Pollution level in distillery effluent and its phytotoxic effect on seed germination and early growth of maize and rice

The effluent from a Lucknow- based distillery (Mohan Meakin Distillery) was analyzed for physico-chemical and biological parameters of pollution and concentration of potentially toxic heavy metals (Cd, Cr, Ni and Zn) and the effect of the distillery effluent, as such and on 50% dilution with tap water was studied on seed germination and seedling growth of maize (Zea mays L.) and rice (Oryza sativa L.). The effluent was wine red in colour and highly acidic (pH approximately 55) and possessed decaying alcoholic smell. The effluent contained high values of different pollution parameters, particularly total solids, 3450 mgl(-1) (soluble plus suspended solids), alkalinity 1500 mgl(-1), biological oxygen demand (BOD, 1649 mgl(-1)) and chemical oxygen demand (COD, 2036 mgl(-1)). It had very low values of dissolved oxygen (DO, 0.34 mgl(-1)). The heavy metals (Cd, Cr, Ni and Zn) content, particularly the nickel concentration (0.029 mg l(-1)) was high. Use of the distillery effluent, even on 1:1 dilution with tap water inhibited germination and early seedling growth of maize and rice. In both maize and rice, more so in the former germination % of seeds, length of radicle and plumule and the fresh and dry weight of the seedlings were significantly reduced. The emerging leaves of the seedlings also developed visible effects of toxicity some of which resembled the symptoms of nickel toxicity. Our observations suggest that the effluent, as discharged from the distillery carry a heavy load of pollutants. Its discharge into the river Gomti poses a potential threat to the aquatic life, perticularly during the summer months when the water flow in the river is drastically reduced. The distillery effluentis also harmful for irrigating crops grown along the drain carrying it.     

Assessment of physico-chemical properties and metal contents of water and sediments of Bodo Creek,Niger Delta,Nigeria

Some physico-chemical properties and the concentrations of the metals Fe, Mn, Ni, Cd, Cr, Co, Cu, Pb, and Zn in water and sediments were examined from September 2011 to January 2012 in Bodo Creek, where oil spills have been recurrent. Temperature, pH, total dissolved solid, conductivity, salinity, dissolved oxygen, biological oxygen demand (BOD), chemical oxygen demand (COD), total hardness, sulfate, nitrate, and phosphate were determined in surface water. Particle size, total organic matter (TOM), and pH were also determined in the sediments. The parameters were within permissible limits except the mean values of BOD, COD, total hardness, and sulfate that exceeded levels permissible for domestic use. The sediments consisted mainly of sand, with TOM ranging from 0.2% to 5.5%. With the exception of cadmium that was below detection limit, metal levels (mg kg^?1) in the sediments were 12 (Mn), 1070 (Fe), 10 (Cu), 10 (Zn), 5.3 (Cr), 1.1 (Pb), 1.0 (Ni), and 0.5 (Co) while in water they were 24, 98, 21, 6.9, 4.0, 0.6, 0.18, and 0.16, respectively. The latter were higher than World Health Organization recommended permissible levels for both surface and drinking water.     

Exposure to Selected Heavy Metals Through Water Ingestion in an Area Under the Influence of Tanneries

This study evaluated the potential toxicological risk posed to human health due to the exposure to heavy metals by water ingestion in an area affected by tanneries – the Cadeia-Feitoria hydrographic basin (Brazil). River water was collected at 10 sites, every 3 months, from July 1999 to April 2000. After acid digestion, total metal concentration was determined by inductively coupled plasma optical emission spectrometry (Cd, Cu, Cr, Ni, Zn), flame atomic absorption (Al, Fe, Pb, Mn), or cold vapor atomic absorption spectrometry (Hg). Cr(VI) was complexed with diphenyl-carbazide and detected by UV–vis spectrometry. In order to quantify the risk of exposure, the risk assessment methodology employed by the Environmental Protection Agency of the United States was applied at a screening level. The assumed scenarios included extreme exposure patterns (ingestion of untreated water, conversion of Cr(III) to Cr(VI), temporal peaks of pollution). Fe, Al, Cd, Hg, and Pb were not included in the risk analysis, since they showed a low toxicity potential or were undetected in the samples. The selected metals presented Hazard Quotients < 1, in the following order of increasing risk: Cu < Cr(III) < Zn < Ni < Mn < Cr(VI). Hazard indexes, representing the additive effect of contaminants, were also low in the basin (< 1), but comparatively increased in the lower reach of Feitoria and Cadeia Rivers. Although noncarcinogenic risk levels did not suggest possible adverse toxicological effects to the human population, a considerable deviation from background conditions was observed downstream the area where tanneries are mainly located.     

