Total COD Removal Efficiency Research Articles

Improving methane production and 4-chlorophenol removal in anaerobic digestion of corn straw by adding Phanerochaete chrysosporium and biochar under microaerobic conditions

The stable lignocellulose structure in the straw is the main obstacle for methane production during its anaerobic digestion, and the residual chlorophenols in the straw further increase the difficulty. In this study, the anaerobic digestion of corn straw containing 4-chlorophenol was enhanced by the addition of Phanerochaete chrysosporium and biochar. The results revealed that P. chrysosporium significantly increased the soluble COD concentration and total COD removal efficiency in the anaerobic digestion of corn straw, which initially contained a small amount of residual oxygen (4.1–4.5 mg/L). The accumulative methane production of the P. chrysosporium-coupled biochar (PC-BC) group and the PC group with P. chrysosporium alone were 232.9 ± 3.0 mL and 201.7 ± 5.1 mL, respectively, which were significantly higher than the control group (19.4 ± 1.0 mL) with the sterilized P. chrysosporium. The presence of biochar increased 4-CP removal rate to 93.3 %, which was 15.2 % higher than the control. Additionally, FTIR analysis indicated that the addition of P. chrysosporium and biochar enhanced the decomposition of lignocellulose structure. Moreover, the sludge capacitance and electron transfer capacity were highest in the PC-BC group. Also, microbial community analysis showed that biochar could enrich dechlorinating bacteria (e.g., Sedimentibacter) and electroactive microorganisms, which further enhanced dechlorination and methanogensis.

Enhanced Organics Removal Using 3D/GAC/O3 for N-Containing Organic Pharmaceutical Wastewater: Accounting for Improved Biodegradability and Optimization of Operating Parameters by Response Surface Methodology

Pharmaceutical industry effluents often contain high concentrations of refractory organic solvents, chemical oxygen demand (COD), and total dissolved solids (TDSs). These wastewaters, including N-containing organic solvents known for their persistence and toxicity, pose significant environmental challenges. The study evaluated the efficacy of 3D/Granular Activated Carbon (GAC)/O3 treatment compared to linear process additions when treating real pharmaceutical wastewater, and revealed a 2.73-fold enhancement in COD mineralization. The process primarily involves the direct oxidation of monoprotic organic acids found in real pharmaceutical effluents, such as acetic and formic acid, crucially influencing mineralization rates. Optimal conditions determined via the response surface methodology were 125 g/L GAC, 30 mA/cm2, and 75 mg/L O3, achieving high total organic carbon (TOC) and COD removal efficiencies of 87.19 ± 0.19% and 89.67 ± 0.32%, respectively (R2 > 0.9), during verification runs. Current density emerged as the key parameter for organic abatement, aligning with the emphasis on direct oxidation at the anode surface. This integrated approach enhances biodegradability (BOD5/COD) and reduces acute toxicity associated with persistent N-containing solvents, demonstrating promising applications in pharmaceutical wastewater treatment.

Fe(II)/Fe(III) cycle actuating a novel process to remove organics in waste pit mud from Maotai: Performance and mechanism

In this study, a novel method relying on iron cycle through intermittent aeration was proposed to treat organic matter in waste sealed pit mud from Moutai. Firstly, ferrihydrite was used to verify dissimilatory iron reduction could remove organics from the pit mud; then, the effect of iron cycle induced by intermittent aeration on organics was investigated. The results showed that the removal efficiency of organics was increased by 8.2 % after the addition of ferrihydrite, then intermittent aeration was carried out, Fe(II) content decreased after aeration and increased again after stopping aeration, indicating that iron cycle occurred. Additionally, the total chemical oxygen demand (TCOD) content further decreased by18.8 % in the reactor with intermittent aeration, significantly higher than that in the unaerated group (11.8 %) (p < 0.05). Due to the short aeration time (about once a week, 200–500 mL/min, 30 min for each aeration), aerobic microorganisms were undetected, which further indicated that iron cycle enhanced the removal of organics. Finally, intermittent aeration was conducted in the fermentation system of pit mud without adding iron, and the indigenous iron in the pit mud was also recycled. After 31 days, the TCOD removal efficiency increased by 15.6 % in the aeration group compared with that in the control group. Microbial analysis showed that some microorganism that degraded refractory organics, including iron reducing bacteria, were enriched in the aerated reactors, such as WCHB1–32, ADurb. bin053–1, Lentimicrobium, and Aneurinibacillus, Geobacteraceae. These indicated that organic matter removal can be enhanced by relying on its indigenous iron.

