城市污水处理厂污泥热值及影响因素分析

以重庆市主城区城市污水处理厂污泥为研究对象,测定了污泥的热值并分析了影响污泥热值的主要因素,探讨了水分对热值利用的影响。结果表明:元素分析法和量热仪法测定的污泥热值较吻合;污水水质、排水体制、污水及污泥处理工艺通过影响污泥挥发分的含量而影响污泥热值,建议消化污泥和合流制区域污水处理厂污泥不宜采用焚烧处理。污水处理厂污泥具有自持燃烧特性时的最高含水率为68%;通过元素分析发现,不同污水处理厂污泥挥发分元素的计量组成基本一致,可用计量化学式CH1.72O0.55N0.12S0.03粗略地表示重庆市主城区污水处理厂污泥挥发分的组成。     

我国污水处理厂污泥含砂特征及成因调研

对我国南方某市7座污水处理厂脱水污泥固体组成进行调研，并从污水处理厂进水水质、砂的粒度分布、沉砂池效率及二级处理有机负荷角度进行污泥泥质成因分析。调研结果表明，该市污水处理厂污泥有机质含量整体较低，砂含量偏高，并随季节有一定规律变化。污水处理厂进水含砂量高、砂的粒度小，沉砂池效率低，二级处理污泥有机负荷低是污泥有机质含量低、含砂量高的主要原因。     

初沉池污泥厌氧消化效能及主要影响因素分析

以某初沉池污泥厌氧消化系统为研究对象,通过对其5年的运行数据进行分析,研究了厌氧消化系统的效能及主要影响因素。结果表明,初沉池污泥中挥发性固体含量占总固体含量的比例(VS/TS)在40%~80%,且随季节呈周期性变化;污泥中可降解有机物的降解率为98.9%~99.0%,消化气产量与进泥量正相关,消化气中甲烷和二氧化碳的含量为68.6%~69.2%和23.9%~24.6%。随着污泥停留时间(SRT)的延长,消化池容积产气率下降,污泥产气率和VS去除率升高;进泥含固率和VS/TS的增高使消化池容积产气率、污泥产气率和VS去除率呈现增大趋势。因此,为保持厌氧消化池高效产气,进泥含固率宜控制在5%左右,SRT宜控制在30d左右。     

白龙港污水处理厂生物处理污泥产量分析与预测

准确了解城市污水处理厂的污泥产量,不仅对污水处理厂的运行管理有指导意义,也有利于后续污泥的处理与处置。对上海白龙港污水处理厂生物处理工艺污泥产量的设计值、实际运行值进行计算,分析不同污泥产量计算方法的特点。并对重新启用初沉池后污泥产量的变化进行了详细的测算和分析,结果表明,重新启用初沉池后污泥产量比超越初沉运行时有所减少,减轻了后续污泥处置负荷。     

城市污水A~2/O处理工艺剩余污泥产率研究

利用规模为100m3/d的中试装置,在污水处理厂内研究了正置A2/O工艺在不同工况下的剩余污泥产率。试验结果表明,剩余污泥表观产率(Yobs)随污泥负荷的提高而增大,随泥龄的延长而减小,随温度的升高而减小;污泥合成产率(Y)与污泥负荷、泥龄和温度关系不大;衰减系数(Kd)随污泥负荷的提高而减小,随泥龄的延长而增大,随温度的升高而增大。在本试验条件下,Yobs值为0.35～0.49kgVSS/kgBOD5,Y值为0.67～0.72kgVSS/kgBOD5,Kd值为0.025～0.035d-1。     

活性污泥法处理中污泥总量控制的讨论

污水生化处理过程中涉及到的变量很多,但是真正可以用于调控污水处理厂运行过程的变量却很少,这使得污水处理厂的调控方式不是很灵活。重点研究了污泥总量控制,分别讨论了剩余污泥排放量、回流污泥排放量这两个操作变量在调控污水处理过程中的表现。     

广东清远出台污泥处理处置规划

十二五期间,清远市规划新建29座城镇污水处理厂,设计处理能力共计39.5万m~3/d,预计污泥产生量为113.75t/d,年产量为41518.75t。由此可知,清远市十二五期间所有污水处理厂投产并达到满负荷时,污泥产量估算为209.5t/d,年产量为76467.5t。污泥的无害化处置直接关系到当地生态和环保的可持续发展。     

