城市污水处理厂的污泥膨胀研究分析

通过对北京市大型城市污水处理厂优势丝状菌鉴定及温度、生物选择器和溶解氧对污泥膨胀影响的研究分析,发现脱氮除磷工艺普遍会在冬季发生由Microthrix parvicella茵引起的污泥膨胀.研究了温度与SVI的变化规律,分析了出水亚硝酸氮和SVI的相关性,并对生物选择器和不同DO浓度对污泥膨胀的影响进行了分析.     

城市污水处理厂剩余污泥热值估算方法研究

污水处理厂剩余污泥所具有的热值是衡量其能量利用价值的重要指标。目前的热值分析方法检测步骤繁琐、成本高,在污水处理厂的实际应用中有一定的困难。以北京市5座污水处理厂的剩余污泥为研究对象,通过测量污泥样品的挥发性固体(VS)与总固体(TS)含量和污泥的热值,发现污泥的VS/TS与污泥热值具有良好的线性关系,由此确定出估算污泥热值的计算公式。并采用多座污水处理厂的污泥数据对公式的适用性进行验证。对比分析表明,该公式能较准确地估算污泥热值,且其操作和所需仪器设备更为简单,能够根据污水处理厂日常对VS和TS的分析值快速估算污泥的热值。     

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。     

Aeration of anaerobically digested sewage sludge for COD and nitrogen removal: optimization at large-scale.

The paper will report about the experiences at an Austrian large wastewater treatment plant of 720,000 population equivalents, where anaerobically digested sewage sludge is further stabilised under aerobic conditions. Enhanced stabilisation of the anaerobically digested sludge was required at the plant in order to get a permit for landfill disposal of the dewatered stabilized sludge. By implementing a post-aeration treatment (SRT approximately 6d; 36 degrees C) after anaerobic digestion the organic content of the anaerobically well digested sludge can be decreased by 16%. Investigations on site showed that during digested sludge post-aeration anoxic phases for denitrification are needed to provide stable process conditions. In this way the pH value can be kept in a more favourable range for micro-organisms and concrete structures. Additionally, inhibition of the biological process due to nitrite accumulation can be avoided. By optimising the aeration/pause ratio approximately 45% of total nitrogen in digested sludge can be removed. This significantly improves nitrogen removal efficiency at the wastewater treatment plant. NH(4)-removal occurs mainly through nitritation and denitritation with an efficiency of 98%. The costs/benefit analysis shows that post-aeration of digested sludge results in an increase of total annual costs for wastewater treatment of only 0.84%, corresponding to 0.19 Euro/pe/a. Result of molecular biological analyses (DGGE) indicate that all four ammonium-oxidizing bacteria species present in activated sludge can survive anaerobic digestion, but only two of them can adapt in the digested sludge post-aeration tanks. Additionally, in the post-aerated digested sludge a further ammonium-oxidizing bacteria species was identified.     

Behaviour of endocrine disrupting chemicals during the treatment of municipal sewage sludge.

Agricultural application of municipal sewage sludge has been emotionally discussed in the last decades, because the latter contains endocrine disrupting chemicals (EDCs) and other organic micropollutants with unknown fate and risk potential. Bisphenol A (BPA) was chosen as a model substance to investigate the influence of sludge conditioning on the end-concentration of EDCs in sludge. Adsorption studies with radioactive-labelled BPA showed that more than 75% BPA in anaerobically digested sludge is bound to solids (log Kd = 2.09-2.30; log Koc = 2.72-3.11). Sludge conditioning with polymer or iron (III) chloride alone had no influence on the adsorption of BPA. After conditioning with iron (III) chloride and calcium hydroxide desorption of BPA took place. Apparently, it occurred due to the deprotonation of BPA (pKa= 10.3) as the pH-value reached 12.4 during the process. The same behaviour is expected for other phenolic EDCs with similar pKa (nonylphenol, 17beta-estradiol, estron, estriol, 17alpha-ethinylestradiol). This study shows high affinity of BPA to the anaerobically digested sludge and importance of conditioning in the elimination of EDCs during the sludge treatment. Addition of polymer is favourable in the case of sludge incineration. Conditioning with iron (III) chloride and calcium hydroxide shows advantages for the use of sludge as fertiliser.     

