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     

Performance of Granular Activated Carbon (GAC) Adsorption and Biofiltration in the Treatment of Biologically Treated Sewage Effluent

Abstract

In this study, the performance of GAC adsorption and biofiltration systems in treating biological treated sewage effluent (BTSE) was evaluated in terms of organic removal efficiency, organic fractions, and molecular weight distribution (MW) of organic matter (OM) removed. The GAC biofilter removed 23.5% and 61% of the hydrophobic fractions and hydrophilic fractions of OM in the BTSE respectively. MW distribution studies of GAC filter and GAC adsorption revealed the following: Hydrophobic fraction of the effluent showed a peak at 345 dalton after GAC biofiltration and 256 dalton after GAC adsorption, whereas, with hydrophilic fractions, peaks at 46,178 and 345 daltons were observed after GAC biofiltration and peaks at 46,178 and 256 daltons after GAC adsorption. Transphilic fraction showed the peaks at 12,783 dalton with GAC biofiltration, and 1,463 dalton with GAC adsorption. The performance of the GAC biofilter was successfully mathematically modelled.     

生物法处理挥发性有机废气(VOCs)的研究

生物法处理挥发性有机废气是近年来逐步发展起来的一项废气治理新技术,具有效率高、投资及运行费用低、无二次污染、安全性好等优点。文章主要概述了有机废气生物处理的3种主要形式：生物过滤池、生物滴滤塔和生物洗涤器的原理、流程以及研究进展,比较了以上3种反应器的优缺点,并提出了现存问题和将来的研究方向。     

两级生物膜处理合成洗涤剂废水

采用厌氧生物滤池(AF)—好氧生物接触氧化(BCO)联合工艺对合成洗涤剂(LAS)废水进行处理试验。结果表明,AF反应器在HRT=24h、温度(32±2)℃、pH为7～8、营养母液质量浓度5mg/L条件下,BCO反应器在HRT=12h、常温、DO为4～5mg/L条件下,对LAS和COD的去除率分别可达到85%和95%,出水达到国家《污水综合排放标准》(GB8978—1996)规定的一级排放标准。     

臭氧-活性炭-反硝化生物滤池在污水再生回用中的应用

在酒仙桥污水处理厂建立200m3/d的示范工程进行高品质再生水的生产,在二级出水强化脱氮除磷的基础上,采用臭氧(O3)-活性炭(GAC)-反硝化生物滤池(DNBF)工艺进行试验研究。经过13个月的试验证明,该工艺由于O3在脱色除臭基础上,能够强化活性炭滤池的生物多样性及活性,从而使出水CODCr能够长期稳定在30mg/L以下,NH3-N小于1mg/L。在外加碳源CH3COONa条件下,系统经DNBF后出水TN小于2mg/L。同时试验发现,为了实现经济节能及良好的污水再生效果,DNBF和O3单元在流程中的位置设置非常关键,有别于污水二级处理工艺。     

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.     

泥炭生物过滤器去除甲硫醚的微生物学研究

研究了泥炭和接种活性污泥的泥炭作为填料的生物过滤器去除甲硫醚（DMS）恶臭气体的情况,确定了生物过滤器中降解DMS的优势微生物种群,填料是原始泥炭的生物过滤器几乎不能去除DMS,接种活性污泥的泥炭生物过滤器则能有效地去除低浓度DMS气体。去除DMS适宜的pH值范围是7－5．45。微生物学分析表明,生物过滤器中去除DMS的优势种群是来源于活性污泥的非嗜酸化能自养型硫氧化菌。     

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。     

贝壳填料曝气生物滤池的硝化特性研究

贝壳粗糙的表面及其合有的大量碳酸钙，可作为生物膜的载体及硝化反应的碱度来源。以海产弃物贝壳为生物膜载体，通过改变进水氨氮浓度及pH值，考察了贝壳填料曝气生物滤池的硝化脱氮规律。结果表明：对于氨氮〈120mg／L的原水，贝壳溶解提供的碱度能够满足硝化反应的需要，因此硝化反应进行得比较完全，对氨氮的去除率不受进水氨氮浓度的影响，可达90％以上；而当进水氨氮浓度达240mg／L时，因贝壳溶解提供的碱度不能完全满足硝化反应之所需，硝化反应将停滞，但对氨氮的去除率仍可达65％左右。此外，进水pH值对贝壳填料曝气生物滤池去除氨氮的效果及出水pH值基本没有影响。     

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。