Optimizing hydraulic retention time of high-rate activated sludge designed for potential integration with partial nitritation/anammox in municipal wastewater treatment

The integration of high-rate activated sludge (HRAS), an effective carbon redirection technology, with partial nitritation/anammox (PN/A) is a novel AB treatment process for municipal wastewater. In this study, an airlift HRAS reactor was operated in the continuous inflow mode for 200 d at a wastewater treatment plant. The balance between potential PN/A system stability and peak HRAS performance under decreasing hydraulic retention time (HRT) was optimized. Energy consumption and recovery and CO2 emissions were calculated. The results showed that the optimal HRT suitable with the PN/A process was 3 h, achieving 2–3 g/L mixed liquor volatile suspended solid, 67.8 % chemical oxygen demand (COD) recovery, 81 % total COD removal efficiency, 2.27 ± 1.03 g COD/L/d organic loading rate, 62 % aeration reduction, and 0.24 kWh/m3 power recovery potential. Such findings hold practical value and contribute to the development of the optimal AB process capable of achieving energy autonomy and carbon neutrality.

Elucidating the role of ferric chloride on carbon capture from low-strength municipal wastewater in high-rate activated sludge process: Parameter optimization and crucial mechanism

To enhance organics capture efficiency from low-strength municipal wastewater of China, FeCl3 enhanced high-rate activated sludge (FC-HRAS) process was established in this work. Effects of sludge concentration and FeCl3 dosage on carbon capture in FC-HRAS were investigated. The optimum sludge concentration of 2.0 g/L and FeCl3 dosage of 30 mg Fe/L were obtained, with total COD removal efficiency of 76.8%. Carbon balance analysis showed that FC-HRAS increased organics capture proportion by 91.8% while reducing loss from oxidative metabolism compared to HRAS. The potential mechanism of enhanced carbon capture for FC-HRAS was further explored. Adding Fe(III) caused coagulation of organics by increasing the Zeta potential in wastewater. Impacted by charge neutralization “compression” and coagulation floc “encirclement”, sludge particle sizes decreased, leading to increases of internal surface area and adsorption site of sludge for binding with bacteria; it facilitated the biological flocculation of FC-HRAS. Meanwhile, Fe(III) binding with proteins in EPS induced formation of “protein shell – β polysaccharides kernel” sludge structure and reduction of sludge negative charge, which intensified sludge stability and agglomeration. These factors explained the increase in organics capture proportion. The decrease in metabolism loss of organics could be attributed to the increase in organics transfer resistance in sludge EPS and selective elimination of heteromorphic bacteria (e.g., denitrifiers) in sludge. This work provided guidance for energy-neutral and cost-saving wastewater treatment in China.

Sludge floc characteristics and microbial community in high-rate activated sludge and high-rate membrane bioreactor for organic recovery

High-rate activated sludge (HRAS) and high-rate membrane bioreactor (HRMBR) are considered as potential processes for organic recovery through bioflocculation and biosorption of particulate COD and colloidal COD with sludge flocs. In this study, bioflocculation and biosorption, in terms of sludge floc characteristics and microbial community, in HRAS and HRMBR was investigated in relation to organic recovery performance for low strength wastewater treatment. HRAS and HRMBR were operated at two different solids retention times (SRTs) of 2 and 0.8 days. Reducing the SRT of HRAS from 2.0 to 0.8 days resulted in failure in total COD (tCOD) removal efficiency (from 79 ± 2 to 34 ± 13 %) and lowering organic recovery (from 40.8 to 15.7 %). This contrasted with HRMBR, which showed high tCOD removal efficiency (84 ± 2 and 84 ± 1 %) and organic recovery (43.4 and 46.3 %) at both SRTs of 2.0 and 0.8 days. Analysis of sludge floc characteristics showed that the lower organic recovery of the HRAS operated at an SRT of 0.8 days could be associated with poor bioflocculation and biosorption, as evidenced by relatively larger floc size, higher extracellular polymeric substance, higher protein/polysaccharide ratio, and higher zeta potential value of the sludge. These characteristics were in contrast to the HRMBR operated at an SRT of 0.8 days, that exhibited the highest organic recovery among the reactors studied. The microbial taxa Bdellovibrio, Clostridium sensu stricto 9, Hyphomicrobium, and Ideonella could play a role in the poor bioflocculation and biosorption in HRAS. Rhodanobacter, Enterobacter, Terrimonas, Nakamurella, and Mizugakiibacter may be associated with bioflocculation and biosorption and organic recovery in HRMBR. The results of this study enhanced our understanding on the relationships between the microbial community, sludge floc characteristics, and organic recovery performance of HRAS and HRMBR for future optimization of the systems.

