Characterization and modelling of denim‐processing wastewaters for activated sludge

The study involved characterization of denim‐processing wastewaters, mainly to generate the necessary experimental data for the modelling and evaluation of the activated sludge process. The striking feature of the wastewater quality was the excessive suspended solids content requiring effective removal before biological treatment. COD fractionation was, however, typical for a textile effluent in general, with a biodegradable fraction of 90%, a readily biodegradable COD ratio of 20%, a predominantly soluble slowly biodegradable fraction of 55–60% and negligible particulate inert COD. Hydrolysis was identified as the significant step in the biodegradation kinetics with rate coefficients quite specific to plant operation. Evaluation of the hydrolysis kinetics showed that the magnitude of the slowly biodegradable COD could be reduced with a higher hydraulic detention time, effectively improving the quality of the soluble effluent. © 2001 Society of Chemical Industry     

COD fractionation and biodegradation kinetics of segregated domestic wastewater: black and grey water fractions

BACKGROUND: Household wastewater was segregated to grey and black water components as part of a recent approach aiming to separate wastewater fractions for more efficient treatment and reuse. Chemical oxygen demand (COD) fractionation and biodegradation characteristics of black and grey water were determined by means of model calibration of the oxygen uptake rate profiles. An ASM1 type of model modified for endogenous respiration was selected for this purpose. RESULTS: Calibration identified, aside from the readily biodegradable COD, two hydrolysable COD fractions in the black water, and only a single, slowly biodegradable COD fraction, in the grey water. The relative magnitude of the readily biodegradable COD fraction was high compared with typical domestic sewage, especially for grey water, and the level of particulate inert COD fraction, was relatively low. Biodegradation of soluble COD fractions in both wastewaters approximated typical rates observed for domestic sewage. However, the hydrolysis rate of the slowly biodegradable COD was quite low, reflecting the characteristics and impact of settleable organic matter. CONCLUSION: Based on the process rates obtained, aerobic biodegradation was equally effective for black and grey water fractions, both for the removal of soluble COD and the stabilization of particulate COD. Copyright © 2010 Society of Chemical Industry     

Biodegradability of slaughterhouse wastewater with high blood content under anaerobic and aerobic conditions

In this work, the biodegradability of wastewater from a slaughterhouse located in Ke?an, Turkey, was studied under aerobic and anaerobic conditions. A very high total COD content of 7230 mg dm^?3 was found, due to an inefficient blood recovery system. Low BOD₅/COD ratio, high organic nitrogen and soluble COD contents, were in accordance with a high blood content. A respirometry test for COD fractionation showed a very low readily biodegradable fraction (S_S) of 2%, a rapidly hydrolysable fraction (S_H) of 51%, a slowly hydrolysable fraction (X_S) of 33% and an inert fraction of 6%. Kinetic analysis revealed that hydrolysis rates were much slower than these of domestic sewage. The results underlined the need for an anaerobic stage prior to aerobic treatment. Tests with an anaerobic batch reactor indicated efficient COD degradation, up to around 80% removal. Further anaerobic degradation of the remaining COD was much slower and resulted in the build up of inert COD compounds generated as part of the metabolic activities in the anaerobic reactor. Accordingly, it is suggested that an appropriate combination of anaerobic and aerobic reactors would have to limit anaerobic degradation to around 80% of the tCOD and an effluent concentration above 1000 mg dm^?3, for the optimum operation of the following aerobic stage. © 2003 Society of Chemical Industry     

Effect of Ozonation on Biodegradability Characteristics of Surplus Activated Sludge

