Chemical Oxygen Demand Of Wastewater Research Articles

Effective treatment of the wastewater from ceramic industry using ceramic membranes.

Emissions of organic compounds, heavy metals and chemicals used in the ceramic industry cause significant organic and inorganic pollution of water. The effluent must be treated before it is discharged into a water body. International and EU laws control the chemical oxygen demand (COD) of the wastewater. Conventional technologies, such as sedimentation, flocculation and biological treatment, have lots of drawbacks, whereas membrane technologies give many benefits, as they are chemical-free and allow a reduction of the treatment steps. One-step wastewater nanofiltration with ceramic membranes of 450 Da cut-off is able to reduce the COD of ceramic wastewater to a sufficient level. However, the working time without cleaning is limited and the rejection of membranes can be significantly reduced due to fouling. Multistage filtration can be the solution. Filtration experiments with various combinations (MF, UF and NF) of ceramic membranes were performed at a laboratory scale with single-channel membranes and at pilot scale with 7-, 19- and 151-channel membranes in order to permanently reach the limit value of a COD below 80 mg/L and to increase the operating time. Four types of membranes were sequentially tested in the cross-flow mode: MF (200 nm pore size), UF (2,000 Da), NF (450 Da) and NF (200 Da). 5-day Biological Oxygen Demand (BOD) tests were performed in order to examine the wastewater biodegradability. The test results with single-channel membranes showed that in terms of the highest COD rejection and the highest permeability, the best combination was that of MF and UF membranes. Here, UF membranes were sufficient to reach the limit values. As for the multi-channel membranes, the combination of MF and NF (450 Da) was the best and the final COD concentration ranged from 11 to 48 mg/L. 5-day BOD bottle tests showed a COD/BOD ratio of 3.8, which opened up possibilities for combined treatment.

Removal of phenols and COD from petroleum refinery wastewater using electrocoagulation method

This study investigates the possibility of removing phenols and chemical oxygen demand (COD) from petroleum wastewater (refinery wastewater) using an electrocoagulation (EC) reactor supplied with aluminium electrodes. The influence of current density (CD) (4 to 12 mA/cm2), distance between electrodes (DBE) (20 to 40 mm), and treatment time (T) (up to 120 min) was investigated by carrying out several sets of batch flow experiments. The concentrations of COD and phenols were measured using the Hach-Lang spectrophotometer and standard cuvette tests (LCK 514, LCK 314, or APC 400 for COD, and LCK 346 or LCK 345 for phenols (according to the residual concentration). The results of the present study confirmed the ability of the electrocoagulation method to reduce the concentrations of both phenols and COD in petroleum wastewater within a relatively short treatment time. It has been found that the best removal efficiency of COD and phenols were 80% and 58%, respectively. The best removal efficiency was attended, after 100 min of electrolysing, at CD of 8 mA/cm2 and DBE of 20 mm.

Multivariate autoregressive modelling and conditional simulation for temporal uncertainty analysis of an urban water system in Luxembourg

