Effluent Chemical Oxygen Demand Research Articles

Predicting wastewater treatment plant quality parameters using a novel hybrid linear-nonlinear methodology

Biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS) and total suspended solids (TSS) are the most commonly regulated wastewater effluent parameters. The measurement and prediction of these parameters are essential for assessing the performance and upgrade of wastewater treatment facilities. In this study, a new methodology, combining a linear stochastic model (ARIMA) and nonlinear outlier robust extreme learning machine technique (ORELM) with various preprocesses, is presented to model the quality parameters of effluent wastewater (ARIMA-ORELM). For each of the studied parameters, 144 different (144 × 8 models) linear models (ARIMA) are presented, with the superior model of each parameter being selected based on statistical indices. Moreover, 48 nonlinear models (ORELM) and 48 hybrid models (ARIMA-ORELM) were considered. The use of linear and nonlinear approaches to model the linear and nonlinear terms (respectively) of each time series in the hybrid model increased the efficiency and accuracy of the predictions for all of the time series. The influent wastewater nonlinear TSS model and the effluent COD and BOD models attained the best performance with a high correlation coefficient of 0.95. The use of hybrid models improved the prediction capability of all quality parameters with the best performance being achieved for the effluent BOD model (R2 = 0.99).

Developing a multi-criteria decision support system based on fuzzy analytical hierarchical process (AHP) method for selection of appropriate high-strength wastewater treatment plant

The selection of an optimum treatment process for high-strength wastewater is complicated. Familiarity with wastewater treatment methods is not enough to design a plant and requires a multidisciplinary knowledge base. In this research, five alternative wastewater treatment methods for high-strength wastewater were investigated and ranked based on the analytic hierarchy process (AHP) fuzzy method: upflow anaerobic sludge blanket (UASB) + membrane bioreactor (MBR), UASB + extended aeration (EA), anaerobic baffled reactor (ABR), anaerobic lagoon (ANL) + aerated lagoon (AL), and sequencing batch reactor (SBR) + ABR. These treatment methods were ranked based on five criteria, namely energy consumption, effluent total suspended solids (TSS), effluent chemical oxygen demand (COD), cost, and level of technology. The different options of the wastewater treatment plant were rated by expert decision-makers in this field. The results show that for typical high-strength wastewater, the use of an UASB reactor followed by a MBR is the most appropriate alternative for treating the wastewater.

Dynamic soft sensing of organic pollutants in effluent from UMIC anaerobic reactor for industrial papermaking wastewater

With the rapid development of paper industry, the pressure of environmental pollution is going more and more serious. Recently, resource utilization of wastewater by anaerobic digestion has become a feasible way to solve this problem. In order to maintain the safe and efficient production of the process, a novel adaptive soft sensor model was developed to infer the chemical oxygen demand (COD) of paper mill effluent in this paper. First, the principal component analysis technique was performed in this model so as to eliminate the col-linearity between the process variables and accordingly obtain the low-dimensional feature principal component. Then, the least square support vector machine method was used to construct a quantitative regression model between principal component and the effluent COD. Along with it, particle swarm optimization was implemented to search for the best value of the LSSVM model parameters, namely the kernel parameters and the regularization factor. Finally, an online calibration strategy was designed to adapt to the process dynamic changes in an adaptive iterative manner. When the constructed model tested for performances in a full-scale factory, the average relative deviation and maximum deviation are 1.80% and 6.26%, respectively. The experimental results show that this proposed soft sensor model is featured with high accuracy and strong dynamic stability, and it can provide good guidance for COD prediction and optimal control of paper mill wastewate treatment.