城市污水处理厂不同污泥厌氧消化的产气研究

选取北京市某污水处理厂剩余污泥、初沉污泥和混合污泥作为研究对象,在中温(35℃)条件下,进行污泥产气速率和产气量的对照试验,结果表明:剩余污泥、初沉污泥和混合污泥的日平均产气量分别为218.8 mL/(d·L泥)、339.2 mL/(d·L泥)和419.4 mL/(d·L泥),总产气量分别为3.5 m3/m3泥、5.43 m3/m3泥和6.71 m3/m3泥,分别达到理论产气量的44.02%、72.79%和78.39%;剩余污泥、初沉污泥和混合污泥产气中CH4和CO2等主要组分含量的差异并不显著;从污泥的产气速率、产气量和消化性能分析,不同污泥之间的相互关系是:混合污泥＞初沉污泥＞剩余污泥,可见城市污水处理厂中初沉污泥(或混合污泥)比单独的剩余污泥更适宜于采用厌氧消化工艺.     

上海在建的三座大型城市污水处理厂介绍(一)--上海石洞口污水处理厂

介绍了上海市在建的三座大型污水处理厂的基本情况石洞口污水处理厂采用二级加强生物除磷脱氮工艺,白龙港污水处理厂采用一级加强物化法除磷处理工艺,竹园第一污水处理厂采用一级加强生物化学絮凝处理工艺;同时对三座污水处理厂的工艺流程,主要设计技术参数及污泥处理,总工程造价等进行了说明.     

关于活性污泥工艺中剩余污泥量计算的讨论

根据酒仙桥污水处理厂2001年3～10月运行数据及方庄污水处理厂2001年1～6月运行数据,探讨了活性污泥工艺中剩余污泥量计算的有关问题.通过建立污泥产率系数与MLVSS/MLSS比值的关系,论述了污泥产率系数会在较大范围内变化的原因.     

Experience with phosphorus removal and sludge handling and disposal in Flanders.

The way excess sludge must be disposed of is a key factor in the choice of the appropriate phosphorus removal technique at municipal wastewater treatment plants. In Europe the ongoing trend of tightening the sludge spreading rules called for a serious reduction of its agricultural utilisation and the expansion of the (co-)incineration disposal route, which led to a shift towards more sophisticated sludge handling techniques. This paper illustrates the impact of different sludge handling techniques on the performance of chemical and enhanced biological phosphorus removal at municipal WWTPs. The main conclusion is that although enhanced biological phosphorus removal is particularly sensitive to the problem of return liquors from sludge treatment processes indirect dewatering and anaerobic stabilisation cannot be discarded altogether when considering its implementation.     

Phosphorus recycling in sewage treatment plants with biological phosphorus removal.

In this paper, phosphorus balances are calculated for the wastewater purification and sludge treatment stages for wastewater treatment plants (WWTPs) applying Enhanced Biological Phosphorus Removal (EBPR). The possible P-recovery potential is then estimated and evaluated regarding different locations along the process of wastewater purification and sludge treatment, taking the different phosphorus bonding forms into account. Caused by the more favourable bonding forms in the excess sludge as well as possibly also in the sludge ash a recovery of the phosphorus seems especially favoured for WWTPs with EBPR. The processes available for a P recycling are named, and special regard is given to the Phostrip-process, which is a possible recycling process already tested in practice. Further R&D demand consists in basic research regarding disintegration, fermentation or acidic total digestion of excess sludge followed by phosphorus precipitation including separation of the precipitates, MAP-precipitation and separation from digested sludge and on the ability to extract phosphorus and heavy metals from sewage sludge ash. These investigations are a precondition to enable purposeful process developments. At the present state the cost of recycled phosphorus earned from wastewater, sludge and ash, respectively, are a multiple higher than the costs for raw phosphate taking into account the suitable processes. Thus, up to now no phosphorus recycling with a defrayal of costs is possible. The future importance of phosphorus recycling will depend on the market price for raw phosphate, the recycling costs and, furthermore, on the general political framework.     

