Biological sludge solubilisation for reduction of excess sludge production in wastewater treatment process.

A novel sludge disintegration system (JFE-SD system) was developed for the reduction of excess sludge production in wastewater treatment plants. Chemical and biological treatments were applied to disintegrate excess sludge. At the first step, to enhance biological disintegration, the sludge was pretreated with alkali. At the second step, the sludge was disintegrated by biological treatment. Many kinds of sludge degrading microorganisms integrated the sludge. The efficiency of the new sludge disintegration system was confirmed in a full-scale experiment. The JFE-SD system reduced excess sludge production by approximately 50% during the experimental period. The quality of effluent was kept at quite a good level. Economic analysis revealed that this system could significantly decrease the excess sludge treatment cost.     

对我国污水处理污染物排放标准的思考

"十五"其间,针对国民经济、社会发展和国家安全的需求,国家实施"人才、专利和技术标准"三大战略."十一五"期间,科技部将"关键技术标准推进工程"列为"十一五"国家科技支撑计划重大项目,其中包括"环境污染物排放关键技术标准研制".国家对技术标准如此重视,足以看出我国技术标准远落后于社会发展的需求,污水处理排放标准也同样存在很多问题,亟待修改完善.     

Characteristics of WWTP sludge after drying in greenhouse for agricultural purposes

The sludge generated by sewage treatment which meets regulatory standards can be used in agriculture. With this understanding, the focus of this study is the evaluation of the agricultural characteristics and inorganic substances in excess activated sludge, which was subjected to drying in a greenhouse. The variables (factor) evaluated during the drying process were: type of sludge (digested or not digested), addition of lime to the sludge, and the physical layout and rotation of sludge in the greenhouse. The parameters monitored for this assessment were moisture, volatile solids and pH. The greenhouse cover and sides were made of translucent plastic to allow the penetration of solar radiation and prevent water from entering. A impermeable floor was used. The sludge was generated in sewage treatment plants located in the metropolitan region of Grande Vitória, Espírito Santo, Brazil. The solar drying of wastewater sludge in a greenhouse presented satisfactory results.     

A PCR-DGGE approach to evaluate the impact of wastewater source on the antibiotic resistance diversity in treated wastewater effluent

Increased incidence of antibiotics in human-affected environments is raising concerns about increase in acquired antibiotic resistance by environmental bacteria. Wastewater collection and treatment systems are likely significant anthropogenic sinks and vectors for antibiotics and associated antibiotic resistance. Typical municipal treatment plants collect wastewaters of various sources, including well-established antibiotic resistance reservoirs such as hospitals, intensive care units and nursing homes, and integrate them with sources not commonly identified as major sources of antibiotic resistance, such as residential or industrial sources. A comprehensive PCR-DGGE diversity analysis of wastewater antibiotic-resistant bacteria was performed to evaluate the role of various wastewater sources in the discharge of antibiotic resistance by a municipal treatment plant. Wastewater sources are clearly inducing resistance in the final effluent but the role of each source type is highly variable, likely as a function of variable environmental conditions or water use patterns. Comparisons between primary treatment and secondary treatment stages indicate a strong role of the intensity of the wastewater treatment in the diversity profiles of antibiotic-resistant bacteria. While pervasiveness of antibiotic resistance in the system impedes clear discrimination between sources in the tested system, there are indications of specific source type related impacts.     

大型城市污水处理厂活性污泥法污泥膨胀防控对策

详细解析了倒置A2/O工艺污泥膨胀发生前后的运行状况及活性污泥性状,通过水质数据对比和运行参数比较,探讨在大型城市污水处理厂建立污泥膨胀预警评价体系的可能性。利用工艺参数对典型工艺进行优化调控,提前预防污泥膨胀或在污泥膨胀初期进行防控。     

Evaluation of the ReVAQ project to achieve safe use of wastewater sludge in agriculture.

