Performance of a novel up-flow electrocatalytic hydrolysis acidification reactor (UEHAR) coupled with anoxic/oxic system for treating coking wastewater.

In this study, the performance of a novel up-flow electrocatalytic hydrolytic acidification reactor (UEHAR) and anoxic/oxic (ANO2/O2) combined system (S2) was compared with that of a traditional anaerobic/anoxic/oxic (ANA/ANO1/O1) system (S1) for treating coking wastewater at different hydraulic retention time (HRT). The effluent non-compliance rates of chemical oxygen demand (COD) of S2 were 45 %, 35 %, 25 % and 55 % lower than S1 with HRT of 94, 76, 65 and 54 h. The removal efficiency of benzene, toluene, ethylbenzene and xylene (BTEX) in S2 was 10.6 ± 2.4 % higher than that in S1. The effluent concentration of volatile phenolic compounds (VPs) in S2 was lower than 0.3 mg/L. The dehydrogenase activity (DHA) and adenosine triphosphate (ATP) of O2 were enhanced by 67.2 ± 26.3 % and 40.6 ± 14.2 % compared with O1, respectively. Moreover, COD was used to reflect the mineralization index of organic matter, and the positive correlation between COD removal rate and microbial activity, VPs, and BTEX was determined. These results indicated that S2 had extraordinary microbial activity, stable pollutant removal ability, and transcendental effluent compliance rate.

Iron Recycle-Driven Organic Capture and Sidestream Anaerobic Membrane Bioreactor for Revolutionizing Bioenergy Generation in Municipal Wastewater Treatment.

The practicality of intensifying organic matter capture for bioenergy recovery to achieve energy-neutral municipal wastewater treatment is hindered by the lack of sustainable methods. This study developed innovative processes integrating iron recycle-driven organic capture with a sidestream anaerobic membrane bioreactor (AnMBR). Iron-assisted chemically enhanced primary treatment achieved elemental redirection with 75.2% of chemical oxygen demand (COD), 20.2% of nitrogen, and 97.4% of phosphorus captured into the sidestream process as iron-enhanced primary sludge (Fe-PS). A stable and efficient biomethanation of Fe-PS was obtained in AnMBR with a high methane yield of 224 mL/g COD. Consequently, 64.1% of the COD in Fe-PS and 48.2% of the COD in municipal wastewater were converted into bioenergy. The acidification of anaerobically digested sludge at pH = 2 achieved a high iron release efficiency of 96.1% and a sludge reduction of 29.3% in total suspended solids. Ultimately, 87.4% of iron was recycled for coagulant reuse, resulting in a theoretical 70% reduction in chemical costs. The novel system evaluation exhibited a 75.2% improvement in bioenergy recovery and an 83.3% enhancement in net energy compared to the conventional system (primary sedimentation and anaerobic digestion). This self-reliant and novel process can be applied in municipal wastewater treatment to advance energy neutrality at a lower cost.

Magnetic iron oxide nanoparticle enhanced microwave pretreatment for anaerobic digestion of meat industry sludge.

Our study investigates the effects of iron oxide (Fe3O4) nanoparticles combined microwave pretreatment on the anaerobic digestibility and soluble chemical oxygen demand (SCOD) of meat industry sludge. One of our main objectives was to see whether the different microwave-based pretreatment procedures can enhance biogas production by improving the biological availability of organic compounds. Results demonstrated that combining microwave irradiation with magnetic iron oxide nanoparticles considerably increased SCOD (enhancement ratio was above 1.5), the rate of specific biogas production, and the total cumulative specific biogas volume (more than a threefold increment), while having no negative effect on the biomethane content. Furthermore, the assessment of the sludge samples' dielectric properties (dielectric constant and loss factor measured at the frequency of 500 MHz) showed a strong correlation with SCOD changes (r = 0.9942, R2 = 0.99), offering a novel method to evaluate pretreatment efficiency.

Enhanced reduction of sulfate by iron-carbon microelectrolysis: interaction mechanism between microelectrolysis and microorganisms.

