脱水污泥热调质的特性

热调质方法是污泥深度脱水的有效办法之一。研究结果表明,污泥热调质过程中反应温度和反应时间对污泥热调质效果影响较大,搅拌速度影响较小。当反应温度从160℃升至180℃,反应时间从30 min增至60 min时,污泥溶液中挥发性悬浮固体(VSS)急剧溶解,释放出细胞里的结合水,表明污泥细胞破壁的温度条件为160～180℃,时间条件为45～60 min。热调质后污泥的比阻变化较大。随着反应温度的不断提高,比阻不断减小,污泥的脱水性能越来越好。实验确定了污泥热调质的最佳反应条件为:反应温度180℃,反应时间60 min,搅拌转速30 r/min。在此条件下,压滤后泥饼含水率约50%,滤液中COD浓度可达19 000 mg/L,有利于后续污泥的消化。

Properties of dewatered sludge thermal conditioning

Thermal conditioning is one of the effective methods to improve the sludge deep dewaterability.Results show that compared to stirring speed,reaction temperature and time have more influences on sludge thermal conditioning.As the reaction temperature rose from 160 ℃ to 180 ℃,reaction time increased from 45 min to 60 min,the volatile suspended solids(VSS) dissolve quickly and release the cells’ bound moisture,showing that the main conditions of broking sludge cells’ wall are that reaction temperature is 160~180 ℃,reaction time is 45~60 min.The specific resistance of sludge has a great change after thermal conditioning.With the increasing of reaction temperature,specific resistance to pressure filtrate decreases continuously and the dewaterability of sludge becomes better and better.The experimental results show that the conditions of thermal conditioning which reaction temperature is 180 ℃,reaction time is 60 min,stirring speed is 30 r/min,are the best and the water content of filter cake is about 50% in this case after filter press.Under the best reaction conditions,there are more organic matters dissolving in the filtrate causing the COD concentration reaching 19 000 mg/L.Especially it is good for the anaerobic digestion for the sludge.