大薸生态塘-渔业模式对猪场粪污沼液氮磷消纳研究

Removal of Nitrogen and Phosphorus in Piggery Methane Fluid by Pistia stratiotes Ecological Pond-Fishery System

规模化畜禽养殖的废物排放是中国农村生态环境污染的主要原因之一,如何生态处理这些废物是当前生态建设亟待解决的问题。该文通过盆栽试验并结合一定规模示范,研究了以大薸(Pistia stratiotes)为生态塘的水质净化植物,同时作为渔业饵料设计的生态塘-渔业模式对猪场粪污沼液中氮、磷的消纳。结果表明,沼液中氮、磷浓度在合适范围(NH_4^+-N为3.0~5.0 mg/L,TP为0.38~0.63 mg/L)时,大薸生长速度较快,7 d内平均单株有效分蘖数可达9.3个,鲜重增重率则达140.8%;大薸具有较强的水质净化能力,氮的平均去除率达97.2%,磷达85.1%。生态塘(400 m^2)示范结果进一步证实,大面积种植大薸并用作饵料(放养模式为青-草-鲢-鳙-鲫-扁),水体的氮、磷并未出现持续升高现象,相反,总体下降,说明大薸生态塘-渔业养殖模式能够有效地消纳沼液中的氮、磷。据捕捞对象总产量及其体内氮、磷含量,在维持水质不变的前提下,1 hm^2生态塘1年可安全消纳猪场粪污沼液约2 761 m^3(相当氮为726.8 kg,磷为74.6 kg)。沼液-大薸-养鱼放养模式的年利润为全投喂配合饲料养鱼利润的200%左右。该结果说明,生态塘-渔业模式可有效地利用水环境中的氮、磷,实现污水的生态处理。

The waste discharge of large-scale livestock and poultry breeding is one of the main sources for pollution of rural ecological environments in nationwide scale, and how to deal with these wastes is a challenge. The removal of nitrogen（N）and phosphorus（P） in piggery methane fluid was investigated using both pot trial and a certain scale pilot. Pistia stratiotes were chosen as aquatic and fish food in ecological fishery pond. The results showed that when concentrations of N and P in biogas slurry was in the appropriate range, such as NH4＋-N was 3.0 to 5.0 mg/L, TP was 0.38 to 0.63 mg/L, Pistia stratiotes were growing faster, effective tiller number of per plant up to 9.3 and the fresh biomass increased by 140.8 % within 7 d.Pistia stratiotes could uptake NH4＋-N and TP in water column by 97.2% and 85.1%, respectively, suggesting a strong ability to purify water quality. The results of ecological pond（400 m2） demonstrated that large-scale cultivation and harvesting Pistia stratiotes could made the water quality stable sustainably. Using Pistia stratiotes as fish food in the ecological pond-fishery system, concentrations of N and P in water column was not raised, on the contrary, continuously declined, suggesting the system was effective in removing N and P in the piggery methane fluid. Based on total yield of fishing targets and the content of N and P in fish bodies, given that water quality keep stable, the estimated potential of 1 hm2 ecological pond could annually safely uptake about 2 761 m3 biogas slurry, equivalent to 726.8 kg N and 74.6 kg P. The annual profit of the biogas slurry-Pistia stratiotes-fishery system was 200% as high as that of all feeds for feeding fish. The results indicate that the oxidation pond-fishery system can effectively utilize N and P to achieve the ecological treatment of polluted water bodies.