稻草—绿狐尾藻复合人工湿地技术处理养猪废水综合效益分析

摘要

The issue of environmental pollution of wastewater has become a major bottleneck in the sustainable development of livestock and poultry production, which attracts great attention of the publics. This paper took a large-scale pig farm with living pigs 50 000 heads in Shaoxing City, Zhejiang Province as an example, and systematically analyzed the integrated environmental and economic benefits of an ecological pollution control technology using rice-straw and Myriophyllum elatinoides.Results showed that the influent concentrations of chemical oxygen demand(COD), total nitrogen (TN), ammonia nitrogen (NH4+-N) and total phosphorus (TP) of the wastewater varied in the ranges of 753.0-2 487.5, 294.8-1 290.0, 273.2-1 078.0, and 21.75-49.3 mg/L, respectively. However, the highest concentrations of COD, TN, NH4+-N and TP were 65.0, 26.0, 40.5, and 5.0 mg/L in the effluent, respectively. The annual average removal rates in the demonstration engineering were COD 96.4%, TN 97.9%, NH4+-N 99.3%, and TP 90.6%, respectively. The water quality of the effluent was significantly better than the national wastewater discharge standard (GB 18596—2001).In the aspect of ecological benefits by using pollution control technology of rice straw and M.elatinoides,the annual reduction amounts of pollutant COD, TN, NH4+-N, and TP were 53.0, 29.1, 25.4, and 1.1 tons per ten thousand heads, respectively. The direct benefit of the engineering through aquaculture and green fodder utilization was about 12 000 Yuan per ten thousand heads under normal running conditions.In short,the rice straw-M.elatinoides farming wastewater treatment technology is a new ecological pollution control technology with low investment, low running cost, and certain economic benefit, which is in line with the current social needs of "environmental friendliness"and "resource saving" in China. This technology is significantly better than the general industrial pollution control technology and is worth promoting the application.%养殖废水环境污染已经成为影响畜禽养殖业可持续发展的主要瓶颈问题,受到社会各界的高度关注.以浙江绍兴某大规模养猪场(存栏生猪5万头)为例,采用稻草—绿狐尾藻(Myriophyllum elatinoides)生态治理技术,系统分析养殖场废水处理的综合环境效益和经济效益.结果表明:工程进水的化学需氧量(Chemical oxygen demand,COD)、总氮(TN)、氨氮(NH4+-N)和总磷(TP)进水浓度变化范围分别为753~2487.5、294.8~1290、273.15~1078 和21.75~49.3 mg/L,而系统末端出水的COD、TN、NH4+-N和TP浓度最高依次为65、40.5、26和5 mg/L,全年工程系统对COD、TN、NH4+-N和TP的总去除率分别为96.4%、97.9%、99.3%和90.6%,且出水水质均显著优于国家养殖废水排放标准(GB 18596—2001).从生态效益而言,稻草—绿狐尾藻生态治理技术对COD、TN、NH4+-N和TP的年减排量分别可达到53.0、29.1、25.4和1.1 t/万头.工程在正常运行条件下,还通过水产养殖、青饲料利用等途径每年可产生直接经济效益1.2万元/万头.研究表明,稻草—绿狐尾藻养殖废水生态治理技术是一项投资少、运行成本低、可产生一定经济效益的生态治污新技术,符合当前"环境友好"和"资源节约"的社会需求,显著优于一般的工厂化污染治理技术,值得推广应用.