Enhancement of chemical-oxygen demand and color removal of distillery spent-wash by ozonation.

Distillery spent-wash has very high organic content (75,000 to 125,000 mg/L chemical-oxygen demand [COD]), color, and contains difficult-to-biodegrade organic compounds. For example, anaerobic treatment of the distillery spent-wash used in this study resulted in 60% COD reduction and low color removal. Subsequent aerobic treatment of the anaerobic effluent resulted in enhancement of COD removal to 66%. In this paper, the effect of ozonation on various properties of the anaerobically treated distillery effluent, including the effect on its subsequent aerobic biodegradation, was investigated. Ozonation of the anaerobically treated distillery effluent at various ozone doses resulted in the reduction of total-organic carbon (TOC), COD, COD/TOC ratio, absorbance, color, and increase in the biochemical-oxygen demand (BOD)/COD ratio of the effluent. Further, ozonation of the anaerobically treated distillery effluent at an ozone dose of 2.08 mg/mg initial TOC and subsequent aerobic biodegradation resulted in 87.4% COD removal, as compared to 66% removal when ozonation was not used.     

Combination of ozonation with conventional aerobic oxidation for distillery wastewater treatment

Laboratory-scale experiments were conducted in order to investigate the effect of ozone as pre-aerobic treatment and post-aerobic treatment for the treatment of the distillery wastewater. The degradation of the pollutants present in distillery spent wash was carried out by ozonation, aerobic biological degradation processes alone and by using the combinations of these two processes to investigate the synergism between the two modes of wastewater treatment and with the aim of reducing the overall treatment costs. Pollutant removal efficiency was followed by means of global parameters directly related to the concentration of organic compounds in those effluents: chemical oxygen demand (COD) and the color removal efficiency in terms of absorbance of the sample at 254 nm. Ozone was found to be effective in bringing down the COD (up to 27%) during the pretreatment step itself. In the combined process, pretreatment of the effluent led to enhanced rates of subsequent biological oxidation step, almost 2.5 times increase in the initial oxidation rate has been observed. Post-aerobic treatment with ozone led to further removal of COD along with the complete discoloration of the effluent. The integrated process (ozone-aerobic oxidation-ozone) achieved approximately 79% COD reduction along with discoloration of the effluent sample as compared to 34.9% COD reduction for non-ozonated sample, over a similar treatment period.     

Treatment of distillery spent-wash by ozonation and biodegradation: significance of pH reduction and inorganic carbon removal before ozonation.

This study is aimed at exploring strategies for mineralization of refractory compounds in distillery effluent by anaerobic biodegradation/ozonation/aerobic biodegradation. Treatment of distillery spent-wash used in this research by anaerobic-aerobic biodegradation resulted in overall COD removal of 70.8%. Ozonation of the anaerobically treated distillery spent-wash was carried out as-is (phase I experiments) and after pH reduction and removal of inorganic carbon (phase II experiments). Introduction of the ozonation step resulted in an increase in overall chemical oxygen demand (COD) removal, with the highest COD removals of greater than 95% obtained when an ozone dose of approximately 5.3 mg ozone absorbed/mg initial total organic carbon was used. The COD removal during phase II experiments was slightly superior compared with phase I experiments at similar ozone doses. Moreover, efficiency of ozone absorption from the gas phase into distillery spent-wash aliquots was considerably enhanced during phase II experiments.     

A novel thermotolerant Pediococcus acidilactici B-25 strain for color, COD, and BOD reduction of distillery effluent for end use applications

The present study was aimed to characterize physico-chemical and microbial population of distillery effluent and isolate a novel thermotolerant bacterium for color, COD, and BOD reduction of spentwash. The level of alkalinity, TSS, DO, COD, BOD, TN, ammonical nitrogen, nitrate nitrogen, phosphorous, potassium, chloride, and calcium of spentwash (SW), bioreactor effluent (BE), and secondary treated effluent (STE) were well above the permissible limits. The level of color, TS, and TDS were under the permissible limits for STE but not for SW and BE. The microbial population was higher in BE. The results revealed that effluent was highly polluted and require suitable treatment before discharge. A novel thermotolerant bacterium, identified as Pediococcus acidilactici, was isolated which exhibited maximum 79 % decolorization, 85 % COD, and 94 % BOD reduction at 45 °C using 0.1 %, glucose; 0.1 %, peptone; 0.05 %, MgSO4; 0.05 %, K₂HPO₄; pH 6.0 within 24 h under static condition. The ability of this strain to decolorize melanoidin at minimum carbon and nitrogen supplementation warrants its possible application for effluent treatment at industrial level. In addition, it is first instance when melanoidin decolorization was reported by P. acidilactici. This study could be an approach towards control of environmental pollution and health hazards of people in and around the effluent distillery unit.     

