Effluent Chemical Oxygen Demand Research Articles

Prediction of Wastewater Treatment Plant Performance Using Multivariate Statistical Analysis: A Case Study of a Regional Sewage Treatment Plant in Melaka, Malaysia

The wastewater quality index (WWQI) is one of the most significant methods of presenting meaningful values that reflect a fundamental characteristic of wastewater. Therefore, this study was performed to develop a prediction approach using WWQI for a regional wastewater treatment plant (WWTP) in Melaka, Malaysia. The regional system of WWTP provides a huge amount of registered data due to the many parameters recorded daily. A multivariate statistical analysis approach was applied to analyze the database. In this approach, principal component analysis (PCA) was used to reduce the dimensionality of datasets obtained from the field municipal WWTP, and multiple linear regression (MLR) was used to predict the performance of WWQI. Seven principal component analyses were derived where the eigenvalue was above 1.0, explaining 71.01% of the variance. A linear relationship was observed (R2 = 0.85), p-value < 0.05, and residual values were uniformly distributed above and below the zero baselines. Therefore, the coefficients of the WWQI model are directly dependent on influent biological oxygen demand (BOD), effluent BOD, influent chemical oxygen demand (COD), and effluent COD values. The experimental results showed that the model performed well and can be used to predict WWQI for each WWTP individually and provide better achievements.

Study on Treatment of Tiny Pollution Water with PAC-HUM System in Kuitun River

Kuitun city, Xinjiang is dry and short of water, so it is urgent to treat and utilize all kinds of unconventional water. In view of this problem, we conducted a study on the treatment of tiny pollution water in Kuitun River. We investigated the effect of dosage of powder activated carbon (PAC) on hollow-fiber ultrafiltration membrane (HUM) performance. The results show that the stable operation time of hollow fiber ultrafiltration membranes lengthened and the rate of reduction of the flux was reduced when the PAC dosage was increased. The addition of PAC had no obvious effect on the resistance of membrane filtration. We conducted experiments to evaluate the effect of ultrafiltration of tiny pollution water in combination with PAC. When the parameters of operation and PAC dosage were appropriately regulated, the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and ferric ions (Fe) reached 62%, 32% and 90%, respectively. When the PAC dosage was 200 mg/L, 100 mg/L and 150 mg/L, the highest removal rates were achieved under normal temperature and pressure. The effluent COD was less than 5.0 mg/L, NH3-N was less than 1.5 mg/L and Fe was less than 0.5 mg/L, achieving better results than the quality standard of surface water (GB3838-2002). The treated water can be discharged into the river or recirculated to utilities. The fouled membrane was cleaned by water rinsing, water/acid rinsing and water/alkali rinsing, with recovery ratios of 44%, 81% and 88%, respectively. The results of this study can serve as a foundation for the efficient utilization of water resources and the development of new water treatment technologies in Xinjiang.

A novel two-stage anoxic/oxic-moving bed biofilm reactor process for biological nitrogen removal in a full-scale municipal WWTP: Performance and bacterial community analysis

The application of a novel two-stage anoxic/oxic-moving bed biofilm reactor (TS-A/O-MBBR) was validated in a full-scale municipal wastewater treatment plant (WWTP), and its working mechanism was analysed for biological nitrogen removal in this study. Over one year, at a hydraulic residence time of only 9.8 h, the effluent chemical oxygen demand, ammonia nitrogen and total nitrogen (TN) concentrations remained below 40, 2 and 15 mg/L, which met strict emission standards. The seven compartments in this unit performed different functions, and together accomplished organics and nitrogen removal. TN removal could be controlled by the external carbon sources dosage added to the postanoxic compartments to cost effectively meet the standard with the lowest cost. The maximum TN removal efficiency and minimum effluent TN concentration reached 91.76 % and 4.12 mg/L, respectively. The bacterial communities differed in the suspended solids and preoxic, postanoxic and oxic biofilms (r = 0.87 and P = 0.001). The top 30 most abundant identified bacterial genera in biofilms included 24 denitrifying genera and 2 nitrifying genera. The most abundant biofilm genus was Methylotenera, which played important roles in denitrification in the anoxic compartments. 1 and 24 denitrifying genera were only abundant in the postanoxic and preanoxic compartments, respectively. Nitrosomonas and Nitrospira were abundant in the oxic compartments, and played roles in nitrification. This study verified the feasibility of the TS-A/O-MBBR process in a full-scale WWTP, and investigated its working mechanism.

