Comparison of heavy metal removal efficiencies in four activated sludge processes

The removal efficiencies of heavy metals(As, Cr, Cu, Ni, Pb and Zn) were investigated in the 17 operating municipal wastewater treatment plants(WWTPs) and compared with those in four main activated sludge processes. Significant differences of heavy metal removal efficiencies were observed among four activated sludge processes. The removal efficiency for As(75.5%) in the oxidation ditch(OD) process is significantly higher than that in the conventional activated sludge(CAS) process(38.6%) or sequencing batch reactor(SBR) process(51.4%). The mean removal efficiencies for Cu and Ni in the OD process are 90.5% and 46.7%, respectively, while low mean removal efficiencies are observed for Cu(69.9%) and Ni(16.5%), respectively, in the SBR process. The removal efficiencies for Cu and Ni in the OD process are significantly higher than those in the anaerobic-anoxic-oxic(A2-O) process. These results highlight the differences of removal efficiencies for heavy metals in different processes and should be considered when selecting a wastewater treatment process.

Rapid aerobic granulation using biochar for the treatment of petroleum refinery wastewater

Aerobic granular sludge technology has great potential for the treatment of petroleum refinery wastewater.However,strategies to shorten the granulation time and improvement the stability still need to be developed.In this work,biochar was prepared from waste petroleum activated sludge(biochar-WPS) and used in a sequencing batch reactor for the treatment of petroleum refinery wastewater.Biochar-WPS presented the surface area of 229.77 m2/g,pore volume of 0.28 cm3/g,H/C and O/C atomic ratios of 0.42 and 0.21,respectively.The porous structure and a high degree of hydrophilicity were found to facilitate microbial colonization and adhesion as well as particle aggregation.Application of biochar-WPS resulted in the formation of more substantial and stable aerobic granules(~66% of granules> 0.46 mm diameter) 15 days earlier compared with the control.The addition of biochar-WPS enhanced the average removal efficiency of chemical organic demand(~3%),oil(~4%)and total nitrogen(~10%) over the control.Increased microbial richness and diversity were observed within the formed granules and had an increased(~4%) proportion of denitrifying bacteria.These results indicate that an aerobic granulation mechanism using biochar-WPS is a feasible option for the treatment of petroleum refinery wastewater.

Experimental study on pressurized activated sludge process for high concentration pesticide wastewater

Pressurized biochemical process derived from traditional activated sludge processes is an innovative technology for wastewater treatment. The main advantage of the pressurized process is that the oxygen transfer barrier can be overcome by increasing the dissolved oxygen level. In this study, high concentration pesticide wastewater was treated by pressurized activated sludge process. It was found that the removal of chemical oxygen demand （COD） increased steadily with the increase of operating pressure, aeration time, and sludge concentration. When the operation pressure was 0.30 MPa and the aeration time was 6 hr, 85.0%-92.5% COD, corresponding to an effluent COD of 230-370 mg/L, was removed from an influent COD of 2500-5000 mg/L. The obtained outlet COD concentration was lower than 350-450 mg/L for the identical process operated under the atmospheric pressure. In addition, pressurized biochemical process could produce a higher COD volumetric loading rate at 5.8-7.6 kg COD/（m^3.day）, compared with 2.0-2.8 kg COD/（ma.day） using the same equipment at the atmospheric pressure. The COD concentration followed a modified Monod model with Vmax 2.31 day-1 and Ks 487 mg/L.

Kinetics of aerobically activated sludge on terylene artificial silk printing and dyeing wastewater treatment

Aerobically activated sludge processing was carried out to treat terylene artificial silk printing and dyeing wastewater (TPD wastewater) in a lab-scale experiment, focusing on the kinetics of the COD removal. The kinetics pa-rameters determined from experiment were applied to evaluate the biological treatability of wastewater. Experiments showed that COD removal could be divided into two stages, in which the ratio BOD/COD (B/C) was the key factor for stage division. At the rapid-removal stage with B/C>0.1, COD removal could be described by a zero order reaction. At the mod-erate-removal stage with B/C<0.1, COD removal could be described by a first order reaction. Then Monod equation was introduced to indicate COD removal. The reaction rate constant (K) and half saturation constant (KS) were 0.0208-0.0642 L/(gMLSS)h and 0.44-0.59 (gCOD)/L respectively at 20 C-35 C. Activation energy (Ea) was 6.05104 J/mol. By comparison of kinetic parameters, the biological treatability of TPD wastewater was superior to that of traditional textile wastewater. But COD removal from TPD-wastewater was much more difficult than that from domestic and industrial wastewater, such as papermaking, beer, phenol wastewater, etc. The expected effluent quality strongly related to un-biodegradable COD and kinetics rather than total COD. The results provide useful basis for further scaling up and efficient operation of TPD wastewater treatment.