Sulfate wastewater has a wide range of sources and greatly harms water, soil, and plants. Iron-carbon microelectrolysis (IC-ME) is a potentially sustainable strategy to improve the treatment of sulfate (SO42-) wastewater by sulfate-reducing bacteria (SRB). In this study, an iron-carbon mixed micro-electrolysis bioreactor (R1), iron-carbon layered bioreactor (R2), activated carbon bioreactor (R3), and scrap iron filing bioreactor (R4) were constructed by up-flow column experimental device. The performance and mechanism of removing high-concentration sulfate wastewater under different sulfate concentrations, hydraulic retention times (HRT), and chemical oxygen demand (COD)/SO42- were discussed. The results show that the iron-carbon microelectrolysis-enhanced SRB technology can remove high-concentration sulfate wastewater, and the system can still operate normally at low pH. In the high hydraulic loading stage (HRT = 12 h, COD/SO42- = 1.4), the SO42- removal rate of the R1 reactor reached 98.08%, and the ORP value was stable between - 350 and - 450 mV, providing a good ORP environment for SRB. When HRT = 12 h and influent COD/SO42- = 1.4, the R1 reactor sulfate removal rate reached 96.7%. When the influent COD/SO42- = 0.7, the sulfate removal rate was 52.9%, higher than the control group. Biological community analysis showed that the abundance of SRB in the R1 reactor was higher than that in the other three groups, indicating that the IC-ME bioreactor could promote the enrichment of SRB and improve its population competitive advantage. It can be seen that the synergistic effect between IC-ME and biology plays a vital role in the treatment of high-concentration sulfate wastewater and improves the biodegradability of sulfate. It is a promising process for treating high-concentration sulfate wastewater.

Performance evaluation and chemical oxygen demand removal of tannery wastewater through the aerobic-anaerobic route.

With characterized for complex and maximum substance (suspended solids, broke up oil, a mixture of inorganic and chromium sulfides), tannery wastewater was subjected to a treatment process on removal of chemical oxygen demand (COD) via upstream anaerobic sludge blanket reactor where we found reduced departure efficiencies and that process limits were affected by the assortments in regular stacking rates, closeness of chromium, and sulfides. Hence, a combination of the aerobic-anaerobic hybrid reactor was set up for sequential treatment to determine possible COD reduction. This study investigated the biological degradation of tannery wastewater in a laboratory-scale sequential up-flow aerobic-anaerobic reactor. The aerobic zone at the top was packed with spherical ball-shaped polyhedral polypropylene, and the anaerobic zone at the bottom was packed medium with granular media. The aeration flow rate varied by 2 L/min, 4 L/min, and 6 L/min in the aerobic zone, and the reactor maintained an organic loading rate (OLR) of 5 kg COD/m3/d. Parameters like COD and gas yield assess the performance of the reactor. The maximum COD of 86% is removed in the anaerobic zone with an aeration rate of 6 L/min, and the 1800-mL methane gas yield is measured by the 29th day.

How do aeration mode and influent carbon/nitrogen ratio affect pollutant removal, gas emission, functional genes and bacterial community in subsurface wastewater infiltration systems?

This study investigated the influences of aeration mode and influent carbon/nitrogen ratio on matrix oxygen concentration, pollutant removal, greenhouse gas emission, functional gene abundances and bacterial community in subsurface wastewater infiltration systems (SWISs). Intermittent or continuous aeration enhanced oxygen supply at 0.6 m depth in the matrix, which improved organics removal, nitrogen removal, the abundances of bacterial 16S rRNA, amoA, nxrA, narG, napA, nirK, nirS, norB, nosZ genes, bacterial community Alpha diversity, the relative abundances of Actinobacteria at 0.6 m depth, the relative abundances of Chloroflexi, Gemmatimonadetes, Bacteroidetes and Firmicutes at 0.9 and 1.2 m depth and reduced CH4 and N2O conversion efficiencies, the abundance of mcrA gene with carbon/nitrogen ratio of 12 and 16 compared with non-aeration. Increased carbon/nitrogen ratio resulted in higher TN removal efficiencies and lower CH4 and N2O conversion efficiencies in aeration SWISs than those in non-aeration SWIS. Intermittent aeration SWIS obtained high removal efficiencies of 83.2, 85.4 and 90.8% for TN, NH4+ -N and COD and low conversion efficiency of 0.21 and 0.65% for N2O and CH4 with optimal carbon/nitrogen ratio of 12. However, high TN (82.6%), NH4+ -N (84.9%) and COD (92.2%) removal efficiencies and low CH4 (0.67%) and N2O (0.23%) conversion efficiencies were achieved in continuous aeration SWIS with carbon/nitrogen ratio of 16.