The use of wastewater sludge on arable land in Sweden has been limited for some years due to the low quality, in some respects, of the sludge and to the reluctance of farmers and the food industry to use it. To improve the quality of the sludge, the ReVAQ project has been started, and it now involves seven municipal wastewater organisations. The goal of the project is to introduce a process in which the quality is successively improved by a series of actions taken by society. These actions include tracking and eliminating sources of heavy metals and other substances. As there are numerous sources of some of the substances, the work concentrates on the major sources. Another important activity is to provide information to the users of the wastewater system. The project is being evaluated by Urban Water AB. The results from the first two years indicate that it may be possible to reach the primary technical goal: to obtain a sludge quality that corresponds to that of household wastewater. The more ambitious goal of reaching a quality corresponding to that of WC water (the sum of urine and faeces) does not seem realistic without far-reaching changes in society. The organisations involved, which take the work seriously and are goal-oriented, have achieved measurable results in a short time. The work is also accepted and supported by the board members. More effort is needed, however, to inform the users about the system, and to [motivate them to] change their behaviour regarding matters such as the purchase of everyday products and the use of the toilet facilities.     

基于污染物通量的潘家口—大黑汀水源地水污染生态补偿量化研究

回顾我国水污染补偿的研究及实践,分析潘家口—大黑汀水源地及入库河流的水质状况,在明确考核断面及考核指标的基础上,建立基于污染物通量的水污染补偿量化估算模型,并根据2013年潘家口—大黑汀水源地入库河流的水质和水量监测数据,估算入库河流水污染生态补偿量。     

给水厂排泥水处理系统废水调节设施的改造

已建成给水厂增建排泥水处理系统时,原有生产废水调节设施需完成从直接排放到截留匀化的功能转换,其改造具有重要意义.针对混合截留与分别截留两种不同的生产废水调节设施,通过对生产废水调节设施提升设备和有效容积的复核,提出了相应的改造措施.最后介绍了某规模20万m3/d水厂原有废水池改造的情况.     

A unique, environmentally sustainable and cost-effective programme to re-vegetate military training lands utilising composted wastewater biosolids at a large Canadian military training centre.

The Greater Moncton Sewerage Commission has developed, in concert with National Defence Canada, an environmentally sustainable and cost effective biosolids management and land reclamation programme at the Canadian Forces Base (CFB) Gagetown, New Brunswick, Canada (the second largest land based Military Training Facility in the British Commonwealth). The use of composted biosolids to revegetate military training lands is thought to be a unique application for the beneficial use of biosolids. Results and practical experience gained from this approach to successfully re-vegetate initial sections of extremely large and vast tracts of these lands are described. The paper also overviews the Commission's modern 115000 m3 x d(-1) advanced, chemically assisted primary wastewater treatment facility and associated alkaline (lime) sludge stabilisation process. Planning strategies, security aspects, special and unique challenges in operating adjacent to an active military training facility, costs, spreading techniques, monitoring, next steps and conclusions are also presented.     

虚拟水理论在河北省农业用水管理中的战略应用分析

从河北省水资源匮乏的实际以及虚拟水理论入手,调查分析了河北省主要粮食产品的区域贸易量和出口贸易量以及由此引发的虚拟水的流出量,得出河北省2000-2005年输出的虚拟水总量平均为20.78亿m3,这期间粮食作物灌溉用水量平均为202.48亿m3,占粮食作物用水量的10.26%。据此,在深入探究虚拟水理论应用于农业用水管理的理论基础上,进一步提出虚拟水理论在河北省农业用水管理中的应用思路。     

The reuse of treated wastewater for agricultural purposes in Nicaragua; Central America.

The first subsurface flow wetland (SSFW) system for about 1,000 PE, was constructed in Nicaragua in 1996 to apply this technology in the form of an integral project, combining the treatment of domestic wastewater with its reuse for crop production in small and medium size communities. The SSFW-effluent meets all standards established in the national regulations for wastewater reuse in agriculture, except for faecal coliforms, existent at an average concentration of 7 x 10(4) MPN/100 ml. A conventional surface irrigation method was used to irrigate different crop species selected to establish their risk of contamination. To judge the potential health risk for consumers and farmers, samples of vegetables and fruits harvested in the dry seasons of the years 1997 to 2002, were analyzed for the presence of pathogenic microorganisms like faecal coliforms, salmonella and shigella. In addition, a yield comparison between crops irrigated with well water using chemical fertilizers, and crops irrigated with the effluent of the SSFW-system was made, to analyze the economical benefits of the wastewater reuse.     

