Complex Effluents Research Articles

Removal of Recalcitrant Organic Compounds From an Industrial Complex Effluent by Heterogeneous Fenton‐Type Treatment

Because of their chemical complexity, industrial chemi‐mechanical pulping effluents are evaporated and burned, in spite of the high associated cost involved in these processes. The aim of this study was to remove recalcitrant compounds from this kind of wastewater using a Fenton‐type treatment. The main parameters involved in the process and their influence on the results were determined. Homemade catalysts based on CuO, Fe2O3, NiO, and ZnO, supported on γ‐Al2O3 have been tested for catalytic oxidation, and the CuO/γ‐Al2O3 catalysts showed the greatest effect on total organic carbon (TOC) reduction (52.7%). A series of two‐level factorial experiments was subsequently applied to evaluate the most favorable range of conditions for CuO/γ‐Al2O3 application. The studied variables were hydrogen peroxide concentration ([H2O2], g/L), active phase content (metal oxide supported on alumina,%), mass of catalyst (metal oxide/alumina system, g), and reaction temperature (°C). The highest reduction of all parameters was obtained at the superior level of all variables with CuO/γ‐Al2O3, achieving reductions of chemical oxygen demand (COD) and TOC between 40 and 50%. Increasing catalyst mass did not produce additional benefit. This variable has a significant effect only on the reduction of aromatic compounds. At its low level, reduction in aromatic content exceeded 80%. Color reduction was influenced only by temperature (maximum reduction of 90%).

Application of advanced oxidation process (H2O2/UV) for removal of organic materials from pharmaceutical industry effluent

Pharmaceutical wastewater is one of the major complex and toxic industrial effluents containing little or no biodegradable organic matters. In this study, H2O2AJV based advanced oxidation process (AOP) was used to remove organic materials from pharmaceutical industry effluent. For the chemical oxygen demand (COD) removal radiation of medium pressure mercury vapor UV lamp was used in the presence of hydrogen peroxide (H2O2/UV). Results indicated that the efficiency of COD removal depends on the initial concentration of H2O2, oxidation time and pH. The efficiency of COD removal at low H2O2 concentration was very low even coupled with UV light, which can be attributed to the low generation of hydroxyl radicals (OH·). At high concentration of H2O2 (500 mg/dm³) and optimum pH (pH = 4), 87.6% removal efficiency could be achieved during 70 min oxidation. For high concentration of H2O2 (500 mg/dm³) at pH 3 and 7, the maximum COD removal efficiency was 28.5% and 15.2% respectively, indicating significant roles of pH and H2O2 concentration in the process of COD removal. Application of advanced oxidation process (H2O2/UV) for removal of organic materials from pharmaceutical industry effluent. Available from: https://www.researchgate.net/publication/317775668_Application_of_advanced_oxidation_process_H2O2UV_for_removal_of_organic_materials_from_pharmaceutical_industry_effluent [accessed Jul 17, 2017].

제약공단 방류수 유입 하천에서의 항생제 내성 bacteria에 관한 연구

Objectives: The purpose of this study was to characterize penicillin G resistant bacteria in surface water from pharmaceutical complex effluent. Methods: Surface water was sampled from pharmaceutical complex effluent in Gyeonggi-do Province, Korea in March 2015. Water samples were plated in triplicate on tryptic soy agar plates with 32 mg/L of penicillin G. Penicillin G resistant bacteria were selected from the effluent and subjected to 16S rRNA analysis for the penicillin G resistant species determination. Identified resistant strains were tested for resistance to various antibiotics. Results: Penicillin G resistant bacteria were present at 8.0% in terms of culturable heterotrophic bacteria. Identified penicillin G resistant bacteria exhibited resistance to more than nine of the antibiotics studied. These resistant bacteria are gram negative and are closely related to pathogenic species. Conclusion: Multi-antibiotic resistant bacteria in the surface water of pharmaceutical complex effluent suggest the need for disinfection and advanced oxidation processed for pharmaceutical effluent.

Biosorption of hexavalent chromium by microorganisms

Microorganisms perform an important function in the bioremediation of contaminated soils, water and effluents. Bacteria, fungi, yeasts and microalgae and cyanobacteria, are low-cost biotechnological tools for the treatment of large volumes of complex effluents containing Cr(VI). As from the selection and identification of new microorganisms and the evolution of Modern Biotechnology, molecular techniques and the characteristics of microorganisms such as their versatility and capacity to adapt to different environments, permit that the biosorption of Cr(VI) be an alternative for the removal of contaminants. Variations in the cell composition, morphology and way of growth, as also a study of the operational conditions, allow for the application of aerobic or anaerobic microorganisms, live or dead, in the removal of Cr(VI). Thus the characteristics of the biosorbents applied in the removal of Cr(VI), the biosorption processes, reactors and bioreactors, and the research developed with a view to the biosorption will be discussed in this review.

