传统活性污泥法污水厂增加脱氮功能的研究

我国现有的传统活性污泥法污水处理厂能去除COD和BOD等碳素污染物 ,而往往不具备脱氮能力 ,因此其出水是水体氮素的重要污染源 .介绍的在中试研究基础上的传统活性污泥法投料AO脱氮新工艺 ,能使传统活性污泥工艺在保持较高BOD和COD去除率的同时 ,具有良好的脱氮功能 .研究表明 ,新工艺中试运行稳定 ,出水水质优于国家排放标准 ,对COD和氨氮的平均去除率分别为 88%和 73% .     

活性污泥过程MISO神经网络模型

用误差反向传递 ( BP)神经网络模拟了活性污泥过程 ,发现使用多输入多输出 ( MIMO)神经网络来模拟活性污泥过程变量间关系时 ,线性部分误差较小 ,非线性部分误差较大 ;但若用数个多输入单输出 ( MISO)神经网络的组合来模拟时 ,则对活性污泥过程的线性或非线性关系均能很好模拟     

微生物量对印染废水中的基质去除速率的影响

基于Monod方程,引入微生物量函数,建立了考虑微生物量作用的基质去除速率方程,并利用基质去除的零级反应速率求解有关参数.活性污泥好氧处理印染废水时,所需要的微生物量与反应时间密切相关,当HRT为24h,MLSS为2.2g·L-1,基质去除率为83%;而当HRT为12h,要达到相同的基质去除率,MLSS须维持在4.0g·L-1.当MLSS≤2.5g·L-1,基质去除速率与微生物量成正比;当MLSS为4.0g·L-1,基质去除速率约为最大值的86.2%,而且MLSS≥4.0g·L-1,基质去除速率随MLSS的变化不明显.所建立的基质去除速率方程能够较好地反映微生物量对基质去除速率的影响.     

Comparison of three sequential extraction procedures to describe metal fractionation in anaerobic granular sludges

In the last few decades, several sequential extraction procedures have been developed to quantify the chemical status of metals in the solid phase. In this study, three extraction techniques (modified [A. Tessier, P.G.C. Campbell, M. Bisson, Anal. Chem. 51 (1979) 844]; [R.C. Stover, L.E. Sommers, D.J. Silvera, J. Water Pollut. Con. F. 48 (1976) 2165]; and the Bureau Communautaire de Reference (BCR) [K.F. Mossop, C.M. Davidson, Anal. Chim. Acta 478 (2003) 111]) were applied to study the distribution of trace (Co, Ni, Zn and Cu) and major (Mn and Fe) elements in two different anaerobic granular sludges from full-scale methanogenic wastewater treatment plants. The Stover scheme displayed a higher number of fractions that induces a poor recovery compared to the other schemes. The sequential extraction scheme recommended by BCR and the modified Tessier scheme gave similar trends and are sufficiently repeatable and reproducible for application in fractionation studies. However, the BCR scheme seems to be of limited utilisation to study anaerobic matrixes because the extraction stage for its reducible fraction may release substantial amounts of trace elements bound to the organic/sulfides fraction, and consequently, the recovery of trace elements in the oxide fraction may be overestimated at the expense of the oxidisable fraction. As a final conclusion, the modified Tessier scheme seems to be the most suitable scheme to study the metal partitioning in anaerobic granular sludges.     

Flow characteristics of primary and digested sewage sludge

Summary Rheological study of sewage sludge is useful for the design, operation and control of sewage treatment plants. The rheology is highly dependent on physical, chemical and biological characteristics of the sludge. A pipeline rheometer is described in this paper for measurement of rheological properties of the sludge. Primary sewage sludge is a complex flocculated suspension having no fixed particle dimension, shape, size distribution or surface characteristics. The information available so far on rheology of sewage sludge is not suitable for application in design because of the lack of data on physico-chemical characteristics of this sludge.Primary and digested sewage sludge are non-Newtonian in character. Both exhibit yield stress and while primary sludge is shear-thinning in nature, digested sludge has been found to be shear-thickening. Parabolic and yield-power law models have been used to express the experimental data obtained for sludges at various concentrations and temperatures. Yield stress of primary sludge varies exponentially with concentration and linearly with temperature within the short temperature range studied. Primary sludge is found to be antithixotropic at low shear stress. Digested sludge does not exhibit time dependency.With 9 figures and 5 tables     

Influence of ultrasonication and Fenton oxidation pre-treatment on rheological characteristics of wastewater sludge

