混凝-吸附对二级出水中氮和磷的去除特性研究

针对生活污水的二级处理出水,研究了混凝-吸附对二级出水中氮和磷的去除特性,以筛选出最优的二级出水中氮磷的去除工艺。结果表明,混凝出水总磷去除率达96.30%,总氮、氨氮出去效果较差。采用混凝-活性炭吸附出水总磷、总氮、氨氮的去除率分别是92.59%、76.97%、33.40%,总氮、氨氮浓度不能达到景观用水回用标准。混凝-沸石吸附出水总磷、总氮、氨氮的去除率分别是87.04%、86.17%、65.20%,去除效果好,浓度均达到再生水景观回用标准。因此,选用混凝-沸石吸附联合处理工艺去除二级出水中的氮和磷,为优化再生水处理工艺,保障再生水水质安全提供技术支持。

Influence of subsequent curing on water sorptivity and pore structure of steam-cured concrete

Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cured condition on concrete, the water sorptivity and pore structure of steam-cured concretes exposed to different subsequent curing conditions were investigated after steam-curing treatment. The capillary absorption coefficient and porosity of the corresponding concretes were analyzed, and their mechanisms were also discussed. The results indicate that water sorptivity and pore structure of steam-cured concrete are greatly influenced by the curing condition used in subsequent ages. Exposure steam-cured concrete to air condition has an obviously bad effect on its properties and microstructures. Adopting subsequent curing of immersing steam-cured concrete into about 20℃ water after steam curing period can significantly decrease its capillary absorption coefficient and porosity. Steam-cured concrete with 7 d water curing has minimum capillary absorption coefficient and total porosity. Its water sorptivity is decreased by 23% compared with standard curing concrete and the porosity is 9.6% lower. Moreover, the corresponding gradient of water sorptivity and porosity of steam-cured concrete both decrease, thus mictostructure of concrete becomes more homogeneous.