Overall evaluation of a multi-stage reverse electrodialysis reactor series system for organic wastewater treatment and power generation

A multi-stage reverse electrodialysis reactor (REDR) series system for organic wastewater treatment and power generation is proposed in this paper. An energy evaluation method is developed for the first time by analyzing the electrical energy and oxidative degradation energy conversion efficiencies of the system. The influences of the current and feed solution velocity on the overall performances of the system are investigated by experiments. Results demonstrate that a high current can enhance the gross output power but reduce the net output power and total energy conversion efficiency. A peak value of the total COD removal can be obtained at an appropriate current. A low feed solution velocity can improve the performance of the system except for the lower net output power. Although the electrical energy conversion efficiency reduces as the serial number of REDR increases, the oxidative degradation energy conversion efficiency increases significantly, which results in the total energy conversion efficiency enhancement. Under the given experimental conditions, the maximal values of the net output power, total COD removal and total energy conversion efficiency are 1.05 W, 450.98 mg·L−1, and 11.41%, respectively.

Retrofitting a full-scale multistage landfill leachate treatment plant by introducing coagulation/flocculation/sedimentation and ultrafiltration process steps.

Considering that landfilling still remains among the most commonly used methods for the confrontation of solid wastes, effective methods should be applied to treat the leachate generated, due to its recalcitrant nature. In this work, a full-scale system consisting of two SBRs operating in parallel (350 m3 each) and two activated carbon (AC) columns operating in series (3 m3 each) was retrofitted by introducing a coagulation/flocculation/sedimentation (C/F/S) unit of 7.8 m3 and an ultrafiltration (UF) membrane of 100 m2 to effectively treat landfill leachate. The raw leachate was characterized by high COD and NH4+-N concentration, i.e., 3095 ± 706mg/L and 1054 ± 141mg/L respectively, a BOD/COD ratio of 0.22, and high concentrations of certain heavy metals. Leachate processing in this retrofitted multistage treatment system resulted in total COD removal efficiency of 89.84%, with biological treatment, C/F, UF, and AC contributing 46.31%, 4.68%, 15.98%, and 22.87% to the overall organic content removal. The retrofitted scheme achieved an overall NH4+-N and TKN removal of 92.03% and 91.75% respectively, attributed mostly to the activity of an effective nitrifying community. Color number (CN) was reduced by 26.96%, 10.29%, 15.94%, and 5.39% after the activated sludge, the C/F, the UF, and the AC adsorption process respectively, corresponding to a 58.91% overall decrease. Regarding heavy metal removal, all elements examined, apart from Ni, i.e., effluent As, Cd, Co, Cr, Cu, Hg, Mg, Mn, and Pb, were below the legislative limits set by the national authorities for restricted or unrestricted irrigation. Lastly, total operating expenses (OPEX) were estimated as equal to 72,687 €/year or 6.64 €/m3.

Solid slow-release carbon source assembled microbial fuel cell for promoting superior nitrogen removal in an aerobic granular sludge bioreactor

Although the coupling process of microbial fuel cell (MFC) and activated sludge is widely used for organic matter removal and electric energy recovery, the problem of high effluent nitrate still exists due to the lack of influent carbon source. Herein, a poly (butanediol succinate) (PBS) assembled MFC was established in an aerobic granular sludge (AGS) bioreactor for simultaneous promoting nitrogen removal and electricity generation. Compared to AGS-Control group, the total inorganic nitrogen (TIN) and COD removal efficiencies of AGS-MFC group were improved to 84.3 ± 2.6% and 93.5 ± 0.5% after 100-days operation. The average output voltage and the maximum power density of the MFC module were 223.7 mV and 59.6 mW/m2, respectively. Through high-throughput sequencing analysis, Thauera-related denitrifying bacteria had the highest relative abundances (20.0% and 31.4%) in both bioreactors. The relative abundance of Nitrosomonas-related ammonia oxidizing bacteria (AOB) in AGS-MFC (1.8%) was enriched than AGS-Control (1.1%). In MFC module, Thauera (16.2%) with denitrification and power generation was dominant in anodic biofilms under PBS enhancement. This study provides scientific basis for the application of submersible MFC enhanced deep nitrogen removal under aerobic conditions.

