A comprehensive simulation approach for pollutant bio-transformation in the gravity sewer

A comprehensive pollutant transformation model for sewer systems is established. The model comprises fermentation, sulfate reduction and ammonification processes. Biochemical reactions related to distinct carbon sources are depicted in the model. Pollutant transformation is attributed to different biochemical reaction processes. Presently, several activated sludge models (ASMs) have been developed to describe a few biochemical processes. However, the commonly used ASM neither clearly describe the migratory transformation characteristics of fermentation nor depict the relationship between the carbon source and biochemical reactions. In addition, these models also do not describe both ammonification and the integrated metabolic processes in sewage transportation. In view of these limitations, we developed a new and comprehensive model that introduces anaerobic fermentation into the ASM and simulates the process of sulfate reduction, ammonification, hydrolysis, acidogenesis and methanogenesis in a gravity sewer. The model correctly predicts the transformation of organics including proteins, lipids, polysaccharides, etc. The simulation results show that the degradation of organics easily generates acetic acid in the sewer system and the high yield of acetic acid is closely linked to methanogenic metabolism. Moreover, propionic acid is the crucial substrate for sulfate reduction and ammonification tends to be affected by the concentration of amino acids. Our model provides a promising tool for simulating and predicting outcomes in response to variations in wastewater quality in sewers.     

改性纳米铁原位反应带修复范围影响因素研究

为了解蔗糖改性纳米铁原位反应带在地下含水层中的形成规律,在二维模拟装置中创建原位反应带,研究了石英砂介质颗粒大小?地下水流速?浆液注入浓度?注入量及注入方式对反应带修复范围的影响.结果表明:反应带宽度随介质粒径及地下水流速的增加而增大,粗砂中反应带宽度约为细砂的3倍;当地下水流速由0.1m/d增加到1.0m/d时,反应带宽度分别增加了14.9%和106.4%.浆液分次注入的方式可使反应带初始宽度增加19.8%;较小的浆液浓度有利于反应带在水流方向和含水层垂向修复范围的扩展.     

Biodegradation of 2-methylisoborneol by bacteria enriched from biological activated carbon

One of the most common taste and odour compounds (TOCs) in drinking water is 2-methylisoborneol (2-MIB) which cannot be readily removed by conventional water treatments. Four bacterial strains for degrading 2-MIB were isolated from the surface of a biological activated carbon filter, and were characterized as Micrococcus spp., Flavobacterium spp., Brevibacterium spp. and Pseudomonas spp. based on 16S rRNA analysis. The removal efficiencies of 2-MIB with initial concentrations of 515 ng·L^-1 were 98.4%, 96.3%, 95.0%, and 92.8% for Micrococcus spp., Flavobacterium spp., Brevibacterium spp. and Pseudomonas spp., respectively. These removal efficiencies were slightly higher than those with initial concentration at 4.2 mg·L^-1 (86.1%, 84.4%, 86.7% and 86.0%, respectively). The kinetic model showed that biodegradation of 2-MIB at an initial dose of 4.2 mg·L^-1 was a pseudo-first-order reaction, with rate constants of 0.287, 0.277, 0.281, and 0.294 d^-1, respectively. These degraders decomposed 2-MIB to form 2-methylenebornane and 2-methyl-2-bornane as the products.     

淀粉酶促进剩余污泥热水解的研究

考察了微好氧条件下,外加淀粉酶对污水处理剩余污泥热水解的影响,以及水解过程中污泥上清液各成分的变化情况,并对酶水解过程的动力学进行了分析.结果表明,淀粉酶的加入对剩余污泥的热水解有促进作用.在最适温度50℃,酶投加量0.5g/L条件下,水解4h后,污泥中SCOD/TCOD达到30.98%,比未加酶时高7.68%.在淀粉酶催化作用和热水解的共同作用下,污泥固体溶解,大分子碳水化合物被水解成小分子糖类,固相蛋白质溶出,并进一步水解.污泥水解过程中,上清液糖、蛋白质浓度均呈现先增加后降低趋势.加酶后污泥上清液中糖、蛋白质浓度分别于4h、6h达到最大值271.43mg/L和1437.37mg/L.污泥水解反应前4h内,VSS溶解率和SCOD/TCOD增加迅速,符合一级反应动力学,4h后反应趋于平衡.4h时VSS溶解率达到22.01%.     

