复合介质渗透反应格栅去除地下水中的氨氮

针对受低浓度氨氮污染的地下水,实验筛选组合了不同的反应介质,利用串联的多介质填充柱模拟渗透反应格栅,通过物理吸附及生物硝化-反硝化作用来实现氮的去除。结果表明,在进水氨氮浓度为10 mg/L、流速为0.5 m/d的条件下,模拟柱对氨氮的去除率达到98%以上,且不会出现亚硝酸盐及硝酸盐浓度的升高。水体经过释氧柱后溶解氧由2mg/L升高至10 mg/L以上,表明释氧材料可提供硝化细菌所需的好氧环境。好氧柱中填充易于生物挂膜的生物陶粒及对氨氮有较强吸附能力的沸石,二者联用通过生物硝化-物理吸附协同作用实现对氨氮的去除,其中生物作用实现的氨氮去除量占总去除量的50%左右。后续厌氧反应柱填充海绵铁除氧并利用松树皮颗粒作为碳源,创造反硝化菌生长条件,硝酸盐氮浓度可由10 mg/L降低至5 mg/L以下,实现对好氧反应阶段所产生的硝酸盐的去除,避免了地下水的二次污染。     

傍河型水源井氨氮阻断与去除工程设计案例分析

针对沈阳市傍河型水源地的氨氮(NH+4-N)污染问题,通过野外研究区的水文地质调查,在查明研究区NH+4-N污染特征的基础上,结合室内批试验、柱实验和数值模拟,筛选出最佳的NH+4-N去除方案,提出了研究区渗透反应格栅(PRB)构建方案,并成功构建了示范工程尺度的PRB,用以去除地下水中的NH+4-N污染.室内批实验和柱实验表明,利用微生物硝化作用结合沸石的吸附作用去除地下水中NH+4-N是可行的.通过对研究区水质数值模拟,发现构建有一定弧度的PRB能最大限度的保护水源井.在PRB的构建过程中,利用高压旋喷技术和旋挖技术解决了大深度(30 m)PRB的构建问题,且PRB建成运行监测表明,示范工程尺度的PRB能有效阻断和去除地下水中NH+4-N.     

Application of aluminosilicate clay mineral-based composites in photocatalysis

Aluminosilicate clay mineral (ACM) is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring. In past two decades, in-depth understanding on unique layered structure and abundant surface properties endows ACM in the emerging research and application fields. In field of solar-chemical energy conversion, ACM has been widely used to support various semiconductor photocatalysts, forming the composites and achieving efficient conversion of reactants under sunlight irradiation. To date, classic ACM such as kaolinite and montmorillonite, loaded with semiconductor photocatalysts has been widely applied in photocatalysis. This review summaries the recent works on ACM-based composites in photocatalysis. Focusing on the properties of surface and layered structure, we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM, i.e., type 1:1 and type 2:1. Not only large surface area and active surface hydroxyl group assist the substrate adsorption, but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts. Besides, we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process. This review could inspire more upcoming design and synthesis for ACM-based photocatalysts, leading this kind of economic and eco-friendly materials for more practical application in the future.     

Impact of δ-MnO2 on the chemical speciation and fractionation of Cr(III) in contaminated soils

Environmental Science and Pollution Research - Oxidation of Cr(III) by birnessite (δ-MnO2) was an important geochemical reaction determining the toxicity and mobility of dissolved Cr(III) in...