The study investigates the effect of sludge ozonation on solid matter species, disintegration properties, sludge components, and solubilization characteristics under different operating conditions. Ozonation of surplus activated sludge samples taken from the secondary settling tank of a domestic wastewater treatment plant indicates that soluble nitrogen, phosphorus and COD concentrations proliferate as a consequence of extending the ozone feeding time. A steady increase both in soluble nitrogen concentration and ratio of organic phosphorus to soluble phosphorus is observed through ozonation where specific ozone doses range between 4 and 11 mg O₃/g SS. Combined treatment of chemical oxidation and aerobic biodegradation to surplus activated sludge is also applied to improve the biodegradability of organic matter by partial chemical oxidative pretreatment with as little specific ozone consumption as possible. The partial oxidation by integrated ozonation is operated as a pre-oxidation step for the subsequent biological degradation, due to the fact that the competition with biological degradation in removing biodegradable organic compounds is avoided and most probably a more biodegradable sludge composition is obtained by means of ozonation. Combined treatment of chemical oxidation and aerobic biodegradation conducted to scrutinize the synergic effect of the coupled treatment system reveals that TS and COD removal efficiencies of ozonated sludge samples cannot be improved beyond the third aerobic biodegradation step.     

Ozonation of complex industrial park wastewater: effects on the change of wastewater characteristics

BACKGROUND: Ozonation of complex industrial park wastewater was carried out in a semi‐batch reactor. The variation of wastewater characteristics was evaluated based on the analysis of 5‐day biochemical oxygen demand (BOD₅) concentration, BOD₅/chemical oxygen demand (COD) ratio, COD fractionation, and dissolved organic carbon (DOC) molecular size distribution before and after ozonation. RESULTS: The experimental results indicated that low efficiency of COD removal with increasing tendency of BOD₅ concentration generally appeared after ozonation. Also, the BOD₅/COD ratio increased from an initial of 0.27 to a maximum of 0.38. The COD fractionation tests revealed that most of the inert soluble COD was transformed to biodegradable soluble COD at 30 min of reaction time. Additionally, the DOC molecular size distribution tests showed that the fraction larger than 500 kDa was significantly decreased and the fraction smaller than 2 kDa was increased when the reaction time was prolonged to 240 min. CONCLUSION: This study verified that partial oxidation of the complex industrial park wastewater by ozonation could enhance wastewater biodegradability. The biodegradability enhancement was primarily because the inert soluble COD fraction was converted to the biodegradable soluble COD and the high molecular weight fraction of DOC was shifted toward the low molecular weight fraction. Copyright © 2009 Society of Chemical Industry     

The influence of influent distribution and blood content of slaughterhouse wastewater on the performance of an anaerobic fixed‐film reactor

This paper evaluates the performance of a laboratory‐scale anaerobic fixed‐film reactor (AFFR) with arranged media treating slaughterhouse wastewater. The reactor was operated at 20 °C, its organic loading rate was increased from 1.8 to 9.2 kg COD m^?3 d^?1, and it had a short hydraulic residence time (5–9 h). The influence of wastewater concentrations on its performance was studied by artificially increasing the blood content of the wastewater. The efficiency of the removal of organic matter decreased from 70% to 54% as the superficial velocity increased from 0.12 to 0.97 m h^?1, due mainly to distribution defects, as had been confirmed experimentally by tracer tests. The kinetics of the anaerobic processes was limited by substrate availability, even at high COD concentrations (between 700 and 1100 mg dm^?3) due to a high content of slowly biodegradable and inert compounds present in the wastewater from the slaughterhouse. It was observed that a large amount of the organic matter had accumulated inside the reactor instead of being removed by methanogenic digestion. Furthermore, the fraction of organic matter held inside the reactor varied significantly in relation to the blood content of the wastewater. Copyright © 2005 Society of Chemical Industry     

Effect of stream segregation on ozonation for the removal of significant COD fractions from textile wastewater

Ozonation was tested on selected streams of cotton finishing textile plant wastewater for optimizing chemical oxygen demand (COD) removal. For this purpose, significant COD fractions in the wastewater were experimentally identified and the effect of ozone on these fractions was investigated. Ozonation experiments were performed with a 1 dm³ sample volume. Ozone treatment of batches of raw wastewater provided, at a rate of 62 mg min^?1 and a gas feeding time of 15 min, achieved complete colour removal but only 21% COD reduction. Increasing the feeding time to 30 min slightly increased the COD removal to 32%. At this feeding time, removal of the readily biodegradable COD was 60%, but soluble inert COD reduction remained at 16%, indicating selective preference of ozone for simpler compounds. At low concentrations, ozone was mainly influential on soluble COD compounds. Longer feeding times also affected particulate compounds, resulting in the solubilization of the COD fractions. Pre‐ozonation of the dye‐house wastewater, as a segregated stream, proved much more effective in the breakdown of refractory organic compounds, rendering the overall plant effluent more amenable to biological treatment. © 2002 Society of Chemical Industry     