Evaluating the seasonal changes of some water quality parameters of the Buyuk Melen River Basin (Duzce, Turkey)

In this study, some heavy metal concentrations (Pb, Zn, Fe, Cr, Cu), suspended sediment, chemical oxygen demand (COD), biological oxygen demand (BOD), cyanide, phenol, fecal coliform and total coliform water parameters were determined in the streams (Kucuk Melen, Asarsuyu, Ugursuyu, Buyuk Melen and Aksu) of Buyuk Melen Watershed that provides drinking water to Istanbul in Western Black Sea Region of Turkey. Measurements of water quality parameters were done monthly in eleven separate stations (4 in Kucuk Melen Stream, 1 in Asarsuyu Stream, 1 in Ugur Stream, 1 in Aksu Stream and 4 in Buyuk Melen Stream) from August 2001 to August 2002. The seasonal changes in water quality parameters were evaluated statistically. The results, the parameters, COD, BOD, Pb, Zn, Fe, Cr, Cu, cyanide, fecal coliform, total coliform and suspended sediment showed significant differences among seasons and streams (ANOVA; P <0.05). According to Turkish Standarts (TS) 266, European Union (EU) and World Health Organization (WHO) criteria, the maximum values of each parameter in streams within the Buyuk Melen watershed are recorded and evaluated in this study.     

Assessment of drain water receiving effluent from tanneries and its impact on soil and plants with particular emphasis on bioaccumulation of heavy metals

In the present study, impact of tannery and other industrial effluents on the physico-chemical characteristics of loamy drain water and their consequent impact on soil and plants irrigated with effluent have been studied. The study reveals most of the parameter pH, BOD5 and COD at sampling station I was higher than station II. Waste water quality at both Stations I and II exceeded prescribed limits (BIS) for safe disposal of effluents into the surface water Samples of soil and vegetables from the land irrigated with loamy drain water has been collected and analyzed for Cu, Zn, Ni, Cr Pb and Cd. The different metals showed different enrichment factor for loamy drain water irrigated soil and are as follows: Cd 30% (max), Pb 26%, Zn 18%, Cr 5%, Cu 5%, Ni 2% (min). For plant samples collected at polluted sites are Ni 46% spinach (whole plant) (max), Zn 42% spinach (whole plant), Cr 39% spinach (whole plant), Cu 33% spinach (whole plant), Pb 20% potato tuber, Cd 20% potato tuber (min). The levels of Zn 145, Cu 5.25, and Ni 39.25 microg/ g in spinach, Pb 29.25, Cr 38. 25 and Cd 3.2 microg/g in potato tuber grown on polluted soil irrigated with contaminated drain water were found more than the reference value, which may create chronic health hazard problem to human and cattle through food chain in long run. Accumulation of toxic heavy metals may be build up in the agriculturally productive land where it is treated with contaminated effluent enrich with metals in turn bio-concentrated in the edible fodder/plants.     

