Levels and distributions of polychlorinated biphenyls in sewage sludge of urban wastewater treatment plants

Concentrations of polychlorinated biphenyls （PCBs） have been measured in sewage sludge samples from 8 urban wastewater treatment plants in Beijing, China. The PCB congeners were analyzed by isotope dilution high resolution gas chromatography/high resolution mass spectrometry method. The concentration of PCBs ranged from 65.6 to 157 ng/g dry weight （dw）, with a mean value of 101 ng/g dw. The dioxin-like PCB WHO-TEQs （World Health Organization-Toxic Equivalents） of the sludge were lower than 1 pg /g dw. Consequently, all the concentrations of PCBs in sludge samples were below the upper limit for land application according to the Chinese legislation law for agriculture use. The PCB homologue profiles in sludge samples were dominated by tri-CBs and tetra- CBs. Similar distributions have been found in one of the Chinese PCB commercial products. The patterns of dioxin-like and indicator congeners observed in this study were quite similar in all samples. The predominant congener for dioxin-like and indicator PCBs were PCB-118 and PCB-28, respectively, while PCB-126 had the highest TEQ value.

Current Seasonal Variations in Physicochemical and Heavy Metals Parameters of Sewage Treatment Plant Effluent and Suitability for Irrigation

The study aims to investigate the current extent of physicochemical parameters and heavy metal contamination in the effluent of the Jaganpur sewage treatment plant (STP), Dayalbagh, Agra India. Majority of the nearby farmers have access to use of STP effluent in irrigation purposes for growing major edible crops. The problems of using STP effluent for irrigation purpose, continuous water quality analysis required. To check the quality of irrigation water, substantial physicochemical parameters accordance to Indian Standards (IS-Reaffirmed 2002/2003) analysed to calculate Sodium absorption ratio (SAR) and Residual sodium carbonate (RSC). To estimate the heavy metal pollution index (HPI) and metal quality index (MQI), toxic Heavy metals such as As, Cr, Mn, Fe, Ni, Cu, Zn, Pd, Cd, Co, and B also determined in the STP effluent with an AAS and results verified with ICP-OES against certified standards. The high value of SAR (range 13 to 20) and RSC (range -10 to 11) in STP effluent exceeded the permissible limit for irrigation purpose. On the other hand, HPI and MQI values (1692.4 and 58.1, respectively) show that high metal contamination mainly due to industrial and domestic wastewater does not treat appropriately in the sewage treatment plant. Thus it is suggested that further studies are carried out on the STP effluents to improve the water quality through proper treatment. Treated wastewater used for irrigation purposes needs to analyse the contamination like heavy metals and pinpoint the pollution sources.

Deep learning-based intelligent management for sewage treatment plants

It is generally believed that intelligent management for sewage treatment plants(STPs) is essential to the sustainable engineering of future smart cities.The core of management lies in the precise prediction of daily volumes of sewage.The generation of sewage is the result of multiple factors from the whole social system.Characterized by strong process abstraction ability,data mining techniques have been viewed as promising prediction methods to realize intelligent STP management.However,existing data mining-based methods for this purpose just focus on a single factor such as an economical or meteorological factor and ignore their collaborative effects.To address this challenge,a deep learning-based intelligent management mechanism for STPs is proposed,to predict business volume.Specifically,the grey relation algorithm(GRA) and gated recursive unit network(GRU) are combined into a prediction model(GRAGRU).The GRA is utilized to select the factors that have a significant impact on the sewage business volume,and the GRU is set up to output the prediction results.We conducted a large number of experiments to verify the efficiency of the proposed GRA-GRU model.

Discussion on the Problems and Developing Trend of Construction of Sewage Treatment Plants in Small Towns

Existing problems of sewage treatment plants in small towns were summarized firstly,and then the developing trend of construction of sewage treatment plants in small towns was discussed from the aspects of project decision,site selection,design,processing technology and construction financing models. Finally,outlooks for its future development were proposed to provide reference for the construction of sewage treatment plants in small towns in future.