Efficient treatment of tannery wastewater through aeration, coagulation, and algal pond.

BACKGROUND: Tannery wastewater effluents contain many toxic and carcinogenic heavy metals and physiochemical parameters that need to be removed before these effluents enter in the main water bodies or rivers. In this study, the effluents from the tannery industry are treated through aeration, coagulation, and Chlorella vulgaris pond treatment processes for the removal of physiochemical: parameters only. METHODS: The effect of removal efficiencies (%) was studied on the physicochemical parameters, including salinity, electrical conductivity (EC), total dissolved solids (TDS), turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD). RESULTS: The key results showed that the removal of EC, TDS, turbidity, TSS, BOD, and COD was 80.2%, 67%, 81%, 80.8%, 68.6%, and 100%, respectively, in raw wastewater treatment having 25, 50, and 70 g of algae C. vulgaris doses. The removal efficiencies (%) of salinity, EC, TDS, turbidity, TSS, BOD, and COD were 83%, 87.1%, 77.1%, 80%, 40%, 97%, and 98%, respectively, during coagulated wastewater treatment with three doses of algae. The observed improvement in treated wastewater indicated that the removal efficiencies (%) of salinity, EC, TDS, turbidity, TSS, BOD, and COD were 85.7%, 39.3%, 81.3%, 67.8%, 50.3%, 97%, and 98%, with C. vulgaris. CONCLUSION: This study confirmed that the treatment of tannery wastewater by these processes increased the pollutant removal efficiencies as all the physiochemical parameters were exceeding the permissible limits. RESULTS CONTRIBUTION IN FUTURE: This research will be helpful to treat the industrial wastewaters or effluents before it further mixes up in the main water streams. In this way, water quality will be better, aquatic life will be saved, and further researchers can analyze more ways for efficient treatments as they have a baseline data through this study findings. PRACTITIONER POINTS: One of the most pollutant sources in terms of both physical and chemical parameters is the produced wastewater from tannery industries. The effluents from tannery industry are treated through aeration, coagulation, and algae ponds treatment processes. These treatment made the tannery wastewater as environmental friendly.

Optimization of oil industry wastewater treatment system and proposing empirical correlations for chemical oxygen demand removal using electrocoagulation and predicting the system's performance by artificial neural network.

The alarming pace of environmental degradation necessitates the treatment of wastewater from the oil industry in order to ensure the long-term sustainability of human civilization. Electrocoagulation has emerged as a promising method for optimizing the removal of chemical oxygen demand (COD) from wastewater obtained from oil refineries. Therefore, in this study, electrocoagulation was experimentally investigated, and a single-factorial approach was employed to identify the optimal conditions, taking into account various parameters such as current density, pH, COD concentration, electrode surface area, and NaCl concentration. The experimental findings revealed that the most favorable conditions for COD removal were determined to be 24 mA/cm2 for current density, pH 8, a COD concentration of 500 mg/l, an electrode surface area of 25.26 cm2, and a NaCl concentration of 0.5 g/l. Correlation equations were proposed to describe the relationship between COD removal and the aforementioned parameters, and double-factorial models were examined to analyze the impact of COD removal over time. The most favorable outcomes were observed after a reaction time of 20 min. Furthermore, an artificial neural network model was developed based on the experimental data to predict COD removal from wastewater generated by the oil industry. The model exhibited a mean absolute error (MAE) of 1.12% and a coefficient of determination (R2) of 0.99, indicating its high accuracy. These findings suggest that machine learning-based models have the potential to effectively predict COD removal and may even serve as viable alternatives to traditional experimental and numerical techniques.

Biodegradability enhancement of waste lubricating oil regeneration wastewater using electrocoagulation pretreatment.