Microbial decolourisation of pulp and paper mill effluent in presence of nitrogen and phosphorus by activated sludge process

The effect of pH, nutrient and aeration was studied on the removal of colour and reduction of BOD, COD and heavy metals with addition of readily available source of nitrogen and phosphorus in concentration of 1.0 g/L. Recalcitrant compound was effectively degraded by active microbial consortia. The isolated bacteria were identified as Pseudomonas putida (S1), Citrobacter sp. (S4) and Enterobacter sp. (S5). These organisms not only decolourised effluent upto 97% but reduced BOD, COD, phenolics and sulfide upto 96.63, 96.80, 96.92 and 96.67% respectively within 24 hrs of aeration and the heavy metals were removed upto 82-99.80%. The TSS and TDS were sharply reduced due to degradation. The absorption maxima was also decreased to 90%. However, in control without the microbial consortium no noticeable change was produced.     

Toxicological evaluation of bacterial decolourised anaerobically treated distillery effluent with common duckweed (Lemna minor)

Duckweed (Lemna minor) a small vascular plant, grows rapidly, is sensitive to a wide variety of toxicants and is easy to culture. A method is described that measures duckweed frond growth, chlorophyll, protein and biomass content as indicator of growth inhibition. The physico-chemical analysis of anaerobically treated distillery effluent revealed high BOD (28,000 mg/l), COD (52,400 mg/l) and dark brown colour (180,000 Co. Pt.). This effluent showed high toxicity to Lemna minor after 96 h of exposure in laboratory condition. EC50 of the fronds for chlorophyll, protein and biomass was found to be 25%, however, the bacterial decolourised effluent showed reduction of BOD (87.50%), COD (84.50%) and colour (76%). Further the toxicity evaluation with Lemna minor showed toxicity reduction up to 63% for all tested parameters. The EC50 noted for chlorophyll, protein and biomass was 100% concentration of decolourised effluent.     

Assessing geochemical influence of traffic and other vehicle-related activities on heavy metal contamination in urban soils of Kerman city,using a GIS-based approach

Heavy metal pollution caused by traffic activities is increasingly becoming a great threat to urban environmental quality and human health. In this paper, soils of Kerman urban and suburban areas were collected to assess the potential effects of traffic and other vehicle-related pollution by heavy metal accumulation in soils. Eighty-six samples were collected along streets and from residential and rural sectors, as well as vehicle-related workshops from depth of 0–5 and 15–20 cm and analyzed by flame atomic absorption spectrometry (FAAS) for heavy metals (Cd, Cr, Cu, Pb, Sn and Zn), as well as major elements (Al, Ca, Fe and Mn). Several hot-spot areas were identified in the composite geochemical maps produced based on Geographical Information System (GIS) technology. The majority of the hot-spot areas were identified to be vehicle-related workshops, fuel stations and road junctions. The most polluted hot-spot in the study area was located in soils close to a car battery processing workshop in the southwestern part of Kerman city, with concentrations of Cd (0.32 mg/kg), Cr (169 mg/kg), Cu (250 mg/kg), Pb (5,780 mg/kg), Sn (27.2 mg/kg) and Zn (178 mg/kg) of 1, 8.5, 8.3, 230, 13.5 and 3 times more than the relevant mean concentrations in natural soils, respectively. Traffic pollution has resulted in significant accumulation of heavy metals in soils and sediments, and that level of accumulation varied remarkably among elements. Based on X-ray diffraction analysis, most parts of soils and sediments of the Kerman basement consist of calcite and clay minerals. Abundance of clay minerals and medium to alkaline pH causes low mobility of heavy metals in soils of Kerman.     

Bioaccumulation of heavy metals in Octopus vulgaris from coastal waters of Alexandria (Eastern Mediterranean)

Heavy metal concentrations (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were determined in various tissues (hepatopancreas, branchial hearts, salivary gland, gills, genital tract, mantle, arms and skin) of Octopus vulgaris collected from three different contaminated sites in front of Alexandria (Egypt) during 2000. All collected tissues displayed high enrichment factors when compared to ambient levels. Heavy metal concentrations in most tissues displayed significant differences among sites, sizes and sex. This study suggests that hepatopancreas, and to a lesser extent branchial hearts, are better indicators of chronic Cu, Fe, Zn and Cd contamination than edible tissues. The enrichment factor (EF) for heavy metals in the hepatopancreas and in edible tissues allowed discriminating our samples into three main groups; (1) EF?>?55 (Cu), (2) EF ranging from 15 to 7.5 (Fe, Cd and Zn) and (3) EF?相似文献   