Integration of catalytic ozonation and adsorption processes for increased efficiency of textile wastewater treatment

Advanced and optimized textile wastewater treatment by catalytic ozonation and activated carbon (AC) adsorption was investigated. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that Mn and Ce oxides were successfully loaded on the γ-Al2 O3 support, and MnO2 , Mn2 O3 , CeO2 , and Ce2 O3 were the main components of the catalyst. Actual textile wastewater from biochemical effluent was used as experiment wastewater. The removal efficiencies of chemical oxygen demand (COD) and chromaticity were approximately 30.6% (414-287mg/L on average) and 99.3% (4,033 times to 27 times on average), respectively during the 30-day on-site continuous-flow test with an ozone dosage, contact time, and gas-liquid ratio of 100mg/L, 15.7min, and 2.9, respectively. Following 1g/L AC adsorption, the effluent COD concentration was reduced to 40mg/L. By contrast, AC adsorption without catalytic ozonation as pretreatment required 10g/L AC dosage to achieve similar treatment results. Gas chromatography-mass spectrometry analyses indicated that volatile phenols, sulfides, and aniline in wastewater were completely removed after treatment. Inductively coupled plasma results further showed that the active components of MnOx -CeOx in the catalyst were stable after continuous use for 60days. PRACTITIONER POINTS: Mesoporous catalyst synthesized by impregnating MnOx -CeOx on γ-Al2 O3 support. Catalytic ozonation and AC adsorption were combined to degrade organics. Maximum degradation of COD and chromaticity by optimizing process variables. The efficiency of the method was compared to that of single AC adsorption.

Online prediction of effluent COD in the anaerobic wastewater treatment system based on PCA-LSSVM algorithm.

Since anaerobic wastewater treatment is a nonlinear and complex biochemical process, reasonable monitoring and control are needed to keep it operating stably and efficiently. In this paper, a least-square support-vector machine (LS-SVM) was employed to construct models for the prediction of effluent chemical oxygen demand (COD) in an anaerobic wastewater treatment system. The result revealed that the performance of the steady-state model based on LS-SVM for predicting effluent COD was acceptable, with the maximum relative error (RE) of 11.45%, the mean average percentage error (MAPE) of 0.79% and the root mean square error (RMSE) of 3.08 when training, and the performance fell slightly when testing. Even though, the correlation coefficient value (R) between the predicted value and the actual value of 0.9752 could be achieved, which means this model can predict the variation of effluent COD in general. The dynamic-state models under three kinds of shock loads, which were concentration, hydraulic, and bicarbonate buffer absent, showed good forecasting performance, the correlation coefficient values (R) all excelled 0.99. Among these three shocks, the dynamic LS-SVM model under bicarbonate buffer absent shock achieved the optimal performance and followed by the dynamic-state model under hydraulic shock. This paper provides a meaningful reference to improve the monitoring level of the anaerobic wastewater treatment process.

High-efficiency treatment of benzaldehyde residue using two-stage fluidized-bed/fixed-bed catalytic system

ABSTRACT A novel two-stage fluidized-bed/fixed-bed catalytic system was developed for the treatment of benzaldehyde residue. The effects of reaction temperature, oxygen concentration, space velocity on the purification of benzaldehyde production residue were investigated. The effluent chemical oxygen demand (COD) was less than 70 mgO2/L and the COD removal efficiency was higher than 99.83% under our experimental condition (fluidized-bed and fixed-bed temperature of 300–400°C, the flow rate of residue of 10 mL/h and O2 excessive rate of 20). The volatile organic compounds (VOCs) of the outlet were not detected after the treatment. The high-efficiency performance of the process can last for at least 600 h in the stability experiment. It was also verified by gas chromatography–mass spectrometry (GC–MS) analysis that most organic pollutants in the residue were significantly removed after treatment. These results suggest that the two-stage fluidized-bed/fixed-bed catalytic system could be a promising technology for the dispose of chlorine-containing polymer organics in the chemical industry.