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。     

Aeration of large-scale municipal wastewater treatment plants: state of the art.

Aeration is the most energy-intensive operation in wastewater treatment, amounting to 45-75% of plant energy costs. Fine-pore diffusers are today almost ubiquitous in municipal wastewater aeration, due to their advantageous aeration efficiency (mass of oxygen transferred per unit energy required). Nevertheless, older municipal treatment facilities and many industrial treatment plants are still equipped with coarse-bubble or surface aerators. Fine-pore diffusers are subject to two major disadvantages: a) fouling, if not cleaned periodically; b) decrease in oxygen transfer efficiency caused by dissolved surfactants. Coarse-bubble and surface aerators are typically not subject to the traditional problems affecting fine-pore diffusers. Nonetheless, they achieve oxygen transfer at the expense of increased energy intensity. The increased biomass concentration associated with high mean cell retention time (MCRT) operations has a beneficial effect on aeration. Nutrient-removing selectors are able to further increase aeration efficiency, as they sorb and utilize the readily available substrate which otherwise would accumulate at bubble surfaces and dramatically decrease aeration efficiency. We summarise here our 30-year long experience in aeration research, and results obtained with clean- and process-water tests are used to show the beneficial effects of high MCRT operations, the beneficial effect of selectors, and the decline of aeration efficiency due to dissolved surfactants.     

Membrane-coupled anaerobic digestion of municipal sewage sludge.

Membrane-coupled anaerobic digestion utilizes a concept of simultaneous sludge digestion and thickening. Membranes may successfully be applied to eliminate the need for thickening polymers and avoid their likely inhibitory effect on anaerobic biomass. A 550 L completely mixed anaerobic digester was operated under mesophilic conditions (35 degrees C). Two ultrafiltration membrane systems were evaluated for their potential in membrane-coupled anaerobic digestion: vibrating and cross flow. A volatile solids reduction of 590% was achieved at an average mixed liquor suspended solids concentration of 1.8%. The substrate utilization rate was 1.3 d(-1). The vibrating membrane operated at a flux of 1.6-2.0 m3/m2-d and the tubular membrane fluxes in the range 3.4-3.6 m3/m2-d.     

生物流化床法处理城市污水处理厂污泥回流液的可行性研究

以城市污水处理厂污泥回流液为研究对象,研究生物流化床法降低污泥回流液中氮磷浓度的效果,并分析了COD/TN与COD/TP值对生物流化床脱氮除磷的影响.结果表明,COD_(Cr)浓度对脱氮影响不大,而对除磷有较大影响.在COD_(Cr)为500 mg/L,进水TN为115 mg/L时,TN的去除率最大为72.05%,此时,COD/TN值为4.35.在COD_(Cr)为480 mg/L,进水TP为11.25 mg/L时,TP的去除率最高为36.98%,此时COD/TP为42.67.生物流化床法对降低高浓度氮磷污泥回流液具有一定的去除效果,TN去除率可达56.35%,TP去除率为28.96%.     

上海市中心城区污水处理厂污泥特性及处理处置路线分析

对上海市中心城区污水处理厂一般脱水和深度脱水污泥的重金属、养分含量和含水率等泥质特性指标进行了系统分析。将污泥泥质指标与污泥处理处置利用标准和政策对比表明,上海市中心城区污水处理厂污泥不宜采用填埋、土地利用或建材利用的处置方式。从污泥减量化、无害化、稳定化和资源化的角度考虑,宜采用污泥焚烧。当采用污泥焚烧时,应注重污染物排放标准控制及资源利用,并适当调增排水费以维持污水污泥设施的建设及长期运行的需求。     

Biosensor-based control of nitrification inhibitor in municipal wastewater treatment plants.

