低温条件下污泥静置沉降时间对城市生物沥浸污泥脱水性能的影响

研究城市生物沥浸污泥脱水性能与污泥静置沉降时间的关系,对城市污泥生物沥浸工程化应用具有指导性作用.因此,以城市生物沥浸污泥为研究对象,研究了低温条件下(5℃和15℃)污泥静置0～6d过程中,污泥pH值和脱水性能(用比阻γ表征)的变化情况.同时,对实验室污泥比阻与厢式压滤机中试结果进行了相关性分析.结果表明:温度增加将有利于污泥沉降,在实际运行中沥浸污泥可选择静置0.5d再进行压滤脱水.随着静置时间的延长,冬季(5℃)和春季(15℃)城市沥浸污泥pH值和比阻均呈逐渐上升的趋势.静置6d后,pH值分别从3.93和3.87上升到5.10和5.32,比阻γ分别从1.72×1012m·kg-1和1.76×1012m·kg-1上升到3.08×1012m·kg-1和5.82×1012m·kg-1.实验室污泥比阻测定和厢式压滤机中试结果表明,不同静置时间下污泥比阻γ与压滤机压滤脱水V-t/V曲线(V:滤液体积;t:过滤时间)斜率k呈极显著正相关关系,说明用污泥比阻γ能准确地反映出生物沥浸污泥的压滤脱水性能.这对生物沥浸技术在工程上的应用和推广具有重要意义.

Effect of sedimentation time on dewaterability of bioleached municipal sewage sludge at low temperatures

Relationship between sedimentation time and dewaterability of bioleached municipal sewage sludge may play a significant role in the engineering application of sewage sludge bioleaching. Under low temperature conditions (5 ℃ and 15 ℃), the change of the pH value and dewaterability of bioleached sludge during different sedimentation times (0~6 day) were investigated in this study. Meanwhile, specific resistance to filtration (SRF) as an index of sludge dewaterability was also assessed through practical dewatering operation by using chamber filter press device. The results showed that the increase of the temperature would improve sludge sedimentation. It was suggested that the optimal sludge sedimentation time was 0.5 day prior to sludge dewatering by using chamber filter press device in engineering application. The pH and SRF value of bioleached sludge increased gradually from day 0 to day 6 for sedimentation either in winter (5 ℃) or in spring (15 ℃). For example, the pH of bioleached sludge increased from 3.93 on day 0 to 5.10 on day 6 in winter and from 3.87 to 5.32 in spring. Correspondingly, the SRF rose from 1.72×1012 m·kg-1 on day 0 to 3.08×1012 m·kg-1 on day 6 in winter and from 1.76×1012 m·kg-1 to 5.82×1012 m·kg-1 in spring. Furthermore, it was found that there was significant positive correlation bewteen the SRF and the slope(k) of V-t/V (V: filtrate volume; t: pressure time) under different sedimentation times, indicating that the SRF value obtained in laboratory study could reflect accurately the dewaterability of bioleached sludge in practical engineering. Therefore, the outcome of this study was very helpful in the engineering application of sludge bioleaching.