Anaerobic submerged membrane bioreactor (AnSMBR) treating municipal wastewater at ambient temperature: Operation and potential use for agricultural irrigation

A 496 L pilot scale anaerobic submerged membrane bioreactor (AnSMBR) for the treatment of municipal wastewater was evaluated during a year of stable operation at ambient (28–10 °C) temperature, and inoculated with mesophilic inoculum. The temperature was the main parameter affecting the process performance. The chemical oxygen demand (COD) of the effluent was around 150 mg O2/L in the summer period, operating with a volumetric loading rate (VLR) of 5 kg COD/m3 d and hydraulic retention time (HRT) of 8–10 h, with a specific methane production between 0.09 and 0.14 Nm3/kg CODremoved. However, during the winter season, an important increase of effluent COD was observed, and therefore the VLR was decreased to values around 1 kg COD/m3 d in order to recover the quality of the effluent. Biogas production was negligible in this period. The effluent complies with the parameters stipulated by Spanish law regarding the use of treated wastewater for agricultural irrigation.

The effect of fermented superphosphate pretreatment and step-feed mode on biological denitrification of piggery wastewater

Chemical pretreatment can reduce NH3-N levels in piggery wastewater to a certain extent, but the lack of a carbon source for subsequent biological treatment leads to a low denitrification efficiency and poor total nitrogen (TN) removal percentage. Taking superphosphate (SP) pretreatment (SP/Pretreatment) as the control, this research studies the influence of fermented superphosphate (FSP; SP plus a carbon source) pretreatment (FSP/Pretreatment) on biological denitrification in a subsequent biological treatment step. Furthermore, the removal of pollutants under different influent modes is also evaluated. The experimental results show that with the addition of the SP pretreatment, the removal percentage of NH3-N was 52%, and the chemical oxygen demand (COD)/TN ratio increased from 0.36 to 0.71. However, with the addition of the FSP pretreatment, the removal percentage of NH3-N reached 64%, and the COD/TN ratio increased to 2.28. The combination of the FSP pretreatment and a subsequent sequencing batch reactor (SBR) step in the step-feed influent mode resulted in the best denitrification, with a TN removal percentage of 57%. This result was 51% higher than that of the SP/Pretreatment-SBR system, indicating that the addition of the FSP pretreatment improves the biological denitrification of piggery wastewater. After the full treatment process for piggery wastewater, the effluent COD was 57.33 mg·L−1, the NH3-N was 66.32 mg·L−1, and the total phosphorus (TP) was 1.17 mg·L−1, all of which meet the emission standards of the “Fouling Standards for Pollutants in the Livestock Breeding Industry” (GB 18596–2001) (400 mg·L−1 COD, 80 mg·L−1 NH3-N, 8 mg·L−1 TP).

Performance of continuous pilot subsurface constructed wetland using Scirpus grossus for removal of COD, colour and suspended solid in recycled pulp and paper effluent

Abstract Pulp and paper mill industry is already known as an extensive water user and hence produces large volume of wastewater. Phytoremediation has merits to offer due to its environmentally friendly, relatively low cost and easy maintenance. This work focused on the performance of a continuous pilot subsurface flow (SSF) system of constructed wetlands in removing chemical oxygen demand (COD) representing organic carbon, colour and suspended solids from recycled pulp and paper mill under 5-day hydraulic retention time (HRT) for 95 days. In this study, there were two tanks based on the SSF system; one tank planted with Malaysian native bulrush (Scirpus grossus) and another tank without plants acting as a control. It was found that the SSF system with S. grossus was much better compared to the SSF control. Throughout the 95-day exposure, the planted SSF system have achieved removals of 66.1, 55.8 and 87.2% for COD, colour and suspended solid (SS), respectively. However, the control SSF system without plants has lower performance for all the three parameters (62.4% COD, 44.4% colour and 84.8% SS), giving evidence that constructed wetlands is an efficient technology to phytoremediate COD, colour and SS from recycled pulp and paper effluent.

