Slurry-phase ozonation for remediation of sediments contaminated by polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a group of toxic, persistent, bioaccumulating organic compounds containing two or more fused aromatic rings. They are listed by the U.S. Environmental Protection Agency as priority pollutants because of their carcinogenicity and toxicity. Employing ozonation as a remediation technique, this work investigated the treatability of a sediment sample from a freshwater boat slip subjected to coal tar contamination over a long period. The contaminated sediment sample contained high levels of PAHs in the forms of naphthalene, phenanthrene, pyrene, and benzo[a]pyrene, among other byproducts present in the humic and solid phases of the sediment. The objectives of this work were to examine (1) the degradation of PAHs in the contaminated sediment as treated by ozonation in the slurry form, (2) the effects of ozonation upon the soil matrix and the biodegradability of the resultant PAH intermediates, and (3) the feasibility of a combined technique using O3 as a pretreatment followed by biological degradation. The sediment was made into 3% w/w soil slurries and ozonated in a 1.7-L semi-batch, well-stirred reactor equipped with pH control and a cold trap for the gaseous effluent. Samples were collected after different ozonation durations and tested for biochemical oxygen demand (BOD), chemical oxygen demand (COD), UV absorbance, and toxicity, along with quantitative and qualitative determinations of the parent and daughter intermediates using gas chromatography/flame ionization detection (GC/FID), GC/mass spectrometry (MS), and ion chromatography (IC) techniques. The GC/MS technique identified 16 compounds associated with the humic and solid phases of the sediment. Intermediates identified at different ozonation times suggested that the degradation of PAHs was initiated by an O3 attack resulting in ring cleavage, followed by the intermediates' oxidation reactions with O3 and the concomitant OH radical toward their mineralization. Results suggested that ozonation for 2 hr removed 50-100% of various PAHs in the solid and liquid phases (as well as the aqueous and gaseous media resulting from the treatment process) of the sediment sample and that organic and inorganic constituents of the sediment were also altered by ozonation. Measurements and comparisons of BOD, COD, UV absorbance, and toxicity of the samples further suggested that ozonation improved the bioavailability and biodegradability of the contaminants, despite the increased toxicity of the treatment effluent. An integrated chemical-biological system appeared to be feasible for treating recalcitrant compounds.     

Modeling the aerobic metabolism of polyphosphate-accumulating organisms enriched with propionate as a carbon source.

In enhanced biological phosphorus removal (EBPR) systems, polyphosphate-accumulating organisms (PAOs) are primarily responsible for removing phosphate from wastewater. Propionate is an abundant carbon substrate in many EBPR plants and has been suggested to provide PAOs an advantage over their carbon competitors--the glycogen-accumulating organisms (GAOs). The aerobic metabolism of PAOs enriched with a propionate carbon source is studied in this paper. A metabolic model is proposed and experimentally validated to characterize the aerobic biochemical transformations by PAOs. The model predicts very well the experimental data obtained from the enriched PAO culture through solid-, liquid-, and gas-phase analyses. This model may be combined with previously formulated metabolic models to better describe the biochemical activity of PAOs with acetate and propionate as the primary carbon sources. Furthermore, it can also facilitate the study of the effect of different carbon sources on PAO-GAO competition.     

铝件表面处理废水治理所得化学污泥的再生利用研究

对混凝法处理铝件表面处理废水治理所得化学污泥再生利用进行了研究，得到了适宜的操作条件。结果表明，用浓硫酸溶解污泥的最佳用量为0．14～0．16mL／g湿污泥，湿污泥的溶解率可达90％，铝的溶出率也可达95％以上。把污泥的溶解液作混凝剂回用于印染废水的混凝处理也取得了良好的效果，其COD去除率≥80％，脱色率≥90％。实现了资源的二次利用，改善了作业环境，获得了较好的经济效益和社会效益。     

河流水环境中的非突发性水质风险模型研究

把影响水质模型的随机因素看成一个具有零均值的维纳过程，建立一个研究非突发性水质风险的随机微分动态模型，并对该维纳过程强度进行了估值。研究表明，水环境中的随机因素是引起非突发性风险的一个重要原因。     

微污染钦用水生物处理中痕量有机物生物降解研究述评

生物膜工艺可以有效去除微污染饮用水源中痕量有机污染物，第二级利用是稳态生物膜降解痕量有机物的主要机理。自然有机物可以作为初级基质支持稳态生物膜的生长，而痕量的合成有机物能作为第二级基质被生物膜降解，缓慢衰减的非稳态生物膜在一段时期内仍能保持对痕量有机物的高效降解。     

两级SBR与传统SBR工艺的对比研究

用两级SBR工艺（TSSBR）处理COD与氮浓度较高的工业废水，SBR1去除有机物，SBR2主要进行硝化反硝化。TSSBR与传统SBR工艺相比，COD降解速率和硝化反应速率明显提高，COD去除率由84％提高到93％，2种工艺的反硝化速率没有明显差别。在原水COD浓度较高的情况下，TSSBR可有效克服高COD浓度对硝化反应的抑制，硝化反应速率是传统SBR的2倍。对于COD和氮浓度较高的工业废水，TSSBR明显优于传统SBR，是一种理想的处理工艺。     

富氧尾气中NOx催化净化的研究进展

本文对富氧条件下NOx 催化净化的研究现状进行了综述 ,并对其存在的问题进行了探讨     

论新形势下如何做好建设项目环境管理工作

本文根据作者多年从事建设项目环境管理工作的经验体会,分析了当前建设项目环境管理工作面临的形势,论述了做好建设项目环境管理工作应着重把握的几个问题     

微生物酸化的生产应用研究

分析了折流式酸化池在抗生素废水处理工程中的运行效果和水质变化对酸化作用的影响。实践证明经微生物酸化 ,CODCr去除率达到 1 4%～ 1 9% ,出水VFA增量达 2 .0倍以上。     

染料废水处理的有效工艺

为解决染料废水的治理问题，在工艺试验研究的基础上，成功的采用了“预处理－电化学还原－混凝沉淀－厌氧－＝接触氧化”工艺，并设计出一套处理能力为８０ｍ＾２／ｄ的工艺，经运行检测各项指标均达到国家二级排放标准，其中ＣＯＤｃｒ、色度、硝基苯、苯胺类的去除率分别为９９．２％、９９．９９％、９９．９％、９９．３５。经过运行证帝该工艺性能稳定、操作简单、投资省、运转成本低易行管理。