Occurrence and reduction of pharmaceuticals in the water phase at Swedish wastewater treatment plants

During the last decade, several screening programs for pharmaceuticals at Swedish wastewater treatment plants (WWTPs) have been conducted by research institutes, county councils, and wastewater treatment companies. In this study, influent and effluent concentrations compiled from these screening programs were used to assess the occurrence and reduction of non-antibiotic pharmaceuticals for human usage. The study is limited to full-scale WWTPs with biological treatment. Based on the data compiled, a total of 70 non-antibiotic pharmaceuticals have been detected, at concentrations ranging from a few ng/L to several μg/L, in the influent water. The influent concentrations were compared with the sale volumes and for many pharmaceuticals it was shown that only a small fraction of the amount sold reaches WWTPs as dissolved parent compounds. Pharmaceuticals with low reduction degrees at traditional WWTPs were identified. Further comparison based on the biological treatment showed lower reduction degrees for several pharmaceuticals in trickling filter plants compared with activated sludge plants with nitrogen removal.     

Relevance of the sludge retention time (SRT) as design criteria for wastewater treatment plants for the removal of endocrine disruptors and pharmaceuticals from wastewater.

Wastewater treatment plants (WWTPs) represent a significant source for the input of micro pollutants as endocrine disruptors (EDs) or pharmaceutically active compounds (PhACs) into the aquatic environment. Treatment efficiency of WWTPs often is reported, taking into account only inflow and effluent concentrations without further specification of the WWTP investigated. In order to allow comparison and evaluation of the removal efficiency of different layouts and concepts in wastewater treatment, additional information like the sludge retention time (SRT) and sludge load (F/M ratio) are necessary. Presented results from different WWTPs show correlation of removal of EDs and PhACs to the SRT. Compared to WWTPs with high F/M ratio implementation of the nitrification process on WWTPs results in a significant increase of the removal efficiency for EDs and PhACs. This paper describes an approach to determine comparable removal rates for different activated sludge systems based on mass balance and SRT.     

Assessing the elimination of estrogenic activity in advanced wastewater treatment with a reporter gene-based bioassay.

Estrogen-like chemicals, so-called xenoestrogens, have become a topic of concern because they are potentially capable of disturbing the hormonal balance of wildlife and humans. Effluents of wastewater treatment plants (WWTPs) are presumably the major source of xenoestrogens in the aquatic environment. In this study, we investigated eight WWTPs with respect to their input, elimination efficiency, and output of estrogenic activity by means of a reporter gene-based bioassay. All WWTPs employed activated sludge treatment with nitrification/denitrification and tertiary treatment (second nitrification and/or filtration). Estradiol equivalents (EEQs) in the influents of the WWTPs were between 5.7 and 65.8 ng/L. The greatest inputs were found in plants treating pure domestic sewage and in samples collected in winter. Process waters either had no estrogenic activity or EEQs in the range of raw sewage, depending on the source of the process water. EEQs of effluents ranged from mostly below quantification limit (0.8 ng/L) to a maximum of 5.4 ng/L in secondary and 1.4 ng/L in tertiary effluents. These findings demonstrate the elimination efficiency of the activated sludge treatment and the further improvement by additional tertiary treatment. However, several concentrated effluents elicited little, but detectable estrogenic responses in the bioassay.     

Bulking control by low-dose ozonation of returned activated sludge in a full-scale wastewater treatment plant

Sludge bulking is still a problem in the operation of state-of-the-art wastewater treatment plants (WWTPs). The ozonation of returned activated sludge (RAS) is an innovative option as a non-specific measure for the control of filament growth. The applicability of sludge ozonation for bulking control of a large wastewater treatment plant was investigated. At a full-scale WWTP one lane was equipped with a sludge ozonation plant for RAS. The implemented sludge ozonation of RAS was tested against the two identical references lanes of the same WWTP. The positive effect on settleability could be clearly proven. Low-dose sludge ozonation could be a technical alternative in comparison with the established chemical measures for bulking control.     

Model-based evaluation of nitrogen removal in a tannery wastewater treatment plant.