Using Ti/Ti0.7Ru0.3O2 anode-type with a Flow Cell System for the Electrochemical Treatment of a Tannery Wastewater

ABSTRACT The electrochemical oxidation of a real wastewater discharged by the baths of “Dar Dbagh” tannery (DDT) in Fez city (Morocco) was performed using Ti/Ti0.7Ru0.3O2 anode (a dimensionally stable anode (DSA)-type electrode) underflow condition. The effect of different operational parameters, namely chloride ions concentration, electrolysis time, current density, initial pH, and temperature has been studied in detail. The discoloration and chemical oxygen demand (COD) removal have been taken as the key experimental indicators to monitor the electrochemical treatment process of DDT wastewater. The obtained results have shown that the best degradation rates (i.e., 100% and 56% of de-colorization and COD removal, respectively) were accomplished under acidic conditions at 20 mA cm−2 as a current density in the presence of 0.033 M Na2SO4 + 0.800 M NaCl as supporting electrolyte at room temperature. The maximum reduction of the effluent COD attained using Ti/Ti0.7Ru0.3O2 anode consuming 39.24 kWh per m3 clearly shows that DSA electrodes could be a good alternative for the remediation of DDT effluents.

Integrated soft sensor of COD for WWTP based on ASP model and RBF neural network

For wastewater treatment process (WWTP), mechanism model for activated sludge process (ASP) is unsuitable for estimating the effluent COD (Chemical Oxygen Demand) as the parameters of ASM (Activated Sludge Model) series models are varying with operating conditions. This paper presents an integrated model to predict the effluent COD. The model consists of two sub-models which are simplified mechanism model of ASP and RBFNN (RBF Neural Network) with variable structure (VSRBFNN). ASP model can express the dynamic biochemical reactions occurred in WWTP, and VSRBFNN is used to reduce the prediction error of the ASP model as an error compensation model. To reduce the complexity of the mechanism model of ASP, the parameters of mechanism model are fixed. The layout and the parameters of VSRBFNN can be adjusted according to the training data, and the stable learning algorithm can restrict the modeling error of VSRBFNN within a bounded domain. The output value of the integrated model is weighted sum of those of two sub-models, where the weights denote the contributions of the two “sub-models” to the prediction error of integrated model and are rectified according to the relative prediction error online. The structure of the integrated soft sensor is concise and real-time capability is improved. Simulations show that the presented soft sensor has satisfactory prediction accuracy under various operating characteristics.

Aggregation-induced demulsification technology for the separation of highly emulsified oily wastewater produced in the petrochemical industry

To improve the resource utilization of oily wastewater emulsion produced in the petrochemical industry, an aggregation-induced demulsification (AID) technology, consisting of multi-stage packed beds filled with polyurethane sponge in a gradient configuration mode, was developed in this study. Based on the verification on the technical principle of AID, an industrial-scale setup was performed, targeting on removing highly emulsified oil in wastewater. The results showed that when the inlet pressure was 0.2–0.4 MPa and average temperature of raw water was 35 °C, the chemical oxygen demand (COD) in the emulsion was reduced from 3000-12450 mg/L to below 500 mg/L with simultaneous recovery of emulsified oil. When the flow was 600–1300 L/h, the average COD of the final effluent was 329 mg/L with an oil removal efficiency of 93.52%. In addition, the AID technology achieved the environmental protection goal with advantages of zero chemical consumption and simplified treatment process, thus providing a cleaner alternative for oily wastewater treatment.

Integrating operating conditions to develop a neural network for predicting organics removal and power density in an earthen microbial fuel cell treating leachate

Nowadays, the acceptability of artificial neural networks (ANNs) to develop models for biological treatment systems has been broadened instead of the complex mechanistic mathematical model. The present study attempts to train neural networks to predict organics removal and power output from an earthen microbial fuel cell treating acidogenic leachate obtained from kitchen waste. To model the effluent chemical oxygen demand (COD) and volatile fatty acid (VFA) values and power density, the study used four input parameters: influent COD, and VFA, hydraulic retention time, and anode electrode surface area. Among the multiple algorithms employed, the Bayesian inference proved to deliver a winning model to forecast the response variable with an overall high coefficient of determination of 0.9890. This high correlation for a biological system employing a real substrate, i.e. leachate, ensures the model’s reproducibility and adequacy. Additionally, the statistical error criteria for model efficacy showed acceptable values. Besides, the study performs validation runs with an error of approx. 11% with conservative predictions. Ultimately, the ANN model fared well in predicting the response for effluent COD and power output when compared with kinetic study (Han-Levenspiel) and statistical equation (from ANOVA) to the experimental values.