As a sustainable management of fossil fuel resources and ecological environment protection, recycling used lubricating oil has received widespread attention. However, large amounts of waste lubricating-oil regeneration wastewater (WLORW) are inevitably produced in the recycling process, and challenges are faced by traditional biological treatment of WLORW. Thus, this study investigated the effectiveness of electrocoagulation (EC) as pretreatment and its removal mechanism. The electrolysis parameters (current density, initial pH, and inter-electrode distance) were considered, and maximal 60.06% of oil removal was achieved at a current density of 15 mA/cm2, initial pH of 7, and an inter-electrode distance of 2 cm. The dispersed oil of WLORW was relatively easily removed, and most of the oil removal was contributed by emulsified oil within 5-10 µm. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that effective removal of the biorefractory organic compounds could contribute to the improvement of biodegradability of WLORW. Thus, the 5-day biochemical oxygen demand/chemical oxygen demand ratio (BOD5/COD) was significantly enhanced by 4.31 times, which highly benefits future biological treatment. The routes of WLORW removal could be concluded as charge neutralization, adsorption bridging, sweep flocculation, and air flotation. The results demonstrate that EC has potential as an effective pretreatment technology for WLORW biological treatment.

Modified air-Fenton with MIL-88A for chemical oxygen demand treatment in used coolant oil.

Coolant oil from auto part manufacturing contains additives resulting in high chemical oxygen demand (COD) in wastewater. In this study, COD treatment of coolant oil was investigated in a metal-organic framework (MOF) with MIL-88A by a modified air-Fenton (MAF) process by varying synthetic coolant oil concentrations (1-5%), pH (3-9), air-flow rate (1-2 L/min), amount of MIL-88A (0.2-1.0 g), and reaction time (30-180 min). The results were analyzed using central composite design (CCD) and response surface methodology (RSM) using Minitab ver. 19. The characteristic MIL-88A was characterized by XRD that showed a spindle-like shape with 2θ at 10.2° and 13.0°. The FTIR spectrum revealed the vibrational frequencies at Fe-O (564 cm-1), C-O (1391 and 1600 cm-1), and C = O (1216 and 1710 cm-1). The optimum treatment efficiency was studied from 30 CCD conditions in the presence of coolant oil (5%, COD ~ 132,000 mg/L), pH (9), air flow rate (2 L/min), and MIL-88A (1 g) within 177 min. The results obtained from the experiment and the COD prediction were found to be 92.64% and 93.45%, respectively. The main mechanism of iron(III) in MIL-88A is proposed to be the production of hydroxyl radical (·OH) that oxidizes the organic matter in the coolant oil. Moreover, the MAF process was applied to the used industrial coolant oil and was found to be 62.59% efficient.

Treatment of diluted palm oil mill effluent (POME) synchronous with electricity production in a persulfate oxidant-promoted photocatalytic fuel cell.

Attributable to the prosperous production growth of palm oil in Malaysia, the generated palm oil mill effluent (POME) poses a high threat owing to its highly polluted characteristic. Urged by the escalating concern of environmental conservation, POME pollution abatement and potential energy recovery from the effluent are flagged up as a research topic of interest. In this study, a cutting-edge photocatalytic fuel cell (PFC) system with employment of ZnO/Zn nanorod array (NRA) photoanode, CuO/Cu cathode, and persulfate (PS) oxidant was successfully designed to improve the treatment of POME and simultaneous energy production. The photoelectrodes were fabricated and characterized by field emission scanning electron microscopy with energy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and Brunauer, Emmett, and Teller analysis (BET). Owing to the properties of strong oxidant of PS, the proposed PFC/PS system has exhibited exceptional performance, attaining chemical oxygen demand (COD) removal efficiency of 96.2%, open circuit voltage (Voc) of 740.0 mV, short circuit current density (Jsc) of 146.7 µA cm-2, and power density (Pmax) of 35.6 µW cm-2. The pre-eminent PFC/PS system performance was yielded under optimal conditions of 2.5 mM of persulfate oxidant, POME dilution factor of 1:20, and natural solution pH of 8.51. Subsequently, the postulated photoelectrocatalytic POME treatment mechanism was elucidated by the radical scavenging study and Mott-Schottky (M-S) analysis. The following recycling test affirmed the stability and durability of the photoanode after four continuous repetition usages while the assessed electrical energy efficiency revealed the economic viability of PFC system serving as a post-treatment for abatement of POME. These findings contributed toward enhancing the sustainability criteria and economic viability of palm oil by adopting sustainable and efficient POME post-treatment technology.

