净水厂排泥水处理工艺设计

分析总结了净水厂排泥水规模确定及常用工艺流程,以甘肃碌曲县某净水厂排泥水处理系统为例,介绍了排泥水处理系统各建(构)筑物的主要功能和设计计算要点,以期为排泥水处理系统的设计提供借鉴。     

南洲水厂排泥水处理工艺的研究与设计

通过对排泥水进行沉降试验,得到了南洲水厂排泥水处理系统设计的基本数据.供水量为100万m3/d的南洲水厂排泥水处理系统工艺流程为:排泥水调节、浓缩、平衡、离心机脱水.该系统在调试运行期间,各工艺单元均能按照设计要求正常工作,脱水后的污泥含固率达到36.3%～39.2%,取得较好的处理效果.     

北京市第九水厂排泥水处理系统改造设计分析

随着排泥水处理技术研究的不断深入,以及净水厂排泥水处理工程设计经验的不断丰富,排泥水处理系统设计更加科学化和合理化。北京市第九水厂排泥水处理系统正式运行已十余年,运行中发现了一些需要改进的地方。在对北京市第九水厂目前所面临的水源水质情况及排泥水处理系统运行中存在的问题进行分析的基础上,提出了改造方案并总结了实际工程设计时应注意的一些设计要点。     

排泥水处理系统药剂试验及工艺改进

保定中法供水有限公司排泥水处理系统采用Densadeg高密度浓缩沉淀技术,在实际运行中出现跑矾花的问题,影响了系统的正常运行.为此分别在排泥水处理系统进水、药剂选择、工艺参数调整等环节进行了改进.同时为了达到了节能降耗的目的,还对部分机电设备进行了更换,取得了较好的经济效益,排泥水处理系统日耗电节约200～300kW·h.     

净水厂生产排泥水处理工艺研究与设计

通过对净水厂生产排泥水的产生和水质特性进行分析,确定沉淀池排泥水和滤池反冲洗废水为净水厂排泥水的主要组成,结合设计干泥量的计算确定排泥水处理规模,在分析排泥水处理系统工艺流程布置特点的基础上对排泥水收集、调节、浓缩和脱水工艺进行分析,并对其中排水池、排泥池、浓缩池、平衡池、脱水工艺和场地布置的设计要点进行总结。     

长江水源水厂排泥水处理研究

对长江水源水厂排泥水处理进行了研究,确定了长江水源水悬浮固体含量与浊度的关系,对水厂干泥量和排泥水总量进行了估算;通过动态浓缩试验,确定了斜板浓缩池运行优化条件;测定了排泥水的颗粒粒径分布、固体成分组成和污泥比阻;并简要介绍了污泥机械脱水和泥饼处置方法.     

临江水厂排泥水处理系统设计

按照《上海市供水专业规划》和《关于加强本市环境保护和建设的实施意见一行动计划》要求,实施临江水厂排泥水处理系统的建设来减少水厂自身运行的废水对水体造成的污染。水厂沉淀池排泥水及滤池反冲洗水统一收集后,通过调节、浓缩、机械脱水,使污泥含固率提高,排泥水处理后达标排放。     

临江水厂排泥水处理系统设计

为减少临江水厂自身运行给水体造成的污染,建设排泥水处理系统,将沉淀池排泥水及滤池反冲洗水统一收集后,通过调节、浓缩、机械脱水,提高污泥含固率,使排泥水处理后达标排放。临江水厂二期采用高速重力斜板澄清池工艺,由于需要加细砂,砂的漏失增加了日产干污泥量。详细介绍了工程方案的选择和设计参数,并指出了一些设计中值得探讨的问题。     

给水厂和污水处理厂混合排泥水的沉降性能试验研究

给水厂沉淀池排泥水排入江河、湖泊不仅污染环境,也是对水资源的浪费,对给水厂沉淀池排泥水进行处理具有重要意义.通过对给水厂沉淀池排泥水的沉降性能和变化规律进行试验研究,发现给水厂沉淀池排泥水沉降性能良好且比较稳定,其与污水处理厂絮凝沉淀池排泥水进行共同沉降处理,可明显提高污水处理厂絮凝沉淀池排泥水的沉降性能,且两种排泥水混合后,污泥体积还会出现一定程度的减量.     