Optimization of phenol biodegradation by efficient bacteria isolated from petrochemical effluents

Phenol is an environmental pollutant present in industrial wastewaters such as refineries, coal processing and petrochemicals products. In this study three phenol degrading bacteria from Arak Petrochemical Complex effluent were isolated which consume phenol. Molecular analysis was used to identify bacteria and isolated bacteria were identified as Rhodococcus pyridinivorans (NS1),Advenella faeciporci (NS2) andPseudomonas aeroginosa (NS3). Among the isolated strains, NS1 had the highest ability to degrade phenol. In order to observe the best yield in phenol biodegradation using NS1, optimization was performed using one factor at a time of experimental design to investigate the effect of four factors, including pH, temperature, phosphate and urea concentration. The optimal biodegradation condition through or tho pathway was pH = 8, urea = 1 g/L, temperature = 30∞C and K 2 HPO 4 = 0.5 g/L. Under the suggested condition, a biodegradation efficiency of 100% was achieved. Moreover, NS1 has shown growth and phenol degradation in concentrations between 250 to 2000 mg/L. In a nutshell, the results revealed that phenol efficiently consumed by NS1 as the sole carbon source. Obviously, the isolate strain may be seen as an important tool in the bioremediation of wastewater effluent, petrochemical complex.

BIODEGRADACIÓN DE VINAZAS DE CAÑA DE AZÚCAR MEDIANTE EL HONGO DE PUDRICIÓN BLANCA Pleurotus ostreatus EN UN REACTOR DE LECHO EMPACADO

<p>Sugarcane vinasses are considered a complex effluent because of its organic load, low pH, high temperature, and by the presence of recalcitrant substances such as melanoidins and phenolic compounds. The aim of this work was to evaluate the potential of the fungus <em>Pleurotus ostreatus</em> to carry out the biodegradation of sugarcane vinasses in a fixed-bed bioreactor. The experiments evidence the potential of the fungus <em>Pleurotus ostreatus</em> to carry out the decolorization (83%), the removal of the Chemical Oxygen Demand (COD=87%) and the Biochemical Oxygen Demand (BOD<sub>5</sub>=92%), the reduction of total suspended solids (83%) and volatile suspended solids (72%) of vinasses. The technical simplicity of the proposed alternative as well as process performance reveals the potential of the fungus <em>Pleurotus ostreatus</em> for the treatment of sugarcane mill effluents.</p>

Treatment of hospital laundry wastewater by UV/H2O2 process.

Hospitals consume a large volume of water to carry out their activities and, hence, generate a large volume of effluent that is commonly discharged into the local sewage system without any treatment. Among the various sectors of healthcare facilities, the laundry is responsible for the majority of water consumption and generates a highly complex effluent. Although several advanced oxidation processes (AOPs) are currently under investigation on the degradation of a variety of contaminants, few of them are based on real wastewater samples. In this paper, the UV/H2O2 AOP was evaluated on the treatment of a hospital laundry wastewater, after the application of a physicochemical pretreatment composed of coagulation-flocculation and anthracite filtration. For the UV/H2O2 process, a photoreactor equipped with a low-pressure UV-C lamp was used and the effects of initial pH and [H2O2]/chemical oxygen demand (COD) ratio on COD removal were investigated through a randomized factorial block design that considered the batches of effluent as blocks. The results indicated that the initial pH had no significant effect on the COD removal, and the process was favored by the increase in [H2O2]/COD ratio. Color and turbidity were satisfactorily reduced after the application of the physicochemical pretreatment, and COD was completely removed by the UV/H2O2 process under suitable conditions. The results of this study show that the UV/H2O2 AOP is a promising candidate for hospital laundry wastewater treatment and should be explored to enable wastewater reuse in the washing process.