Assessing diatom distribution in Cambay Basin, Western Arabian Sea: impacts of oil spillage and chemical variables.

Freshwater and marine diatoms produce the majority of the oxygen in aquatic systems. Estimates range from 12,000 to 30,000 species, and spatial distribution varies globally. There is significant variation in diatom diversity based on geographical and environmental conditions as well as the physicochemical characteristics of the habitat. Therefore, understanding the underlying factors that contribute to changes in diatom community structures requires a comprehensive understanding of taxons. A study of diatom assemblages from the Cambay Basin, Western Arabian Sea, was conducted, particularly on oil fields. A total of 37 samples were collected; nine were from oil fields. We evaluated micro-oil spills using Fourier transform infrared (FTIR) analysis and microscopic techniques. Correlations were established through the ordination analysis of pernicious physical and chemical water variables (BOD, COD, TDS, pH, temperature, and DO), including principal component analysis (PCA). The oil field sites showed more total dissolved solids (TDS) and chemical oxygen demand (COD) than the respective marine control sites. The study does not display a cause-and-effect relationship, but we observed a positive correlation between increasing silica concentrations and diatom growth in oil fields. In contrast, high aluminium concentrations in oil fields negatively impacted the growth of diatom assemblage and abundance. When surveyed in nine oil fields, we found that Gomphonella pseudosphaerophorum and Nitzschia palea are well adapted to oil concentrations up to 40 ppm.

Treatment of coking wastewater using a needle coke electro-Fenton cathode: optimizing of COD, NH4+-N, and TOC removal and characterization of pollutants.

Coking wastewater is a typical organic refractory wastewater characterized by high chemical oxygen demand (COD), NH4+-N, and total organic carbon (TOC). Herein, coking wastewater was treated using a heterogeneous electro-Fenton (EF) system comprising a novel iron-loaded needle coke composite cathode (Fe-NCCC) and a dimensionally stable anode. The response surface methodology was used to optimize the reaction conditions. The predicted and actual COD removal rates were 92.13 and 89.96% under optimum conditions of an applied voltage of 4.92 V, an electrode spacing of 2.29 cm, and an initial pH of 3.01. The optimized removal rate of NH4+-N and TOC was 84.12 and 73.44%, respectively. The color of coking wastewater decreased from 250-fold to colorless, and the BOD5/COD increased from 0.126 to 0.34. Gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy show that macromolecular heterocyclic organic compounds decomposed into straight-chain small molecules and even completely mineralized. The energy consumption of the EF process was 23.5 RMB Yuan per cubic meter of coking wastewater. The EF system comprising the Fe-NCCC can effectively remove pollutants from coking wastewater, has low electricity consumption, and can simultaneously reduce various pollution indicators with potential applications in the treatment of high-concentration and difficult-to-degrade organic wastewater.

Electrochemical treatment of wastewater containing urea-formaldehyde and melamine-formaldehyde.

The wastewater containing urea-formaldehyde (UF) and melamine-formaldehyde (MF) from the medium-density fiberboard (MDF) lamination factory disposed into the waterbodies adversely affects human health and aquatic life. Therefore, its treatment before discharge is necessary. Researchers have used various techniques to treat this type of wastewater in the past, but none have tried electrochemical (EC). However, EC can potentially remove pollutants such as chemical oxygen demand (COD), total organic carbon (TOC), formaldehyde (FA), total nitrogen (TN), nitrogen nitrate (NO3-N), and other hydrocarbons. Hence, this study uses the EC technique to treat wastewater containing UF and MF with aluminium electrodes. The experiments were run in batch mode with a 250 mL working volume in a 500 mL Pyrex glass beaker using a variable DC power supply (0-30 V and 0-5 A). The impacts of various parameters, including reaction time (RT) 30-240 min, current density (CD) 8.66-51.94 mA/cm2, inter-electrode distance (IED) 1-2 cm, and mixing speed in the range of 60-120 rpm were examined to achieve the best pollutant removals. The best removal percentage was reached at the optimized conditions of 150 min RT, 43.28 mA/cm2 CD, 1.5 cm IED, and 80 rpm: 81.1% TOC, 61.5% COD, 76.7% TN, 28.3% NO3-N, and 55.2% FA. During the EC process, electrodes and energy consumption were estimated at around 2.367 (g/L) and 0.18 (kWh/L), respectively. A kinetic analysis was also carried out to determine the pollutant's removal trend. This study concluded that the pseudo-first-order kinetic model was the best fit for removing TOC and FA with regression coefficients of 0.96 and 0.83, respectively.