Wastewater treatment for ships experiencing large temperature changes： the activated sludge/membrane-biofilm reactor

A particular challenge to treatment systems for ship wastewater comes from low and variable temperatures. We evaluated the temperature response (35–15 °C) of a novel biological treatment system involving activated sludge followed by a membrane-biofilm reactor: the activated sludge/membrane-biofilm reactor (AS-ABfMemR). In this study, a pilot-scale AS-ABfMemR achieved over 96% chemical oxygen demand (COD) and 94% total nitrogen (TN) removal from a ship wastewater (550–960 mgCOD·L−1 and 52–77 mgTN·L−1) with a continuous operation with a hydraulic retention time of 12 h at 25 °C. The effluent COD and TN concentrations met IMO discharge standards at temperatures as low as 17 °C, which reduced the energy consumption for wastewater heating. The COD and TN removals of the biofilm stage became important (up to 34% and 35%, respectively) at low temperatures, and this compensated for the deterioration in performance of the aerobic sludge. The genus Azospira dominated in the biofilm's denitrification removal for TN at low temperature. In addition, the buildup of trans-membrane pressure was so slow that backwashing was not needed over the 90 days of continuous operation. These conclusions indicate that the pilot-scale AS-ABfMemR technology is an effective way for real ship sewage treatment under temperature variations.

How to eliminate the toxic impact of extreme salinity on the ecology of activated sludge? Experimental verification with pickle plant effluents

AbstractBACKGROUNDThe study defined a sustainable management scheme to eliminate the toxic impact of extreme salinity on the ecology and performance of an activated sludge process. The scheme was implemented on a plant treating pickle plant effluents involving significant flow and salinity transients. It was conducted in two phases. Firstly, the plant was operated without attenuating extreme salinity transients, enabling observation of all adverse impacts on the microbial ecology. The second phase was implemented with a new management scheme tempering all salinity gradients revealing the recovery of the microbial ecology into a stable and sustainable state.RESULTSInitially, the microbial community could not cope with rapid salinity increase and exhibited significant changes resulting in the predominance of filamentous microorganisms, disruption of the floc structure and almost total loss of eukaryotic microorganisms. Settling problems and deterioration of effluent quality were observed, followed by plasmolysis and repeated total loss of the biomass. The new waste management strategy allowed only transients limited to ±500 μS cm−1 in the influent; in this way, the microbial ecology steadily improved. The effluent chemical oxygen demand could be maintained below 80–90 mg L−1 with no appreciable particulate matter escape.CONCLUSIONSResults identified sharp salinity transients as the key factor triggering total destruction of activated sludge. The novel scheme provided conclusive evidence that a stable microbial community could be maintained even when continuously exposed to a salinity level of around 10 000 μS cm−1 in the reactor, provided that variations remained limited to ±500 μS cm−1, ensuring satisfactory effluent quality. © 2022 Society of Chemical Industry (SCI).

Aerobic post-treatment of effluent from anaerobic reactors fed with residues from 1G and 2G sugarcane biorefineries.