Identifying the source and accessing the spatial variations,contamination status,conservation threats of heavy metal pollution in the river waters of Sunderban biosphere reserve,India

This study emphasizes on identification of source and accessing the spatial variation of dissolved heavy metals (Cu, Cd, Fe, Ni, Pb and Zn) in the rivers of Sundarban Biosphere Reserve India, the UNESCO world heritage site. ANOVA (Analysis of Variance), PCA (Principal Component Analysis) as well as FA (Factor Analysis) are used for assessing the significant difference in means of metals concentration among the sites and understanding the sources of these pollutants. Three principal components with cumulative variance of 32, 55, and 73 %, show that Pb, Ni and Cd are closely associated with each other indicating an anthropogenic origin of these metals. Heavy metal evaluation index (HEI) values indicate that areas close to densely populated sites are affected by elevated metals concentration due to anthropogenic activities. The ratio between the concentration of Cd, Ni and Pb in sites and the maximum respective permissible limit for these metals for conserved habitat is Log₁₀ normalized to understand the threats of these pollutants over the distributaries of Sundarbans. Pb pollution is prevalent in the areas that rely on the fossil fuel-operated boats, for transport, whereas higher Cd concentration is found in the areas dependent on rechargeable batteries to meet their energy demand. So these anthropogenic activities and mal-practices may be responsible for the heavy metal pollution in this region. The study concludes that gradual increase in metal pollution in river water due to anthropogenic activities, particularly Pb and Cd, could have a negative impact on the conserved flora and fauna of this ecosystem.     

美达棉纤维挂载生物膜法处理石化废水中油

本文介绍了利用美达棉纤维持载生物摸法处理石化废水中油的试验结果。当废水在柱内停留时间为６．３ｈ，废水中油的处理效果是令人满意的。在同一含停留时间下入流水的ＣＯＤｃｒ从４２０ｍｇ／Ｌ变到１８３２ｍｇ／Ｌ时，出流水的ＣＯＤｃｒ在１６８．５ｍｇ／Ｌ以下。     

Ecological and human health risk assessment of heavy metal contamination in soil of a municipal solid waste dump in Uyo,Nigeria

The study assessed the levels of some heavy metals in soils in the vicinity of a municipal solid waste dumpsite with a view to providing information on the extent of contamination, ecological risk of metals in the soils and human health risk to the residents in Uyo. Soil samples were collected in rainy and dry seasons and analyzed for metals (Pb, Cd, Zn, Mn, Cr, Ni and Fe) using atomic absorption spectrometry. The concentrations of heavy metals (mg/kg) at the dumpsite in rainy season were Pb (9.90), Zn (137), Ni (12.56), Cr (3.60), Cd (9.05) and Mn (94.00), while in dry season, the concentrations were Pb (11.80), Zn (146), Ni (11.82), Cr (4.05), Cd (12.20) and Mn (91.20). The concentrations of metals in the studied sites were higher than that of the control site (P < 0.05). Pollution indices studies revealed that soil samples from dumpsite and distances from 10 and 20 m east of the dumpsite were highly polluted with cadmium. Ecological risk assessment carried out showed that cadmium contributed 98–99 % of the total potentially ecological risk. No probable health risk was observed as the total hazard index of all the metals was less than one. However, children were found to be more susceptible to heavy metal contamination than adult.     