Advances in Research of Characteristics and Removal of Microplastics in Sewage Treatment Plants

Microplastic pollution has become a worldwide issue.The discharge of sewage treatment plants(STPs)or wastewater treatment plant(WWTPs)is an important way for microplastics to enter the environment.This study reviewed the sources and occurrence characteristics(type,size,color and components)of microplastics in domestic and foreign sewage plants.It elaborated the removal principles of microplastics by primary,secondary and tertiary treatments.In addition,the removal effects of various treatment units and different processes on microplastics were summarized.In the future,the removal mechanism of microplastics in sewage treatment plants should be discussed in more depth,so as to further improve the removal rate of microplastics by optimizing and transforming traditional sewage treatment processes.Therefore,it is necessary to develop new technologies/processes specifically for the removal of microplastics and promote them to practical applications.

Behavior of Antibiotic-Resistant Fecal Coliforms in the Stream of a Sewage Treatment Plant in Tokyo

We are confronting a new threat in the prevalence of antibiotic-resistant bacteria followed by epidemic spread in aquatic environments in metropolitan areas because damage from river floods is increasing remarkably in Japan due to global extreme weather. The sewer penetration rate is about 100% in Tokyo and reclaimed water from sewage treatment plants accounts for over 50% of all water in both the down- and mid-stream areas of local rivers. The water quality of these rivers, which contain microflora, seems to be seriously affected by reclaimed water. In this study, we collected water samples on July 17, 2018 and examined the behavior of antibiotic-resistant fecal coliforms in the stream of a sewage treatment plant in Tokyo. Extended-spectrum β-lactamase (ESBL)-producing fecal coliforms with encoding genes were found;the CTX-M-1, CTX-M-9, TEM, and SHV groups were found to have survived in the final effluent to the river after sterilization with sodium hypochlorite.

Water Analyses, Eco-Balance and Socio-Demographic Analyses as Prerequisites for Solutions of the Sewage Treatment Problems in Rural Areas

The implementation of the EU-water framework directive (EU-WFD) demands a financeable and adaptable sewage treatment, creating a need for action especially in rural areas, where the “good ecological status” is often not reached even though the sewage works fulfill the legal minimum requirements. Therefore the construction of new, more efficient wastewater treatment plants is advisable. Due to the precarious financial situation in most rural areas, many municipalities can however not master the necessary funds for an improved waste water infrastructure. A large part of the costs would have to be shouldered by the local population in the form of additional sewage levies, leading to massive socio-economic strain. Hence, different solutions, which are tailored to the socio-economic, demographic and environmental characteristics of rural areas and fulfill the legal requirements, need to be developed. One possible approach is presented in the form of the Dirlammen case study (municipality Lautertal, Hesse, Germany). It consists of 1) biological and physicochemical analyses of the waste waters, 2) a modified eco-balance for the construction of a new sewage works and 3) socio-economic and demographic analyses of the population. It serves as a tool for the assessment of the influencing ecological, socio-economic and demographic factors on the sewage problems in rural areas. These findings can easily be transferred to other rural areas with a similar configuration and thus deliver the basis for a generally applicable approach to these problems. The results of the comprehensive analysis have shown for the municipality Dirlammen/Lautertal that the continued operation of the existing pond sewage plant is, with regards to the ecological, socio-economic and demographic points of view, preferable to the construction of a new waste water treatment plant. With regard to the sustainability principles of the sewage treatment and the objectives of the EU-WFD, existing sewage works should be operated for as long as the sewage treatment is feasible within technical and legal boundaries. With the construction of new facilities on the other hand, the expected improvement of the water quality has to be weighed against the ecological impairments caused by the construction itself. Rural waste water plans have to be developed for the long-term, taking not only the ecology into account but also the demographic change. Possible approaches in this regard could be a shift towards a decentralized waste water treatment concept and–even more important–improvements of the river morphology. But also the reduction of the diffuse pollution from agricultural sources should be considered for the development of strategies for the improvement of the ecological state. Short-term optimization measures in the existing sewage works might also improve the water quality until the long-term development plans can be implemented. In particular the challenges of the demographic change and linked with that the changing requirements for the rural waste water treatment must be addressed by any future plans. Only with the help of such a comprehensive approach the dangers of bad planning and unacceptable socio-economic burdens can be minimized.

