波式潜流人工湿地基质与污水磷素去除关系研究

Relations Between Phosphorus Removal in Sewage and Medium in Wavy Subsurface Constructed Wetland

通过分析测试研究了波式潜流人工湿地(WavySubsurfaceFlowConstructedWetland,简称W-SFCW)运行期间基质的磷素沉积量,以便解析不同人工湿地基质对于污水磷素去除的关系。试验污水为经短时厌氧预处理的化粪池污水,并在相同试验条件下与水平潜流人工湿地(HorizontalSubsurfaceflowConstructedWetland,简称SFCW)进行了对比分析。在近2年的人工湿地连续试验期间,分别于2003年11月、2004年5月和2004年11月测定了两种人工湿地基质的磷素沉积量。结果表明,随着人工湿地运行时间的延续,污水中的磷从以人工湿地基质吸附为主,逐渐变成以难溶性磷酸盐的沉积为主;为了人工湿地持续高效地去除TP,用释放Ca2+等金属离子的基质能够促进不溶磷酸盐的沉积;W-SFCW由于使所有水流不断与土壤层、砾石层和豆石层反复接触,生成难溶性磷酸盐的几率大大高于SFCW,能够比SFCW更加显著地促进磷沉积。

Phosphorus precipitation on the bedding materials in the system of wavy subsurface flow constructed wetland （W-SFCW） was studied so as to analyze the relationship between bedding materials and phosphorus removal. Sewage from the septic tank, briefly treated through an anaerobic reactor, was used as the influent wastewater feeding both the horizontal subsurface flow constructed wetland （SFCW） and W- SFCW systems under the same conditions. Precipitation capacity of phosphorus on the medium was measured in W-SFCW and SFCW in Nov. of 2003, May and Nov. of 2004. The two years results show that phosphorus adsorption on the bedding materials was the dominant process in the early stages but insoluble phosphate precipitation was in the later stages. In order to achieve high efficiency of phosphorus removal, materials able to release Ca^2＋ or other metal ions were used so as to facilitate the formation of insoluble phosphates. W-SFCW system, which provides more interaction surfaces for wastewater to react with soil, oval stone and small-sized stone layers, showed higher chances to form insoluble phosphate than SFCW.