污水土地生态处理脱氮技术的中型试验研究

Pilot study of removing nitrogen from sewage in under ground-ditch-pattern soil treatment system

地沟式污水土地生态处理工艺,是自然生态净化与人工工艺相结合的小规模污水处理回用技术。它是采用土壤毛细管浸润扩散原理的浅型土壤处理技术,在人工可控条件下,将污水科学、合理地投配到设计定型的装置内,利用污水的能量,把其所携带的污染物,通过人工基质(土壤、砂、碎石等,填料-水-微生物-植物系统)的物质循环和能量流动,逐级降解;在不同的污染负荷、水力负荷下,完成一系列物理、化学、物理化学和微生物化学、生物化学的反应。通过以贵州典型的黄壤土为主配比的人工土作为处理系统填料的现场中型试验,探讨地沟式污水土地处理系统的脱氮效果及其影响因素。地沟式污水土地生态系统对氨氮和总氮去除效果良好,去除率分别达到84 .7%和70 .7% ,出水氨氮(14 .0 mg/L )和总氮(2 4 .7mg/L ) ,达到建设部颁发的生活杂用水水质标准。对处理系统微生物数量及分布的研究表明:处理系统中氮转化细菌丰富,氨化细菌为10 3～10 6 cfu MPN/g(土壤) (cfu:形成菌落数:MPN:最大可能数量) ,亚硝化菌为10 3～10 6 MPN/g(土壤) ,硝化菌10 4～10 6 MPN/g(土壤) ,反硝化细菌为10 3～10 6 MPN/g(土壤)。由硝化/反硝化实现生物脱氮是土地生态处理系统去除总氮的主要途径;建立土壤、土壤微生物。

Underground-ditch-patter soil treatment is a procedure whereby sewage is treated through self-purification in conjunction with manual techniques in a small scale system. This process is a kind of fleet soil zoology treatment technology, which relies on the principles of diffusion and capillary action in soil. Under artificially controlled conditions, sewage was distributed into the designated system equipped with a series of devices composed of soil, sand, pebbles, and a soil-water-animalcule-filling system, and was gradually decomposed as a result of a series of physical, chemical and biological reactions in different pollutant loadings and HRT(retention time). Through the pilot plant of underground-ditch-patter soil zoology treatment system filled with soil mainly confected by yellow clay - the typical soil type found in Guizhou, this paper investigates the efficacy of such systems in removing nitrogen and the different factors that influence the rate of removal of nitrogen. Results showed that average removal rates of NH^+_4-N and TN were 84.7% and 70.7%, with average effluent concentrations of NH^+_4-N, TN being 14.0mg/L, 24.7mg/L respectively, which meets the standard for water reuse issued by the Ministry of Construction of China. Nitrogen transformation bacteria analysis revealed that there were abundant nitrogen transformation bacteria in the pilot system. 10~3~10~6cfug(soil,colony for ming unit), 10~3~10~6MPN/g(soil,most probable number), 10~4~10~6 MPN/g(soil), 10~3~10~6 MPN/g(soil), were obtained respectively for ammonifying bacteria, nitrite bacteria, nitrate bacteria, denitrifying bacteria. Nitrogen in the influent was mainly eliminated through biological removal via nitrification/denitrification processes. Improving the nitrification performance through alterations in the soil-water-animalcule-plant environment proved to be the key to enhancing nitrogen removal rate. Results showed that appropriate concentrations of C/N are necessary for the process of denitrification. Moreover, when the pilot system was implemented with HRT of 4.5h, the effluent concentrations of NH^+_4-N was 18.48mg/L and the removal rates of NH^+_4-N was 82.87%, which met the standard for wastewater emission control regulations II(<25 mg/L). Underground-ditch-patter soil zoology treatment system has much potential in disposal loadings. At a reduced cost compared to existing mechanisms and with easy operation and management, this technique has many opportunities for further research and development.