Slaughterhouse Wastewater Characterization and Treatment: An Economic and Public Health Necessity of the Meat Processing Industry in Ontario, Canada

The characteristics of the slaughterhouse effluents and current wastewater treatment practices in the province of Ontario, Canada are analyzed. Meat processing plants are found to produce large amounts of wastewater due to the slaughtering process and cleaning of their facilities. Furthermore, the composition of the wastewater varies according to the type and number of animals slaughtered and the water requirements of the process. However, the slaughterhouse wastewater usually contains high levels of organics and nutrients. Several slaughterhouses in Ontario discharge their wastewater into the municipal sewer system after primary pretreatment at the meat processing plant. Therefore, due to the high-strength characteristics of the slaughterhouse effluents, an extensive treatment for a safe discharge into the environment is required. Thus, the combination of biological processes and advanced oxidation technologies for slaughterhouse wastewater treatment is evaluated in this study. Results show that the application of combined biological and advanced oxidation processes is recommended for on-site slaughterhouse wastewater treatment.

城市污水处理过程污泥膨胀识别与抑制综述

污泥膨胀是活性污泥法污水处理过程中常见的一类异常工况,且具有严重危害性,研究污泥膨胀的识别和抑制方法对城市污水处理过程正常运行意义重大.本文主要针对城市污水处理过程中污泥膨胀的识别和抑制方法进行综述.首先,文章概述了城市污水处理过程,介绍了污泥膨胀的概念、主要特点、类型和成因;其次,概述了基于微生物生理特征、机理模型、图像识别和数据驱动的污泥膨胀识别方法,分析其发展现状并指出优缺点;然后,概述了基于过程调控和机理特征的污泥膨胀抑制方法,分析其发展现状并对比优缺点;最后,总结全文,指出了城市污水处理过程污泥膨胀识别和抑制面临的主要问题,并对其研究趋势进行了展望.

高效包埋好氧颗粒污泥在农药废水处理中的应用研究

为了高效处理有毒有害的农药废水,研究了包埋好氧颗粒污泥对实际农药废水的处理效果,并对比了包埋好氧颗粒污泥、市政好氧污泥及两者混合体系在实际农药废水活性污泥法处理中的表现。结果表明:在实际农药废水处理中,市政好氧污泥的硝化速率和COD降解速率分别为0.67 mg[N]/(g[SS]·h)和3.54 mg[COD]/(g[SS]·h),两者混合体系的平均硝化速率和COD降解速率分别为5.0 mg[N]/(g[包埋颗粒]·h)和49.05 mg[COD]/(g[包埋颗粒]·h),而包埋好氧颗粒污泥的平均COD降解速率为91.14 mg[COD]/(g[包埋颗粒]·h),并且具有更好的硝化性能,平均硝化速率为18.8 mg[N]/(g[SS]·h)。包埋好氧颗粒污泥对农药废水表现出较强的耐冲击负荷能力,说明了包埋好氧颗粒污泥的投加对提高农药废水氨氮降解效果显著。

活性污泥法污水处理技术在上海的早期传入与实践

20世纪初,上海公共租界工部局为了解决抽水马桶带来的水环境问题,邀请英国化学家福勒来沪进行考察,提出结合活性污泥法的处理方案。文章以活性污泥法污水处理技术传入上海的过程为重点,分析了福勒提出活性污泥法方案的过程,梳理了工程师前往美国、加拿大考察并评估该技术在上海的适用性,探讨了活性污泥法落地上海,建造污水处理实验室的情况。这是活性污泥法首次进入上海,也是第一次传入中国,促进了近代上海的城市现代化建设。活性污泥法在上海的传入,反应了技术移植过程中的常规程序,即提出方案、调研与选择、探索实践模式。活性污泥法的引入,是近代技术进入中国的典型案例。

Oxygen Transfer and Hydrodynamics in a Flexible Fibre Biofilm Reactor for Wastewater Treatment

A flexible fibre biofilm reactor was developed for treatment of organic wastewaters.The hydrodynamic characteristics and mass transfer coefficients of oxygen were studied and compared with those of the conventional activated sludge processes.Tracer experiments were performed to obtain the residence time distributions of the reactors.The results indicated that both reactors could be treated as mixed flow reactors.The effects of flow rates of water and air on the overall mass transfer coefficient of oxygen were investigated,and the correlations between the mass transfer coefficient and the ratio of flow rates were obtained.Compared to the conventional activated sludge reactor,the mass transfer coefficients in the flexible fibre reactor were similar to but slightly lower,and less sensitive to the variation in the ratio of flow rates.It indicated that the fibre packing in the reactor hindered the oxygen transfer to some extent.