Recovery of microbial fuel cells with high COD molasses wastewater and analysis of the microbial community

The microbial fuel cell (MFC) is a green technology that can be used to simultaneously degrade organics and generate energy. In this work, a double-chamber microbial fuel cell (DCMFC) was used to treat molasses wastewater with different concentrations, in batch tests. The results demonstrated that when the COD of the influent wastewater was low (3630 mg/L), the MFC system ran stably for 12 h, the maximum power density reached 3.28 W/m3, the internal resistance was 94 Ω, and a total COD removal efficiency of 88.5% was obtained at the end of the cycle. However, as the influent increased to 9060 mg/L, the performance of the MFC significantly declined due to the accumulation of volatile fatty acids (VFAs) and low pH. Interestingly, 10 days later the MFC system began to recover: output voltage increased from 209 to 535 mV, VFA declined from 2428.25 to 0 mg/L, and pH increased from 4.83 to 6.98. The microbial diversity of the biofilm on the anode was also investigated using high-throughput sequencing technology in order to clarify the effect of microbials on the treatment efficiency. The dominant microbial genera, such as Azospirillum, Sulfuricurvum, Syntrophomonas and Curvibacter, are highly related to the electron transfer and VFA degradation. In addition, Geobacter found on the carbon felt was responsible for electricity generation. These results demonstrate that MFCs could be an efficient way to treat molasses wastewater, because of its great self-recovery capability.

Addition of biomass ash as a promising strategy for high-value biohythane production from the organic fraction of municipal solid waste

In this work, the effect of adding ash from combustion of six locally available biomass types, namely common reed (Phragmites australis), corn stover, eucalyptus sawdust, hazelnut shells, pine chips, and rice husks at different concentrations (2.5, 5, 10, and 20 g/L) on H2 production from the organic fraction of municipal solid waste (OFMSW) was first investigated through batch experiments. The maximum cumulative H2 production of 1124 ± 3.21 mL was achieved using 5 g/L of rice husk ash (RHA), increasing by 644% compared to the control. Then, in a semi-continuous two-stage biohythane production process, the first reactor dedicated to H2 production was supplemented with 5 g/L of RHA and its performance was evaluated at three HRTs (3, 2, and 1 day). The results showed that the highest steady-state volumetric H2 production rate (554 ± 5.48 mL/L/d) and H2 yield (184.7 ± 1.83 mL/g-VSadded) were obtained at 2-day HRT. In the subsequent CH4 production stage, of the three HRTs tested (12, 8, and 4 days), the 12-day HRT resulted in a maximum volumetric CH4 production rate and CH4 yield of 321 ± 2.39 mL/L/d and 727.2 ± 5.46 mL/g-VSadded, respectively, under steady-state conditions. Throughout both stages, the pH remained within a suitable range without the addition of any commercial reagents. The overall energy yield of the two-stage process was found to be 31.2 kJ/g-VSadded, which corresponded to a total COD removal efficiency of 96%. Moreover, the composition of biohythane (H2 + CH4) obtained met the standards of a clean hythane fuel.

Evaluation of Sand Filtration and Activated Carbon Adsorption for the Post-Treatment of a Secondary Biologically-Treated Fungicide-Containing Wastewater from Fruit-Packing Industries