Oxidation of Organics using Mn(H2PO4)2 as a Catalyst for Rapid Determination of COD of Industrial Saline Effluents

Abstract Chemical Oxygen Demand (COD) is a water quality parameter which indicates concentration of organic compounds as oxygen equivalents in aqueous effluent samples. Determination of COD is frequently done using APHA Standard Method which requires 2 h digestion time. There is need for improving the method to reduce analysis time. In this paper, we report the comparative study for determination of COD by Standard Method using Ag2SO4 and a rapid method using Mn(H2PO4)2 as a catalyst for different industrial effluent samples having different chloride concentration. A kinetic study has been carried out by varying time interval, HgSO4 dose and catalyst dose in different concentrated H3PO4:H2SO4 acid mixture ratio. The optimum conditions for industrial sample having low chloride concentration are 0.3g Mn(H2PO4)2, per 15 ml of 1:6 H3PO4: H2SO4, 0.2gm HgSO4 and digestion time of 5 min., whereas the sample having high chloride concentration requires 0.4 g of HgSO4 and digestion time of 20 min. The results obtained from the rapid COD determination method in this study and conventional method is found to be comparable. A water quality analyst would be able to save on digestion time by >90 %, if he chooses to perform the COD test as per the rapid method described herein.

Performance and kinetics of algal-bacterial photobioreactor (AB-PBR) treating septic tank effluent.

Septic tank effluent contains high organic and nutrient contents. This study aimed to evaluate treatment performance of an algal-bacterial photobioreactor (AB-PBR) treating the septic tank effluent. The experimental unit employed a transparent plastic medium made from recycled drinking water bottles for attached-growth biofilm. Red LED lamp (light intensity ∼100 μmol/m2/s) was applied as an energy source for the growth of algal-bacterial biofilm in the AB-PBR. The experimental results showed that AB-PBR operated at the hydraulic retention time (HRT) of 3 days gave the highest chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies of 64, 45 and 35%, respectively, by which the effluent COD concentrations could meet the effluent standards of Thailand, but the effluent TN and TP concentrations needed to be further removed. The Stover-Kincannon model was applied to determine the kinetic values of COD and TN removals with R2 values greater than 0.8. Microbiological examinations indicated Chlorella sp. is the predominant algal species growing in the AB-PBR, while the amplicon sequencing information analytical results revealed the bacterial phylum of Proteobacteria to be the predominant bacterial group.

Novel Anaerobic Electrochemical Membrane Bioreactor with a CNTs Hollow Fiber Membrane Cathode to Mitigate Membrane Fouling and Enhance Energy Recovery.

A novel anaerobic treatment system that combines the impact of applied voltage with membrane filtration over carbon nanotubes hollow fiber membranes (CNTs-HFMs) was developed at low temperature (15-20 °C) to mitigate membrane fouling, treat wastewater, and recover energy (CH4). Herein, electro-assisted CNTs-HFMs served a dual function as the cathode and membrane filtration. In contrast with other two anaerobic membrane bioreactors (AnMBRs; polyvinylidene fluoride hollow fiber membranes and CNTs-HFMs without electro-assistance), the CNTs-HFMs with electro-assistance (-1.2 V applied voltage) had slower transmembrane pressure (TMP) increasing rates and better TMP recovery with a more than 95% effluent chemical oxygen demand (COD) removal rate during an almost 100-day operation period. This result can be attributed to the presence of an electrostatic repulsion force pushing pollutants (mainly extracellular polymeric substances, EPS) away from the membrane surface, thereby hindering the formation of a gel layer and mitigating membrane pore blocking in the anaerobic electro-assisted membrane bioreactor (AnEMBR). Due to the almost two-times higher Methanomicrobia content and more H2-utilizing methanogens than the other two AnMBRs, approximately more than 111.12 mL/gVSS d of CH4 was obtained in the AnEMBR with electro-assistance. This work provides an efficient strategy for mitigating membrane fouling, improving water quality, and enhancing CH4 yield.