Removal of COD from real oily wastewater by electrocoagulation using a new configuration of electrodes.

In order to bring the chemical oxygen demand (COD) concentration down to safe levels for widespread use, this study plans to use a state-of-the-art electrocoagulation reactor (ECR) to treat real oily wastewater discharged from the Al-Muthanna petroleum refinery. A one-side finned (1SF) cathode tube was positioned between two tubular anodes in the continuous ECR, where the active area of the cathode was much more than its submerged volume. Each of these electrodes was made of aluminum and joined in a monopolar parallel to a DC power supply. On COD elimination efficiency, the impacts of operational parameters such as electrolysis time (4-60 min), current density (0.630-5.000 mA/cm2), and flow rate (50-150 ml/min) were explored. In conclusion, Increasing current density and electrolysis duration increases COD removal efficiency, whereas increasing flow rate reduces it. COD removal efficiencies were 82% at optimal electrolysis times of 60 (min), 5 (mA/cm2) current density, and 50 (ml/min) flow rate, with energy consumption of 4.787 (kWh/kg COD) and electrode consumption of 0.544 (g). The investigation results demonstrated that the new reactor could treat oily wastewater within the specified operational limits. It might be used before other, more conventional treatments.

A study on the efficiency of the sequential batch reactor on the reduction of wastewater pollution from oil washing.

Industrial pollution discharges from washing fuel oils pose severe problems for the environment, particularly for the marine environment receiving these discharges. This work evaluates the biological treatment performance of wastewater (90 m3/h) rich in organic matter with low biodegradability using a sequential batch reactor (SBR) on a laboratory scale. The test using SBR was carried out for 25 days on a continuous cycle of 24 h (30 min of filling, 17 h of aeration, 4 h of anoxia, 2 h of settling, and 30 min of emptying). The feasibility of alternative sources of microorganisms from urban wastewater. The performance of the batch sequencing reactor was evaluated using turbidity, total suspended solids, chemical oxygen demand (COD), biological oxygen demand (BOD), ammonium, nitrate, and phenol as indicators. The results obtained showed that the COD/BOD ratio and the pollutant load vary from one campaign to another. The removal efficiency of COD, BOD, TSS (Total suspended solids), ammonium, nitrate, and phenol varies from 81%, 91%, 72%, 100%, 52%, and 63%. Thus, SBR-type treatment could be an interesting way to reduce pollution due to its simplicity, less space occupation, low energy consumption, and not requiring highly qualified personnel.

Combination of zero-valent aluminum-acid system and electrochemically activated persulfate oxidation for biologically pre-treated leachate nanofiltration concentrate treatment.

This study investigated the performance of combined zero-valent aluminum (ZVAl) and electrochemically activated persulfate (PS) oxidation for the leachate nanofiltration concentrate (NFC) treatment. Firstly, operating parameters in the ZVAl procedure were optimized and under the optimum conditions (ZVAl dose 1 g/L, initial pH 1.5) the removal efficiency of the chemical oxygen demand (COD), UV254, and color were 22.39%, 29.03%, and 48.26%, respectively. Secondly, the effect of various anode types (Ti/RuO2, Ti/IrO2, and Ti/SnO2) within the electrooxidation (EO) process was evaluated. The Ti/RuO2 anode was found to be the most effective one in terms of pollutant removal efficiencies and operation cost. The efficiency of single, binary, and hybrid processes was evaluated by control experiments and the results were ranked as PS < ZVAl < ZVAl + PS < EO < EO + PS < EO + ZVAl < EO + ZVAl + PS. In the following part of the study, the Box-Behnken design was preferred to optimize the operating parameters of the hybrid EO + ZVAl + PS process. The COD, UV254, and color removal efficiencies under optimum conditions (4.88 mM PS dose, 1.6 A current applied, and 120 min reaction time) were 62.1%, 75.2%, and 99.9%, respectively. The estimated and experimentally obtained data were close to each other. The pollutant removal efficiencies increased in parallel with the current density and reaction time; however, the effect of the PS dose remained at a negligible level. The obtained results indicate the effectiveness of the hybrid EO + ZVAl + PS process for the treatment of leachate nanofiltration concentrate under optimized conditions.