Effect of lime on speciation of heavy metals during composting of water hyacinth

Composting is attractive and inexpensive method for treatment and biomass disposal of water hyacinth. However, the major disadvantage of water hyacinth composting is the high content of heavy metals in the final compost. Addition of lime sludge significantly reduced most bioavailable fractions (exchangeable and carbonate) of heavy metals. Studies were carried on composting of water hyacinth (Eichhornia crassipes) with cattle manure and sawdust (6:3:1 ratio) and effects of addition of lime (1%, 2% and 3%) on heavy metal speciation were evaluated during 30 days of composting period. The Tessier sequential extraction method was employed to investigate the changes in speciation of heavy metals such as Zinc (Zn), Copper (Cu), Manganese (Mn), Iron (Fe), Lead (Pb), Nickel (Ni), Cadmium (Cd) and Chromium (Cr) during water hyacinth composting. Effects of physicochemical parameters such as temperature, pH and organic matter on speciation of heavy metals were also studied during the process. Results showed that, the total metal content was increased during the composting process. The higher reduction in bioavailability factor (BF) of Cu, Fe, Ni, Cd and Cr was observed in lime 2 treatment about 62.1%, 64.4%, 71.9%, 62.1% and 58.9% respectively; however higher reduction in BF of Zn and Pb was observed in lime 1 treatment during the composting process. Reducible and oxidizable fractions of Ni, Pb and Cd were not observed during the process. Addition of lime was very effective for reduction of bioavailability of heavy metals during composting of water hyacinth with cattle manure and sawdust.     

天津市路面雨水径流重金属污染特征

对天津市3条典型主要交通干线雨水径流中的Cr、Cd、Fe、Cu、Hg 5种重金属进行了取样监测,重点探讨了路面径流重金属的平均质量浓度、冲洗特征、重金属之间以及重金属与悬浮物之间的相关关系,并用聚类分析方法对降雨特征对重金属污染的影响进行了研究。结果表明,天津市路面雨水径流重金属污染严重,Fe、Cr和Cd质量浓度较高,污染贡献率大,为径流主要重金属污染物;重金属污染水平高于国内外城市研究结果,反映出天津市在道路路面环境维护和管理上与其他城市的差距。路面径流的重金属具有明显的径流初期冲洗效应,在径流的初始阶段,重金属质量浓度达到最大值,随着降雨和径流的延续,污染物质量浓度呈波浪性锯齿状下降,至降雨结束,重金属质量浓度最终趋于稳定。径流中不同种类重金属具有同源性,且与径流中的悬浮固体具有明显的相互依存关系,重金属主要以悬浮固体吸附的形式或重金属颗粒形式存在。通过聚类分析可知,重金属污染受降雨强度和前期晴天积累影响显著,其次是降雨量和降雨历时。     

宝鸡城市街尘、土壤及河流沉积物重金属形态迁移特征

在宝鸡城市街尘、土壤及河流沉积物基本理化性质和重金属元素含量分析的基础上,重点研究了重金属元素在街尘、土壤及河流沉积物中的赋存形态和迁移特征.结果表明:在街尘中Cu主要以可氧化态和残余态形式存在,Pb主要以可还原态和可氧化态形式存在,Zn和Cd主要以乙酸可提取态形式存在,Mn、Fe、Co、Ni和Cr主要以残余态形式存在...     

Metal contamination of surface soils of industrial city Sialkot,Pakistan: a multivariate and GIS approach

In this study concentrations of selected metals viz., Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Ni, Pb and Zn in surface soils of Sialkot city known worldwide for tanneries and pharmaceutical industries were measured to assess the status of urban soil pollution and to identify sources of contamination. Hierarchical cluster analysis (HACA) indicated concentrations of Mg and Ca related to parent rock material, Cd, Co, and Pb with traffic related activities, Cr, Cu, Ni and Zn either associated with automobiles activities or industrial pollution and Fe, K and Na related with anthropogenic activities or lithogenous materials. Correlation analyses and principal component analysis based on factor analysis confirmed the results of HACA. Spatial distribution maps exhibited relatively higher concentrations of Cd, Co, Cu, Ni, Pb, Cr and Zn along traffic routes in the city and streams. The results highlighted concentration of Cd, Ni, Cr, Zn, and Pb measured in urban soil exceeded the permissible limit of surface soils and advocated an imperative need for detailed baseline investigations of spatial distribution of heavy metals and other contaminants for the formulation of geochemical database that should be made available to stakeholder involved in monitoring, assessment and conservation of soil contamination for future planning and management of the Sialkot city.     