The effect of potassium cyanide (KCN) on nitrification processes in municipal wastewater treatment plants was studied by batch nitrification tests, which indicated that nitrification processes tend to be inhibited at a lower KCN concentration than the present discharge standard to sewerage. The experiment of the biosensor using nitrifying bacteria was also conducted for continuous monitoring of nitrification inhibitor in influent wastewater, and demonstrated that the biosensor can detect KCN at as low as EC10 of the abovementioned batch nitrification test. Moreover, to determine the effectiveness of application of the biosensor to avoid the impact of KCN due to an accidental spillage in a sewerage system, KCN was intentionally injected into the experimental models of activated sludge process equipped both with and without the biosensor. The model with the biosensor that could detect KCN could divert the wastewater including KCN to a refuge tank, which resulted in the avoidance of upset of the activated sludge process. On the other hand, the model without the biosensor was upset in the nitrification process due to KCN. Such differences demonstrate the effectiveness of the biosensor applied to countermeasures of an accidental spillage of toxic chemicals to avoid upset of nitrification in municipal wastewater treatment plants.     

德国城镇污水处理厂运行概况

介绍了目前德国污水处理厂的总体概况、出水标准、出水水质等级的划分,并对2004年和2008年德国污水处理厂的进、出水水质情况进行了对比。同时也比较分析了上海市城镇污水处理厂的进、出水水质情况。     

Disinfection of sludge using lime stabilisation and pasteurisation in a small wastewater treatment plant.

Removal efficiency of faecal coliforms and helminth eggs was evaluated in a small wastewater treatment plant (WWTP) serving a population of 1,000. This system was formed by the association in series of a UASB reactor and four submerged aerated biofilters. The density of faecal coliforms and the count of helminth eggs were estimated in the liquid and solid phases of the system. Two different methods of disinfecting sludge were investigated: (a) chemical treatment with lime and (b) a physical treatment by pasteurisation. As expected, the association UASB + BF was very efficient at removal of helminth eggs from the final tertiary effluent, but coliforms were still present at high densities. Lime treatment and pasteurisation of sludge were very effective methods of disinfection and produced a sludge safe for final disposal.     

改进型DAT-IAT工艺处理城市污水污泥龄的确定

通过对DAT-IAT工艺存在的问题,提出了改进DAT-IAT工艺的设想,通过试验证明,污泥龄为13d时,改进后的工艺可以保持较高的处理效率.     

Post-aeration of anaerobically digested sewage sludge for advanced COD and nitrogen removal: results and cost-benefit analysis at large-scale.

At a large Austrian municipal wastewater treatment plant enhanced stabilisation of anaerobically digested sewage sludge was required in order to get a permit for landfill disposal of the dewatered stabilized sludge. By implementing a post-aeration treatment after anaerobic digestion the organic content of the anaerobically well digested sludge can be decreased by 16%. Investigations at this plant showed that during digested sludge post-aeration anoxic phases are needed to provide stable process conditions. In this way the pH value can be kept in a more favourable range for micro-organisms and concrete structures. Additionally, under the process conditions applied nitrite accumulation would inhibit the stabilisation process if denitrification is not adequately applied. By optimising the aeration/pause ratio approximately 45% of total nitrogen in digested sludge can be removed. NH4-removal occurs through nitrification and denitrification with an efficiency of 98%. This significantly improves nitrogen removal efficiency at the wastewater treatment plant. The costs/benefit analysis shows that post-aeration of digested sludge results in an increase of total annual costs for wastewater treatment of only 0.84%, corresponding to 0.19 Euro/pe/a. Specific costs for nitrogen removal (0.32 Euro/kgN) are comparable with other biological processes for N-removal in reject water.     