A comparison of two methods for the assessment of stress axis activity in wild fish in relation to wastewater effluent exposure

Riverine fish are particularly vulnerable to chemical exposure – rivers receive chemicals of anthropogenic origin from a variety of sources, one of the most significant being the chemically complex effluents discharged by wastewater treatment works (WWTWs). The extent to which non-reproductive components of the endocrine system in fish may be vulnerable to interference by contaminants associated with WWTW effluent is not well understood, but a significant body of evidence does suggest that contaminants present in the aquatic environment may interfere with the normal function of the neuroendocrine stress axis in fish. Field investigations of stress axis function in free-living populations of fish by measurement of hormone concentrations in blood can be confounded by the remoteness of sampling locations and the size of target species. Two methods for assessing stress axis reactivity in situations where blood samples are unavailable were compared in three-spined sticklebacks in relation to their exposure to WWTWs effluent. Sticklebacks were sampled in two successive years at fifteen sites in north-west England impacted by WWTW effluent and the response of each fish to the combined stressor of capture and a brief period of confinement was evaluated using both whole-body immunoreactive cortisol concentrations (WBIC) and the rate of release of cortisol to water (CRTW). A positive relationship between the magnitude of stress-induced CRTW in sticklebacks of both sexes and WWTW effluent concentration at site of capture was observed in both years. However, the relationship between stress-induced WBIC and WWTW effluent concentration was not consistent. These results suggest that components of WWTW effluent can modulate the magnitude of the neuroendocrine stress response in sticklebacks, and by inference in other fish species, but they raise questions about the measurement and interpretation of stress axis responses in fish via endpoints other than blood hormone concentrations. Possible factors underlying the disparity between the CRTW and WBIC results are discussed.

Behaviour, development and metal accumulation in striped marsh frog tadpoles (Limnodynastes peronii) exposed to coal mine wastewater

Coal mining generates large quantities of complex effluent, and this often contains high levels of dissolved solids, suspended solids, metals, hydrocarbons, salts and other compounds. Substantial volumes of mine wastewater are periodically discharged into the environment, through both planned and accidental releases, and this raises concerns about the potential for adverse impacts on aquatic wildlife. There have been few attempts to explore sub-lethal effects of coal mine wastewater on amphibians compared to other organisms, and this is particularly true for Australian species. To address existing knowledge gaps, we exposed striped marsh frog (Limnodynastes peronii) tadpoles to 25, 50 and 100% coal mine wastewater collected from two holding dams (CMW1 and CMW2) located at an open cut mine in Central Queensland, Australia. The exposure lasted for four weeks, after which survival, growth and development, swimming behaviour, and concentrations of metals and metalloids in tail and liver tissues were assessed. Physico-chemical parameters varied considerably between sites, with higher turbidity, nutrients, total and dissolved organic carbon, alkalinity and arsenic (As) concentrations at CMW1, and higher conductivity, salinity, dissolved solids, hardness and sulfate levels at CMW2. There was no mortality in controls and less than 5% mortality in CMW1 treatments, whereas survival was significantly decreased in tadpoles exposed to CMW2 with 40 and 55% mortality in the 50 and 100% treatments, respectively. Development was significantly delayed in 100% CMW1 wastewater, but tadpole size (growth) was not influenced by the exposure. Hepatosomatic indices were significantly increased in tadpoles exposed to 25 and 50% CMW1 but not the 100% treatment group. Exposed tadpoles (predominantly those exposed to CMW1) exhibited increased activity after very short-term exposure (24h), but this did not persist as animals approached metamorphic climax. At the end of the experiment, tadpoles exposed to both wastewaters had elevated levels of selenium (Se), cobalt (Co) and As in tail and liver tissue compared to controls. Manganese (Mn) levels were also elevated in livers and tails of CMW2 exposed tadpoles. Hepatic tissue accumulated 8–9 times higher concentrations of Co, Mn and Se compared to tail tissue, irrespective of treatments. Future research is warranted to explore possible relationships between metal bioaccumulation, morpho-physiological effects during development, and subsequent higher-level outcomes related to individual performance and population fitness.

Cyanide Formation and Fate in Complex Effluents and its Relation to Water Quality Criteria

Cyanide occurs in many industrial and municipal wastewaters and is often an expected constituent of typical treatment plant wastewater streams. However, a growing number of wastewater treatment plants (WWTPs) across the USA have detected cyanide in cholorinated effluents at levels exceeding influent concentrations. Because water quality criteria and related discharge limits are typically low some of these WWTPs periodically exceed effluent cyanide standards. Potential causes include cyanide formation during wastewater cholrination processes, the presence of interferences that cause false negatives, and false positives caused by artifacts of sample handling or analytical techniques. The possible causes of the apparent cyanide formation phenomenon were investigated in this study. This title belongs to WERF Research Report Series ISBN: 9781843396321 (Print) ISBN: 9781780404073 (eBook)

Locomotor and behavioural responses of empire gudgeons (Hypseleotris compressa) exposed to coal mine wastewater.