A study of control strategies for a clarifier at an industry wastewater treatment plant

Control of clarifier in the activated sludge process is critical for ensuring effective wastewater treatment. This paper is to study appropriate control strategies for a clarifier in an industrial wastewater treatment plant. Five control strategies are proposed, implemented and evaluated in a simulation software （West ＋＋）. The sludge blanket height and the effluent suspended solids concentration were proposed as the measured variable. The manipulated variable was the quantity of polymer added to the system. The strategies were evaluated in terms of their ability to maintain the sludge blanket height below 1.5m, their polymer requirements, their sensitivity to poor tuning and the required control action.

粉末活性炭改善MBBR处理效果的工程应用实例

在某炼化企业高浓度污水处理系统的MBBR反应器中投加75 mg/L的粉末活性炭,从工程应用的角度考察了活性炭投加后MBBR的运行效果。工业装置运行结果表明,在MBBR系统的缺氧单元空床停留时间4 h、好氧MBBR反应器空床停留时间16 h、进水COD≤600 mg/L、氨氮≤40 mg/L、TN≤45 mg/L的运行条件下,MBBR系统保持了长期稳定运行,出水水质满足了设计要求。该工程实例表明,在MBBR装置中少量投加粉末活性炭,是提高在用MBBR装置运行稳定性和处理效果的一个简单、可行且有效的方法。

活性污泥法对油脂废水处理效果研究

在工业废水处理领域,关于油脂废水的处理始终是环境保护中的重要课题。油脂废水主要产生于油脂加工行业中的碱炼、水洗、酸化、中和、脱酸、脱臭等各个工序。该类废水不仅含有高浓度的油脂,还含有磷脂、皂角等有机物,以及酸、碱、盐和固体悬浮物,成分十分复杂。因此,探索有效的废水处理方法对于推动环境保护和实现可持续发展具有重要意义。文章探究了活性污泥法对油脂废水的处理效果,并对比了COD、BOD5、TP的污水处理情况,以期为相关行业的污水处理提供参考。

焦油渣与污泥基活性炭的制备及其处理煤化工废水研究

利用焦油渣、沥青与少量淀粉、酚醛树脂、羧甲基纤维素等,复配出廉价的环保粘结剂配方;以气化筛余物(粉煤)、生化污泥为原料,通过挤压成型、碳化、活化工艺制备活性炭,开展公斤级半中试试验,确定其最优炭化时间为50 min,炭化温度为600℃,活化时间为2.5 h,活化温度为900℃,得炭率达40%。制备所得的4 mm柱状活性炭产品,中孔结构较发达,强度为92.8%,碘值为611 mg/g,比表面积为302.54 m^(2)/g,达到GB/T 7701-2008《煤质颗粒活性炭》的各项指标要求,对煤化工园区污水处理厂尾水COD有较好的去除效果。

二甲基乙酰胺废水与面包生产废水协同处理的研究与应用

本文针对二甲基乙酰胺废水的高COD和TN浓度及生物毒性问题,提出了一种协同处理方案。通过小试试验研究发现,使用面包生产废水作为补充碳源可以有效处理二甲基乙酰胺废水。该研究成果已成功应用于实际生产中,有效降低了废水处理的碳源投加量和处理成本。加强对工业废水处理技术的研发力度,建立废水协同处理的技术规范和标准,鼓励企业间开展合作,实现废水的互补和协同处理,这将有助于为环境保护工作带来更多的思考和启迪。

废油漆桶清洗废水处理工程设计

根据废油漆桶清洗废水高pH值、高COD和悬浮物、可生化性较差的水质特点,设计采用加酸中和-气浮-混凝沉淀-臭氧氧化-水解酸化-缺氧-好氧-MBR组合工艺进行处理。工程运行结果表明,在进水COD、BOD_(5)、SS质量浓度分别为3750、900、450 mg/L,色度为420度时,相应出水分别为110、15、5 mg/L和15度,排水水质满足GB/T 19923—2005《城市污水再生利用工业用水水质》表1规定的洗涤用水标准。该工艺具有运行稳定,操作简单,投资及运行成本低且节约水资源等特点,实现了良好的经济效益和环境效益。