In this work, a sand filtration-activated carbon adsorption system was evaluated to remove the fungicide content of a biologically treated effluent. The purification process was mainly carried out in the activated carbon column, while sand filtration slightly contributed to the improvement of the pollutant parameters. The tertiary treatment system, which operated under the batch mode for 25 bed volumes, resulted in total and soluble COD removal efficiencies of 76.5 ± 1.5% and 88.2 ± 1.3%, respectively, detecting total COD concentrations below 50 mg/L in the permeate of the activated carbon column. A significant pH increase and a respective electrical conductivity (EC) decrease also occurred after activated carbon adsorption. The total and ammonium nitrogen significantly decreased, with determined concentrations of 2.44 ± 0.02 mg/L and 0.93 ± 0.19 mg/L, respectively, in the activated carbon permeate. Despite that, the initial imazalil concentration was greater than that of the fludioxonil in the biologically treated effluent (i.e., 41.26 ± 0.04 mg/L versus 7.35 ± 0.43 mg/L, respectively). The imazalil was completely removed after activated carbon adsorption, while a residual concentration of fludioxonil was detected. Activated carbon treatment significantly detoxified the biologically treated fungicide-containing effluent, increasing the germination index by 47% in the undiluted wastewater or by 68% after 1:1 v/v dilution.

Treatment of Cutting Oil-in-Water Emulsion by Combining Flocculation and Fenton Oxidation

Recently, the disposal of waste oil-in-water cutting emulsion has become an urgent issue because of its extremely high chemical oxygen demand (COD). The present work focuses on treating the waste cutting emulsion generated from the Samsung Thai-Nguyen factory in Vietnam. This work used multistage methods to treat the waste cutting emulsion to meet the wastewater disposal requirement and characterize the oil recovered. The multistage methods consist of the flocculation method (stage 1) and Fenton oxidation (stage 2). The wastewater after stage 1 treatment has a COD reduction efficiency of 98.24% at the condition of pH 5, Al2(SO4)3 2 g/L, C-PAM 12 mg/L, stirring speed 50 rpm, and stirring time 15 minutes. At that condition, the COD value decreased from 147200 mg/L to 2484 mg/L. After stage 2, the COD value further decreased from 2484 mg/L to 85.4 mg/L with total COD removal efficiency increasing to 99.9% at the optimum conditions of pH 3, H2O2 : FeSO4 concentration ratio of 10 : 1, and FeSO4 concentration of 14.04 g/L. After the stage 2 treatment, the wastewater with the COD value of 85.4 mg/L and BOD5 value of 30 mg/L satisfied the Vietnam standard grade B and grade A, respectively, for industrial wastewater. The oil recovered from the treatment has a heating value of 38095 ± 8 kJ/kg, and thus, it could be reusable as fuel gas.

Performance of single-stage partial nitritation and anammox reactor treating low-phenol/ammonia ratio wastewater and analysis of microbial community structure.

Phenol and ammonia are common pollutants in many industrial wastewaters. The partial nitritation and anammox process is a very promisingtechnology for treating phenol-ammonia wastewater. This study was the first time to rapidly achieve the start-up and operation of the single-stage partial nitritation /anammox reactor treating phenol-ammonia wastewater. The optimized ratio of phenol and nitrogen (phenol/NH4 + -N=0.3) was set to start-up the reactor. After 60days of operation, the total nitrogen and COD removal efficiencies were around 73.0% and 79.5%, respectively. The activity of ammonium-oxidizing bacteria was291.1±3.0mg NH4 + -Ng-1 MLVSSd-1 and the specific anammox activity was 20.9±1.0mg NH4 + -Ng-1 MLVSSd-1 . The results indicated that the anammox bacteria had adapted to phenol condition and remained stable activity after the 60days' operation in the reactor. The sequence analysis of 16SrRNA showed that the microbial community structure evolved to a balanced distribution that the removals of phenol and ammonia could be achieved simultaneously. PRACTITIONER POINTS: Phenol/N ratio of 0.3 was set to start up the single-stage partial nitritation/anammox reactor. The single-stage partial nitritation /anammox reactor was rapidly started up when treating the phenol-ammonia wastewater. Total nitrogen removal rate and COD removal efficiencies could achieve to 73.0% and 79.5%, respectively. Microbial community structure evolved to stable distribution of which AOB, anammox bacteria, denitrification bacteria and heterotrophic nitrification bacteria coexisted.