Coal mining generates large quantities of complex effluent and may pose a threat to aquatic wildlife. Despite this, few studies have explored the consequences of exposure to mine wastewater on aquatic organisms, and this is particularly true for the Australian environment. We investigated sub-lethal behavioural responses in a native Australian fish exposed to wastewater from two releasing dams (CMW1 and CMW2) located at an open cut coal mine in Central Queensland. Swimming activity and movement of empire gudgeons (Hypseleotris compressa) were assessed during a two-week exposure using video-tracking software. Increased activity was observed in exposed fish after 7 and 14 days. Specifically, we found a significant increase in the mean velocity and mobility of fish exposed to CMW1 treatments. Exposed fish also spent on average 23% more time in the peripheral zone compared to controls after 14-d exposures. A similar response pattern was observed in fish exposed to CMW2, but differences between treated and control fish did not generally reach statistical significance. Alterations to normal swimming activity and movement patterns can be indicative of a stress response in fish, and could subsequently lead to negative population-level impacts by increasing the conspicuousness of exposed individuals to predators, or by altering foraging abilities. More research is warranted to explore relationships between behavioural and physiological outcomes, including endocrine disruption, and subsequent population-level outcomes in aquatic organisms at risk of exposure to coal process-affected water.

Biogas production in an anaerobic sequencing batch reactor by using tequila vinasses: effect of pH and temperature.

In recent years, anaerobic digestion has been recognized as a suitable alternative for tequila vinasses treatment due to its high energy recovery and chemical oxygen demand (COD) removal efficiency. However, key factors such as the lack of suitable monitoring schemes and the presence of load disturbances, which may induce unstable operating conditions in continuous systems, have limited its application at full scale. Therefore, the aim of this work was to evaluate the anaerobic sequencing batch reactor (AnSBR) configuration in order to provide a low cost and easy operation alternative for the treatment of these complex effluents. In particular, the AnSBR was evaluated under different pH-temperature combinations: 7 and 32 °C; 7 and 38 °C; 8 and 32 °C and 8 and 38 °C. Results showed that the AnSBR configuration was able to achieve high COD removal efficiencies (around 85%) for all the tested conditions, while the highest methane yield was obtained at pH 7 and 38 °C (0.29 L/g COD added). Furthermore, high robustness was found in all the AnSBR experiments. Therefore, the full-scale application of the AnSBR technology for the treatment of tequila vinasses is quite encouraging, in particular for small and medium size tequila industries that operate under seasonal conditions.

Proteomic changes in Corbicula fluminea exposed to wastewater from a psychiatric hospital.

The increase use of pharmaceutical compounds in veterinary practice and human population results in the ubiquitous presence of these compounds in aquatic ecosystems. Because pharmaceuticals are highly bioactive, there is concern about their toxicological effects in aquatic organisms. Therefore, the aim of this study was to assess the effects of an effluent from a psychiatric hospital (containing a complex mixture of 25 pharmaceutical compounds from eleven therapeutic classes) on the freshwater clam Corbicula fluminea using a proteomic approach. The exposure of C. fluminea to this complex effluent containing anxiolytics, analgesics, lipid regulators, beta blockers, antidepressants, antiepileptics, antihistamines, antihypertensives, antiplatelets and antiarrhythmics induced protein changes after 1 day of exposure in clam gills and digestive gland more evident in the digestive gland. These changes included increase in the abundance of proteins associated with structural (actin and tubulin), cellular functions (calreticulin, proliferating cell nuclear antigen (PCNA), T complex protein 1 (TCP1)) and metabolism (aldehyde dehydrogenase (ALDH), alcohol dehydrogenase, 6 phosphogluconate dehydrogenase). Results from this study indicate that calreticulin, PCNA, ALDH and alcohol dehydrogenase in the digestive gland and T complex protein 1 (TCP1)) and 6 phosphogluconate dehydrogenase in the gills represent useful biomarkers for the ecotoxicological characterization of psychiatric hospital effluents in this species.

Potential application of a bioemulsifier-producing actinobacterium for treatment of vinasse.