COD fractionation and parameter estimation for combined sewers by respirometric tests

This paper evaluates the effects of the pipeline retention time in sewer systems and the dilution by stormwater runoff on COD fractions and kinetic parameters of samples from two large‐scale wastewater treatment plants (WWTPs) fed with combined sewers, one collected from adjacent residential areas (Sewer Q) and the other undergoing long pipeline transportation (Sewer B). With four batch tests, COD fractions and kinetic parameters of two sewers were obtained by numerical computation based on activated sludge models (ASMs) modified by a dual hydrolysis mechanism. Long pipeline transportation significantly influenced the content and existence of heterotrophic biomass fractions in sewers, and the percentage of the fraction in Sewer B (17%) was higher than that in Sewer Q (9%). Compared with Sewer Q, long pipeline retention also resulted in lower concentrations of hydrolysable fractions and particulate inert COD in Sewer B, as well as an increase in the hydrolysis rate coefficient of particulate hydrolysable COD from 0.90 day^?1 in Sewer Q to 1.83 day^?1 in Sewer B. Results of samples from Sewer B during a typhoon event showed high variations of COD fractions and parameters, indicating the necessity for COD fractionation and parameter calibration before applying ASMs to wet weather cases. Copyright © 2008 Society of Chemical Industry     

膜-好氧组合工艺处理餐饮废水的研究

采用无机膜 -好氧组合工艺对高浓度餐饮废水 (COD 15 0 0 0mg/L)进行处理。考察了进水COD浓度、溶解氧浓度、水力停留时间对好氧反应器处理效果的影响。结果表明 ,当水力停留时间大于 5 .6h时 ,废水的COD去除率高于 90 % ,温度对处理效果影响不大。对好氧出水用无机膜进行分离 ,最终出水COD小于 2 5mg/L ,浊度小于 1NTU。     

An investigation on the optimal location of ozonation within biological treatment for a tannery wastewater

The objective of this study was to evaluate the optimal location of ozonation within biological treatment for a typical tannery wastewater by giving special attention to biodegradability‐based chemical oxygen demand (COD) characterization. As treating the raw tannery effluent solely by biological treatment is not adequate to meet the discharge standards owing to the high level of biorecalcitrant COD at the outlet, the application of chemical oxidation, i.e. ozone together with biotreatment (pre‐ozonation or in mid‐ozonation or post‐ozonation) was investigated. The tannery effluent under investigation had initially inert soluble COD (S_I1) and particulate COD (X_I1) fractions corresponding to 9% and 13% of the total COD (C_T1), respectively, whereas each component of the biodegradable part—readily biodegradable COD (S_S1), rapidly hydrolysable COD (S_H1), and slowly hydrolysable COD (X_S1)—accounted for around 26% of the total COD (C_T1). Pre‐ozonation, undesirably competing with biotreatment for the removal of degradable organics, was shown to be insufficient both in terms of total COD (C_T1) and inert COD (C_I1) removal efficiencies. The scheme of biological treatment + ozonation + biological treatment could be applied successfully when 42.8 mg O₃ min^?1 was introduced for 5 min with a utilized ozone percentage of 76% at a point in biological treatment where the readily biodegradable COD (S_S1) was depleted through biochemical reactions. Such an alternative yielded satisfactory outcomes when both total COD (C_T) and inert COD (C_I) removal efficiencies per utilized ozone ratios were considered. With post‐ozonation, on the other hand, the highest inert COD (C_I) removal efficiencies together with an effluent quality meeting the discharge standards could be obtained. Copyright © 2006 Society of Chemical Industry     

微电解+ABR+SBR处理有机化工废水

有机化工废水成分复杂、浓度高、毒性大、色度深、难以生物降解。采用微电解技术可以破坏废水中污染物的结构,使有机废水易生物降解;后续采用ABR+SBR技术处理,COD去除率可达到96%以上,BOD去除率达98%以上,出水COD、BOD符合GB8978-1996《污水综合排放标准》一级标准。     