改进型DAT-IAT工艺处理城市污水污泥最佳回流比的确定

通过对DAT-IAT工艺存在问题的分析,提出了改进DAT-IAT工艺的设想,通过试验证明,污泥最佳回流比在200%～300%时,改进后的工艺可以保持较高的处理效率.     

Population dynamics of chromate reducing bacteria in a bioreactor system developed for the treatment of chromate wastewater

The population dynamics of microbes was investigated in a bioreactor system for the treatment of chromate wastewater supplemented with chromate reducing bacteria Enterobacter cloacae strain HO-1. In this study, respiratory quinone profile and PCR techniques were used to analyse the microbial population. The change in microbial community structure and density was observed on the basis of the respiratory quinone profile since the predominant quinone of HO-1 is ubiquinone-8 (Q-8) and the amount of quinone is proportional to the cell mass the quantity of microbes and the Q-8 fraction of the total quinones were increased after cultivation with aeration, while long-term operation brought about a decrease in the fraction of Q-8. In addition, the amount of HO-1 was determined by the PCR amplification rate under conditions where the amplification was exponential to the reaction cycles. The cell density of HO-1 and total microbes determined from these procedures compared well with the numbers of HO-1 cells counted selectively using agar plates containing chromate.     

Effects of ORP, recycling rate, and HRT on simultaneous sulfate reduction and sulfur production in expanded granular sludge bed (EGSB) reactors under micro-aerobic conditions for treating molasses distillery wastewater

An expanded granular sludge bed (EGSB) reactor was adopted to incubate the sludge biogranule that could simultaneously achieve sulfate reduction and sulfide reoxidization to elemental sulfur for treating molasses distillery wastewater. The EGSB reactor was operated for 175 days at 35 °C with a pH value of 7.0, chemical oxygen demand (COD) loading rate of 4.8 kg COD/(m3 d), and sulfate loading rate of 0.384 kg SO(4)(2-)/(m3 d). The optimal operation parameters, including the oxidation reduction potential (ORP), recycling rate, and hydraulic retention time (HRT), were established to obtain stable and acceptable removal efficiencies of COD, sulfate, and higher elemental sulfur production. With an ORP of -440 mV, a recycling rate of 300%, and HRT of 15 h, the COD and sulfate removal efficiencies were 73.4 and 61.3%, respectively. The elemental sulfur production ratio reached 30.1% when the elemental sulfur concentration in the effluent was 48.1 mg/L. The performance results were also confirmed by the mass balance calculation of sulfate, sulfide, and elemental sulfur over the EGSB reactor.     

对2006年版《室外排水设计规范》污泥负荷概念的商榷

现行<室外排水设计规范>(GB 50014-2006)中采用了两个污泥负荷概念,由此引起设计人员的困惑和生物反应池体积计算的混乱.为此,对污泥负荷概念的来龙去脉进行了归纳分析,认为源自F/M的负荷概念更符合实际,建议在规范修订时统一污泥负荷的定义.     

Filtration characteristics of immersed coarse pore filters in an activated sludge system for domestic wastewater reclamation.

The filtration characteristics of two different module configurations with coarse pore filter (non-woven fabric) were investigated for sludge floc separation in an activated sludge reactor for domestic wastewater reclamation. A polypropylene non-woven fabric filter (35 g/m2) was used for the two different module configurations, one flat and one tubular type, each with a filtration area of 0.052 m2. The different module types, submerged in the oxic compartment of A/O (anaerobic/oxic) type reactors, were operated simultaneously. The filtration fluxes were gradually increased from 0.5 to 1.2 and 1.73 m/d. The filtration pressures were more stably maintained for the tubular type module than the plate type. The tubular type module installed horizontally with two-side suction showed less filtration pressures than the tubular type module installed vertically with one-side suction. The solid separation was significantly high showing less than 5 mg/L effluent solids. The organic and T-N removal efficiencies were around 95 and 50%, respectively. The 85% removal of T-P was achieved with 20 mg/L injection of PAC (poly-aluminum chloride).     