Abstract. Uncertainty is often ignored in urban water systems modelling. Commercial software used in engineering practice often ignores the uncertainties of input variables and their propagation because of a lack of user-friendly implementations. This can have serious consequences, such as the wrong dimensioning of urban drainage systems (UDSs) and the inaccurate estimation of pollution released to the environment. This paper introduces an uncertainty analysis in urban drainage modelling, built on existing methods and applied to a case study in the Haute-Sûre catchment in Luxembourg. The case study makes use of the EmiStatR model which simulates the volume and substance flows in UDS using simplified representations of the drainage system and processes. A Monte Carlo uncertainty propagation analysis showed that uncertainties in chemical oxygen demand (COD) and ammonium (NH4) loads and concentrations can be large and have a high temporal variability. Furthermore, a stochastic sensitivity analysis that assesses the uncertainty contributions of input variables to the model output response showed that precipitation has the largest contribution to output uncertainty related with water quantity variables, such as volume in the chamber, overflow volume, and flow. Regarding the water quality variables, the input variable related to COD in wastewater has an important contribution to the uncertainty for the COD load (66 %) and COD concentration (62 %). Similarly, the input variable related to NH4 in wastewater plays an important role in the contribution of total uncertainty for the NH4 load (34 %) and NH4 concentration (35 %). The Monte Carlo (MC) simulation procedure used to propagate input uncertainty showed that, among the water quantity output variables, the overflow flow is the most uncertain output variable, with a coefficient of variation (cv) of 1.59. Among water quality variables, the annual average spill COD concentration and the average spill NH4 concentration were the most uncertain model outputs (coefficients of variation of 0.99 and 0.82, respectively). Also, low standard errors for the coefficient of variation were obtained for all seven outputs. These were never greater than 0.05, which indicates that the selected MC replication size (1500 simulations) was sufficient. We also evaluated how the uncertainty propagation can more comprehensively explain the impact of water quality indicators for the receiving river. While the mean model water quality outputs for COD and NH4 concentrations were slightly above the threshold, the 0.95 quantile was 2.7 times above the mean value for COD concentration and 2.4 times above the mean value for NH4. This implies that there is a considerable probability that these concentrations in the spilled combined sewer overflow (CSO) are substantially larger than the threshold. However, COD and NH4 concentration levels of the river water will likely stay below the water quality threshold, due to rapid dilution after CSO spill enters the river.

Utilization of prawn to reduce the value of BOD and COD of textile wastewater.

In the textile sector especially in the wet processing area, a large quantity of water is utilized together with specific chemicals for raw material processing. If the wastewater after the chemical treatment is directly discharged to the environment, it is hazardous for the living organism and also the aquatic life of nature. In this study, the cephalothorax and abdomen shell of the prawn was processed to obtain chitosan and the textile wastewater was treated with the obtained chitosan to reduce the value of biological oxygen demand (BOD) and chemical oxygen demand (COD). The reduction rate of BOD, COD was significant, and in the acceptable range of discharge water quality. In order to compare the performance of prawn shell treatment, similar untreated wastewater was treated separately by using the microorganism. The reduction of BOD and COD was analyzed differently for both microorganisms and prawn shell treatment which indicated the superiority in the reduction of BOD and COD of wastewater by using prawn shell treatment. The traditional process used in the purpose of wastewater treatment could be upgraded by using the naturally obtained chitosan which could also be easily applicable at a low cost. The used convenient procedure to obtain chitosan from prawn and to apply chitosan to reduce the value of BOD and COD could be efficacious in the new era to treat wastewater naturally, effectively.

Adsorption of COD in wastewater by Activated Carbon from Rice Husk

Organic pollution occurs due to the presence of organic compound that will causing oxygen depletion and gives potential adverse impacts on human health and the environment. Wastewater from the fish cracker industry typically has high chemical oxygen demand (COD) and it is needed to be treated before release to water bodies in order to reduce the organic pollution. The treatment of COD was done using rice husk activated carbon (RHAC) that produced from agricultural wastes that contributed to waste minimization and reduce the environmental pollution. Therefore, this study emphasized on the feasibility of rice husk activated carbon for removing the COD from fish cracker wastewater. It was also to identify the optimization factors (pH, flow rate and initial concentration of COD) that affecting adsorption by rice husk activated carbon. RHAC was produced by chemical activation using phosphoric acid, H3PO4 and a real wastewater from fish cracker industry was collected, characterized, and treated by using continuous fixed bed column adsorption method. The result shows that the adsorption of COD by RHAC was optimum at pH 2, flow rate 5 ml/min and 5 % v/v initial COD concentration with the COD removal at 31.8% (150 mg/L) which comply with Standard B. Thus, RHAC could be used to develop an alternative method and suitable carbonaceous substances that was used to treat water and wastewater.