东北地区水厂沉淀池排泥控制模式探讨

沉淀池的排泥对其运行效果有着直接、重要的影响。沉淀池排泥有多种控制技术。通过水厂运行记录数据和生产性试验结果 ,从水处理系统运行优化角度进行技术经济分析 ,探讨了给水处理厂沉淀池排泥的控制模式。指出受东北地区水质特点影响 ,在给水处理厂主要可变费用中 ,排泥水费所占的比例只有 4 %,而且沉淀池排泥水水质是有规律变化的。排泥历时主要受原水浊度的影响 ,在同一原水条件下排泥过程曲线变化趋势是相同的。因此 ,推荐建立原水浊度～排泥历时关系曲线 ,以此确定一种简单直观的时间模式控制沉淀池排泥。     

Rain events and their effect on effluent quality studied at a full scale activated sludge treatment plant.

The effect of rain events on effluent quality dynamics was studied at a full scale activated sludge wastewater treatment plant which has a process solution incorporating pre-denitrification in activated sludge with post-nitrification in trickling filters. The incoming wastewater flow varies significantly due to a combined sewer system. Changed flow conditions have an impact on the whole treatment process since the recirculation to the trickling filters is set by the hydraulic limitations of the secondary settlers. Apart from causing different hydraulic conditions in the plant, increased flow due to rain or snow-melting, changes the properties of the incoming wastewater which affects process performance and effluent quality, especially the particle removal efficiency. A comprehensive set of on-line and laboratory data were collected and analysed to assess the impact of rain events on the plant performance.     

Reduction of excess sludge production using mechanical disintegration devices.

The usability of mechanical disintegration techniques for the reduction of excess sludge production in the activated sludge process was investigated. Using three different disintegration devices (ultrasonic homogeniser, stirred media mill, high pressure homogeniser) and different operational parameters of the disintegration, the effect of mechanical disintegration on the excess sludge production and on the effluent quality was studied within a continuously operated, laboratory scale wastewater treatment system with pre-denitrification. Depending on the operational conditions and the disintegration device used, a reduction of excess sludge production of up to 70% was achieved. A combination of mechanical disintegration with a membrane bioreactor process with high sludge age is more energy effective concerning reduction of sludge production than with a conventional activated sludge process at lower sludge ages. Depending on the disintegration parameters, the disintegration has no, or only minor, negative effect on the soluble effluent COD and on the COD-removal capacity of the activated sludge process. Nitrogen-removal was slightly deteriorated by the disintegration, whereas the system used was not optimised for nitrogen removal before disintegration was implemented.     

Treatment of textile dyes in two-phase and single-phase anaerobic bio-treatment systems.

This research integrates two different concepts of anaerobic biotechnology- two-phase anaerobic treatment and anaerobic granular sludge bed technology, in treatment of colored wastewaters from textile industries. Four anaerobic reactors based on upflow anaerobic sludge blanket (UASB) technology were used as acid reactors and an expanded granular sludge bed (EGSB) reactor was used as a methane reactor. A conventional single-phase anaerobic reactor, working on EGSB technology was run in parallel to compare the performances of the two systems. Reactors were operated at different hydraulic retention times. The results from the study, which span over a period of 400 days, indicated that the two-phase system produces a higher quality of effluent in terms of color, COD and suspended solids than single-phase anaerobic treatment when operated under similar conditions. Alkalinity requirement of two-phase system was also observed to be lower than that of single-phase system which is important regarding design consideration.     

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.     

The formation of colour during biological treatment of pulp and paper wastewater.

