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研究报告

Effects of gravitational sedimentation on separation of swine wastewater and biogas fermentation

摘要：采用重力沉淀法对猪场污水进行浓稀分离,并对分离得到的稀污水和浓污水进行沼气发酵实验,以考察沉淀分离对猪场污水沼气发酵的影响.结果表明,分离得到的稀污水体积占原污水的71.5%,相对于原污水,体积减少了28.5%,而COD、BOD₅、SS、TN、TP浓度却分别减少了59.3%、64.4%、85.8%、36.7%和70.9%.分离得到浓污水体积占原污水体积的28.5%,却回收了70%以上COD与BOD₅、95%以上的SS、65%的TN和85%的TP.绝大部分产沼气的底物都被分离到浓污水中,浓污水沼气产量占总产气量的85.5%.沉淀分离可以提高沼气发酵效率,在相同的发酵温度、COD负荷下,浓污水平均池容产气率为1.68 L·L^-1·d^-1,比原污水和稀污水分别高25.3%、145%.通过重力沉淀,可以获得更好的升温效果,提高沼气发酵效率,沼渣沼液利用及污水达标处理也更加容易.

Abstract：To investigate the effect of sedimentation separation on biogas fermentation using swine wastewater, gravitational sedimentation was employed in this study to separate raw swine wastewater into low-content and concentrated liquids. The liquids were further used to produce biogas. The results showed that, in comparison with the raw wastewater, volume of the separated low-content liquid accounted for 71.5% of the raw wastewater, corresponding to 28.5% decrease. However, concentrations of COD, BOD₅, TN and TP of the low-content liquid decreased by 59.3%, 64.4%, 85.8%, 36.7% and 70.9%, respectively. On the other hand, the volume of the concentrated liquid, which accounted for 28.5% of the raw wastewater, contained more than 70% of COD and BOD₅, more than 95% of SS, 65% of TN and 85% of TP. Most of the substrates for biogas generation stayed in the concentrated liquid after the separation, and this liquid contributed to 85.5% of total biogas yield. The efficiency of biogas fermentation also increased through the sedimentation separation. The average volumetric biogas production rate of the concentrated liquid was 1.68 L·L^-1·d^-1, which was 25.3% and 145% higher than those of the raw wastewater and the low-content liquid. In conclusion, gravitational sedimentation was able to improve the heating, get access to higher efficiency of biogas fermentation and simplify the treatment of the digestate and swine wastewater.