Aerobic Treatment of a Nitrogen-Limited Chemical Process Waste water

Abstract

Nitrogen transformations and their effect on aerobic suspended growth treatment of an industrial wastewater were studied in three parallel bench-scale reactors operated at 5 "C at mean cell residence times (MCRT) of 15, 30, and 60 days. In normal process wastewater, the bulk of influent nitrogen was in organic form, and the fraction transformed was almost totally incorporated into synthesized biomass. Assimilative control by heterotrophs maintained ammonianitrogen levels below permitted effluent levels, and nitrification was not significant. Although volatile suspended solids had a nitrogen content of only 5% to 8%, effective organics removal was maintained, and total organic carbon and filtered daily average five-day biochemical oxygen demand (BODS) were below permitted effluent levels. A marked improvement in settleability and lower effluent total suspended solids was achieved by adding ammonia-nitrogen to the wastewater in excess of stoichiometric growth requirements.

During a batch production cycle of a cationic chemical, the ratio of nitrogen to chemical oxygen demand and the fraction of the total influent nitrogen in soluble form increased in the wastewater. Reactor effluent ammonia levels increased to above permit levels at all three MCRTs during treatment of wastewater containing cationic production effluents. The magnitude of ammonia increase was greater for longer MCRTs, suggesting that synthesis of cell mass was not capable of assimilating the increased ammonia supply under these non-steady conditions. The experimental results suggest several potential strategies for operating the aerobic process at the treatment facility, including adding nitrogen to improve settleability and discontinuing these additions when wastewater contains a high ratio of nitrogen to chemical oxygen demand and an elevated soluble nitrogen fraction     

Simultaneous nitrification-denitrification and clarification in a pseudoliquified activated sludge system.

This paper describes results from a pilot study of a novel wastewater treatment technology, which incorporates nutrient removal and solids separation to a single step. The pseudoliquified activated sludge process pilot system was tested on grit removal effluent at flowrates of 29.4 to 54.7 m3/d, three different solid residence times (SRT) (15, 37, and 57 days), and over a temperature range of 12 to 28 degrees C. Despite wide fluctuations in the influent characteristics, the system performed reliably and consistently with respect to organics and total suspended solids (TSS) removals, achieving biochemical oxygen demand (BOD) and TSS reductions of > 96% and approximately 90%, respectively, with BOD5 and TSS concentrations as low as 3 mg/L. Although the system achieved average effluent ammonia concentrations of 2.7 to 3.2 mg/L, nitrification efficiency appeared to be hampered at low temperatures (< 15 degrees C). The system achieved tertiary effluent quality with denitrification efficiencies of 90 and 91% total nitrogen removal efficiency at a total hydraulic retention time of 4.8 hours and an SRT of 12 to 17 days. With ferric chloride addition, effluent phosphorous concentrations of 0.5 to 0.8 mg/L were achieved. Furthermore, because of operation at high biomass concentrations and relatively long biological SRTs, sludge yields were over 50% below typical values for activated sludge plants. The process was modeled using activated sludge model No. 2, as a two-stage system comprised an aerobic activated sludge system followed by an anoxic system. Model predictions for soluble BOD, ammonia, nitrates, and orthophosphates agreed well with experimental data.     

Ultrasound and ozone assisted biological degradation of thermally pretreated and anaerobically pretreated distillery wastewater