Colour discharges are gaining renewed focus in the pulp and paper industry as increasingly strict regulatory limits are placed on wastewater quality and aesthetics. In-mill process improvements, such as ECF bleaching and oxygen delignification, have decreased wastewater colour loadings. However, a survey of 12 pulp and paper mill systems found that effluent treatment using aerated stabilisation basins (ASB) leads to average increases in colour of 20-40%. In some instances, this phenomenon may even double the influent colour levels. Activated sludge systems did not produce a colour increase. The measured increases that follow ASB secondary treatment may be sufficient for a mill to fail prescribed discharge standards. A detailed field survey focusing on sections of an integrated bleached kraft mill ASB treatment system was undertaken. The average increase in colour at the final point of discharge was 45%. The major changes in colour concentration occurred in the inlet to the main treatment pond, and in polishing ponds that followed the main treatment pond. Both of these areas receive little or no aeration. No significant change was observed in the highly aerated main pond. These results, along with literature reports, suggested that redox conditions play a major role in influencing colour behaviour. To test this, two series of paired continuously stirred reactors were used to treat whole mill effluent from two ECF bleached kraft mills in parallel. The first series initially treated under anaerobic conditions, followed by an aerobic reactor, while the second series reversed this order. With the initial anaerobic stage, effluent colour increased by 18% and 19% for the first and second series respectively. Subsequent treatment by aerobic bacteria further increased colour by 14% and 6%, for a total increase of 32% and 25%. Initial aerobic treatment, however, did not lead to any significant change in colour for either effluent. Further anaerobic treatment following aerobic conditions produced only small increases in colour. These results are consistent with the ASB and activated sludge system survey, suggesting that anaerobic conditions at the head of treatment systems initiate the observed increases in effluent colour in ASB treatment systems.     

Nitrogen removal in multi-stage wastewater treatment plants by using a modified post-denitrification system

Systems in which denitrification follows nitrification (post-denitrification) copy the natural sequence of nitrogen removal. The disadvantage of post-denitrification, however, is that an external carbon source must be added to the denitrification reactor. In the concept discussed in this paper, excess sludge from a high loaded activated sludge plant is used as carbon source and as source of denitrifiers in a three-stage system. The sludge is fed into a anoxic reactor placed in between the nitrification reactor (e.g., trickling filter) and the final clarifier. Two different operation methods were investigated at a pilot-scale system set up at the Ingolstadt wastewater treatment plant Low nitrate effluent values were obtained at high sludge feeding rates, but at the expense of a significant increase in turbidity and NH4-N effluent concentrations. This problem could be solved by a reduction of the sludge feeding rate and by applying intermittent feeding. The effluent turbidity was kept at an acceptable level, but denitrification was relatively slow in progress. To achieve both low effluent turbidity and low nitrate discharge, a combination of pre- and post-denitrification is recommended.     

Advanced treatment by anaerobic process followed by aerobic membrane bioreactor for effluent reuse in paper mill industry.

The operation of an activated sludge process at a paper mill (AIPM) in Hedera, Israel, was often characterized by disturbances. As part of a research and development project, a study on new biological treatment was initiated. The study included the operation of three pilot units: a. anaerobic treatment by upflow anaerobic sludge blanket (UASB); b. aerobic treatment by two pilot units including activated sludge and membrane bioreactor (MBR), which have been operated in parallel for comparison reasons. The pilot plant working on anaerobic treatment performed COD reduction from 2,365 to 755 mg/L, expressed as average values. Based on the pilot study, a full scale anaerobic treatment system has been erected. During a period of 100 days, after achieving steady state, the MBR system provided steady operation performance, while the activated sludge produced effluent characterized by oscillatory qualities. The following results, based on average values, indicate much lower suspended solids concentrations in the MBR effluent, 2.5 mg/L, as compared to 25 mg/L in the activated sludge. The ability to develop and maintain a concentration of over 11,000 mg/L of mixed liquor volatile suspended solids in the MBR enabled an intensive bioprocess at relatively high cell residence time. This study demonstrates that the anaerobic process, followed by aerobic MBR can provide effluent of high quality which can be considered for economic reuse in the paper mill industry.     