Vinasse is a complex effluent created during production of ethyl alcohol, which can present serious pollution hazard in areas where it is discharged. A variety of technologies, many based upon recovery of the effluent via microbial pathways, are continually being evaluated in order to mitigate the pollution potential of vinasse. The present work reports on initial advances related to the effectiveness of the actinobacterium Streptomyces sp. MC1 for vinasse treatment. Alternative use of raw vinasse as a substrate for producing metabolites of biotechnological interest such as bioemulsifiers, was also evaluated. The strain was able to grow at very high vinasse concentrations (until 50% v/v) and remove over 50% of the biodegradable organic matter in a time period as short as 4 d. Potentially toxic metals such as Mn, Fe, Zn, As, and Pb were also effectively removed during bacterial growth. Decrease in the pollution potential of treated vinasse compared to raw effluent, was reflected in a significant increase in the vigour index of Lactuca sativa (letucce) used as bioremediation indicator. Finally, significant bioemulsifier production was detected when this strain was incubated in a vinasse-based culture medium. These results represent the first advances on the recovery and re-valuation of an actual effluent, by using an actinobacterium from our collection of cultures.

Simultaneous biosorption of selenium, arsenic and molybdenum with modified algal-based biochars

Ash disposal waters from coal-fired power stations present a challenging water treatment scenario as they contain high concentrations of the oxyanions Se, As and Mo which are difficult to remove through conventional techniques. In an innovative process, macroalgae can be treated with Fe and processed through slow pyrolysis into Fe-biochar which has a high affinity for oxyanions. However, the effect of production conditions on the efficacy of Fe-biochar is poorly understood. We produced Fe-biochar from two algal sources; “Gracilaria waste” (organic remnants after agar is extracted from cultivated Gracilaria) and the freshwater macroalgae Oedogonium. Pyrolysis experiments tested the effects of the concentration of Fe3+ in pre-treatment, and pyrolysis temperatures, on the efficacy of the Fe-biochar. The efficacy of Fe-biochar increased with increasing concentrations of Fe3+ in the pre-treatment solutions, and decreased with increasing pyrolysis temperatures. The optimized Fe-biochar for each biomass was produced by treatment with a 12.5% w/v Fe3+ solution, followed by slow pyrolysis at 300 °C. The Fe-biochar produced in this way had higher a biosorption capacity for As and Mo (62.5–80.7 and 67.4–78.5 mg g−1 respectively) than Se (14.9–38.8 mg g−1) in single-element mock effluents, and the Fe-biochar produced from Oedogonium had a higher capacity for all elements than the Fe-biochar produced from Gracilaria waste. Regardless, the optimal Fe-biochars from both biomass sources were able to effectively treat Se, As and Mo simultaneously in an ash disposal effluent from a power station. The production of Fe-biochar from macroalgae is a promising technique for treatment of complex effluents containing oxyanions.

Proposal to optimize ecotoxicological evaluation of wastewater treated by conventional biological and ozonation processes.

A mixture of urban and hospital effluents (50% v/v) was evaluated for ecotoxicity with an advanced bioassay battery. Mixed effluents were tested before any treatment, after biological treatment alone, and after biological treatment followed by a tertiary ozonation (15 mg O3/L). Laying a high value on the continuance of organisms' fitness, essential to preserve a healthy receiving ecosystem, the main objective of this study was to combine normalized bioassays with newly developed in vivo and in vitro tests in order to assess alteration of embryo development, growth and reproduction, as well as genotoxic effects in aquatic organisms exposed to complex wastewater effluents. Comparison of the bioassays sensitivity was considered. Contrary to the lack of toxicity observed with normalized ecotoxicity tests, endpoints measured on zebrafish embryos such as developmental abnormalities and genotoxicity demonstrated a residual toxicity in wastewater both after a biological treatment followed or not by a tertiary O3 treatment. However, the ozonation step allowed to alleviate the residual endocrine disrupting potential measure in the biologically treated effluent. This study shows that normalized bioassays are not sensitive enough for the ecotoxicological evaluation of wastewaters and that there is a great need for the development of suitable sensitive bioassays in order to characterize properly the possible residual toxicity of treated effluents.

Ozone-Induced Biodegradability Enhancement and Color Reduction of a Complex Pharmaceutical Effluent

The treatment of a complex pharmaceutical effluent using a combination of ozonation and biological treatment is reported with the use of ozonation as a pre- and posttreatment. Pretreatment facilitated biodegradability index (BI = BOD/COD) enhancement of up to 0.44 along with COD and color reduction of up to 42% and 33%, respectively. Subsequent anaerobic biodegradation of effluent indicated negligible biogas generation; however, aerobic biodegradation of pretreated effluent resulted in COD reduction (73%) and color reduction (62%), which was also indicated by the biokinetic parameters. Further, ozonation as a posttreatment led to higher overall COD (87%) and color (93%) removal.

