基于全混合厌氧反应器厌氧发酵猪粪产生沼液的环境影响分析

为了探究基于全混合厌氧反应器工艺处理猪粪产生沼液的主要成分和沼液还田的环境影响,通过采集3个规模化养殖场的猪粪、经厌氧发酵产生的沼液及沼液灌溉后的土壤样品,分别检测分析了样品中化学需氧量(COD)、5日生化需氧量(BOD5)、重金属含量和营养元素等物质含量。结果表明:基于全混合厌氧反应器工艺处理猪粪后,沼液中COD和氨氮的去除率分别为63%～82%和37%～75%;沼液重金属中锌、铜含量相对较高,分别为2.1×10~4μg/L和3.8×10~3μg/L;沼液和饲料中重金属含量的相关系数达0.93～0.95;施用沼液后土壤中营养元素增加幅度为0.3～14倍,重金属含量基本能够达到Ⅰ级土壤标准要求。合理的施用沼液可增加土壤中有益成分的含量,不会对土壤造成明显的重金属污染,其种植作物可食用部分的重金属含量满足食品安全的要求。

Environmental Impact Analysis of Biogas Slurry Generated by Pig Manure Anaerobic Treatment Based on CSTR

In order to explore the main components of biogas slurry and environmental impact of biogas slurry returning based on continuous stirred tank reactor (CSTR), this paper collected pig manure from 3 large-scale farms, biogas slurry produced by pig manure anaerobic fermentation treatment, and soil samples irrigated with biogas slurry, tested and analyzed the COD (chemical oxygen demand), BOD5, heavy-metal elements and nutritive elements in the samples. The results showed that the removal rates of COD and ammonia nitrogen in biogas slurry were 63%~82% and 37%~75%, respectively, after treating pig manure anaerobic fermentation based on CSTR. The contents of Zn and Cu in biogas slurry were relatively higher, which were 2.1×104 μg/L and 3.8×103 μg/L, respectively. The correlation coefficients for heavy-metal content between biogas slurry and fodder were 0.93~0.95. The increase of nutritive element in soil after applying biogas slurry was 0.3~14 times and heavy-metal content in soil could basically reached Ⅰ level soil standard. Rational application of biogas slurry could increase nutritive contents in soil, and there was no significant heavy metal pollution to soil. The heavy metal contents in edible part of crops planted in soil fertilized by biogas slurry could meet food safety requirement.