剩余污泥低温热水解中试
Pilot study of the thermal hydrolysis of excess waste sludge at low temperatures

中国污泥有机物质量比低,厌氧消化速率慢、产气少, 60℃左右的热水解是改善措施之一。该文在热水解罐中进行了剩余污泥低温热水解的中试研究,采用热泵供热。对水力停留时间(HRT)、 温度(T)、 污泥含固率和有机物质量比(CVSS/CSS)等对剩余污泥低温热水解的影响以及重要性进行了分析。试验结果表明: 低温热水解的最佳工艺条件为: HRT为1 d, 温度54~60℃,污泥含固率3%。加碱可以促进水解,当污泥含固率5%时,调节pH到10可使VSS去除率和有机物溶出率分别增加46.8%和100%。正交试验结果表明: 温度、污泥含固率和有机物质量比都是热水解的关键影响因素,各因素对VSS去除率和有机物溶出率影响的重要性顺序一致,由大到小的顺序为: 污泥含固率、温度、有机物质量比。在最佳工况下,剩余污泥低温热水解后进行中温(35℃)厌氧消化,消化时间10d的情况下,沼气产量比未低温热水解时增加44%。
Abstract： With low organic matter content, sludge in China has low reaction rates and low biogas production rates. Thermal hydrolysis at about 60 ℃ will enhance the digestion. Thermal hydrolysis of excess sludge at low temperatures was conducted in thermal tanks with a heat pump as a heat source. The effects of hydraulic retention time (HRT), temperature (T), solid content and organic matter ratio (CVSS/CSS) of the sludge on thermal hydrolysis were analyzed. The results showed that the optimal operating conditions for thermal hydrolysis was HRT=1 d, T=54-60℃, and a solid content=3%. Adding alkalis enhanced the hydrolysis, with a solid content of 5%, NaOH was added to increase the pH to 10 to increase the VSS removal rate by 46.8% and the solution rate of organic substances by 100%. Orthogonal experiments indicated that the temperature, solid content and CVSS/CSS were all crucial to the VSS removal rate and the solution rate of the organic matter. The solid content had the largest effect followed by the temperature and CVSS/CSS. The biogas production rate of the sludge hydrolyzed with optimal conditions during 10 days anaerobic digestion at 35℃ was 44% higher than that of sludge without hydrolysis.