鸡粪厌氧发酵沼液达标处理工艺研究

摘要

为解决鸡场沼气工程沼液后续处理问题,以某养鸡场沼气工程全混式发酵池出水沼液处理为例,研究鸡粪厌氧发酵沼液的达标处理工艺.从鸡粪厌氧发酵沼液的特点出发,采用生化法与物化法相结合工艺处理沼液,并考查了3种不同组合的工艺处理效果.先以小试试验确定工艺最佳运行参数,再中试运行考查工艺的处理效果.结果表明:采用鸟粪石- SBR -混凝工艺处理鸡粪厌氧发酵沼液,沼液CODCr由9 200 mg/L降至280 mg/L,NH4+-N由3 200 mg/L降至36 mg/L,TP由270 mg/L降至3.3 mg/L,达到畜禽养殖业污染物排放标准(GB 18596-2001);对于鸡粪厌氧发酵沼液中NH4+-N的去除,直接采用SBR处理,微生物会受到游离氨抑制,NH4+-N去除率不足30％,生化处理前必须采用预处理降低NH4+-N负荷；鸡粪厌氧发酵沼液生化性良好,但仍含有一定量难降解 CODCr,,采用生化处理结合物化工艺进行深度处理可以以较低成本实现达标排放.%To solve subsequent treating problems of cbicken farm biogas project slurry, a research was carried out on treatment processes of anaerobically digested effluent of chicken manure for meeting the discharging standard-a case study of treatment of CSTR fermentation tank effluent of a biogas project. Based on the characteristics of anaerobically digested effluent of chicken manure, bio-chemical treatment combined with physical-chemical process was used to treat the biogas slurry. In addition, effects of three different processes combination method were investigated. First, bench scale experiment was carried out to determine the optimal operation parameters , and then pilot scale devices were introduced to examine the effect of the process. Results showed when using struvite - SBR - coagulation process treating anaerobically digested effluent of chicken manure, C0DCr decreased from 9 200 mg/L to 280 mg/L, NH4+-N decreased from 3 200 mg/L to 36 mg/L, TP decreased from 270 mg/L to 3, 3 mg/L, finally the effluent met the standard GB 18596-2001. To remove NH4+-N in chicken manure slurry, pretreatment is essential. Because of inhibition of free ammonia to microorganism, NH4+ -N removal rate is less than 30% while using SBR directly treating chicken manure slurry. Biodegradability of anaerobically digested effluent of chicken manure is good, but the amount of refractory CODCr is considerable. Using bio-chemical treatment combined with physical-chemical advanced process can meet the discharging standard with lower cost.