Trace metals in fish,sediment and water from the south west coast of the Arabian sea,Pakistan

Concentrations of ten metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Hg) in the edible muscle of Arius maculatus captured from eight different near‐shore and off‐shore sites off the south west coast of the Arabian Sea, Pakistan, were determined by atomic absorption spectrophotometry. Relevant water and sediment samples from the sites were also analysed for the metals. Zinc showed the highest metal concentration (6.763 μg/g, wet weight) in the muscle of the fish, while Mn and Hg showed lowest level (0.019 μg/g, wet weight). Of all the metals investigated, largest scatter (measured as σ) was observed for Zn (σ = 2.058 /μg/g) in fish muscle, for Fe and Mn in sediment (σ = 27481 and 44.50 μg/g) and for As in water (σ = 0.270 μg/L). The metal distribution data pertaining to water, fish and sediment were examined on the basis of simple metal correlations. The statistical study revealed that Ni, Cr, Pb and Cu had significant positive correlations (r > 0.830 at ρ = 0.01). The finding substantiated a trace metal concentration gradient in the area, thereby indicating that the local marine environment is contaminated by anthropogenic sources.     

Cadmium removal mechanistic comparison of three Fe-based nanomaterials: Water-chemistry and roles of Fe dissolution

● nZVI, S-nZVI, and nFeS were systematically compared for Cd(II) removal. ● Cd(II) removal by nZVI involved coprecipitation, complexation, and reduction. ● The predominant reaction for Cd(II) removal by S-nZVI and nFeS was replacement. ● A simple pseudo-second-order kinetic can adequately fit Fe(II) dissolution. Cadmium (Cd) is a common toxic heavy metal in the environment. Taking Cd(II) as a target contaminant, we systematically compared the performances of three Fe-based nanomaterials (nano zero valent iron, nZVI; sulfidated nZVI, S-nZVI; and nano FeS, nFeS) for Cd immobilization under anaerobic conditions. Effects of nanomaterials doses, initial pH, co-existing ions, and humic acid (HA) were examined. Under identical conditions, at varied doses or initial pH, Cd(II) removal by three materials followed the order of S-nZVI > nFeS > nZVI. At pH 6, the Cd(II) removal within 24 hours for S-nZVI, nFeS, and nZVI (dose of 20 mg/L) were 93.50%, 89.12% and 4.10%, respectively. The fast initial reaction rate of nZVI did not lead to a high removal capacity. The Cd removal was slightly impacted or even improved with co-existing ions (at 50 mg/L or 200 mg/L) or HA (at 2 mg/L or 20 mg/L). Characterization results revealed that nZVI immobilized Cd through coprecipitation, surface complexation, and reduction, whereas the mechanisms for sulfidated materials involved replacement, coprecipitation, and surface complexation, with replacement as the predominant reaction. A strong linear correlation between Cd(II) removal and Fe(II) dissolution was observed, and we proposed a novel pseudo-second-order kinetic model to simulate Fe(II) dissolution.     