Adsorption characteristics of organics in the effluent of ultra-short SRT wastewater treatment by single-walled, multi-walled, and graphitized multi-walled carbon nanotubes

With a conceptual shift in sewage treatment from ‘waste pollution’ to ‘vehicle of resource and energy recovery’ and the further intensification of the energy crisis, the separation and recovery of carbon resources from discharged sewage has gained increasing recent attention in the field of water treatment. The ultra-short Solids Retention Time (SRT) activated sludge process (SRT ≤ 4 d) is highly efficient for separating organic matter and improving the energy recovery rate in wastewater treatment plants, but the effluent quality is relatively poor. If organics in the ultra-short SRT effluent can be reduced further to separate and recover carbon resources, the process may soon replace the traditional activated sludge process. We conducted physical adsorption carbon recovery experiments in an ultra-short SRT (SRT = 2 d) activated sludge system using three carbon nanotubes. Considering that Chemical Oxygen Demand (COD) arises from a mixture of organic compounds, and because humic acid (HA) makes up a large fraction of the effluent and can cause great environmental harm, further experiments were conducted on the adsorption of HA in the effluent COD to three nanotubes. This study proposes a novel method to completely remove organics from the effluent from ultra-short SRT activated sludge processes and reveals nanotube adsorption properties and mechanisms.

Evaluation of the efficiency of coagulation/flocculation and Fenton process in reduction of colour, turbidity and COD of a textile effluent

ABSTRACTThe present study investigated the efficiency of physicochemical processes of coagulation and flocculation and Fenton advanced oxidative process in reducing the parameters of colour, turbidity and Chemical Oxygen Demand (COD) of a real effluent from a textile industry. During the physicochemical process, the efficiencies of different coagulants (aluminium polychloride (Polifloc 18), ferric chloride (Acquafloc FC40), aluminium sulphate combined with organic coagulant (AST) and aluminium sulphate) and nonionic (FX NS2), cationic (FX CS6 and FX CS7) and anionic (FX AS6 and AN905) flocculants were tested. After the tests, 72.60% of COD, 36.25% of colour and 98.59% of turbidity were removed, using aluminium polychloride coagulant and AN 905 flocculant. It was also evaluated the effect of Fenton advanced oxidative process application in removal of colour, COD and turbidity of the effluent previously treated through the physicochemical process. Removals of these parameters were analysed in two different pH ranges (pH 6.0 and 7.0). In both pH 6.0 and pH 7.0, reductions were observed in all analysed parameters, obtaining 170.78 mg O2/L of COD, 22.19 mg/L of colour and 0.80 NTU of turbidity (at pH 6.0) and 151.80 mg O2/L of COD, 26.73 mg/L of colour, 0.94 NTU of turbidity (at pH 7.0), which demonstrates the efficiency of this process in the reduction of parameters analysed.

Treatment of campus domestic wastewater using ambient-temperature anaerobic fluidized membrane bioreactors with zeolites as carriers

An anaerobic fluidized-bed bioreactor (AFBR) connected with an anaerobic fluidized membrane bioreactor (AFMBR) in series with natural zeolites as carriers was used to treat the campus domestic wastewater (chemical oxygen demand (COD) of 130 ± 38 mg/L) at ambient temperature (20–35 °C) in this study. Results indicate that the attached growth of anaerobic microbes was observed on the surface of zeolite and 95% of COD were removed in the AFBR after 30 days of batch operation. When the AFBR-AFMBR system was run with a HRT from 3 to 4 h, the COD, biochemical oxygen demand (BOD), and suspended solid (SS) were removed by 84, 87, and 96%, respectively, with the corresponding effluent COD, BOD, and SS of 20, 8, and 2 mg/L, respectively. Overall, 41% of the COD removal was attributed to coupling with sulfate reduction by sulfate-reducing bacteria in this study. In the AFMBR, the transmembrane pressure remained lower than 0.2 bar at the membrane flux of 10 L/m2-h. The membrane module was operated consecutively for 333 days without chemical cleaning. In addition, the maximum substrate utilization rate of 37 g/L-d determined based on the modified Stover-Kincannon equation elucidates that the organics in the campus domestic wastewater were readily biodegraded. This facilitated the AFBR-AFMBR system removing the organics to the levels lower than the discharging limits.