Computer modelling has been used in the last 15 years as a powerful tool for understanding the behaviour of activated sludge wastewater treatment systems. However, computer models are mainly applied for domestic wastewater treatment plants (WWTPs). Application of these types of models to industrial wastewater treatment plants requires a different model structure and an accurate estimation of the kinetics and stoichiometry of the model parameters, which may be different from the ones used for domestic wastewater. Most of these parameters are strongly dependent on the wastewater composition. In this study a modified version of the activated sludge model No. 1 (ASM 1) was used to describe a tannery WWTP. Several biological tests and complementary physical-chemical analyses were performed to characterise the wastewater and sludge composition in the context of activated sludge modelling. The proposed model was calibrated under steady-state conditions and validated under dynamic flow conditions. The model was successfully used to obtain insight into the existing plant performance, possible extension and options for process optimisation. The model illustrated the potential capacity of the plant to achieve full denitrification and to handle a higher hydraulic load. Moreover, the use of a mathematical model as an effective tool in decision making was demonstrated.     

Biological treatment of sludge digester liquids.

Nitrogen removal in side stream processes offers a good potential for upgrading wastewater treatment plants (WWTPs) that need to meet stricter effluent standards. Removing nutrients from these internal process flows significantly reduces the N-load to the main treatment plant. These internal flows mainly result from the sludge processing and have a high temperature and a high concentration of ammonia. Therefore, the required reactor volumes as well as the required aerobic SRT are small. Generally, biological treatment processes are more economical and preferred over physical-chemical processes. Recently, several biological treatment processes have been introduced for sludge water treatment. These processes are available now on the activated sludge market (e.g. SHARON, ANAMMOX and BABE processes). The technologies differ in concept and in the limitations guiding the application of these processes for upgrading WWTPs. This paper reviews and compares different biological alternatives for nitrogen removal in side streams. The limitations for selecting a technology from the available ones in the activated sludge market are noted and analysed. It is stressed that the choice for a certain process is based on more aspects than pure process engineering arguments.     

Anaerobic co-digestion of sludge with other organic wastes in small wastewater treatment plants: an economic considerations evaluation.

This paper deals with an economic comparison between costs and incomes in small wastewater treatment plants where the anaerobic co-digestion process of sludge and biowaste with energy recovery is operated. Plants in the size range 1,000-30,000 persons equivalent (pe) were considered in the study: typical costs, comprehensive of capital and operating costs, were in the range euro69-105 per person per year depending on the plant size: the smaller the size the higher the specific cost. The incomes deriving from taxes and fees for wastewater treatment are generally in the range euro36-54 per person per year and can only partially cover costs in small wastewater treatment plants. However, the co-treatment of biowaste and the use of produced energy for extra credits (green certificates) determine a clear improvement in the possible revenues from the plant. These were calculated to be euro23-25 per person per year; as a consequence the costs and incomes can be considered comparable for wastewater treatment plants (WWTPs) with size larger than 10,000 pe. Therefore, anaerobic co-digestion of biowaste and sludge can also be considered a sustainable solution for small wastewater treatment plants in rural areas where several different kinds of biowaste are available to enhance biogas production in anaerobic reactors.     

Evaluating the stabilisation degree of digested sewage sludge: investigations at four municipal wastewater treatment plants.

Further reduction of volatile suspended solids (VSS) during a post-stabilisation step was applied to evaluate the stabilisation degree of digested sewage sludge. For this purpose digested sludge was collected at four municipal wastewater treatment plants (WWTPs) and further stabilised in lab-scale chemostat reactors either under anaerobic or aerobic conditions. Experimental results showed that even in adequately digested sludge a consistent amount of VSS was degraded during aerobic post-stabilisation. It seems that aerobic conditions play a significant role during degradation of residual VSS. Additionally, specific VSS production (gVSS/peCOD110.d) as well as specific oxygen uptake rate were shown to be suitable parameters to assess the degree of sludge stabilisation at WWTPs. Fourier transform infrared spectroscopy was used to reveal changes in the sludge composition. Spectra of treated and untreated sludge samples indicated that the major component of residual VSS in stabilised sludge for instance consisted of biomass, while cellulose was absent.