Cu~(2+)、Zn~(2+)、Cd~(2+)、Cr~(6+)和Mn~(2+)对萼花臂尾轮虫联合急性毒性研究

为探究重金属复合污染对轮虫的毒性影响,以萼花臂尾轮虫为受试动物,选择Cu~(2+)、Zn~(2+)、Cd~(2+)、Cr6+和Mn~(2+)等5种重金属,采用水生毒理联合效应相加指数法开展了其24 h联合急性毒性作用的评价研究。结果显示,Cu~(2+)、Zn~(2+)、Cd~(2+)、Cr6+和Mn~(2+)等5种重金属对萼花臂尾轮虫24 h半数致死浓度分别为:0.00616 mg·L~(-1),12.62 mg·L-1,2.89 mg·L-1,17.29 mg·L-1和67.32 mg·L-1。联合急性毒性实验结果显示,等毒性配比的Cu~(2+)-Cr6+(0.00385-10.806 mg·L-1)和等浓度配比的Cu~(2+)-Zn~(2+)(0.0199-0.0199 mg·L-1)、Cu~(2+)-Cd~(2+)(0.0181-0.0181 mg·L-1)、Cu~(2+)-Cr6+(0.0118-0.0118 mg·L~(-1))、Zn~(2+)-Cd~(2+)(3.475-3.475 mg·L-1)二元联合测试液的作用结果显示为拮抗效应,其余二元联合测试液的作用结果则均显示是协同效应。等毒性配比的Cu~(2+)-Cr~(6+)-Mn~(2+)(0.00210-5.902-22.981 mg·L-1)和等浓度配比的Cu~(2+)-Cd~(2+)-Mn~(2+)(0.00727-0.00727-0.00727 mg·L-1)三元联合测试液的作用结果显示为拮抗效应,其余三元联合测试液的作用结果则均显示是协同效应。等浓度配比的Cu~(2+)-Zn~(2+)-Cd~(2+)-Cr6+(0.00907-0.00907-0.00907-0.00907 mg·L-1)、Cu~(2+)-Zn~(2+)-Cd~(2+)-Mn~(2+)(0.00898-0.00898-0.00898-0.00898 mg·L~(-1))、Cu~(2+)-Zn~(2+)-Cr6+-Mn~(2+)(0.00819-0.00819-0.00819-0.00819 mg·L~(-1))四元联合测试液的作用结果显示为拮抗效应,其余四元联合测试液的作用结果的则均显示是协同效应。Cu~(2+)-Zn~(2+)-Cd~(2+)-Cr~(6+)-Mn~(2+)等毒性(0.00074-1.520-0.348-2.082-8.107 mg·L~(-1))和等浓度(0.00582-0.00582-0.00582-0.00582-0.00582 mg·L-1)配比的五元联合测试液作用结果均显示是协同效应。     

Optimization of thermophilic anaerobic-aerobic treatment system for Palm Oil Mill Effluent (POME)

Optimization of an integrated anaerobic-aerobic bioreactor (IAAB) treatment system for the reduction of organic matter (Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) concentrations) in Palm Oil Mill Effluent (POME) to legal standards with high methane yield was performed for the first time under thermophilic condition (50°C–55°C) by using response surface methodology (RSM). The experiments were conducted based on a central composite rotatable design (CCRD) with three independent operating variables, organic loading rates in anaerobic compartment (OLR_an) and mixed liquor volatile suspended solids (MLVSS) concentration in anaerobic (MLVSS_an) and aerobic compartments (MLVSS_a). The optimum conditions for the POME treatment were determined as OLR_an of 15.6 g COD·L^-1·d^-1, MLVSS_an of 43100 mg·L^-1, and MLVSS_a of 18600 mg·L^-1, where high aerobic COD, BOD and TSS removal efficiencies of 96.3%, 97.9%, and 98.5% were achieved with treated BOD of 56 mg·L^-1 and TSS of 28 mg·L^-1 meeting the discharge standard. This optimization study successfully achieved a reduction of 42% in the BOD concentrations of the final treated effluent at a 48% higher OLR_an as compared to the previous works. Besides, thermophilic IAAB system scores better feasibility and higher effectiveness as compared to the optimized mesophilic system. This is due to its higher ability to handle high OLR with higher overall treatment efficiencies (more than 99.6%), methane yield (0.31 L CH₄·g^-1 COD_removed) and purity of methane (67.5%). Hence, these advantages ascertain the applicability of thermophilic IAAB in the POME treatment or even in other high-strength wastewaters treatment.