Study on suitability of single and hybrid constructed wetland for treating sewage for a small community

In this study an attempt is made to study the comparison of effectiveness of single constructed wetland and hybrid constructed wetland for treating wastewater. Single constructed wetland is made with Phragmites Australis. The flow of water is vertical. Hybrid constructed wetland is made with vertical flow constructed wetland allied with water hyacinth based free floating wetland system. Primary treated sewage is allowed to the wetland. Water quality parameters namely Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) are measured before and after treatment. Two case studies have been in this study. In first study the water is allowed for one day contact time in single constructed wetland. In second case study, the treated water from one wetland is immediately transferred to other wetland. It is evident that, a hybrid constructed wetland gives better result in removing BOD and COD in wastewater. It is observed that there is no significant difference is observed in removing TSS removal. The water is allowed to different type of plants may increase the removal efficiency. The maximum BOD removal is obtained for hybrid wetland is 86% at one day detention time. The COD removal is obtained at one day is 48%.

Low Level Electricity Production and COD Removal in Wastewater Using a Dual Chamber Microbial Fuel Cell with Pseudomonas Fluorescens as Biocatalyst

Urbanization intensifies global energy crisis and contributes largely to environmental pollution. The use of microbial fuel cell (MFC) helps in addressing both problems. This study aims to construct a low-cost MFC which simultaneously produce low level electricity and has the capacity to lower chemical oxygen demand in wastewater. The MFC used various carbon sources and copper wire as electrodes. Variation in voltages were observed using various carbon sources in solution. The microbial fuel cell utilizing P. fluorescens was able to produce voltage of more than 800 mV in fermented rice and more than 1000mV for both sewage sludge and kitchen sink wastewater substrates. It was also observed that the COD reduction was seen in different types of wastewater.

Using Fly Ash And Bottom Ash Boiler Of Palm Oil Factories As Adsorbents For Adsorption Of Color In Artificial Liquid Waste

This study aims to determine the ability of battom ash and fly ash in adsorbing artificial wastewater dye (PtCo) and chemical oxygen demand (COD) with three variations of adsorbent used in adsorption column. This research begins with the process of washing, drying and sieving adsorbent. Then proceed with the activation process of adsorbent using HCl 1 M which is heated at 90 0C for 1 hour accompanied by stirring. The adsorption system used is continuous (column) with up-flow flow pattern and using the pump to provide pressure so that the influent can pass through the adsorbent contained in the column. The characteristic analysis of adsorbent was done on moisture content, ash content, and iodine absorption. The highest moisture content and ash content obtained were 0.6% with fly ash adsorbent before activation and 0.285% with fly ash adsorbent after activation. Compared with SNI 06-3730-95 has been appropriate, while the iodine drainage from bottom ash was 35.38 mg/g and fly ash of 50.76 mg/g and none meet SNI 06-3730- 95 of 750 mg/g. The highest efficiency results in dye and COD were found in adsorption column with fly ash adsorbent with color value of 96.96% and COD concentration of 83.26%, followed by stratified columns with combined adsorbent between battom ash and fly ash with color values of 53 , 93% and COD of 62.82%, and adsorbent by using battom ash efficiency of highest color value of 53.03% and COD of 71.08%. The highest adsorption capacity was obtained by using adsorption column with battom ash and fly ash (BF) adsorbent of 8.42 mg/g, followed by fly ash (FA) of 7.53 mg/g and battom ash (BA) of 7, 37 mg/g.

Micro-pressure swirl reactor (MPSR) for efficient COD and nitrogen removal of high-concentration wastewater.

A micro-pressure swirl reactor (MPSR) was developed for carbon and nitrogen removal of wastewater, in which dissolved oxygen (DO) gradient and internal circulation could be created by setting the aerators along one side of the reactor, and micro-pressure could be realized by sealing most of the top cap and increasing the outlet water level. In this study, velocity and DO distribution in the reactor was measured, removal performance treating high-concentration wastewater was investigated, and the main functional microorganisms were analyzed. The experiment results indicated that there was stable swirl flow and spatial DO gradient in MPSR. Operated in sequencing batch reactor mode, distinct biological environments spatially and temporally were created. Under the average influent condition of chemical oxygen demand (COD) concentration of 2,884 mg/L and total nitrogen (TN) of 184 mg/L, COD removal efficiency and removal loading was 98% and 1.8 kgCOD/(m3·d) respectively, and TN removal efficiency and removal loading reached up to 90% and 0.11 kgTN/(m3·d) respectively. With efficient utilization of DO and simpler configuration for simultaneous nitrification and denitrification, the MPSR has the potential of treating high-concentration wastewater at lower cost.