Particle size distribution based evaluation of biodegradation and treatability for leachate from organic waste

BACKGROUND: The study evaluated the relationship between particle size distribution (PSD) of chemical oxygen demand (COD) and treatability of leachate generated by organic waste. PSD determinations were performed together with physico‐chemical and biological treatability studies. Leachate biodegradation was also evaluated by means of oxygen uptake rate (OUR) profiles and experimental results were used for calibration of the adopted mathematical model. RESULTS: The leachate was characterized by a COD content of 80 000 mg L^?1 in summer. PSD analysis showed a bimodal distribution with around 60% of the COD below 2 nm and 25% above 1600 nm. Chemical treatment by lime and alum provided limited COD removal (30‐35%). The extent of COD removal was higher than the particulate COD fraction above 1600 nm, it also occurred in the soluble range below 2 nm through adsorption. A modeling study indicated three major COD fractions that could be correlated with PSD analysis: readily biodegradable COD and slowly biodegradable COD in the soluble range and hydrolyzable COD fraction in the particulate range. CONCLUSION: PSD‐based COD fractionation adequately explained limitations of chemical treatment efficiency; it was also a reliable complement to the currently used respirometric tests for biodegradation, providing insight to the fate of different COD fractions included in the soluble range (<2 nm) and yielding concrete supporting information on the generation of soluble residual microbial products. Copyright © 2011 Society of Chemical Industry     

MBR-光催化氧化处理印染废水的试验研究

利用MBR-光催化氧化的组合工艺处理某纺织园区综合废水,对反应装置进行了连续运行效果的考察.结果表明,MBR对废水COD、浊度,色度降解率分别达到93.5%、99.9%和98.9%;MBR中污泥沉降性能明显优于SBR,能有效控制污泥膨胀现象;出水的透光性大大提高,经光催化氧化后COD、BOD、浊度、色度分别稳定在35.0mg·L~(-1)、2.7 mg·L~(-1),2.3NTU、3倍,水质达到GB 18918-2002的一级A排放标准和CJ/T48-1999的生活杂用水要求.     

Inert COD fractions in two-stage treatment of a pulp and paper mill effluent

Two-stage biological treatment schemes are often prescribed for pulp and paper mill effluents with high COD concentrations, in order to meet effluent standards. Recent conceptual developments in biological treatment of wastewaters indicate that the stoichiometry of the inert organic components is the key issue in performance predictions and the kinetics of degradable organic fraction play a relatively less important role in the compliance of effluent limitations. Besides, the differentiation between initially inert COD and inert metabolic products is very important in two-stage systems, as what is biodegradable for one phase may become non-biodegradable for the next phase in which a different microbial community is sustained. In this study a pulp and paper mill effluent is characterized in terms of its inert COD fractions and the changes induced by two-stage biological treatment to these fractions are observed. © 1998 SCI     

新型厌氧反应器COD去除影响因素研究

以模拟高浓度有机废水为研究对象,采用新型厌氧反应器对COD去除影响因素进行了为期4个月的试验研究,考察了污泥负荷、水力停留时间(HRT)、容积负荷、进水COD、VFA、出水SS等因素对COD去除的影响。结果表明,影响COD去除的主要因素是污泥负荷、HRT和容积负荷,次要因素是进水COD、VFA和出水SS,当反应器内COD污泥负荷在0.297 2～0.464 7 kg.kg-1.d-1之间、HRT=7 h时,COD的去除效率维持在72%～90%。     

微电解—水解酸化-硝化反硝化工艺处理假发生产废水

采用微电解—水解酸化-硝化反硝化工艺处理假发生产废水,微电解去除废水中的色度和其他污染物,并提高废水的可生化性,以利于后续生化处理;水解酸化提高后续处理的容积负荷,提高去除效率,对进水中有机氮的氨化作用明显,硝化反硝化可将水解产生的NH3-N全部转化。运行结果表明,进水COD为1 100 mg/L、氨氮为120 mg/L的情况下,该工艺降解COD及脱氮效果良好;处理工艺保证系统出水COD〈40 mg/L,氨氮〈5 mg/L,达到了《污水综合排放标准》一级标准。     