This study aimed to evaluate an activated sludge system as a post-treatment step of anaerobic effluents from the co-digestion of sugarcane vinasse and hemicelluloses hydrolysate. The system consisted, initially, of a two-stage anaerobic system followed by a continuously fed activated sludge, all in bench scale. After adaptation of aerobic microorganisms to effluent conditions, the anaerobic digestion was conducted in a single-stage anaerobic reactor, increasing the influent organic loading rate (OLR) of activated sludge from 0.73 to an average of 2.36 gCOD/L·day. Under optimal conditions (12-h hydraulic retention time [HRT]), a 62 ± 9% efficiency was observed on the aerobic post-treatment, resulting in effluent chemical oxygen demand (COD) of 414.3 ± 95 mg/L. Overall efficiency of the combined system (anaerobic + aerobic) averaged 88 ± 3%. Influent and effluent characteristics were then analyzed by Folin-Ciocalteau method, UV-Vis spectrophotometry, and gas chromatography-mass spectrometry (GC-MS) for identification of potentially toxic and recalcitrant compounds. Compounds that absorb light within the visible spectra were well removed by the combined treatment system. Most compounds identified by GC-MS in the influent were completely removed by aerobic microorganisms. Saturated fatty acids such as adipic acid, hexadecanoic acid, and octadecanoic acid were observed in the final effluent, as well as other potentially toxic compounds such as stigmasterol, di-isobutyl phthalate, and benzene. Activated sludge proved to be an efficient post-treatment for anaerobic co-digestion, able to cope with changes of anaerobic effluent quality and providing a final effluent of stable organic load. However, phenol removal was not efficient and further studies could be performed to optimize its degradation. PRACTITIONER POINTS: Conventional activated sludge with a 12-h HRT was capable of handling significant OLR variation, providing a final effluent with lower and stable COD concentration. Glucose addition for carbon supplementation was necessary during the start-up of activated sludge. Compounds that absorb light within the visible spectra were mostly removed by the combined (anaerobic-aerobic) treatment system. Most potentially toxic compounds were well removed in the post-treatment system. Saturated fatty acids, VFA, phenols, and low molecular weight aromatic compounds remained in the final effluent.

Coagulation enhanced high-rate contact-stabilization process for pretreatment of municipal wastewater: Simultaneous organic capture and phosphorus removal

High-rate contact-stabilization is criticized as its unsatisfactory organic elimination performance and failure for the phosphorus removal, which greatly restricts its engineering implementation. In this work, coagulation enhanced high-rate contact-stabilization process was established to realize simultaneous carbon capture and phosphorus removal in a single treatment unit. Results showed that under a molar ratio of 2:1 (metal ion: P), effluent chemical oxygen demand and total phosphorus less than 50 and 0.50 mg·L-1 could be stably achieved, respectively. Under the ∼ 8% mineralization efficiency, approximate 80% of influent organic carbon was captured as sludge. Coagulation precipitation and bioflocculation both contributed to carbon removal. Over-dosage of coagulants would induce reactive oxygen species accumulation and sludge activity decline. Microbial abundance and redundancy analysis revealed that the dosed coagulants would cause a selective pressure and lead to a reduced microbial richness. For a practical application, an optimized dosing of mixed coagulants was suggested to maximize the carbon capture and phosphorus removal. This work may provide guidance on sustainable carbon management for municipal wastewater sector.

The sustainable utilization of anaerobic digestion effluents treating in suspended filler algae assisted systems

Significant amounts of anaerobic digestion effluents (ADE) containing high concentration of inorganic salts (source of nitrogen and phosphorus) and hardly degradable organic matter are produced during the generation of biogas using livestock manure. Without appropriate treatment, the imbalanced carbon to nitrogen ratio may lead to severe pollution of the environment. Considering different environmentally friendly processes such as recycling, energy regeneration, and sustainable development, suspended fillers were added to traditional algal-bacterial symbiosis (ABS) systems. In the present research, three systems including suspended filler algae assisted bio-reactor (SFA-PBR), no filler algae assisted bio-reactor (NFA-PBR), and single activated sludge system (ABS) were examined. Changes in bacterial communities were analyzed using high throughput sequencing. In addition, the mechanisms of ADE degradation in the presence and absence of suspended algae fillers were studied by comparing their effect on the degradation of COD (chemical oxygen demand), TN (total nitrogen), AN (ammonia nitrogen), and TP (total phosphorus). Systems where the ratio of active microalgae to bacteria was higher promoted the interaction between the two types of microorganisms, accelerating the stability of the ABS. Thus, the daily COD degradation rate in the stage was still high. Flora such as microalgae and bacteria were embedded in the filler spheres, which increased the microorganisms resistance to the poor environment induced by high concentrations of inorganic nutrients and organic matter present in the ADE. This favored the sustainable water utilization of ADE. After the treatment in the SFA-PBR system, the COD degradation rate was 75.32 %. The effluent COD concentration was 334.21 ± 39.18 mg/L. TN and AN degradation rates were 89.34 and 91.32%, respectively. The TN and AN concentrations in the effluent were 35.42 ± 2.65 and 29.97 ± 2.65 mg/L, respectively. The degradation rate of TP was 95.39 %. The effluent TP concentration was 0.86 ± 0.18 mg/L. The Chao diversity and ACE index values in the SFA-PBR system were higher than those of other groups. This result further supports the conclusion formulated with the Shannon diversity index result. Specifically, the effective sequence in the SFA-PBR system group presented a higher degree of homogeneity and abundance.

