关键词: 全混合厌氧反应器, 沼液, 重金属, 环境影响分析

Abstract: 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.

Key words: CSTR, biogas slurry, heavy metal, enviromental impact analysis