Treatment performances of floating wetlands: A decade of studies in North Italy

Floating treatment wetlands (FTWs) are one of the most recent eco-technologies to treat low-quality polluted wastewaters in already existing retention ponds, without subtracting other soil surface for the treatment of wastewaters. This study assessed the depuration performances of eight different FTWs (1 pilot-scale and 7 full-scale plants) treating municipal wastewaters, agricultural runoff and digestate liquid fraction, in North Italy. The concentration of different pollutants was monitored before and after the FTWs barriers: total nitrogen (TN), nitrate nitrogen (NO3-N), ammonia nitrogen (NH4-N), total phosphorus (TP), orthophosphate (PO4-P), chemical oxygen demand (COD) and turbidity. Considering all the case studies, pollutants inflowing concentrations were highly variable, due to the different composition of wastewaters used in the trials (TN: 0.3–520.0 mg L−1, median value 19.1 mg L−1; NO3-N: <0.001–61.5 mg L−1, median value 2.6 mg L−1; NH4-N: <0.001–310.0 mg L−1, median value 3.6 mg L−1; TP: 0.02–44.9 mg L−1, median value 5.7 mg L−1; PO4-P: <0.001–32.9 mg L−1, median value 4.1 mg L−1; COD: 2.1–6152.0 mg L−1, median value 67.5 mg L−1). Wastewater nitrogen forms and COD concentrations were reduced after passing the FTW with median abatements of 44.1% for TN, 34.6% for NO3-N, 16.7% for NH4-N, and 25.2% for COD. Only Phosphorus concentrations were not affected by the FTWs. Wastewater turbidity ranged from 3.4 to 3075.0 NTU and the median value of 77.7 NTU was significantly reduced by 22.1% after the FTWs, thus suggesting that plant root systems were active in physical wastewater filtration. In three case studies E. coli was also monitored and abatements ranged from 19.5 and 95.1%. The results obtained after ten years of study indicated that FTWs represented an efficient and economic wastewater management system, which provided a positive ecosystem service and therefore reduced the human footprint on the environment.

Stepwise treatment of undiluted raw piggery wastewater, using three microalgal species adapted to high ammonia

A high ammonia concentration and chemical oxygen demand (COD) in piggery wastewater force it to be diluted before conventional microalgal treatment to reduce ammonia toxicity. Incomplete treatment of ammonia and COD in piggery wastewater may cause eutrophication, resulting in algal blooms. This study tried to treat raw piggery wastewater without dilution, using three strains of microalgae (Chlorella sorokiniana, Coelastrella sp. and Acutodesmus nygaardii) that outcompeted other algae under heterotrophic, mixotrophic, and autotrophic conditions, respectively, through adaptive evolution at high ammonia concentration. The three stepwise processes were designed to remove (1) small particles, COD, and phosphorus in the 1st heterotrophic C. sorokiniana cultivation, (2) ammonia and COD in the 2nd mixotrophic Coelastrella sp. cultivation, and (3) the remaining ammonia in the 3rd photoautotrophic A. nygaardii cultivation. To enhance ammonia uptake rate, each algal species were inoculated after 2-day nitrogen starvation. When the N-starved three species were inoculated at each step sequentially at 7 g/L for 2 days, the final phosphorus, COD, and ammonia removal efficiencies were 100% (16.4–0 mg/L), 92% (6820–545 mg/L), 90% (850–81 mg/L) and turbidity (99%) after total 6 days.