Simultaneous removal of ammonia nitrogen and sulfide by coupled anammox and sulfur autotrophic denitrification process from industrial wastewater

This work presents an experimental study on the coupling between anammox and sulfur autotrophic denitrification for simultaneous removal of ammonia nitrogen and sulfide in industrial wastewater, leading to less environmental pollution. In a low-load continuous operation mode hybrid anaerobic baffled reactor (HABR) was started with 7 <pH<8.2 and temperature 30–35 °C. After 60 d of continuous operation successful enrichment of methanogenic granular sludge (MGS) size 7 and 5 mm was achieved. In the mature granular sludge phase (HRT 10 h), with influent chemical oxygen demand (COD) 1100 mg/L, the effluent COD 90 mg/L and removal efficiency was 90%. The MLSS, MLVSS, and f values were 9520, 6980, and 0.7. After 42 d of continuous operation with influent COD 600–700 mg/L, NO3−-N 250-300 mg/L, and COD/NO3−-N 2 to 2.8 (temperature 30–35 °C and pH 6.5–7.5) successful enrichment of denitrifying granular sludge (DGS) was achieved. In the research, the anammox start-up periods in MGS and DGS reactors are 86 and 118 d. An experimental comparative analysis to explore the influence of COD/TN 1:1,1:1.8,1:4.5, and 1:8.5 on the two reactors was performed. For COD/TN 1:1.8, the NH4+-N, NO2−-N, and TN removal efficiency were 54%, 73%, and 52%. The removal efficiency of the #2 reactors NH4+-N, NO2−-N, and TN were 50%, 60%, and 55%. S2−/NO3−-N of 2:5, 3.5:5, 5:5, 6.5:5 were investigated. Influent pH 7.5–8.0, temperature 30–35 °C and HRT 6.5 h, with average influent NH4+-N, NO3−-N, S2−, COD concentration 60, 25, 75, and 25 mg/L, the maximum removal efficiency of #1 reactor was 70%, 97%, 82%, and 100%. For 2# reactor 82%, 99%, 84%, and 100%. When MGS as carrier, the NH4+-N, NO3−-N, and S2− removal efficiency reached 67.67%, 98.59%, and 99.1%. With DGS as carrier, the NH4+-N, NO3−-N, and S2− removal efficiency reached 81.82%, 98.69%, and 84.18%. However, the coupling phase S0 production and productivity results showed that the DGS reactor was significantly better than the MGS reactor. Under the same hydraulic conditions the two reactors successfully coupled after 54 d of operation. Additionally, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analysis, revealed that the microbial community change is related to the concentration of organic matter, nitrogen and sulfur in the water. Building on these findings, future study will focus on the optimization of the mix design to provide practical engineering guidance.

Optimization of electrolytic system type for industrial reverse osmosis concentrate treatment to achieve effluent quality and energy savings

This study demonstrated the remarkable potential of electrolytic system type for industrial reverse osmosis concentrate (ROC) treatment on effluent quality and energy requirements. Following their individual system optimization, the required current density decreased from 20 mA cm−2 for the batch system during 4 h of electrolysis, to 5 mA cm−2 for a continuous-flow system (CFS) without effluent recirculation (CFS-A), and 3 mA cm−2 for a CFS system with a rear (CFS-B) or front (CFS-C) buffer tank for effluent recirculation (R = 1). The final or effluent chemical oxygen demand (COD) and NH4+−N levels were 31 and 0.4 mg L−1 (Batch), 24 and 0.56 mg L−1 (CFS-A) and 5.7–8.1 and 0.24–0.34 mg L−1 (CFS-B or -C), respectively. Besides the highest pollutant removal, the optimized CFS-B and -C systems also achieved the highest treatment capacity and energy efficiency, and the lowest effluent toxic organic byproduct levels due to the homogeneous diffusion characteristic of CFS systems, and the reutilization of long-lived active chlorine species (ACS) oxidants in CFS-B/C electrolytic effluent. As compared with the optimized CFS-B system, the optimized CFS-C system at an identical recirculation ratio further achieved the lowest effluent ACS level due to the ACS consumption in the front buffer tank (rather than direct discharge in the CFS-B system) and lower flow rate into the electrochemical cell (than that in the CFS-B system), and was finally recommended for future engineering implementation.