Total concentrations and different fractions of heavy metals in sewage sludge from Guangzhou, China

Dewatered municipal sludge samples were collected from five municipal wastewater treatment plants （WWTPs） and one industrial WWTP in Guangzhou, China. A number of agricultural parameters and total metal concentrations in the sludge were determined. Metal speciation was also studied. The results showed that sewage sludge had high organic carbon, and was rich in such nutrients as N and P. The concentrations of Mn, Zn, and Cu were the highest, followed by Ni, Pb, and Cr, Cd had the lowest concentration. In addition, the concentrations of the aforementioned heavy metals in the sludge samples were higher than those recorded in the background data for crop soils. With the exception of Cu and Cd from site S1, and Ni from sites S1, $2, and $5, all other metal concentrations conformed to permissible levels prescribed by the national application standard of acid soil in China （GB 18918--2002）. The results of the BCR sequential extraction showed that the concentrations of Mn and Zn were predominant in acid-soluble/exchangeable and reducible fractions. Cu was principally distributed in oxidizable and residual fractions, whereas Cr was present in oxidizable and residual fractions, Pb was found in the state of residual fractions, and the distribution of Ni and Cd did not show significant characteristics.

Experimental Study on Anaerobic Digestion of Remaining Sludge in Municipal Wastewater Treatment Plant

Along with the development and progress of environmental protection management,it is necessary to pay full attention to the disposal of excess sludge in the process of urban sewage treatment plant management.It is necessary to ensure effective integration of management mechanisms and management paths.To a certain extent,it can improve the actual efficiency of digestion and treatment work and lay a foundation for the optimal operation of environmental protection management.In this paper,the treatment of excess sludge in a sewage treatment plant is studied.The method and results of anaerobic digestion test of excess sludge in a sewage treatment plant are discussed for reference only.

污水处理厂温室气体排放特征与减排技术研究

污水处理厂是温室气体的重要排放源,必须探索和应用有效的减排技术,提升温室气体减排能力。深入分析污水处理厂温室气体排放特征,有助于更好地应用减排技术。直接排放与间接排放是污水处理厂温室气体的两种主要排放形式。结合污水处理厂温室气体的来源,以山东省某污水处理厂为例,核算2018-2020年温室气体直接排放量与间接排放量,然后根据污水处理厂温室气体排放特征,分析污水处理厂温室气体的减排措施。总体来说,要科学选择污水处理工艺,合理调节工艺运行参数,有效减少温室气体排放量。

污水厂尾水对河流水质和底泥细菌群落的影响

污水厂的出水即尾水,其排放关系到受纳水体的水质和生态状况。分析了武汉市某污水厂尾水排放指标,采用水槽试验探究了污水厂尾水对河流水质指标和底泥细菌群落的影响。结果表明:尾水排放促进了河水中硝酸盐氮的降解,总磷去除更加稳定;尾水使河水pH值提高了0.3、电导率上升幅度55%、溶解氧降低了0.6 mg/L。尾水排放之后,底泥细菌群落的丰富度升高、多样性降低,抑制厌氧菌Anaerolineaceae和SBR1031,促进好氧菌Pseudomonas;反硝化菌Azospira、Dechloromonas、Pseudomonas、Sphingomonas增多,促进了NO_(3)^(-)-N的降解。底泥中致病菌奈瑟菌属、军团菌属、消毒残生细菌相对丰度上升。

长江大保护试点城市某污水处理厂尾水湿地净化效果研究

为探寻污水处理厂配套尾水湿地净化效果,以长江大保护试点城市某污水处理厂尾水湿地为例,通过现场调查与采样,分析湿地出水水质特征,探讨影响湿地污染物去除效率因素。结果表明:尾水湿地出水COD、NH_(3)-N及TP浓度满足设计目标,潜流湿地对COD去除率较高,表流湿地对氨氮及磷的去除率较高,优于涵养塘;湿地实际运行水力负荷、水力停留时间和污染物负荷与设计值不符,影响污染物去除效果;据此提出湿地运行优化建议,促进湿地深度脱氮除磷,提升尾水湿地效能;运行优化可提高潜流湿地污染物去除率,同时污水处理厂减少碳排放94.74 gCO_(2)m^(3)。研究结果可为该尾水湿地运行管理及长江大保护试点城市系列污水处理厂配套尾水湿地设计与运维提供参考。