Electrochemical oxidation process on palm oil mill effluent waste activated sludge: optimization by response surface methodology.

Biological-based treatment as the conventional treatment for palm oil mill effluent (POME) in open-ponding system face a well known rate-limiting step which is hydrolysis. In this study, electrochemical oxidation (EO) by a ruthenium oxide-coated titanium (Ti/RuO2) electrode was introduced as a pre-treatment for POME waste activated sludge (WAS). Surface morphology and elemental analysis were investigated using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Response surface methodology type central composite design was used in this study to understand the relationship between the independent and dependent variables. Analysis of variance (ANOVA) was used to validate the model of the studied variables. The correlation coefficients (R2) indicated a close agreement between the experimental results and the predicted values, with high R2 values of 0.9044-0.9773. Multiple response optimization suggested that the range of current density (17-27 mA/cm2) and electrolysis time (55-75 min) at a fixed concentration of sodium chloride (10 g/L), resulted in mixed liquor volatile suspended solids (MLVSS) removal >20%, capillary suction timer (CST) reduction >43%, extracellular polymeric substances (EPS) increment <19% and soluble chemical oxygen demand (sCOD) increment >25%. EO appears to be an efficient pre-treatment as well as practical way to improve the POME WAS disintegration and dewaterability.

Evaluate the effectiveness technology for the treatment of oily wastewater.

This work deals with the treatment of oily wastewater produced from the washing of oil-contaminated soil. Untreated oily wastewater contains toxic compounds that might be mutagenic or carcinogenic as total petroleum hydrocarbon (TPH) and heavy metals. Based on the water quality analysis, the tested samples contained a high concentration of TPH, chemical oxygen demand (COD) and turbidity with an average value of 67,500 mg/l, 48,240 mg/l and 176 (nephelometric turbidity unit, NTU), respectively. Several technologies were used, such as centrifuging, powdered activated carbon (PAC) and sawdust. The mean values of COD values for sawdust, centrifuging and PAC were 41,067, 25,600 and 13,133 mg/l, respectively. The present study indicated that the coagulation/flocculation processes were more efficient by using aluminium sulphate alum, while the preliminary conclusion derived was that the secondary treatment using an aeration system is capable of lowering the COD values as well as increasing the flocculent mass floc well equal to 4,784 mg/l and 0.69 g, respectively. The microbial seed was able to degrade the biosurfactant, which allows the stability of oil emulsion to be broken down and released easily.

Electrochemical oxidation of palm oil mill effluent using platinum as anode: Optimization using response surface methodology.

This work investigates the electrochemical oxidation of palm oil mill effluent (POME) treatment using platinum (Pt) as anode and graphite as a cathode. The response surface methodology was used to investigate the relationships between different factors conditions (voltage, electrolysis time and chemical support) and responses of the treatment (chemical oxygen demand reduction, colour removal, and total oil removal). A quadratic mathematical model was chosen for all responses using Box-Behnken Design (BBD) with R2 0.9853 for COD reduction, R2 0.9478 for colour removal and R2 0.9185 for total oil removal. According to Derringer's function desirability, under the optimum condition (Voltage 15, electrolysis time 2 h, and 19.95 mg/L NaCl) of POME treatment, 84% of COD reduction, 98% of colour removal and 99% total oil of removal could be achieved. These results indicate that platinum as an anode material is effective for the electrochemical oxidation treatment of POME.