Enhanced decolorization of dyeing wastewater in a sponges-submerged anaerobic reactor

This study was conducted to assess the potential of a sponges-submerged anaerobic baffled reactor (SS-ABR) for enhancing the processing performance of azo dye-contaminated wastewater. A lab-scale four–compartment SS-ABR, with a total volume of 10 L, was operated at 30 °C for 180 days. A total of 14 polyurethane sponges were added in each compartment to treat synthetic wastewater including a commercial azo dye Hellozol HSR Reactive Black. During the entire operation, in synthetic wastewater, starch was used as a sole carbon source, and the true color level was maintained at 1050 ± 98 Pt/Co. Meanwhile, the hydraulic retention time (HRT) and total COD (T-COD) in the influent were changed to evaluate the SS-ABR treatment performance. After the start-up phase, true color and T-COD removal efficiencies were recorded as 65 ± 3% and 83 ± 2%, 68 ± 5% and 81 ± 4%, and 70 ± 5% and 84 ± 2% for HRT and influent T-COD concentration of 18.6 h and 260 mg L−1, 14.6 h and 260 mg L−1, and 14.6 h and 460 mg L−1, respectively. The microbial community analysis showed that bacterial groups involved in dye degradation, such as Clostridium sp., and sulfate-reducing bacteria Desulfomonile sp. and Desulfovibrio sp. were detected prominently in the SS-ABR. Interestingly, the SS-ABR exhibited the dominance of both Geobacter sp. and Methanosarcina sp., and their occurrences in all columns were proportional to each other, revealing the formation of syntrophic relationships.

The effect of olive oil mill and molasses wastewater as a co-substrate during simultaneous textile wastewater treatment and energy generation

The biological treatment of recalcitrant wastewaters in microbial fuel cells (MFCs) rather than chemical, physical, and advanced oxidation processes are low cost and environmentally friendly processes. In this study, sulphate-reducing micro-organisms in MFC anodic chamber were fed with olive oil mill (OMW) and molasses wastewater at various dilution rates for simultaneous wastewater treatment and energy production. A power density of 31 ± 5 W/m2 was achieved at a 1:65 dilution rate (v: v) for molasses wastewater in the presence of sulphate-reducing bacteria. In these conditions, the highest voltage was 990 mV with influent chemical oxygen demand (COD) of 1.200 mg/l. The total COD, sulphate, and colour removal efficiencies were 53.2%, 52.7%, and 41.1%, respectively. The overarching goal of this study was to develop a better understanding of the removal of emerging pollutants in textile, olive mill, and molasses wastewater using microbial fuel cells.

A microbial electrochemical hybrid system for simultaneous sludge treatment, acid production, and desalination

Excess sludge production from wastewater treatment plants has significantly increased, and sludge disposal has become a serious social and environmental problem. In this study, we constructed a microbial electrochemical hybrid system (MEHS) for simultaneous electricity generation, acid and alkali production, desalination, alkali pretreatment, and degradation of sludge. The alkaline solution generated in the MEHS was used for in situ sludge pretreatment. Owing to the efficiency in alkali pretreatment, a higher sludge degradation efficiency was obtained by the MEHS (Total chemical oxygen demand (TCOD) removal efficiency of 57.2%) than by the SMFC (TCOD removal efficiency of 51.7%). Moreover, the MEHS (0.165C) could recover more electricity from the sludge than a traditional single-chamber microbial fuel cell (SMFC, 0.133C). Additionally, the MEHS exhibited excellent performance in desalination (> 50%) and acid production. The system developed in this study provides a new solution for sludge degradation and multifunctional utilization.

Application of halophiles in air cathode MFC for seafood industrial wastewater treatment and energy production under high saline condition

