生物沥滤去除城市污泥中重金属的温度控制研究

Temperature Control in Bioleaching Heavy Metals from Sewage Sludge

以桂林城市污泥作为处理介质、单质硫为能量底物、土著硫杆菌为主要的沥滤微生物,对10～40℃下生物沥滤的酸化效果、沥滤微生物活性和去除重金属的效果进行了研究。结果表明,在单质硫的投配量为3 g/L、曝气强度为1.0 L/min的条件下,当温度为10～30℃时,升高温度能明显提高污泥酸化速度和微生物活性。为缩短生物沥滤时间和提高酸化效果,沥滤体系的最佳运行温度范围为20～30℃,其中温度为28.9℃时沥滤微生物的活性最强,此时硫酸根的产率为461.66 mg/(L.d)。从达标处理和低能耗运行的工程角度考虑,生物沥滤温度可控制在20℃5,d后对Cu、Zn、Cd的去除率分别为47.45%7、7.07%和80.57%,残余重金属含量均符合污泥农用的相关标准。

The sewage sludge taken from Guilin WWTP, elemental sulfur and indigenous Acidithiobacillus thiooxidans were used as treatment medium, substrate and bioleaching microorganisms respectively. The acidification effect of sewage sludge, activity of bioleaching microorganisms and removal rates of heavy metals were investigated at various temperatures from 10 ℃ to 40 ℃. The results show that under the conditions of 3 g/L of sulfur dosage and aeration rate of 1.0 L/min, the acidification rate and microbial activity are increased with temperature rising in the range of 10 ℃to 30℃. The optimum operation temperature range of the bioleaching system is 20℃ to 30℃ so as to shorten bioleaching time and improve the acidification effect. The activity of bioleaching microorganisms is the highest at 28.9 ℃, and sulfate ions yield is 461.66 mg/（L · d）. Considering treatment for meeting the discharge standard and operation with low energy consumption, the bioleaching temperature can be controlled at 20 ℃, and the removal rates of Cu, Zn and Cd are 47.45%, 77.07% and 80.57% respectively after 5 days. The residual concentrations of Cu, Zn and Cd in the treated sludge meet the national standard for agricultural use of sewage sludge.