Development and simulation studies of an unsteady state biofilter model for the treatment of cyclic air emissions of an α‐pinene gas stream

This paper describes the development and simulation of an unsteady state biofilter model used to predict dynamic behaviour of cyclically‐operated biofilters and compares it with experimental results obtained from three, parallel, bench‐scale biofilters treating both periodically fluctuating concentrations and constant concentrations of an α‐pinene‐laden gas stream. The dynamic model, using kinetic parameters estimated from the constant concentration biofilter, was able to predict the performance of cyclic biofilters operating at short cycle periods (ie, in the order of minutes and hours). Steady state kinetic data from a constant concentration biofilter can be used to predict unsteady state biofilter operation. At a 24 h cycle period, the dynamic model compared well with experimental results. For long cycle periods (ie, hours and days), removal efficiency decreased after periods of non‐loading: the longer the period of non‐loading, the poorer the biofilter's performance at the re‐commencement of pollutant loading. At longer time scales the model did not effectively predict transient behaviour, as adsorption and changes in kinetic parameters were not accounted for. Modelling results showed that similar biofiltration performance for the cyclic and constant concentration biofiltration of α‐pinene is expected for biofilters operating solely in the first order kinetics regime. Poorer performance for cyclic biofilters following Monod kinetics spanning the entire kinetics range is expected as the cycle amplitude increases. The most important parameters affecting the performance of a cyclically‐operated biofilter with short cycle periods are: amplitude of cyclic fluctuations, C_{g, max}/C_g, relative value of the half‐saturation constant in the Monod expression, K_s, and effective diffusivity of α‐pinene in the biofilm, D_e. Copyright © 2005 Society of Chemical Industry     

生物滤料滤池处理姚江微污染水源水

通过中试试验,考察了不同滤料介质的生物滤池对于姚江微污染水源水的处理效果。结果表明,双层生物滤料滤池能够有效地去除有机物、氨氮等污染物质,可以延长滤池反冲洗周期,并能在短时间内恢复到正常处理能力,适合于传统滤池的改造。采用颗粒活性炭-石英砂滤料滤池的综合处理效果优于同类型的颗粒活性炭-沸石滤料滤池,通过加入少量臭氧(0.8～1.0mg/L)可以提高生物滤池的去除效果。     

蚯蚓体表与土壤接触界面动态行为仿真

应用离散元软件PFC2D建立了蚯蚓波纹体表与土壤界面动态行为仿真模型,对比分析了光滑和波纹试样的接触界面、接触力场和接触颗粒数以及滑动阻力,得出:当波纹表面的摩擦力与土壤颗粒对波纹凸起处的向后推力之和小于光滑表面的摩擦力时,波纹表面起到减阻作用;如果土壤颗粒对波纹表面凸起处的向后推力过大,波纹会起到增加阻力的作用。另外,试样运动时,波纹表面比光滑表面对土壤的扰动大。随着垂直载荷的增加,波纹表面和光滑表面的滑动阻力均增加,且波纹表面的降阻效果减弱;随着前进速度的增加,2种试样滑动阻力的增加,但波纹表面的滑动阻力的增长小于光滑表面,即速度高时波纹表面降阻明显。结果表明:蚯蚓非光滑表面的减阻能力与接触界面特性和外部条件有关。研究结果可为揭示非光滑表面的减阻机制提供研究方法和参考。     

污泥臭氧减量对淹没式生物膜工艺运行效能的影响

针对淹没生物膜法(SBF)和污泥臭氧化各自在污泥减量方面的优点,提出了化学臭氧化和复合生物膜法相结合的污泥减量工艺,并对臭氧化对SBF运行效能的影响进行了实验研究。通过2个并行的SBF系统污泥臭氧化结果进行对比,结果显示臭氧化能够显著降低系统的污泥产率(0.043 kg/kg,较不加臭氧化的SBF系统下降了76%),同时不对硝化和有机物的去除作用产生明显的影响,系统出水水质良好。     

生物滤池去除污水处理厂臭气的应用研究

研制了一套生物过滤系统,用于处理污水处理厂生化水解池所排放的臭气。以某污水处理厂的生物滤池为研究对象,经过调试使用后,在进口段气体中H2S、NH3的质量浓度分别小于7.0、90.0 mg/m3时,其去除率分别达到90%和99%左右。并通过试验分析了运行时间、进气浓度、填料含水率、温度对除臭效率的影响。     

不同中水回用模式的技术经济分析

根据国内外中水回用的工程实践，总结了目前城市中水回用的典型处理工艺、回用途径，提出了城市中水回用的7种模式，从技术经济角度分别对这几种模式进行了分析，提出了适合我国国情的城市中水回用模式，展望了我国中水回用的发展趋势。     

溪沙蚕对污水厂生物滤池运行的影响及防治措施

在厦门市污水处理二厂的好氧生物滤池（CN池）中发现了溪沙蚕，其对滤池的主要影响是易造成滤头堵塞。对溪沙蚕的防治措施有：①防止海水进入污水管道；②保证生物滤池的正常过滤和反冲洗；③在溪沙蚕繁殖期到来之前，清除CN池底部的沉泥；④在溪沙蚕繁殖季节，对CN池进行强力反冲洗，并适当增加反冲洗次数，以加速溪沙蚕受精卵排出生物滤池。     

无锡市充山水厂深度处理技术改造工程

无锡市充山水厂原采用常规处理工艺,由于太湖水源水污染,特别是有机物、氨氮和藻类污染日趋严重,使出厂水水质安全性难以得到保障.因此在中试基础上对充山水厂进行了技术改造,改造后新工艺为:BIOSMEDI生物滤池-气浮池-臭氧接触池-生物活性炭过滤器-石英砂过滤器,并将消毒剂由原来的氯改为ClO2.改造后的运行结果表明,出厂水水质完全达到《城市供水水质标准》(CJ/T 206-2005).改造工程设计规模1万m3/d,总投资1 500万元,水厂运行费0.86元/m3,较原常规处理增加0.17元/m3.     

Comparison of biological reactors (biofilter,biotrickling filter and modified RBC) for treating dichloromethane vapors

BACKGROUND: Bioreactors used for waste gas and odor treatment have gained acceptance in recent years to treat volatile organic compounds (VOCs). Different types of bioreactors (biofilter, biotrickling filter and rotating biological reactor) have been used for waste gas treatment. Most studies reported in the literature have used one of these systems to treat several types of inorganic and organic gases either individually or in mixtures. Each of these reactors has some advantages and some limitations. Though biodegradation is the main process for the removal of pollutants, the mechanisms of removal and the microbial communities may differ among these bioreactors. Consequently their performance or removal efficiency may also be different. RESULTS: At low loading rate (<35 g m^?3 h^?1), all three bioreactors showed comparable removal efficiencies and elimination capacity, but at higher loading rates, rotating biological contactors (RBC) showed a better performance with higher removal efficiency (40–50%) than both the biofilter and biotrickling filter (20–40%). The biofilter showed a sharp drop in removal efficiency and elimination capacity at high loading rates. CONCLUSIONS: The modified RBC had no clogging problems and no increase in pressure drop when compared with the other bioreactors. It can thus handle pollutant load for a longer period of time. This is the first study attempting to compare the performance of three different bioreactors for removal of the same VOC under different conditions. Copyright © 2010 Society of Chemical Industry