大港油田污水处理厂污泥最终处置设计

根据大港油田集团公司污水处理厂生产的污泥现状,最终决定采用卫生填埋处理.在综合污泥填埋场地形、地物等因素后,确定采用污泥填埋池.在经过对设计规模、挡墙结构、池底防渗、降雨及渗沥液排除等情况研究后,最终设计出半地下圆形结构,池底设高密度聚乙烯土工膜(HDPE)防渗层及砾石排水层的污泥填埋池.     

Production of porous carbonaceous adsorbent from physical activation of sewage sludge: application to wastewater treatment.

With an objective of production of carbonaceous sorbent for industrial effluent treatment, physical activation by steam of biological sludge collected from the municipal wastewater treatment plant of Nantes (France) was studied and optimised using experimental design. Thus, this activation process consists of a carbonisation under N2 atmosphere at 600 degrees C for 1 h, followed by a thermal oxidation using steam (760 degrees C, 0.5 h, 2.5 L/Umin). The global mass yield of the process is equal to 38%. The thermal treatment allows a specific surface area of up to 225 m2/g to be reached, the porous structure being composed of both micropores and mesopores. The content of acidic surface groups is 0.71 mEq/g whereas that of basic surface groups is 0.55 mEq/g. The adsorption properties of the sorbent made from sludge are estimated with regard to various pollutants representative of industrial pollution of wastewaters and compared with those of commercial activated carbon. Whereas the adsorption capacities of organic micropollutants are quite low because of proportionality to the microporosity, the important mesoporosity of the sorbent leads to interesting properties for macromolecules removal from aqueous solutions, such as dyes (q(m) = 175-200 mg/g). Furthermore, the surface functional groups and Ca2+ ions within the materials allow high copper ion adsorption capacities of 140 mg/g to be obtained. Finally, a techno-economic approach shows that the sludge activation process seems to be economically competitive with regard to incineration.     

辽宁省城市污水处理厂污泥处理处置现状与对策

通过实地调查初步摸清了目前辽宁省城市污水处理厂污泥处理处置现状,首次较为全面地掌握了辽宁省已建污水处理厂的污泥产量和处理处置状况,并根据辽宁省实际情况,提出了解决辽宁省污泥处理处置问题的对策和建议.     

Removal of micropollutants in municipal wastewater treatment plants by powder-activated carbon

Micropollutants (MP) are only partly removed from municipal wastewater by nutrient removal plants and are seen increasingly as a threat to aquatic ecosystems and to the safety of drinking water resources. The addition of powder activated carbon (PAC) is a promising technology to complement municipal nutrient removal plants in order to achieve a significant reduction of MPs and ecotoxicity in receiving waters. This paper presents the salient outcomes of pilot- and full-scale applications of PAC addition in different flow schemes for micropollutant removal in municipal wastewater treatment plants (WWTPs). The sorption efficiency of PAC is reduced with increasing dissolved organic carbon (DOC). Adequate treatment of secondary effluent with 5-10 g DOC m(-3) requires 10-20 g PAC m(-3) of effluent. Counter-current use of PAC by recycling waste PAC from post-treatment in a contact tank with an additional clarifier to the biology tank improved the overall MP removal by 10 to 50% compared with effluent PAC application alone. A dosage of 15 g PAC m(-3) to a full-scale flocculation sand filtration system and recycling the backwash water to the biology tank showed similar MP elimination. Due to an adequate mixing regime and the addition of adapted flocculants, a good retention of the fine fraction of the PAC in the deep-bed filter were observed (1-3 g TSS m(-3); TSS: total suspended solids). With double use of PAC, only half of the PAC was required to reach MP removal efficiencies similar to the direct single dosage of PAC to the biology tank. Overall, the application of PAC in WWTPs seems to be an adequate and feasible technology for efficient MP elimination (>80%) from wastewater comparable with post ozonation.