东北地区某城镇污水处理厂碳源投加策略分析

低C/N进水条件造成的生物处理系统反硝化脱氮能力不足已成为我国污水处理厂运行面临的主要挑战。文章应用文献计量学对目前碳源投加策略进行了总结,并以东北地区某城镇污水处理厂为考察对象,结合各碳源的实际应用情况介绍了目前常用的几种主流外加碳源的优缺点,分析了甲醇、乙酸钠、葡萄糖和麦可碳4种碳源投加公式计算理论值与实际碳源投加量之间存在差异的原因,旨在为城镇污水处理厂实现经济、高效、低碳运行碳源投加策略提供技术指导。

雨污合流制地区溢流污染影响因素及管控建议

雨污合流制地区汛期溢流成为城市河流返黑返臭的重要原因,溢流污染的有效控制,对改善水环境,提升人民幸福感、获得感与安全感有着重要作用。针对雨污合流制地区汛期溢流污染防控,总结了合流制溢流污染的特点、对水环境质量的影响以及合流制溢流污染的影响因素等内容,分析了我国溢流污染严重区域的分布特征并提出管控建议。研究发现,我国合流制溢流污水呈现出成分复杂、水量水质变化大、初期雨水水质差等特点,且合流制溢流污染会导致城市面源污染,加重地表水质恶化程度。通过分析合流制溢流污染的2个主要影响因素(降水量和管网条件),初步识别出我国溢流污染严重区域主要集中在东部、南部地区,且相关性分析结果表明汛期降水量及管网密度与区域水质存在中等相关关系。为加强合流制地区溢流污染防控,提出要因地制宜制订汛期雨污溢流污染排放管控标准、开展溢流污染控制技术更新行动、加强汛期雨污溢流污染的全过程管理、加强汛期雨污溢流污染治理成效考核等具体建议,以期为有效控制合流制溢流污染,推动水环境质量持续改善提供参考。

城镇污水厂各工序段对微塑料去除率差异特性分析

污水处理厂被认为是微塑料的主要排放与储存场所.为探究城镇污水处理厂不同处理工序段对污水中微塑料的去除效率差异特性,以内蒙古某污水处理厂为研究对象,通过采用体式显微镜观察,并借助LAS X软件统计分析的方法展开研究,结果表明:污水厂中微塑料的主要存在形态以纤维状为主(61.8%),其次为碎片状与薄膜状,微塑料的尺寸主要集中在0.25-0.50mm(32.9%).一级处理工序中对微塑料去除效果最好的构筑物分别是:粗格栅、细格栅和初沉池,尤其对尺寸小于0.25mm微塑料颗粒的去除效果最好.旋流沉砂池对纤维、碎片和薄膜状微塑料均没有起到积极的去除效果,二级处理工序中的二沉池对微塑料的去除起到了关键作用,其次为纤维生物转盘,其对尺寸介于0.50~1.00mm的微塑料去除效率最高.一级处理工序对3种形状微塑料的去除效率均为正值,且去除效率与微塑料尺寸呈负相关关系.一级处理工序中的构筑物对小尺寸微塑料的去除效率比较稳定,而对大尺寸微塑料的去除效率波动较大,对不同形状微塑料的去除率随污水在各处理构筑物流动方向沿程呈下降趋势.二级处理工序对3种形状微塑料的去除率均呈现为负值,而仅对尺寸小于0.50mm的微塑料去除率为正值.本研究旨在为污水厂提升微塑料去除率的运行管理提供理论指导作用.

不同降雨规模对城镇污水处理厂进水水质水量影响分析

以江苏省中部某城镇污水处理厂2021年进水数据为依据,利用夏波洛-威尔克(S-W)检验法、三角形法等方法,分析城镇污水处理厂进水水质分布;结合2021年降雨量数据,研究不同降雨规模下污水处理厂可生化性、雨水混入比例及生活污水收集率变化,以期为优化污水处理厂雨天运行管理提供数据和科学支撑。结果表明:污水处理厂进水COD服从正态分布,氨氮、总氮和总磷呈正偏态分布;随着降雨规模的增大,雨水混入率由11.1%提高至19.7%,污水处理厂设计规模宜考虑乘以1.2的安全系数;中雨时,污水处理厂进水水质处于较好状态的天数占比最高,大雨时可生化性最差;降雨量越大,生活污水收集率越低,汛期(6-8月)生活污水收集率比枯水期(12月-次年2月)降低20个百分点,应强化汛期6-8月生活污水的收集处理,降低生活污染物排放。