Polyaniline derived carbon membrane and its in-situ membrane fouling mitigation performance in MBR based on metal-free electro-Fenton

An electro-enhanced membrane bioreactor (EMBR) was constructed with polyaniline-based carbon (PAC) separation membrane as the membrane-electrode, which could realize the in-situ electro-generation and activation of H2O2 to ·OH depending on the graphitic and pyridinic N as active sites without metal catalyst. After the continuous operation of the bioreactor for 74 days, approximately 77.41% irreversible membrane fouling occurred on the electrochemically enhanced membrane, which was less than that on the control membrane (85.96%). The ·OH oxidation combined with electrostatic barrier formed by -1.0 V enhanced PAC membrane suppressed the extracellular polymeric substances deposition on membrane. After operation, the strength of total cell, proteins, β-polysaccharides and α-polysaccharides on the membrane without bias were 5.17, 4.32, 9.65 and 16.31, respectively. In EMBR, the corresponding strength were 2.03, 3.35, 2.15 and 6.73. After calculation, the unblocked pores accounted for 35.3% and 78.5% of the total membrane surface in MBR and EMBR, respectively, indicating the fouling was alleviated obviously. Meanwhile, the EMBR owned a satisfactory wastewater treatment effect with average effluent chemical oxygen demand and NH4+-N around 18.98 mg/L and 0.68 mg/L. The successful implementation of this strategy achieved a green and metal-free method for ·OH production with electrochemical effect for membrane fouling control in MBR.

Risk assessment of a municipal extended aeration activated sludge treatment plant using physico-chemical and in vitro bioassay analyses

The present study involves physico-chemical profiling and toxicity assessment of wastewater and sludge samples collected from subsequent treatment stages of extended aeration activated sludge (EAAS) process based municipal wastewater treatment plant (WWTP). Wastewater samples were collected from inlet, aeration tank, final settling tank and outlet, while sludge samples were collected from sludge bed. All the samples were tested for their physico-chemical properties using titrimetry, multi elemental analysis and Gas chromatography and Mass spectrometry (GC–MS)(in scan and SIM (selective ion monitoring) modes). Toxicity testing was done using in vitro bioassays viz., 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cytotoxicity, 7-ethoxyresorufin-O-deethylase (EROD) assay for dioxin-like behaviour and alkaline comet assay for genotoxicity, on human hepato-carcinoma HepG2 cell line. Post-treatment liquid samples showed 12 fold chemical oxygen demand (COD) reduction and met discharge standards for most of the tested parameters. However, detection of organic contaminants such as phenols, phthalates and polycyclic aromatic hydrocarbons (PAHs) and a correlated low toxicity reduction in liquid and sludge samples after treatment revealed the need for up-gradation of the existing testing and treatment technologies. • A multiplicity of organic contaminants detected in effluent and sludge. • 12 fold reduction in effluent chemical oxygen demand (COD) post-treatment. • Slight increase in toxicity of effluent and sludge observed after final clarifier stage. • Correlation observed in COD and the three bioassay results. • Combination of Physico-chemical and toxicity assessments more useful.

REDUCTION OF CHEMICAL OXYGEN DEMAND IN TEXTILE INDUSTRY EFFLUENT USING ASPERGILLUS NIGER

Textile industry effluents are among the most difficult to treat, due to the considerable amount of recalcitrant and toxic substances. Fungal biosorption is viewed as a valuable additional treatment for removing pollutants from textile industry wastewaters. In the present study, the efficiency of Aspergillus niger for chemical oxygen demand (COD) reduction was tested against textile effluents having three dilutions i.e., 25%, 50%, 75% and raw effluent. The result showed that the fungal strain is a promising candidate for the reduction of COD in effluent and can be a cost effective solution to treat the textile industry effluents.