Energy Balance Evaluation in Coking Wastewater Treatment: Optimization and Modeling of Integrated Biological and Adsorption Treatment System

The main objective of this study is to develop and assess a novel wastewater treatment system for coking wastewater to enable maximization of net energy gain. Additionally, a new methodology is proposed for evaluation of energy saving. The new combined biotreatment and adsorption system (A2BA1) is designed with two adsorption reactors placed at the input and output of the biotreatment unit. An energy modeling coupled mathematical simulation (EMMS) methodology is proposed for assessment of the energy balance. The optimal operating conditions (OOCs) are achieved and energy saving rates (ESRs) can also be calculated in the proposed methodology. The results showed that the A2BA1 system enabled energy savings in treatment of volume loads of chemical oxygen demand (COD) and NH3-N in the range 0.82–2.96 kg COD/(m3·d) and 0.06–0.15 kg NH3-N/(m3·d), respectively. Using the EMMS methodology, the operating condition sets of Q18(2506.9, 104.2, 0.98), Q33(3008.1, 101.1, 2.00), and Q36(2524.3, 102.6, 2.02) were found to be the OOCs, and the average value of ESRs of the three OOCs reached 48.3%. In this work, Qi stood for the mathematical set of the ith operating condition comprised of the basic variables (i.e., raw wastewater COD (mg/L), biotreated effluent COD (mg/L), and activated carbon dosage (g/L)). Furthermore, in order to realize net energy gain in the coking wastewater treatment, the adsorbent price of activated carbon should be 54% of the current price for the same adsorption performance. It is concluded that the A2BA1 system and EMMS methodology can help decision-makers design and optimize wastewater treatment in terms of energy savings.

Characteristics of Advanced Treatment of Treated Petrochemical Water by O3-BAC and Analysis of Consortium Structure

The advanced treatment of treated petrochemical water by Ozone-Biological Activated Carbon (O3-BAC) was carried out in this study. The effect of O3 on the removal of Chemical Oxygen Demand (COD) and Spectral Absorption Coefficient (UV254) were investigated. The characteristics of organic matter and the microbial consortium structure of BAC were also investigated at 20 mg·L-1 of O3 dosage concentration, 40 min of O3 single stage contact time and 1.5 h of the empty bed residence time of BAC. Results showed that the effluent COD concentration of O3-BAC was 24 mg·L-1 with the removal efficiency of 40.4%. The COD removal efficiency of O3-BAC was higher than that for the BAC process. The UV254 removal efficiency of O3-BAC was 55.1%. Meanwhile, UV254 correlated with COD with a correlation coefficient of 0.89. The percentage of dissolved organic matters with relative molecular weight less than 1×103 increased from 69.0% to 87.0% after O3 oxidation. The NPOC removal efficiency of O3-BAC (45.8%) was higher than that of the BAC process (23.0%). The NPOC removal efficiency of the BAC unit was mainly achieved by reduction of dissolved organic matters with relative molecular weight less than 1×103. GC-MS analysis results showed that organic substances such as alkanes, unsaturated esters, and phenols had been removed by O3 oxidation. The micro ecological environment of the BAC unit had been significantly improved after O3 oxidation, and the genera with relative abundance over 1.0% increased from 6 to 11. The combined O3-BAC system can be applied to the advanced treatment of petrochemical treated water.

