调节渗沥液pH回灌对厌氧填埋的影响

通过2组模拟厌氧填埋试验,研究了经过40d模拟降雨后将原渗沥液直接回灌和将原渗沥液pH值调节为7.5后进行回灌对填埋气、渗沥液生化指标、渗沥液生物毒性的影响.结果表明,模拟降雨阶段,垃圾迅速酸化,出流渗沥液pH值迅速降低为5.21.将原渗沥液直接回灌,填埋层内酸化环境进一步恶化.调节渗沥液pH值为7.5后回灌,垃圾迅速进入产CH4阶段,第80d时CH4含量达到64.8%并形成良好的甲烷氛围,同时对有机物也有很好的去除效果,至170d时渗沥液BOD5、COD去除率分别为93.5%、89.1%,但回灌后期出流渗沥液可生化性变差.同时随着回灌的进行,渗沥液的生物毒性大大降低,四膜虫24h半致死渗沥液浓度由0.24%增长为3.27%.

Effects of the Leachate Recirculation with pH Adjusted on Anaerobic Landfill

The landfill gas, biochemical indications of leachate and toxicity of leachate had been investigated in two simulated anaerobic bioreactors. After 40 days of simulated rainfall, one reactor was recharged with the original leachate directly while the other one was recharged with the adjusted leachate of which the pH was changed to 7.5. The results indicate that during the simulated rainfall the garbage is acidified rapidly with the pH value decreased to 5.21. Recharged with the original leachate, acidification of the landfill layer is deteriorated. Recirculation of the adjusted leachate, which can produce methane rapidly, can also remove organic pollutants significantly. At the 80^th day methane production rate is up to 64.8%. After 170 days, the removal of BOD₅ comes to 93.5% while the removal of COD is 89.1%. Furthermore, the biological toxicity of leachate decreases significantly and the semi-lethal concentration of leachate to tetrahymena rises to 3.27% from 0.24% within 24 hours.