The present work is aimed at increasing the overall efficiency of the treatment process of distillery spent wash using a combination of different treatment techniques. Initially the effluent samples were subjected to Thermal Pretreatment (TPT-DW) and anaerobic treatment (ANA-DW). Advanced oxidation techniques, viz., Ultrasound (US) and Ozone were then used for further COD reduction followed by the conventional aerobic oxidation using mixed microbial consortium. Pretreatment of TPT-DW with US and Ozone (as stand alone techniques) enhanced the subsequent aerobic oxidation rate. For US treated sample, a maximum of 13% COD reduction was attained at the end of 48 h of aerobic oxidation, while for the ozone treated effluent a maximum of 45.6% COD reduction was obtained as compared to mere 1.8% COD reduction for the control (TPT-DW directly subjected to aerobic oxidation) indicating a 25 times increase in the rate of aerobic biodegradation of ozonated sample. Anaerobically treated effluent sample (ANA-DW) could be successfully treated aerobically. In this case, however, the use of advanced oxidation techniques did not result in any synergistic effects. The rate of the aerobic oxidation was slightly higher for the control (ANA-DW directly subjected to aerobic oxidation) as compared to the sample pretreated using ultrasound or ozonation. TOC analysis revealed that between the two pretreatments studied, ozone was found to be superior over US as it led to both COD as well as TOC reduction during the aerobic oxidation step for ANA-DW effluent stream.     

Selection of an electrolyte to enhance the electrochemical decolourisation of indigo. Optimisation and scale-up

The investigation presented here focussed on the electrochemical decolourisation of a commercial, textile indigo dye, in an undivided electrochemical cell using graphite electrodes. The decolourisation values obtained employing halide salts--sodium chloride, potassium bromide and potassium iodide--and a reductive agent--sodium meta-bisulphite--as electrolytes are higher than those attained when no electrolyte was used. The highest decolourisation value at a low level of electric power consumption was obtained with sodium chloride. Besides, this electrolyte is usually found in the coloured wastewaters of textile industry. Thus, a detailed study was carried out to determine the influence of electrolyte--sodium chloride--and dye concentration on the efficiency of the process expressed in terms of energy consumption and extension of the decolourisation reaction. The scale-up of the treatment with sodium chloride was satisfactorily tested in a 20 l cell.     

Degradation of tetracycline at a boron-doped diamond anode: influence of initial pH,applied current intensity and electrolyte

The anodic oxidation of tetracycline was performed in an up-flow reactor, operating in batch mode with recirculation, using as anode a boron-doped diamond electrode. The influence on the degradation rate of solution initial pH (2 to 12), applied current intensity (25 to 300 A m^?2) and type of electrolyte (sodium sulphate or sodium chloride) were investigated. For the assays run at equal current density, with sodium sulphate as electrolyte, the solution’s initial pH of 2 presented the highest absorbance and chemical oxygen demand removals. Regarding the influence of current density, for equal charge passed, the organic load removal rate decreased with the increase in applied current. When sodium sulphate was used as an electrolyte, high-performance liquid chromatography (HPLC) results have shown an almost complete removal of tetracycline after a 2-h assay. HPLC results have also shown the presence of oxamic acid as one of the intermediates of tetracycline anodic oxidation. The complete removal of tetracycline was much faster in the presence of chloride ions that promoted the complete degradation of this antibiotic in 30 min. However, in the presence of chloride ions, the tetracycline mineralization is slower, as observed by the lower organic carbon removal rate when compared to that of the tetracycline degradation in the presence of sulphate.     

Slaughterhouse wastewater treatment in a full-scale system with constructed wetlands.

This work evaluated the performance of a full-scale system with wetlands for slaughterhouse (abattoir) effluent treatment in the State of Hidalgo, México. The treatment system consisted of a primary sedimentation tank, an anaerobic lagoon, and a constructed subsurface-flow wetland, in series. The wetland accounted for almost 30% of the removal of organic matter. In general, the treatment system achieved satisfactory pollutant removals, but the final effluent could not meet the Mexican environmental regulations for fecal coliform counts, five-day biochemical oxygen demand (BOD5), and total suspended solids (TSS). Overall, removal levels were 91%, 89%, and 85% for BOD5, chemical oxygen demand, and TSS, respectively. However, BOD5 in the final effluent (137 mg/L) was higher than the maximum level of 30 mg/L allowed by the regulatory agency. Although organic nitrogen removal levels were approximately 80%, the nitrogen persisted in oxidation state -3 as ammonia-nitrogen, the removal of which was only 9% in the wetland stage. On average, phosphorus removal was null, and, on occasion, the phosphorus concentration in the treated effluent was higher than that of the influent. Coliform reductions in the overall system were high (on the order of 5 logs on average), whereas the coliform removal in the wetland was between 2 to 3.5 logs. The treatment system was also effective at removing pathogens (Vibrio cholerae, Salmonella, and Shigella). Further laboratory tests with the wetland effluent suggest that post treatment in a sand filter stage followed by disinfection with sodium hypochlorite (NaOCl) could help meet the Mexican discharge regulations, particularly the criteria for coliforms and total BOD5.     