A dual photoelectrode-based double-chambered microbial fuel cell applied for simultaneous COD and Cr (VI) reduction in wastewater

Cerium oxide (CeO2) and cuprous oxide (Cu2O) were used for the first time as photoanode and photocathode, respectively, in a microbial fuel cell (MFC) for simultaneous reduction of chemical oxygen demand (COD) and Cr(VI) in wastewater. The photoelectrodes, viz. Photoanode and photocathode were separately prepared by impregnating activated carbon fiber (ACF) with the respective metal oxide nanoparticles, followed by growing carbon nanofibers (CNFs) on the ACF substrate using catalytic chemical vapor deposition. The MFC, operated under visible light irradiation, showed reduction in COD and Cr(VI) by approximately 94 and 97%, respectively. The MFC also generated high bioelectricity with a current density of ~6918 mA/m2 and a power density of ~1107 mW/m2. The enhanced performance of the MFC developed in this study was attributed to the combined effects of the metal oxide photocatalysts, the graphitic CNFs, and the microporous ACF substrate. The MFC based on the inexpensive transition metal oxides-based photoelectrodes developed in this study has a potential to be used at a large scale for treating the industrial aqueous effluents co-contaminated with organics and toxic Cr(VI).

Biotechnology for Gas-to-Liquid (GTL) Wastewater Treatment: A Review

Gas-to-liquid (GTL) technology involves the conversion of natural gas into several liquid hydrocarbon products. The Fischer–Tropsch (F–T) process is the most widely applied approach for GTL, and it is the main source of wastewater in the GTL process. The wastewater is generally characterized by high chemical oxygen demand (COD) and total organic carbon (TOC) content due to the presence of alcohol, ketones and organic acids. The discharge of this highly contaminated wastewater without prior treatment can cause adverse effects on human life and aquatic systems. This review examines aerobic and anaerobic biological treatment methods that have been shown to reduce the concentration of COD and organic compounds in wastewater. Advanced biological treatment methods, such as cell immobilization and application of nanotechnology are also evaluated. The removal of alcohol and volatile fatty acids (VFA) from GTL wastewater can be achieved successfully under anaerobic conditions. However, the combination of anaerobic systems with aerobic biodegradation processes or chemical treatment processes can be a viable technology for the treatment of highly contaminated GTL wastewater with high COD concentration. The ultimate goal is to have treated wastewater that has good enough quality to be reused in the GTL process, which could lead to cost reduction and environmental benefits.

Evaluation of energy recovery potential in wastewater treatment based on codigestion and combined heat and power schemes

The future goal for wastewater treatment industry is to transform existing wastewater treatment plants (WWTPs) into water and energy recovery facilities (WERFs). The first step to reach this goal is to achieve energy-neutral or energy-positive status in its operations. This research study develops a systematic quantitative analysis to assess the performance of different wastewater treatment scenarios. The effects of the influent wastewater strength (or concentration), plant capacity, primary treatment efficiency, and different supplemental feedstock have been evaluated to assess the potential for energy recovery in WTTPs. Further, energy performance of the WWTP is optimized using different combined heat and power (CHP) schemes. For the first time, a quantitative mass and energy balance methodology was used to evaluate carbon and energy balance and combined heat and power system optimization. Increasing the primary treatment efficiency, process equipment upgrades, and use of supplemental biodegradable organic waste are identified as influential factors. Increasing the removal of chemical oxygen demand (COD) by 10% in primary treatment resulted in an estimated reduction in total energy requirement by 8.5% and increased recoverable energy by 8.8%. This result illustrates that influent wastewater COD strength and the plant capacity may have significant impact on the energy recovery potential. Energy production from a WERF can be enhanced by codigesting sewage sludge with highly biodegradable organic waste. Further analysis shows that specifying an appropriate CHP engine is integral in minimizing the energy losses.