Nanofiltration of treated digested agricultural wastewater for recovery of carboxylic acids

Synthetic solutions of varying concentrations of carboxylic acids, namely acetic and butyric acids (50 mM, 100 mM) and treated digested agricultural wastewater with a carboxylic acids concentration of 21.08 mM of acetic acid and 15.81 mM of butyric acid were processed with a range of nanofiltration membranes and enrichment schemes to concentrate carboxylic acids. The study was conducted with the scope of platform chemicals recovery from complex effluents, investigating the feasibility of nanofiltration as a method of choice. Membrane filtration is easily scalable into various arrangements, allowing versatility in operation and enrichment treatments, which other recovery practices such as liquid extraction do not allow. Among the five nanofiltration membranes used (NF270 (Dow Chemicals, USA), HL, DL, DK (Osmonics, USA), LF10 (Nitto Denko, Japan)) the DK, DL and NF270 were identified as the best candidates for carboxylic acids separation and concentration from these complex effluents, both in terms of retention and permeate flux. These membranes achieved retention ratios, up to 75% giving retentates up to 53.94 mM acetate and 28.38 mM butyrate for the agricultural wastewater. Effluents were modified by the addition of alkali and salts (sodium chloride and sodium bicarbonate), and it was found that highest productivity, retention and flux was achieved at pH 7 but at higher pH there was a significant reduction in flux.

An application of response surface methodology for optimizing coagulation process of raw industrial effluent using Cassia obtusifolia seed gum together with alum

Coagulation is effective, simple to operate, and widely used in treatment of industrial effluent. However, commonly used inorganic coagulants pose detrimental effects on human health and living organisms in long run, and generate large amount of toxic sludge. Thus, this study investigated the optimized use of Cassia obtusifolia alone or combination of alum with lower dosages in treatment of industrial effluent. In this study, raw pulp and paper mill effluent (PPME) was used as a model wastewater in confirming the potential use of C. obtusifolia seed gum as a plant-based coagulant or coagulant aid together with the alum. Response surface methodology (RSM) enabled the study of interactive effects between operating treatment conditions, and to determine the optimal treatment conditions. The analysis of variance results obtained in the present study reflected significant quadratic models and strong correlations between operating conditions and treatment performance. In addition, current findings suggested that the coagulation mechanisms using C. obtusifolia seed gum together with the alum were most likely based on adsorption with inter-particle bridging and charge neutralization. Floc characterization also showed distinctive results, indicating the presence of active functional groups and the thermal stability of floc formed using C. obtusifolia seed gum and alum. Using RSM, optimal dosages of 0.17 and 0.09g/L of C. obtusifolia seed gum and alum, respectively were required to achieve maximum total suspended solids and chemical oxygen demand removals (89.6 and 55.4%, respectively) under natural pH of raw PPME and slow-mixing time of 3.40min. By combining the use of both coagulants, coagulant dosages of C. obtusifolia seed gum and alum could be reduced up to 90.5 and 62.5%, respectively. The present study revealed C. obtusifolia seed gum could be used as a potential plant-based coagulant or coagulant aid in treatment of raw and complex industrial effluent together with reduced dosage of alum.

Simultaneous application of copper and PbO2 anodes for electrochemical treatment of olive oil mill wastewater

Olive oil mill wastewater (OOMW) is a complex effluent that must be treated before discharge into the environment. In this study, a combination of various mechanisms was conducted in an electrochemical cell. Copper and PbO2 anodes were used, while hydrogen peroxide was electro-generated at an activated carbon fiber cathode. Fenton-like reaction and electrooxidation occurred during electrolysis for organic compounds degradation in OOMW. The effects of pH, dilution of OOMW, and electrical current on COD and phenol removals were investigated. The results showed that 78.5% phenol and 60% COD removals were obtained at optimum conditions of 300 mA electrical current, 150 min electrolysis, and pH 3–3.5 (regulated). The regulation of pH during electrolysis significantly developed the treatment efficiency of electrochemical process. Phenol and COD removal kinetics were likely to follow second-order model and first-order model, respectively. Simultaneous application of two anodes had synergic effect on removal efficiency of electrochemical process. Biodegradability (BOD5/COD) was dramatically improved from 0.18 to 0.468 after electrochemical oxidation. It was concluded that the two mechanisms of production of active oxygen and chlorine had synergic effect on electrochemical degradation.