混凝-臭氧氧化法处理三磺泥浆体系钻井废水

三磺泥浆体系钻井废水经混凝处理后的出水化学需氧量(Chemical Oxygen Demand, COD)值稳定在350~600 mg/L,水中残留的COD物质可絮凝性很差. 对水中残留COD物质的主要来源进行了初步的分析. 采用混凝-臭氧氧化法处理三磺泥浆体系钻井废水,在6000 mg/L石灰和2000 mg/L硫酸亚铁(FeSO4)的混凝作用下,COD的脱除率为77.2%;对混凝出水采用臭氧氧化法处理,随初始pH值的升高,臭氧氧化效果增强,随COD值降低,臭氧指数(Ozone Index, OI)显著增大;在pH值为12.5下氧化5 min, COD的氧化去除率达81.2%;混凝-臭氧氧化法两步反应的COD总去除率为95.7%,出水无色,COD<100 mg/L,达到了排放标准.     

新型有机膨润土用于印染废水处理的实验研究

采用二乙烯三胺、环氧氯丙烷合成了一种阳离子型铵盐,用其与十六烷基三甲基溴化铵对钠基膨润土进行复合插层改性,制备得到一种新型有机膨润土;以模拟染料废水和实际印染废水为处理对象,使用改性膨润土进行了吸附脱色实验,吸附完成后加入聚合氯化铝混凝。实验结果表明,与单独投加聚合氯化铝相比,采用改性膨润土吸附后再混凝的方法处理废水,可显著提高脱色率和COD去除率;处理活性艳红X-3B、酸性大红GR与活性艳蓝X-BR三种模拟染料废水时,脱色率分别可达99.4%、84.8%和96.1%;以中试规模处理实际印染废水调节池原水时,COD和色度去除率分别可达51.6%和85.9%;处理实际印染废水好氧生化出水,COD可由121.3mg/L降至65.4mg/L,色度由32倍降至8倍以下。     

慢速可生物降解有机物水解数学模型的研究进展

慢速可生物降解有机物(Xs)是城市污水和工业废水中有机物的主要组成部分,其水解速率是影响营养物去除的关键因素.阐述了Xs对(解的不同机理模型,介绍了不同的水解动力学模型的发展及应用,并对文献报道的动力学参数进行了总结和比较,最后提出Xs水解模型的研究趋势.     

Study of Pre-Treatment of Oil Refinery Wastewater by EEF-Enhanced Micro-Electrolysis

Oil refinery wastewater is rich in organic pollutants and cannot be treated easily. This study involves the pre-treatment of oil refinery wastewater by external electric field (EEF)-enhanced micro-electrolysis technology. The anode was titanium net plated with ruthenium, the cathode was barbed wire, and the Fe/C/Al micro-electrolysis filler as particle electrode. The optimum conditions for EEF-enhanced micro-electrolysis were determined to be as initial pH of 3.0, 10 V EEF voltage, and 0.06 mol/L electrolyte concentrations by studying the influence of different experimental parameters. It was also found that EEF-enhanced micro-electrolysis had a higher efficiency than the traditional micro-electrolysis in the degradation of the organic pollutants present in the oil refinery wastewater. Continuous running results showed the removal rate of COD (chemical oxygen demand), ammonia nitrogen and oil of the effluent was stable, and the average value of the effluent B/C (biochemical oxygen demand/chemical oxygen demand) ratio was 0.454 ± 0.013. The values of EC (energy consumption) and ICE (instantaneous current efficiency) were 9.8 kWh/Kg COD and 340.5%, respectively, when the reaction time was 60 min in oil refinery wastewater pre-treatment by EEF-enhanced micro-electrolysis technology. GC/MS was used to analyze the organic compounds present in the wastewater before and after treatment. UV-visible absorption spectroscopy was used to analyze the degradation process of the organic compounds present in the oil refinery wastewater. The results of these analyses confirmed the technical feasibility of EEF-enhanced micro-electrolysis in the pre-treatment of the oil refining wastewater. Finally, the main mechanism involved in the treatment of refinery wastewater by EEF-enhanced micro-electrolysis technology has been discussed.