The use of Microtox to assess toxicity removal of industrial effluents from the industrial district of Camaçari (BA, Brazil)

The treatment efficiency, as toxicity removal, of complex effluents from the Industrial District of Cama?ari (BA, Brazil), after biological treatment with activated sludge was evaluated using Microtox. Samples of the equalised effluent (EE) were collected prior to treatment together with samples of the treated effluent (TE), which remained 24 h in the treatment plant. Rehydrated colonies of Vibrio fischeri were exposed to sequential dilutions of EE and TE to assess luminosity interference. Values for EC50 were calculated, together with the respective toxicity units. In all, twenty assays of each effluent type were carried out and the mean toxicity removal was 92.71%, while the chemical oxygen demand (COD) presented mean reduction of 83.04%. There was a variability of an order of magnitude between the Microtox results for the two types of effluents. The mean EC50 values were 2.12 for EE and 47.78% for TE. In spite of its weakness in some conditions, the Microtox system demonstrated to work adequately in assessing effluent toxicity removal in this treatment plant and therefore can be used for further toxicity removal programs.     

强化混凝工艺深度处理给水厂排泥废水

水厂废水的综合处理与回用是我国供水行业的新趋势和节水目标所在,采用强化混凝技术进行水厂排泥废水的深度处理。通过混凝剂筛选实验和有机物表征确定最佳混凝剂为高效聚合铝(HPAC),适宜投加量为650 mg/L。当混凝剂HPAC投加量为650 mg/L时,对COD、TOC、浊度和色度的去除率分别为82.5%、89.8%、95%和92.5%,相应的出水值分别为58 mg/L、8.46 mg/L、2.35 NTU、13度,COD满足《污水综合排放标准》(GB 8978-1996)的要求(COD≤100 mg/L),同时实验结果显示聚合氯化铝(PAC)、HPAC、三氯化铁(FeCl3)主要去除分子量处于>1 300 Da范围的有机物,对分子量处于744～1 300 Da之间的有机物去除有限。     

Effects of polydiallyldimethyl ammonium chloride coagulant on formation of chlorinated by products in drinking water.

The objectives of this research work was to evaluate the reduction of THM precursors by cationic p-DADMAC and determine the correlations between the chlorine demand and trihalomethane formation in the presence of electrolyte solutions and ambient light. The chlorine demand was found to be significantly reduced provided that the H2SO4 electrolyte was fed to the sample solutions. The amount of CHCl3 formation was also decreased when the Na2SO4 electrolyte was introduced in spite of the levels of light intensity. The p-DADMAC can not only effectively remove the turbidity but also reduce the formation of CHCl3. The optimum dosage of p-DADMAC for reducing the turbidity, TOC and CHCl3 in the humic acid and source water samples was determined and depended upon the nature of organics.     

Advanced oxidation processes in the treatment of trifluraline effluent

The treatment of an effluent from the production of trifluraline was studied using a 1-L, semi-batch, tank-stirred glass reactor for performing three different advanced oxidation processes (photoperoxidation, Fenton, photo-Fenton). A commercial, medium-pressure mercury lamp was used for sample irradiation. The degradation was monitored by measurements of absorptiometric color reduction, UV-visible absorption spectra, and chemical oxygen demand (COD). The obtained results showed that the photo-Fenton process was the most effective treatment for the trifluraline effluent.     

Advanced Oxidation Processes in the Treatment of Trifluraline Effluent

The treatment of an effluent from the production of trifluraline was studied using a 1-L, semi-batch, tank-stirred glass reactor for performing three different advanced oxidation processes (photoperoxidation, Fenton, photo-Fenton). A commercial, medium-pressure mercury lamp was used for sample irradiation. The degradation was monitored by measurements of absorptiometric color reduction, UV-visible absorption spectra, and chemical oxygen demand (COD). The obtained results showed that the photo-Fenton process was the most effective treatment for the trifluraline effluent.     

Production of electricity from proteins using a microbial fuel cell.