Integration of performance,molecular biology and modeling to describe the activated sludge process

To study process performance and population dynamics in activated sludge, a pilot-scale Membrane Bioreactor (MBR) was installed in a municipal wastewater treatment plant (Aubergenville, France). Since no solids losses occur in the MBR effluent, the sludge residence time (SRT) can be: i) easily controlled by means of the sludge withdrawal, and ii) dissociated from the hydraulic residence time (HRT). A complete characterization of this activated sludge system was performed at three sludge ages (5, 10 and 20 days). Raw and treated wastewater quality, as well as sludge concentration, was analyzed, nucleic probe analysts was performed to determine the heterotrophic and nitrifier populations, and the results were compared to the output from a multispecies model that integrates substrate removal kinetics and soluble microbial products (SMP) production/consumption. This paper presents an integrated analysis of the activated sludge process based on chemical, molecular biology, and mathematical tools. The model was able to describe the MBR system with a high degree of accuracy, in terms of COD removal and nitrification, as well as sludge production and population dynamics through the ratio of active nitrifters/bacteria. Both steady-state and transient conditions could be described accurately by the model, except for technical problems or sudden variations in the wastewater composition.     

Micropollutants removal in an anaerobic membrane bioreactor and in an aerobic conventional treatment plant

The paper expresses an attempt to tackle the problem due to the presence of micropollutants in wastewater which may be able to disrupt the endocrine system of some organisms. These kinds of compounds are ubiquitously present in municipal wastewater treatment plant (WWTP) effluents. The aim of this paper is to compare the fate of the alkylphenols-APs (4-(tert-octyl)) phenol, t-nonylphenol and 4-p-nonylphenol and the hormones (estrone, 17β-estradiol and 17α-ethinylestradiol) in a submerged anaerobic membrane bioreactor (SAMBR) pilot plant and in a conventional activated sludge wastewater treatment plant (CTP). The obtained results are also compared with the results obtained in a previous study carried out in an aerobic MBR pilot plant. The results showed that the APs soluble concentrations in the SAMBR effluent were always significantly higher than the CTP ones. Moreover, the analyses of the suspended fraction revealed that the AP concentrations in the SAMBR reactor were usually higher than in the CTP reactor, indicating that under anaerobic conditions the APs were accumulated in the digested sludge. The aerobic conditions maintained both in the CTP system and in the aerobic MBR favoured the APs and hormones degradation, and gave rise to lower concentrations in the effluent and in the reactor of these systems. Furthermore, the results also indicated that the degradation of APs under aerobic conditions was enhanced working at high solid retention time (SRT) and hydraulic retention time (HRT) values.     

Membrane bioreactor (MBR) sludge inoculation in a hybrid process scheme concept to assist overloaded conventional activated sludge (CAS) process operations

This study analyzes the effect of inoculating membrane bioreactor (MBR) sludge in a parallel-operated overloaded conventional activated sludge (CAS) system. Modelling studies that showed the beneficial effect of this inoculation were confirmed though full scale tests. Total nitrogen (TN) removal in the CAS increased and higher nitrate formation rates were achieved. During MBR sludge inoculation, the TN removal in the CAS was proven to be dependent on MBR sludge loading. Special attention was given to the effect of inoculation on sludge quality. The MBR flocs, grown without selection pressure, were clearly distinct from the more compact flocs in the CAS system and also contained more filamentous bacteria. After inoculation the MBR flocs did not evolve into good-settling compact flocs, resulting in a decreasing sludge quality. During high flow conditions the effluent CAS contained more suspended solids. Sludge volume index, however, did not increase. Laboratory tests were held to determine the threshold volume of MBR sludge to be seeded into the CAS reactor. Above 16-30%, supernatant turbidity and scum formation increased markedly.