Kinetic and Prediction Modeling Studies of Organic Pollutants Removal from Municipal Wastewater using Moringa oleifera Biomass as a Coagulant

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of 50, 100, 150, 200 mg/L, and a control (0 mg/L) treatment were performed for a settling period of 250 min at room temperature. Kinetics and prediction variables of cumulative turbidity, BOD, and COD removal were estimated using simplified first order and modified Gompertz models. Results showed that the maximum removal of turbidity, BOD, and COD were 94.44%, 68.72%, and 57.61%, respectively, using an MO dose of 150 mg/L. Various kinetic parameters, such as rate constant (r), measured (REm) versus predicted (REp) cumulative removal, and specific pollutant removal rate (µm), were also maximum when an MO dose of 150 mg/L was added, the standard error being below 5%. The developed models were successfully validated over multiple observations. This study suggests low cost and sustainable removal of turbidity, BOD, and COD of municipal wastewater using MO seed biomass as a coagulant.

Pre-treatment of distillery spent wash (vinasse) with vortex based cavitation and its influence on biogas generation

Distilleries generate high COD (chemical oxygen demand) wastewater streams that are anaerobically digested to produce biogas with sub-optimal yields. In this work, for the first time, novel vortex-based hydrodynamic cavitation (HC) pre-treatment of these waste streams was investigated for significantly enhancing biogas yields. Molasses spent wash (120,000 ppm COD, India) and vinasse (27,000 ppm COD, Brazil) were pre-treated at varying number of passes (between 1 and 20) through the HC device at constant inflow, biochemical methanation potential (BMP) was measured and described using a first order model. Vortex-based HC pre-treatment led to 14% enhancement (2 passes) in BMP from spent wash (difficult to digest compared to vinasse) with a net energy gain of 1 GJ/ton COD. 10–22% increase in biogas yields from large-scale industrial spent wash digesters confirmed the laboratory findings. The work presented is useful and can be translated to recalcitrant feedstock for enhancing valorization using vortex-based HC pre-treatment.

Method development for evaluating the effectiveness of hydrocarbons on BOD, UBOD and COD removal in oily wastewater.

The effects of different operating parameters on the treatment efficiency of oily wastewater in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) were measured. The analyses of BOD using OxiTop biosensors are reviewed regarding performance characteristics like linearity, response time, precision, agreement between BOD28 values obtained from the biosensors and the ultimate BOD (UBOD), as well as toxic resistance and COD. The wastewater samples were seeded with the bacteria, which were isolated in the current study from Kuwaiti oil-contaminated sand, such as Bacillus mycoidesis and Bacillus subtilis. After 18 days, the margin for saponin solution and oily wastewater using either Rhododcoccus (R), a mixture of Bacillus mycoidesis and Bacillus subtilis (M) or a mixture of R&M exhibited the maximum rate of BOD. It was found that the corresponding COD of the saponin solution (SS) ranged from 1,525 mg/l to 3,890 mg/l by distilled water and the mixture (RM), respectively. The COD of oily wastewater (WW) ranged from 2,900 mg/l to 4,450 mg/l by distilled water and the mixture of (RM), respectively. Moreover, the higher values of BOD28 were recorded when mixtures of bacteria were added together with the saponin solution or oily wastewaters. Furthermore, the average values of UBOD for the oily wastewater with RM or with amendment substance were increased by about 33.5% and 49.5%, respectively. However, BOD 28 /COD ratios for all the selected have been found to be less than 0.4, indicating low aerobic degradability.