Enhancing Real-Time Prediction of Effluent Water Quality of Wastewater Treatment Plant Based on Improved Feedforward Neural Network Coupled with Optimization Algorithm

To provide real-time prediction of wastewater treatment plant (WWTP) effluent water quality, a machine learning (ML) model was developed by combining an improved feedforward neural network (IFFNN) with an optimization algorithm. Data used as input variables of the IFFNN included hourly influent water quality parameters, influent flow rate and WWTP process monitoring and operational parameters. Additionally, input variables included historical effluent water quality parameters for future prediction. The model was demonstrated in a WWTP in Jiangsu Province, China, where prediction of effluent chemical oxygen demand (COD) and total nitrogen (TN) with large variations were tested. Relative to the traditional feedforward neural network (FFNN) model without considering historical effluent water quality parameter input, the IFFNN enhanced prediction performance by 52.3% (COD) and 72.6% (TN) based on the mean absolute percentage errors of test datasets, after its model structure was optimized with a genetic algorithm (GA). The problem of over-fitting could also be overcome through the use of the IFFNN, with the determination of coefficient increased from 0.20 to 0.76 for test datasets of effluent COD. The GA-IFFNN model, which was efficient in capturing complex non-linear relationships and extrapolation, could be a useful tool for real-time direction of regulatory changes in WWTP operations.

Assessment of High Salinity Wastewater Treatment with Dewatered Alum Sludge-Aerobic Membrane Reactor

Abstract The discharge of wastewater containing both high salinity and high organic content without prior treatment is detrimental to aquatic life and water hygiene. In order to integrate the advantages of membrane treatment and biological treatment, and exert the phosphorus removal efficiency of dewatered alum sludge, in this study, an aerobic membrane reactor based on dehydrated alum sludge was used to treat mustard tuber wastewater with salinity of 6.8-7.3 % under the conditions of 30 °C, 20 kPa trans-membrane pressure (TMP) and chemical oxygen demand (COD) of 3300-3900 mg/L. Three replicate reactors were applied to assess the operational performance under different organic loading rate (OLR). The results showed that all reactors were effective in removing COD, ammonia nitrogen (NH4 +-N) and soluble phosphate (SP) under the conditions of 30 °C and 20 kPa of TMP. Meanwhile, the effluent concentration of COD, NH4 +-N and SP all increased while OLR was changed from 1.0 to 3.0 kg COD/m3/day, and the effluent COD and NH4 +-N concentration except for SP could reach the B-level of Chinese “Wastewater quality standards for discharge to municipal sewers” when OLR was less than 3.0 kg COD/m3/day. This indicates that dewatered alum sludge-based aerobic membrane reactor is a promising bio-measure for treating high salinity wastewater.

Efficient removal mechanism and microbial characteristics of tidal flow constructed wetland based on in-situ biochar regeneration (BR-TFCW) for rural gray water

In this work, a biochar regeneration tidal flow constructed wetland (BR-TFCW) was built and its pollutant removal performance in response to different flood/rest time ratios (F/R), microbial community characteristics, pollutant removal mechanisms, and biochar in-situ regeneration mechanisms was explored. The results showed that under the same hydraulic load (1.97 m3/m3 filler), the BR-TFCW depicted the worst effluent chemical oxygen demand (COD) concentration was 45.20 ± 7.90 mg/L (F/R = 3:1), while COD concentration in control group Ⅰ (CG1), which had no rest phase, was 152.85 ± 10.88 mg/L. When F/R was 1:3, 1:1, and 3:1, the BR-TFCW COD removal rates were 90.92 ± 3.97%, 94.95 ± 1.17%, and 99.84 ± 0.21%, respectively. During the flood phase, COD was removed by aerobic degradation and adsorption in the early stage, and anaerobic degradation in the later stage. The BR-TFCW and CG1 microbial communities differed significantly. The BR-TFCW functional bacteria were associated with organic matter degradation and resistance to dehydration and nutrient deficiencies. The CG1 microbial community was comprised of anaerobic bacteria that were associated with fermentation and methanogenesis. During the flood phase, biochar adsorbed COD in the liquid, serving as the primary mechanism by which COD was removed. In the BR-TFCW’s rest phase, microorganisms degraded the organic matter adsorbed by the biochar, which enabled the biochar to undergo biological regeneration. The biochar’s regeneration rate before and after the rest phase was 75.03 ± 1.00%. The cycle of adsorption and biological regeneration maintained the biochar’s adsorption capacity.