effectively in reducing coliforms from the biotreated effluent, boosting the performance of microalgae on nutrients removal. Despite the toxicity to microalgae, they were capable to acclimate to the aqueous matrices tested, reducing efficiently the nutrients content. The combined stages of treatment presented great capacity for depleting up to 97% COD, 99% nitrogen, and 43% phosphorous.

Model-based evaluation of algal-bacterial systems for sewage treatment

Many papers on wastewater treatment by algal-bacterial systems have been published. Current reactor models cannot model the simultaneous removal of organic matter, ammonium and phosphate from an algal-bacterial reactor. Because a powerful theoretical analysis platform is not available, how the consortia function in bioreactors is still not clear. In this study, the activated sludge model NO.3 was extended with a modified algal biokinetics for modeling wastewater treatment by algal-bacterial consortia. The applied model was calibrated and verified by experiments. The model shows that phosphate accumulating organisms (PAOs) and nitrifying bacteria consumed over 80% of phosphate and 60% of ammonium under different aeration conditions, respectively, whereas algae played a minor role in removing nutrients. In addition, the model shows that maintaining alkalinity at 1 mol/m3 (100 mg/L CaCO3) can significantly promote nutrient removal by increasing activities of PAOs and nitrifying bacteria, despite that algae consume less nutrients. Light intensity decreased quickly in suspended algal-bacterial consortia, which was accurately modelled. Compared with algae, bacteria played a more significant role in reducing light intensity. A defined light utilization efficiency decreased by 50% when doubling biomass concentration, showing that concentrated biomass should not be applied at large-scale when artificial illumination is applied. The model predicts that efficient wastewater treatment by algal-bacterial consortia at a biomass concentration of approximately 1 g/L can be achieved in eight hours under non-aerated conditions. This study proved that biological wastewater treatment by algal-bacterial consortia can be modeled, while heterotrophic bacteria, nitrifying bacteria, PAOs and algae simultaneously function in the consortia. The model can be a useful tool to study and optimize algal-bacterial reactors.

Treatment of Real Paper-Recycling Wastewater in a Novel Hybrid Airlift Membrane Bioreactor (HAMBR) for Simultaneous Removal of Organic Matter and Nutrients

In this study, a novel integrated Hybrid Airlift Membrane Bioreactor (HAMBR) composed of oxic, anoxic, and anaerobic zones was developed to simultaneously remove organic matter and nitrogen from real paper-recycling wastewater. The removal efficiencies of Chemical Oxygen Demand (COD), ammonium, nitrite, nitrate and Total Nitrogen (TN) for permeate and supernatant were in the range of 88-99%, 54-83%, 70-90%, 65-95% and 61-90%, respectively. In addition, the membrane fouling was evaluated by Trans-Membrane Pressure (TMP) monitoring during the experimental period at a constant flux of 12 L/m2h,and the rate of TMP increase was 1.75 mbar/day. The results showed that the hybrid airlift membrane bioreactor can be applied effectively to the simultaneous removal of organic and nutrient from real wastewater and the performance of the membrane bioreactor was satisfactory in terms of resistance against membrane fouling phenomenon, which is an important parameter during HAMBR operation.

Performance Evaluation of Microbial Fuel Cell Operated with Pd or MnO 2 as Cathode Catalyst and Chaetoceros Pretreated Anodic Inoculum

Abstract A microbial fuel cell (MFC) is a bioelectrochemical system that can recover bioelectricity from wastewater, with simultaneous organic matter removal from the wastewater. However, due to th...

Simultaneous removal of organic matter and nitrogen compounds from landfill leachate by aerobic granular sludge

ABSTRACT This study aimed at investigating the treatment of landfill leachate using the aerobic granular sludge process in a lab-scale sequential batch reactor (SBR-AGS). The leachate from a giant sanitary landfill localized in the State of São Paulo (Brazil) exhibited high concentration of organic matter (COD 5,300 ± 78 mg L−1) and total nitrogen (TKN 2,630 ± 355 mg L−1). Comparatively, the leachate was added to wastewater in three different volumetric ratios (5, 10 and 20%) and the mixtures were characterized over treatment. The results indicated that there were no significant changes in the behaviour of the biological process even at the highest leachate ratio. The granulation of the aerobic sludge occurred after 90 days of operation and the granules had a diameter of 485–1585 μm. SBR-AGS exhibited removal efficiency of 87–89% for organic matter and at least 98% for total nitrogen, regardless of the leachate ratio. The treated effluent that received 20% of leachate showed 2.7 mg L−1 ammonia and 1.1 mg L-1 nitrate. This study shows that SBR-AGS was able to form large granules, thus promoting a simultaneous nitrification and denitrification (SND) process. We highlighted that SND occurred in low dissolved oxygen concentrations (< 1.5 mg L−1) for 120 days, without compromising aerobic granule integrity. These results suggest that the aerobic granular sludge process is a promising alternative for the co-treatment of landfill leachate and domestic wastewater under tropical climate conditions and its use should be encouraged.