Establishing a Smart Farm-Scale Piggery Wastewater Treatment System with the Internet of Things (IoT) Applications

The conventional piggery wastewater treatment system is mainly a manual operation system which may be well managed by experienced technicians. However, the pig farmers must simultaneously manage their pig production as well as their on-farm wastewater treatment facility. For this study, Internet of Things (IoT) applications were introduced on a 1000-pig farm to establish a smart piggery wastewater treatment system, which was upgraded from a self-developed fully automatic wastewater treatment system. Results showed that the removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and suspended solids (SS) of the piggery wastewater based on the sensor data before and after water quality sensor calibration were 89%, 94%, and 93%, and 94%, 86%, and 96%, respectively. Moreover, the removal efficiency of BOD, COD, and SS of the piggery wastewater based on the analytical chemical data before and after water quality sensor calibration were 93%, 89%, and 97%, and 94%, 86%, and 96%, respectively. Experimental results showed that overall removal efficiency of BOD, COD, and SS of the piggery wastewater after water quality sensor calibration were 94%, 86–87%, and 96%, respectively. Results revealed that the farm-scale smart piggery wastewater treatment system was feasible to be applied and extended to more commercial pig farms for establishing sustainable pig farming.

Uncertainty and sensitivity analysis for reducing greenhouse gas emissions from wastewater treatment plants.

This paper presents the sensitivity and uncertainty analysis of a plant-wide mathematical model for wastewater treatment plants (WWTPs). The mathematical model assesses direct and indirect (due to the energy consumption) greenhouse gases (GHG) emissions from a WWTP employing a whole-plant approach. The model includes: (i) the kinetic/mass-balance based model regarding nitrogen; (ii) two-step nitrification process; (iii) N2O formation both during nitrification and denitrification (as dissolved and off-gas concentration). Important model factors have been selected by using the Extended-Fourier Amplitude Sensitivity Testing (FAST) global sensitivity analysis method. A scenario analysis has been performed in order to evaluate the uncertainty related to all selected important model factors (scenario 1), important model factors related to the influent features (scenario 2) and important model factors related to the operational conditions (scenario 3). The main objective of this paper was to analyse the key factors and sources of uncertainty at a plant-wide scale influencing the most relevant model outputs: direct and indirect (DIR,CO2eq and IND,CO2eq, respectively), effluent quality index (EQI), chemical oxygen demand (COD) and total nitrogen (TN) effluent concentration (CODOUT and TNOUT, respectively). Sensitivity analysis shows that model factors related to the influent wastewater and primary effluent COD fractionation exhibit a significant impact on direct, indirect and EQI model factors. Uncertainty analysis reveals that outflow TNOUT has the highest uncertainty in terms of relative uncertainty band for scenario 1 and scenario 2. Therefore, uncertainty of influential model factors and influent fractionation factors has a relevant role on total nitrogen prediction. Results of the uncertainty analysis show that the uncertainty of model prediction decreases after fixing stoichiometric/kinetic model factors.

Batik Wastewater Treatment Using Simultaneous Process of Electrocoagulation and Electro-Assisted Phytoremediation (EAPR)

The aims of the study are to identify the effectiveness of wastewater treatment from the Batik industry using a simultaneous of electrocoagulation (EC) and electro-assisted phytoremediation (EAPR). Rough horsetail (Equisetum hyemale) was used as an accumulator plant in the EAPR system. Electrocoagulation was conducted for 1 h at a constant voltage of 20 V in 10 L solution, while EAPR was processed for 7 day at a constant voltage of 5 V in 17 L solution. The chemical oxygen demand (COD) of water was determined by closed reflux of colorimetric methods and heavy metal concentration was determined by flame-atomic absorption spectrophotometer. The results showed that the COD decreased by 69.6% after 1 h of electrocoagulation process and up to 80.9% after the EAPR process. The concentration of Cr and Pb decreased as much as 25% and 8.52%, respectively in the similar process. The simultaneous process could extend the heavy metal removal up to 0.28 mg/L for Cr and 0.09 mg/L for Pb in liquid wastewater from the initial concentration. These results showed that the levels of COD and heavy metal concentration in Batik wastewater have reduced in accordance with the Ministry of Environment Decree No. 5/2014 Republic of Indonesia regarding various industries wastewater standard with the threshold limit of 150 mg/L for COD and 1.0 mg/L for Cr on textile industry and 0.1 mg/L for Pb on Class I for another wastewater standard. The estimated cost of operation was US$ 1.509 m–3 indicating the viability of Batik industry wastewater treatment.