超声波技术在污泥处理中的应用

伴随着城市化进程加快与工业迅速发展，产量日益增加的污泥已对城市生态环境造成极其严重的威胁。为了有效地消除这种环境卫生公害，并且促进其资源化，提出了采用超声波技术进行污泥处理之建议，在总结国内外相关研究现状的基础上归纳出该技术的三大主要优势：杀菌、除臭、提高污泥稳定性；污泥减量效果显著；促进污泥中氮、磷量的增加，有利于污泥资源化；改善污泥絮凝脱水性能。最后指出了目前国内该技术所急需解决的问题，以明确今后的研究方向与重点。     

Environmental aspects of the use of NTA as a detergent builder

The behaviour, fate and significance of the detergent builder nitrilotriacetic acid (NTA) has been reviewed with particular reference to the removal of NTA during wastewater treatment and the effects of NTA on heavy metal solubility both during treatment and in the receiving environment. It is concluded that NTA removal during secondary biological treatment is subject to considerable variation, both temporal and between works as a result of changes in NTA load, temperature, water hardness and treatment process parameters. As a result of such variability, effluent NTA concentrations may be sufficient to mobilise heavy metals resulting in metal contamination of receiving waters and potable waters, particularly in areas of low effluent dilution and high water re-use. Removal of NTA during primary sedimentation and septic tank treatment is concluded to be predominantly due to adsorption to the sludge solids while removal in anaerobic sludge digestion is subject to operational characteristics of the treatment works. Disposal of NTA contaminated sludge to land may contaminate groundwaters and affect heavy metal speciation, while the disposal of contaminated sludge or sewage to sea may result in toxic algal blooms, in addition to effects on metal speciation.     

Characteristics of sludge developed under different loading conditions during UASB reactor start-up and granulation

Sludge characteristics available inside the reactor are of vital importance to maximize advantages of UASB reactor. The organic loading rate and sludge loading rate applied during start-up are among the important parameters to govern the sludge characteristics. Effects of these loading rates on the characteristics of the sludge developed are evaluated in six laboratory scale UASB reactors. The sludge characteristics considered are VSS/SS ratio of the sludge, sludge volume index, specific gravity, settling velocity and metal contents of the sludge developed under different loading rates. The experimental results indicate that, for developing good characteristics sludge, during primary start-up from flocculent inoculum sludge, organic loading rate and sludge loading rate should be in the range of 2.0-4.5 kg COD/m3 d and 0.1-0.25 kg COD/kg VSS d, respectively (chemical oxygen demand, COD). Proper sludge granulation and higher COD removal efficiency will be achieved by these loading rates.     

Assessing wastewater metal toxicity with bacterial bioluminescence in a bench-scale wastewater treatment system

The effectiveness of a previously developed toxicity monitoring method for activated sludge wastewater treatment employing a bioluminescent bacterium (Shk1) was evaluated in batch experiments and a bench-scale activated sludge system exposed to heavy metals (Cu, Zn, Ni, and Cd). Influent wastewater (primary clarifier supernatant) and activated sludge from a municipal wastewater treatment plant were used in both batch experiments and in the bench-scale wastewater treatment system. Shk1 bioluminescence was most sensitive to Cd and Zn, followed by Cu, and then Ni in order of decreasing sensitivity. In contrast, activated sludge specific oxygen uptake rate was most sensitive to Cu, followed by Cd and Zn, and finally Ni. The same pattern of sensitivity was observed in batch and bench-scale evaluations. Batch experiments examining the effect of metal adsorption were performed. The adsorption of metals to activated sludge and reduction in bioavailability due to chelation by soluble organics or by precipitation in wastewater was found to be an important effect in mediating differences in toxicity response between bioluminescence and respirometry. Batch adsorption experiments indicated that the activated sludge adsorption capacity was highest for Cu, followed by Cd, Ni, and then Zn. A simple mathematical model for the soluble metal concentration in the aeration basin and clarifier was developed utilizing metal distribution coefficients determined from the batch adsorption experiments. Model predictions compared well with results from the bench-scale activated sludge experiments.     

自热式高温好氧消化的污泥稳定化中试

用自行设计的自热式高温好氧消化(ATAD)工艺中试系统处理城市污水污泥,采用半连续式运行方式,对不同固体停留时间(SRT)下的污泥稳定化效果及消化后污泥的脱水性能、pH值变化和动力学衰减系数(Kd)进行了研究。结果表明,当SRT为10d时,污泥稳定化效果最好,反应器内温度可维持在54~58℃,对挥发性悬浮固体(VSS)的去除率平均达到44.3%,对病原菌的灭活率可达到100%,脱氢酶活性(DHA)下降88.48%,出泥可达到美国A级污泥标准;经消化后污泥的脱水性能明显下降而pH值升高,这是由于在消化过程中有机氮转为氨氮导致污泥上清液中氨氮浓度过高所致;SRT为10d的Kd为0.329d-1,不可降解的VSS浓度为15.09g/L。     

