生物沥浸处理提高城市污泥脱水性能的中试研究:批式运行模式

Improvement of Municipal Sewage Sludge Dewaterability by Bioleaching:A Pilot-Scale Study with Sequence Batch Reaction Model

为了考察生物沥浸法对城市污泥脱水性能的影响.利用一个兼有序批式与连续式运行模式、工作体积为700 L的生物沥浸反应器对城市污泥进行了连续3批生物沥浸中试研究,并采用厢式压滤机对处理后污泥进行脱水处理.结果表明,曝气量为1.2 m3/h,含嗜酸性硫杆菌的酸化污泥与待处理的原始污泥体积比为1∶15时,在90 h内完成首批生物沥浸处理,此时体系pH由沥浸初期的6.11降低至2.33,相应地ORP由初始-134 mV升高至507 mV,污泥的比阻由沥浸初期的1.00×1013m/kg降低至0.09×1013m/kg.后续2批试验在生物酸化污泥与原始污泥体积比1∶1,而微生物营养剂投加量减少25%和50%的情况下,生物沥浸过程可分别在40 h与46 h内完成,污泥的比阻分别降低至0.19×1013m/kg与0.36×1013m/kg.3批生物沥浸后的污泥经过厢式压滤机在0.3～0.4 MPa压力条件下压滤2 h,脱水泥饼含水率为58%,呈土黄色块状,无臭味.另外,生物沥浸后,污泥有机质含量从原来的52.9%变化至48.0%.但泥饼中重金属Cu与Zn脱除率可分别达到58%与88%.因此,生物沥浸处理后压滤脱水可同时实现污泥重金属的脱出和高效脱水的双重目标,而且不损失污泥有机质的含量,是一种值得工程应用的污泥处理新技术.

To observe the bioleaching effect on sewage sludge dewaterability,three consecutive batch bioleaching experiments were conducted through a bioleaching bio-reactor with 700 L of working volume.Subsequently,the bioleached sludge was dewatered by using chamber filter press.The results show that the 1st batch bioleaching process can be finished within 90 hours if the aeration amount was 1.2 m3/h with the 1∶15 mixing ratio of bioleached sludge to raw sludge.The pH of sludge declines from initial 6.11 to 2.33 while ORP increased from initial-134 mV to finial 507 mV.The specific resistance to filtration（SRF） of the tested sludge was decreased from original 1.00×10^13m/kg to final 0.09×10^13m/kg after bioleaching.For the subsequent two batch trials,the bioleaching process can be finished in 40 hours and 46 hours,respectively.Likewise,sludge SRF is also significantly decreased to 0.19×10^13m/kg and 0.36×10^13m/kg if the mixing ratio of bioleached sludge to fresh sludge is 1∶1 although the microbial nutrient substance dosage is reduced by 25% and 50% for 2nd and 3rd batch experiments,respectively.The harvested bioleached sludge from three batch trails is dewatered by chamber filter press with 0.3-0.4 MPa working pressure for 2 hours.It is found that the moisture of dewatered sludge cake can be reduced to 58%,and that the dewatered sludge cake is of khaki appearance and didn＇t emit any offensive odor.In addition,it is also observes that sludge organic matter only changed a bit from 52.9% to 48.0%,but 58% of sludge-borne Cu and 88% of sludge-borne Zn can be removed from sludge by bioleaching process.Therefore,dual goals for sludge-borne heavy metal removal and sludge dewatering of high efficiency can be achieved simultaneously through the approach mentioned above.Therefore,bioleaching technique is of great engineering application for the treatment of sewage sludge.