污泥低温干化冷凝废水处理技术研究及设计案例

污泥干化是污泥热解、焚烧处理过程中的重要环节,其干化过程中产生的废水为冷凝废水。该废水具有总氮高、氨氮高、碱度低、碳氮比低等特点,专门研究该类废水的成果较少。冷凝废水的污染物成分与城镇污水成分相近,不同工况条件下的污泥干化冷凝废水处理工艺不尽相同,建议优先考虑低成本的活性污泥处理法。以四川某污泥低温干化冷凝废水项目为例,详细分析200 t/d污泥干化项目配套建设200 m3/d污水处理系统的处理工艺、各单元设计、建设投资以及运营成本。

浅谈生物法处理含油废水的研究进展

经济的发展使石油的需求量不断增大,并产生了大量的含油废水,对人类健康和环境造成了极大的危害。生物法因处理含油废水成本低、效果好,备受关注。本文介绍了生物膜法、活性污泥法、生态系统净化法等,着重介绍了生物膜法,并提出在今后的生物法研究中应更加注意对耐高温、高盐、高浓度石油废水降解菌株的筛选,以提高生物法的处理效率。

Treatment of a dyeing wastewater from a woolen mill using an A/O membrane bio-reactor

An anaerobic/oxic membrane bioreactor (A/O MBR) was used for treatment of dyeing wastewater from a woolen mill. COD and color of the wastewater were 54—473 mg/L and 40—400 dilution time (DT) respectively. The ratio of BOD 5/COD was less than 0.13. By the A/O MBR process, the average removal of COD, BOD 5, color and turbidity was 82%, 96%, 71% and 99%, respectively. The average COD, BOD 5, color and turbidity of effluent was 37 mg/L, 0.8 mg/L, 40 DT and 0.44 NUT respectively. The effluent COD met the local standard of reuse water in Beijing, China. The average COD volume load of the anaerobic biological tank was 0.0483 kgCOD/(m 3·d) and that of the aeration tank of the MBR was 0.3589 kgCOD/(m 3·d). The sludge load of the MBR was 0.19 kgCOD/(kg·MLSS·d) on average and the maximum of that was 0.4 kgCOD/(kg·MLSS·d). The flux of the A/O membrane bioreactor could be remained at larger than 50 L/(h·m 2·0.1MPa). The results indicated that A/O membrane bioreactor has technical feasibility for treatment of woolen mill wastewater.

Characterization and Laboratory-Scale Treatment of Municipal Drainage Wastewater of Khulna, Bangladesh

The study was conducted to characterize and perform laboratory-scale treatment of municipal drainage wastewater of Khulna, Bangladesh. Wastewater samples were collected from three different points of existing urban drain outlets into the Mayur River around Khulna. Laboratory testing shows the BOD5 and COD concentration of wastewater samples varied from 57 - 226 mg/l and 320 - 435 mg/l, respectively, and the total dissolved solids ranged from 1800 - 2525 mg/l. Therefore, a laboratory-scale treatment technology was developed to treat this wastewater. Treatment technologies adopted were primary sedimentation, followed by aeration, chemical precipitation and filtration. In treated wastewater, BOD5, COD and TDS were found to be in the range of 40 - 115 mg/l, 160 - 256 mg/l and 1356 - 1500 mg/l, respectively. These test results suggest that the performance of laboratory-scale treatment plant was not adequate to fulfil the acceptable limit (ECR’97) for safe disposal into surface water bodies. Due to poor quality of effluents, modification of laboratory-scale treatment plant was made by an activated sludge process followed by granular media filtration. The final BOD5, COD TDS and TSS concentration of effluents was found to be 1.38 - 9.8 mg/l, 32 - 192 mg/l, 590 - 1667 mg/l, and 35 - 95 mg/l respectively, which satisfy ECR’97 standard limits for safe disposal into inland water bodies.

高盐废水生化处理的研究进展

介绍了高盐废水的来源和特征,简述了耐(嗜)盐微生物的分类及其在高盐环境下的反应机理,讨论了含盐量对污染物去除效果的影响,最后对高盐废水生化处理系统的设计和运行优化提出了建议和展望。