城镇复合型污水处理厂水质监测与微生物分析

城镇复合型污水处理厂发挥着处理辖区工业污水与生活污水的作用.其中的生化段是污水处理厂的核心部分,生化处理效果依赖于多样的微生物群落,生物的多样性是高效去除有机物、氮和磷等污染物质的重要保证.在此,对长江流域城镇复合型污水厂L的工艺水质及微生物基因数据进行了系统的分析.首先,对污水厂L进出水与各处理工段水质进行监测,并且对生化段进行了沿程监测,结合运行数据与监测数据,评估了污水处理厂实际运行效果.工业废水进水没有对污水处理厂L造成冲击,各工艺段运行基本稳定,出水水质基本达标.进一步利用宏基因组测序技术,对污水处理厂L氧化沟工艺的活性污泥样本进行了微生物群落结构的研究.结果表明,氧化沟中存在着功能各异的微生物.微生物的多样性和相对丰度在不同区域之间表现出差异,这种差异反映了其适应不同环境条件的能力.通过生态代谢组学分析,探讨了微生物群落的功能特征,群落中不同种微生物在有机物降解、脱氮和除磷等关键生化过程中发挥各自的作用,协同工作以实现废水处理的高效性.通过对污水厂运行监测数据的分析及微生物群落基因的研究,有助于全面地评价并诊断污水厂的运行情况.

基于碳减排的厌氧氨氧化脱氮工艺应用及强化调控进展

随着我国“双碳”目标的提出和水处理行业提标改造的重点落在生物脱氮,污水处理厂从关注满足排放许可限制转向实现碳中和、能量自给及资源回收。厌氧氨氧化(Anammox)技术凭借无需外加有机碳源、占地面积小、污泥产量少以及脱氮效率高等节能降耗与碳减排优势,代表着未来污水生物脱氮的发展方向。基于已有研究成果,梳理对比了传统脱氮与Anammox反应的发展历程;重点综述了新兴短程硝化耦合Anammox(PN-A)工艺、短程反硝化耦合Anammox(PD-A)工艺和甲烷型反硝化耦合Anammox(DAMO-Anammox)工艺在城市主流工况的应用进展;详细探讨了主流Anammox工艺面临低温、进水负荷不均和光照等环境因素冲击时,可施行的“侧流污泥补充至主流”“侧流污水间歇性补充至主流”“驯化生物膜颗粒”等内源性以及外源性的强化调控策略及内在机制;最后围绕分子生物学技术、材料科学、数字信息技术和管理政策,对加快Anammox生物脱氮技术的创新发展与推广应用进行了展望。

采用改良A^(2)O工艺中型城镇污水处理厂碳排放特征研究

运用碳排放因子法,对汕头市4座处理规模相似但A^(2)O工艺各异的中型污水处理厂进行碳排放总量核算与碳排放强度分析。结果表明,采用不同A^(2)O工艺的污水处理厂总碳排放量存在差异,4座污水处理厂总碳排放强度范围为0.317~0.402 kg/m^(3)(CO_(2)-eq)。按处理工艺碳排放从小到大顺序为:多段AO、A^(2)O+厌氧/缺氧调节池、传统A^(2)O、A^(2)O+微曝气氧化沟。但不同处理工艺的碳排放类别组成相似,电力消耗为最主要的碳排放源。与传统的A^(2)O工艺相比,3种改良A^(2)O工艺在减小药耗、CH4排放、N2O排放和污泥处置碳排放源排放强度存在优势,其中多段AO工艺减小总碳排强度的优势最大,据此针对改良A^(2)O工艺的运行碳排优化提出建议。

不同天然水生植物组合降解生活污水效果分析

为达到《四川省岷江、沱江流域水污染物排放标准》(DB51/2311-2016)中相关标准,四川多数生活污水处理厂在原有处理工艺上添加处理单元,从而导致处理成本增加。本研究以执行该地方标准的某生活污水处理厂经格栅后生活污水为研究对象,用选取的水菖蒲、美人蕉、空心莲子草及水芙蓉四种水生植物单独或两两串联降解其主要污染物,以COD_(Cr)、TN、TP及NH^(+)_(4)-N去除率评价其效果。结果表明,美人蕉-水芙蓉组合处理效果最好。