Anaerobic stabilisation and conversion of biopolymers in primary sludge--effect of temperature and sludge retention time

The effect of sludge retention time (SRT) and process temperature on the hydrolysis, acidification and methanogenesis of primary sludge was investigated in completely stirred tank reactors (CSTRs). The CSTRs were operated to maintain SRTs of 10, 15, 20 and 30 days at process temperatures of 25 degrees C and 35 degrees C. The rates of hydrolysis and the biodegradability of primary sludge were assessed in batch reactors incubated at 15 degrees C, 25 degrees C and 35 degrees C. The results revealed that the major amount of sludge stabilisation occurred between 0 and 10 days at 35 degrees C and 10 and 15 days at 25 degrees C. Hydrolysis was found to be the rate limiting-step of the overall digestion process, for the reactors operated at 35 degrees C and 25 degrees C, except for the reactor operated at 10 days and 25 degrees C. At the latter conditions, methanogenesis was the rate-limiting step of the overall digestion process. Proteins hydrolysis was limited to a maximum value of 39% at 30 days and 35 degrees C due to proteins availability in the form of biomass. The biodegradability of primary sludge was around 60%, and showed no temperature dependency. The hydrolysis of the main biopolymers and overall particulate COD of the primary sludge digested in CSTRs were well described by first-order kinetics, in case hydrolysis was the rate-limiting step. Similarly, the hydrolysis of the overall particulate COD of the primary sludge digested in batch reactors were described by first-order kinetics and revealed strong temperature dependency, which follows Arrhenius equation.     

聚季胺盐投加方式对厌氧污泥颗粒化的影响研究

投加阳离子聚合物是加速厌氧污泥颗粒化的有效方法,根据静态试验得出的聚季胺盐投加总量,选定了聚季胺盐的几种投加方式（不同的投加量和投加时间间隔）,研究其对实验室规模下的厌氧序批式反应器（ASBR）中污泥颗粒化的影响.试验以污水厂的厌氧污泥为对象,以污泥颗粒的粒径、沉速及出水COD等作为评价污泥颗粒化进程的指标,分析了各投加方式对污泥颗粒化进程的影响,并挑选出适宜的絮凝剂投加方式.结果表明,不同投加方式对ASBR污泥颗粒化进程有不同影响,建议采用每次投加量为0.16～0.32 mg/gMLSS,投加时间间隔为2～5 d,分5～10次投加的方式.     

新型双污泥脱氮除磷工艺处理生活污水

将活性污泥法与生物膜法相结合，开发出一种新型脱氮除磷处理工艺，成功地解决了传统工艺中硝化细菌与除磷菌之间的泥龄矛盾问题。试验结果表明，该工艺对COD、NH3-N、TP的去除率分别高达85％、95％、90％，同时处理效果稳定，对水质的适应能力也较强。     

Bioleaching of metals from sewage sludge: Microorganisms and growth kinetics

Microbial leaching is one of the advantageous methods of removing heavy metals from sewage sludge, however, the microbiological aspects of this technology have not been studied. This study presents the characterization of the naturally occurring microorganisms, responsible for the metal leaching activity, in 21 different sewage sludges. The results obtained indicate that the bioleaching of metals is carried out by successive growth of less-acidophilic and acidophilic thiobacilli. Several species of less-acidophilic thiobacilli participate in the sludge acidification, but Thiobacillus thioparus is the most important species. In contrast, Thiobacillus thiooxidans seems to be the only species involved in the acidophilic group of thiobacilli. The growth kinetics of the two groups of thiobaciili was followed in five different sewage sludges. After 5 days of incubation in shake flasks, the pH of the sludge was decreased to about 2.0 and this pH decrease solubilized the toxic metals (Cd: 83–90%; Cr: 19–41%; Cu: 69–92%; Mn: 88–99%; Ni: 77–88%; Pb: 10–54%; Zn: 88–97%). The maximum specific growth rate (μ_max) for the less-acidophilic thiobacilli varied between 0.079 and 0.104 h⁻¹ and that for the acidophilic thiobacilli varied between 0.067 and 0.079 h⁻¹.     

Biological sulphate removal in an upflow packed bed reactor

Mine waters and industrial effluents with high sulphate concentrations create a disposal problem in terms of excess mineralization of surface waters. Removal of sulphate can be achieved by various processes including biological techniques, all of which involve appreciable costs. The purpose of this investigation was to improve on known biological methods for the removal of sulphate. Good sulphate removal was obtained by providing anaerobic conditions on a solid medium and maintaining a low hydrogen sulphide concentration by recirculating the water through a photosynthetic reactor for sulphur production.