Toxicity evaluation of textile dyeing effluent and its possible relationship with chemical oxygen demand

Textile dyeing wastewater was the focus of much research because of its adverse effect on aquatic biota. In the present research, textile dyeing influent and effluent samples were collected from four textile dyeing wastewater treatment plants (TDPs) in Guangdong province, China, and their conventional indicators and toxicity were examined to reveal relationships. The relationship between toxicity and chemical oxygen demand (COD) was clearly established at individual TDPs. Results indicated the highest removal efficiencies of 94.4%, 90.6%, 91.9%, 94.6%, 92.8% and 97.5% for TOC, mixed-liquor volatile suspended solids (MLVSS), COD, ammonia nitrogen (NH3-N), total phosphorus (TP) and colour, respectively. The primary clarifier used in TDP3 and TDP4 was beneficial for removing macromolecular organic substances, and membrane filtration and sedimentation basin employed at TDP1 and TDP2, respectively, helped to remove toxic substances. Toxicity to V. fischeri or D. subspicatus was found to be related to certain conventional indicators such as TOC, COD, TP, colour, and MLVSS, and was positively correlated with COD in different textile dyeing effluents (R2 > 0.84). It was recommended that the relationship between toxicity and COD in wastewater should be established individually at each plant. Therefore, this study could be useful in providing suggestions for guiding effluent management when no toxicity experiments were conducted.

Which activated sludge configurations qualify for maximizing energy conservation – Why?

AbstractBACKGROUNDThis paper aimed to provide a critical appraisal on maximizing sludge generation and energy conservation in high‐rate activated sludge (AS) configurations. The role of gravity settling and the positive attributes of high rate membrane bioreactors were emphasized. The appraisal covered data reported in the literature on 40 different experiments testing high‐rate AS configurations for sludge generation and energy conservation.RESULTSIn systems with gravity settling, effluent chemical oxygen demand (COD) was higher than 125 mg L−1 in 60% of the experiments, with similarly high effluent soluble COD values. In high‐rate MBR systems, permeate COD fluctuated around 12–18 mgCOD L−1; in gravity systems, COD loss in the effluent was higher than 200 mg L−1 in 17 runs (65%) and 300 mg L−1 in 12 runs (46%). Corresponding observed yields were only 9–43%. Membrane systems consistently yielded much higher observed yields of 50–60%.CONCLUSIONFor energy recovery, AS systems require a major transition, reducing the sludge age to 1.0–2.0 d; only high‐rate systems are capable of maximizing energy conservation. This argument does not apply to the contact stabilization process, which is inherently unsuitable for energy recovery. A transition is also needed to replace gravity settling by membrane systems for effective control of particulate and soluble COD components. © 2018 Society of Chemical Industry

Using artificial neural network for predicting and controlling the effluent chemical oxygen demand in wastewater treatment plant

PurposeModeling Wastewater Treatment Plant (WWTP) constitutes an important tool for controlling the operation of the process and for predicting its performance with substantial influent fluctuations. The purpose of this paper is to apply an artificial neural network (ANN) approach with a feed-forward back-propagation in order to predict the ten-month performance of Touggourt WWTP in terms of effluent Chemical Oxygen Demand (CODeff).Design/methodology/approachThe influent variables such as (pHinf), temperature (TEinf), suspended solid (SSinf), Kjeldahl Nitrogen (KNinf), biochemical oxygen demand (BODinf) and chemical oxygen demand (CODinf) were used as input variables of neural networks. To determine the appropriate architecture of the neural network models, several steps of training were conducted, namely the validation and testing of the models by varying the number of neurons and activation functions in the hidden layer, the activation function in output layer as well as the learning algorithms.FindingsThe better results were achieved with an architecture network [6-50-1], hyperbolic tangent sigmoid activation functions at hidden layer, linear activation functions at output layer and a Levenberg – Marquardt method as learning algorithm. The results showed that the ANN model could predict the experimental results with high correlation coefficient 0.89, 0.96 and 0.87 during learning, validation and testing phases, respectively. The overall results indicated that the ANN modeling approach can provide an effective tool for simulating, controlling and predicting the performance of WWTP.Originality/valueThis work is the first of its kind in this region due to the remarkable development in terms of population and agricultural activity in the region, which drove to the increase of water pollutants, so it is necessary to use the modern technologies to modeling and controlling of WWTP.