Abstract The present study details the application of potential halophiles obtained from desalination plant for treatment of seafood wastewater and energy production under high saline condition (8%). Air cathode microbial fuel cell (ACMFC) reactor was employed to study the wastewater treatment efficacy of halophiles under high saline condition. Research investigation was performed at different organic load (OL) 0.5, 1, 1.25 and 1.5 gCOD/L under high saline condition. Initial TCOD (Total Chemical Oxygen Demand) removal efficiency at 0.5 gCOD/L was 58 ± 1.2%% with 340 mW/m2 power density by the halophiles in ACMFC. Increment in OL to 1 and 1.25 gCOD/L recorded 85 ± 2.1% and 90 ± 2% TCOD removal with corresponding power density of 550 and 570 mW/m2 in ACMFC operated under saline condition. Further increase in the OL to 1.5 gCOD/L revealed decrease in the TCOD reduction and energy production. The maximum electricity of 980 mV with power density of 570 mW/m2 and 600 mA/m 2 current density was generated at 1.25 gCOD/L. Columbic efficiency was 52% at 0.5 gCOD/L and declined to 33% and 23% at 1 and 1.25 gCOD/L OL concentration. A maximum TSS removal of 78 ± 1.5% was attained at 1.25 gCOD/L OL in ACMFC. The study revealed 1.25 gCOD/L as the optimized OL for potential treatment of seafood industrial wastewater and energy production. Bacterial community analysis performed with samples from anode and sludge region disclosed the presence of dynamic halophilic strains such as Ochrobactrum (MT118968), Marinobacter (MT118969), Martelella (MT118970), Rhodococcus (MT118971), Bacillus (MT118972), Stenotrophomonas (MT118973), Alicyclobacillus (MT118974), Microbacterium (MT118975), Xanthobacter (MT118976), Pseudomonas (MT118977) and Sedimentibacter (MT118978). Predominance of Ochrobactrum, Marinobacter, Martelella, Rhodococcus and Bacillus depicted at 1.25 gCOD/L in the anode and sludge samples from ACMFC.

Nouveau design solar septic tank: Reinvented toilet technology for sanitation 4.0.

The up-flow solar septic tank (UTST) and multi-soil layering (MSL) system has been developed and proposed as “Nouveau Design Solar Septic Tank”. The objective of this study was to verify functionality of the integrated UTST and MSL system for treatment of toilet wastewater (or black water) under actual conditions over a year at the Asian Institute of Technology campus, Pathumthani province, central Thailand. During the operation period which involved fluctuating flow rates, ambient temperatures and black water characteristics, the UTST unit yielded satisfactory performance with the average treatment efficiencies of 9210% for total chemical oxygen demand (TCOD), 7910% for soluble chemical oxygen demand (SCOD), 939% for total 5-days biochemical oxygen demand (TBOD) and 9012% for soluble 5-days biochemical oxygen demand (SBOD), respectively, while the MSL unit could remove 95 3%, and 88 15% of total kjeldahl nitrogen (TKN) and total phosphorus (TP), respectively. The effluent TCOD, TBOD, TKN, nitrite (NO2-N), nitrate (NO3-N), ammonia (NH3) and TP concentrations of the integrated UTST and MSL system were 3927,827,55 mg/L, 22,3924,89,25 and 11 mg/L, respectively, meeting the ISO requirements. The removal efficiencies of TCOD, SCOD, TBOD and SBOD exhibited positive correlation with the ratios of TBOD/TKN, TBOD/SBOD and TBOD/TP. With high treatment efficiencies and effluent quality meeting the ISO requirements, the nouveau design solar septic tank has been demonstrated as an innovative technology toward the sanitation 4.0 concept and the Sustainable Development Goal no. 6 (SDG6).

Degradation of refractory organics in concentrated leachate by the Fenton process: Central composite design for process optimization

The primary aim of this study is inert COD removal from leachate nanofiltration concentrate because of its high concentration of resistant organic pollutants. Within this framework, this study focuses on the treatability of leachate nanofiltration concentrate through Fenton oxidation and optimization of process parameters to reach the maximum pollutant removal by using response surface methodology (RSM). Initial pH, Fe2+ concentration, H2O2/Fe2+ molar ratio and oxidation time are selected as the independent variables, whereas total COD, color, inert COD and UV254 removal are selected as the responses. According to the ANOVA results, the R2 values of all responses are found to be over 95%. Under the optimum conditions determined by the model (pH: 3.99, Fe2+: 150 mmol/L, H2O2/Fe2+: 3.27 and oxidation time: 84.8 min), the maximum COD removal efficiency is determined as 91.4% by the model. The color, inert COD and UV254 removal efficiencies are determined to be 99.9%, 97.2% and 99.5%, respectively, by the model, whereas the total COD, color, inert COD and UV254 removal efficiencies are found respectively to be 90%, 96.5%, 95.3% and 97.2%, experimentally under the optimum operating conditions. The Fenton process improves the biodegradability of the leachate NF concentrate, increasing the BOD5/COD ratio from the value of 0.04 to the value of 0.4. The operational cost of the process is calculated to be 0.238 €/g CODremoved. The results indicate that the Fenton oxidation process is an efficient and economical technology in improvement of the biological degradability of leachate nanofiltration concentrate and in removal of resistant organic pollutants.