Biodegradation of 2,6-ditert-butylphenol by immobilized microorga- nism strains

2,6-Ditert-butylphenol （2,6-DTBP） is a major organic contaminant presenting in acrylic fiber manufacturing wastewaters. This compound is of high bio-resistance due to its complex structure which consists of one phenol group and two highly branched tert-butyl groups. This research attempted to improve the biodegradation efficiency of 2,6-DTBP through various strain immobilization methods. The stratified immobilization can settle oxygen transmission in the single microorganism immobilization, and can realize two-process reaction in the single device by choosing two symbiotic microorganisms. Two effective strains, named F-1-4 and F-3-4, which were screened out in our previous work, were used to degrade 2,6-DTBP after being immobilized in calcium alginate gel. Results indicate that the substrate removal efficiency of various immobilization methods follows the order： stratified 〉 single F-3-4 〉 mixed ≈single F-1-4. The immobilized biodegradation capacity was higher than the free one. After an incubation time of 12 d, 91% of 2,6-DTBP could be degraded by the stratified immobilization method, compared to 79% achieved by the mixed immobilization method with an initial 2,6-DTBP concentration of 100 mg/L. The stratified immobilization satisfies the oxygen demand nature of the aerobic F-3-4 and the facultative F-1-4, thus yielding the highest degradation efficiency. Both the outer layer strain F-3-4 and the inner layer strain F-1-4 can grow actively on the substrate of 2,6-DTBP, as illustrated by SEM images. This study shows that the highly bio-refractory compound, 2,6-DTBP, can be effectively degraded using appropriately inunobilized microorganism strains.

紫外/氯工艺去除煤化工高盐废水中有机物的研究

采用紫外/氯高级氧化工艺处理煤化工高盐废水,探讨了不同投氯量对废水中有机物去除率的影响,并分析了氧化前后紫外吸收、荧光特性和可生化性的变化。首先率定了余氯对COD测试方法的影响,发现了与氯离子影响不同的线性负干扰。结果表明,单独紫外或单独加氯对COD或DOC的作用较小,而紫外/氯工艺对有机物的去除效果显著。在投氯量为240 mg/L、紫外辐照时间为25 min(对应紫外剂量为6000 mJ/cm^(2))条件下,对COD、DOC和UV_(254)的去除率分别达到91.7%、52.3%和69.8%。紫外/氯工艺可以提高废水的BOD_(5)及BOD_(5)/COD值,说明该工艺不会导致出水生物毒性的增加,且废水中的难生物降解有机物可转变为生物降解性良好的物质。单位能耗分析结果表明,增加投氯量可以降低紫外/氯工艺去除单位质量COD的成本。

数据采集设置对DMA流量模式的影响

智能水表监测的水量数据为用水模式确定及供水管网漏损分析提供了重要的基础。然而,数据精度与频度会对分析结果产生重要影响。以10个独立计量区(DMA)入口流量计数据作为基础样本,分析了数据采集周期与精度对最小夜间流量计算以及DMA流量模式分析的影响。结果表明,水表数据采集周期增加会导致最小夜间流量计算结果增大,同时降低流量模式的精细度;数据精度降低会导致流量模式呈阶梯状甚至双线式,无法反映真实的用水模式。水表数据采集周期与精度存在对应关系,在设定时需要相互匹配。

供水管网水质模型的研究进展:经验统计模型

管网水质安全是供水行业长期关注的重点,管网水质模型通过跟踪、评价、预测管网水质变化,在保障管网水质安全方面发挥了重要作用。由于管网内部环境复杂,管网水质微观机理模型的研究难度较大;但随着数据获取能力和分析能力的不断提高,经验统计模型在管网水质模拟中发挥了越来越重要的作用。首先,简介了经验统计模型的原理、常用变量及建模方法,并对比了几种典型算法的优缺点;其次,分别介绍了各类经验模型的研究进展;最后,对未来研究方向进行了展望。

供水管网水质微观机理模型研究及应用进展

管网水质模型是评价供水管网水质、预测水质变化的有效工具。随着管网水质变化机理研究的不断深入,水质模型也不断完善。其中,微观机理模型是一个重要分支,因此有必要重点关注管网水质变化的影响因素及其机理。首先,以余氯衰减模型为例,介绍了模拟单一化学物质转化的微观机理模型的原理;其次,基于余氯衰减、消毒副产物生成、微生物生长模型,重点论述了模拟多物质反应过程的微观机理模型的研究进展;最后,总结了微观机理模型的应用。