重力沉淀对猪场污水的分离效果及其对沼气发酵的影响

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1.68L·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.

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

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.