The effect of ultrasonication and Fenton oxidation as physico-chemical pre-treatment processes on the change of rheology of wastewater sludge was investigated in this study. Pre-treated and raw sludges displayed non-Newtonian rheological behaviour with shear thinning as well as thixotropic properties for total solids ranging from 10 g/L to 40 g/L. The rheological models, namely, Bingham plastic, Casson law, NCA/CMA Casson, IPC Paste, and power law were also studied to characterize flow of raw and pre-treated sludges. Among all rheological models, the power law was more prominent in describing the rheology of the sludges. Pre-treatment processes resulted in a decrease in pseudoplasticity of sludge due to the decrease in consistency index K varying from 42.4 to 1188, 25.6 to 620.4 and 52.5 to 317.9; and increase in flow behaviour index n changing from 0.5 to 0.35, 0.62 to 0.55 and 0.63 to 0.58, for RS, UlS and FS, respectively at solids concentration 10–40 g/L. The correlation between improvement of biodegradability and dewaterability, decrease in viscosity, and change in particle size as a function of sludge pre-treatment process was also investigated. Fenton oxidation facilitated sludge filterability resulting in capillary suction time values which were approximately 50% of the raw sludges, whereas ultrasonication with high input energy deteriorated the filterability. Biodegradability was also enhanced by the pre-treatment processes and the maximum value was obtained (64%, 77% and 73% for raw, ultrasonicated and Fenton oxidized sludges, respectively) at total solids concentration of 25 g/L. Hence, pre-treatment of wastewater sludge modified the rheological properties so that: (1) the flowability of sludge was improved for transport through the treatment train (via pipes and pumps); (2) the dewaterability of wastewater sludge was enhanced for eventual disposal and; (3) the assimilation of nutrients by microorganisms for further value-addition was increased.     

氯化铝对脱水污泥超临界水气化产氢的影响

如何选择或开发合适的催化剂以提高产氢量成为污泥超临界水气化技术,是实现实际应用的关键。选取氯化铝(AlCl_3)作为催化剂,以污水厂脱水污泥为对象,采用间歇式高温高压反应釜,在400℃、24 MPa、30 min的条件下进行超临界水催化气化实验。分析AlCl_3对脱水污泥超临界水气化产氢以及关键产物的影响,探讨AlCl_3的催化机理。结果表明,AlCl_3能够显著促进脱水污泥超临界水气化产氢,在6wt%添加量下氢气产率达到11.52 mol/kg OM,比不添加提高了近43倍。AlCl_3的添加会促进小分子有机物聚合生成酚类物质,抑制小分子聚合生成焦炭。AlCl_3催化机理是水解生成HCl和A_l2(OH)_3。HCl作为酸性水解剂,促进污泥中碳水化合物在亚临界条件下水热解转化成小分子物质,并进一步在超临界条件下气化产生氢气;Al_2(OH)_3作为碱性化合物催化剂,促进水气转化反应促进产氢,二者共同作用促进脱水污泥超临界水气化产氢。     

Thermal decomposition study of sewage sludge and of organicwaste used in the sorption of metals

The conventional treatments of effluents containing heavy metals produce significant quantities of byproducts with recalcitrant characteristics, making necessary looking after alternative techniques in order to avoid the production of new contaminated residues. Sorption process of chromium and zinc in vertical columns loaded with sewage sludge and organic solid waste has been studied in this work. The data from the TG curves of the two sorbents presented significant differences when they were submitted to the metal uptake, being noticed the displacement of the thermal events towards lower temperatures for both types of sorbents studied. As it was expected, for both sorbents, an increase in the mass of samples has been observed at the completion of the thermal tests upon metal uptake. Therefore, these facts demonstrate that during the biosorption process a physico-chemical interaction took place between sorbents and metals, as it was evidenced by the more than 100 K increase in the decomposition temperatures as well as the variation of the ΔH values of the samples.     

活性污泥法脱氮条件的优化研究

采用传统活性污泥法处理模拟生活污水,考察了温度、pH值、C/N比及振荡时间对脱氮效果的影响.实验结果表明,在温度为30℃、pH为7、C/N比是12:1及振荡时间为12h时,污水中氮去除效果最好,脱氮效率可达90％.     

热活化污泥—高钙粉煤灰复合地聚合物的性能与机理研究

研究采用水玻璃激发的高钙粉煤灰和热活化污泥制备复合地聚合物的可行性,并讨论制备的复合地聚合物的性能与机理.结果表明:经900℃焙烧1h的污泥(<45μm)以10%质量分数的掺量取代高钙粉煤灰后研制成的地聚合物具有较好的抗压强度;在复合地聚合物体系中,无定形地聚合物凝胶包裹在球状粉煤灰颗粒周围,有类沸石矿物生成,出现Al—O/Si—O对称伸缩峰及Si—O—Si/Si—O—Al弯曲振动峰.这一研究可以丰富地聚合物原材料的选择,有助于含硅铝相和含钙工业废弃物的资源化利用.