酸度对染料臭氧化脱色效果及溶液毒性的影响

研究了20种染料溶液在臭氧氧化过程中吸光度的变化以及pH对氧化速率的影响,应用发光菌毒性检测法测定了活性翠兰KN-G,直接混纺大红D-GLN和酸性橙Ⅱ三种染料溶液在臭氧氧化过程中的急性毒性. 结果表明:臭氧氧化20种染料的脱色过程符合一级反应动力学,其相关系数(R2)均大于0.950 0,反应溶液的初始pH对染料的脱色率有一定的影响. 染料溶液初始浓度相同时,pH为2的酸性条件更有利于染料的降解,在前45 s,酸性溶液脱色率比中性溶液高出了6%～25%. 在臭氧氧化染料溶液的过程中,溶液接近无色时,毒性较大,但随着氧化的进行其毒性逐渐降低.      

氧化物修饰电极降解有机污染物的电催化特性

采用高温热解氧化沉积法将金属氧化物SnO₂, RuO₂, Cr₂O₃, PdO修饰到钛基体表面,制备得到4种金属氧化物修饰电极.比较4种电极氧化降解苯、苯甲酸、苯酚、苯胺、硝基苯以及甲基橙染料6种有机污染物的氧化电流效率,结果表明,电极在各种介质中的析氧电位和氧化反应传递系数(β值)是衡量电极能否有效处理有机污染物废水的两个重要指标,其中SnO₂电极的析氧电位最高,PbO电极的b值最大,SnO₂电极的β 值次之.这为研制和筛选高效催化电极提供了理论依据.     

土壤正构烷烃微生物降解变化实验分析

在石油烃微生物降解的最佳条件下,利用色谱-质谱联用技术分析测定了石油烃中正构烷烃的降解规律.结果表明,正构烷烃的降解最为明显;正构烷烃的降解随着碳数的增加其降解速度逐渐减小;其中C23烷的降解速度与石油烃整体降解速度相当,碳数小于23的正构烷烃降解速度大于石油烃降解速度,碳数大于23的正构烷烃降解速度小于石油烃降解速度;C16～C25的正构烷烃在0～6*!d内降解速度最快,在7～14 d内达到最低值,之后有逐渐上升的趋势;整个正构烷烃的降解符合二级反应动力学规律.      

参与光化学反应的物质对UV能量吸收的估算

在对北京紫外辐射(UV)观测资料分析的基础上,提出参与光化学反应的物质对UV能量具有吸收作用.计算了1990年12个月实际天气比晴天UV能量的减少值在64～109 W/m2之间,这一减少受臭氧、"水汽"、气溶胶等因子的衰减分别为39.1～66.3,21.5～36.5,3.2～5.5 W/m2(12月除外),12个月的平均值分别为48.3,26.6,4.0 W/m2.计算结果表明,云天大气对UV能量有衰减,其衰减能量中有26.6 W/m2是"水汽的作用",即参与大气光化学反应的物质对UV能量吸收所造成的,此计算值同国外观测与模式的研究结果比较接近.由于现有模式中还没有考虑这一部分能量,所以造成模式结果与观测结果间较大的差异.      

聚苯乙烯热降解动力学参数与降解反应机理关系

基于Arrhenius理论及相关公式,推导出表观活化能与幂指数相对变化关系。这种相对变化关系与聚苯乙烯热降解、热氧化降解、及其在各种添加剂情形下热降解动力学参数变化特征完全吻合。     

易燃混合气体爆炸完全基元反应模型数值模拟

采用完全基元反应模型和高精度ENO格式对易燃混合气体爆炸过程进行了数值研究,对H2/O2/Ar混合气体起爆和爆轰波传播过程的数值模拟结果表明,计算的爆轰波阵面参数和实验相当符合,对轰波反应区化学反应的研究表明,参与反应的不同组分具有不同类型的变化特征,这些特征为爆炸灾害的预防设计提供了线索。