Electricity generation was examined from proteins and a protein-rich wastewater using a single chamber microbial fuel cell (MFC). The maximum power densities achieved were 354 +/- 10 mW/m2 using bovine serum albumin (BSA) and 269 +/- 14 mW/m2 using peptone (1100 mg/L BSA and 300 mg/L peptone). The recovery of organic matter as electricity, defined as the Coulombic efficiency (CE), was comparable to that obtained with other substrates with CE = 20.6% for BSA and CE = 6.0% for peptone. A meat packing wastewater (MPW), diluted to 1420 mg/L chemical oxygen demand, produced 80 +/- 1 mW/m2, and power was increased by 33% by adding salt (300 mg/L sodium chloride) to increase solution conductivity. A wastewater inoculum generated 33% less power than the MPW inoculum. The MFC was an effective method of wastewater treatment, demonstrated by >86% of biochemical oxygen demand and total organic carbon removal from wastewater.     

SMBR处理含油废水出水COD数学模型

根据微生物生长动力学特征以及膜分离特征,建立恒通量下运行的一体式膜生物反应器系统出水COD数学模型,提出膜生物反应器处理效率的数学模型。以实验及模型为基础,分别对进水COD浓度控制在300、400、500 mg/L附近时经过反应器后COD的去除效率进行了比较。通过公式计算的数据和实验数据分析可得:COD去除率的公式计算值与实验结果比较吻合,相对偏差仅为0.0223,为膜系统有机物的去除效果估算提供了基础,可为该类工艺的参数选择与优化提供参考。     

Treatment of domestic wastewater by an hydroponic NFT system

The objectives in this work were to investigate a conceptual layout for an inexpensive and simple system that would treat primary municipal wastewater to discharge standards. A commercial hydroponic system was adapted for this study and the wastewater was used to irrigate Datura innoxia plants. Influent and effluent samples were collected once a month for six months and analysed to determine the various parameters relating to the water quality. The legal discharge levels for total suspended, biochemical oxygen demand and chemical oxygen demand were reached with the plant system after 24 h of wastewater treatment. Total nitrogen and total phosphorus reduction were also obtained. NH4(+)-N was reduced by 93% with nitrification proving to be the predominant removal process. Significant nitrification occurred when the BOD5 level dropped 45 mg/l. Similar results were obtained for six months although the sewage composition varied widely. D. innoxia develops and uses the wastewater as the unique nutritive source.     

Evaporation behaviour of different organic effluents from open surfaces

Production of large quantities of effluents from different industrial units and the problems of their disposal necessitated this evaporation study. The evaporation of water, sewage water, oil refinery effluent, papermill effluent and liquor distillery effluent was observed in glass beakers when placed (i) in an oven at 60 degrees C and (ii) in screen house for 30 days, by periodically weighing of the beakers. In other experiments, the effect of increasing the frequency of stirring on increasing the evaporation efficiency of the liquor distillery effluent (ELD) was examined in detail. All of the organic effluents except ELD had similar evaporation behaviours as water, but formation of a self-forming film caused the evaporation of ELD to be considerably lower. Resistance to evaporation caused by this film was found to be a decreasing function of the frequency of stirring. This study has a bearing on improving the efficiency of evaporation lagoons, and three stirrings in a day with a manually drawn stirrer in a full-scale lagoon are proposed as a practical and economically viable technique to save 44% of lagoon land in arid and semi-arid regions of the world.     

混凝工艺去除合流污水中有机物及营养元素

通过系列杯罐试验混凝处理合流污水，采用硫酸铝（Al₂(SO₄)₃）、硫酸铁（Fe₂(SO₄)₃）、聚合氯化铝（PAC）和聚合氯化铝铁（PAFC）4种混凝剂均能有效去除污水中的 TP、PO^3-₄-P、SS和COD。聚合金属盐（PAC和PAFC）混凝处理效果优于金属盐（Al₂(SO₄)₃和Fe₂(SO₄)₃），达到相同的处理效果的投加量明显低于后者。助凝剂采用聚丙烯酰胺（PAM）、聚乙烯醇（PVA）、自制的高分子聚合物（AN）和活化硅酸（AS），在保持较低混凝剂投加量的条件下可明显提高污水处理效果；添加助凝剂对强化PO^3-₄-P的去除作用不明显，PO^3-₄-P的去除仅与混凝剂的投加量相关。混凝剂和助凝剂对污水中NH₃-N的去除作用相对不显著。SS去除率随混凝剂投加量的变化趋势说明混凝的机理较为复杂，可能存在多种混凝机理共同作用。