Full-cyclic control strategy of SBR for nitrogen removal in strong wastewater using common sensors.

A full-cyclic automatic control strategy for sequencing batch reactors (SBR) was proposed using only common sensors such as ORP, DO and pH. The main objective was to develop a generally applicable and robust control strategy. To accomplish this, various control schemes found in the literature or suggested by authors were examined at diverse ammonia loads and SCOD/NH4(+)-N ratios. Advantages and constraints of each scheme were discussed and compared. Ammonia load was estimated with DO lag time during the aerobic stage, and then the influent pump was manipulated to meet the desired load at the next anoxic stage. A partial denitrification scheme was chosen for the anoxic stage period control, to save anoxic time and external carbon. For external carbon dosage control, intermittent feeding at each anoxic stage was concluded to be a suitable scheme. The anoxic stage period could be successfully controlled by the combination of pH increase and DO increase. Every suggested control scheme was incorporated into a full-cyclic control strategy and tested at 0.02, 0.035, 0.08 kg NH4(+)-N/m3/sub-cycle. From the results, it is expected to perform unmanned automatic SBR operation with this strategy.     

Characterization and evaluation of potential reuse options for wastewater sludge and combined sewer system sediments in Mexico.

Combined sewer systems generate sediments that have characteristics similar to those of primary sludge. Mexico City has such a system composed of a network of pipes, regulation structures (dams, basins) and open channels. The annual generation of sediments is estimated at 2.8 Mm3, which includes 0.41 Mm3 of sludge. As a result, the total capacity for transporting water is reduced considerably, making it necessary to extract yearly an approximate 0.85 Mm3 of those materials and to send them to a final disposal site with a capacity that is being exhausted. As part of the local Governmental effort, this project evaluates the quality of sediments from 6 dams, 4 regulation basins, 2 open channels, and 3 transfer stations. Also, sludge from 20 wastewater treatment plants was sampled. The results showed an important presence of lead and hydrocarbons in some sediments, and some sludge samples contained arsenic and nickel above the limits. Moreover, microbial levels exceeded the limits in all the sediments and sludge samples. Erosion was linked to the generation of an important amount of sediments based on lead concentration. A classification was established to determine the degree of contamination of the sediments as well as the required treatment to allow their potential reuse.     

Characteristic of the sludge from the wastewater treatment plants near Varna city and possibilities for use in agriculture.

During the last few years numerous stations were built for purification of wastewaters in the country. Such a station was opened in Varna town on the Black sea cost. At purification of wastewaters a huge amount of sludge is received. The sludge is accumulated in the WWTP premises, thus hampering its functioning and polluting the environment. The aim of this investigation was to determine the chemical characteristics of the sludge from this station, considering the different modes of treatment: the sludge compactor and the drying beds after some stay. With the sludge from Varna Purification station a pot experiment was set to determine at what levels of loading with sludge the soils differ from each other by the biomass yield and heavy metals content. During the experiment two crops were grown: rape-fodder and rye-grass harvested in two cuts to follow the effects of the sludge use and the post effect in controlled conditions. The experiment was carried out on four soil units: Calcareous Chernozem, Leached Smolnitsa, Leached Cinnamonic Forest soil and Grey Forest soil (Calcic Chernozem, Haplic Vertisol, and two Chromic Luvisols from South and North Bulgaria, respectively).     

Combined quantity management and biological treatment of sludge liquor at Hamburg's wastewater treatment plants--first experience in operation with the Store and Treat process.

Store and Treat (SAT) is a new concept for the management of ammonium-rich process waste waters at wastewater treatment plants. It combines the advantages of quantity management and separate biological treatment, whereby both operations are carried out in the same tank. Now the first full-scale application of that method was realized in Hamburg. As first experience shows the process can help to increase nitrogen removal and to reduce energy consumption.