元素硫颗粒粒径对污泥重金属生物沥滤的影响

以城市污水处理厂剩余污泥作为处理介质,土著嗜酸氧化硫硫杆菌(Acidithiobacillus thiooxidans,A.thiooxi-dans)为主要沥滤微生物,采用序批式生物沥滤装置,就投加150~725μm的不同粒径元素硫对沥滤的酸化效果、硫酸根产率和重金属去除效果的影响进行了研究。结果表明,在元素硫投配量为3 g/L,曝气强度为1.0 L/(min.L)的条件下,元素硫粒径在165~215μm范围减小时能显著改善污泥酸化速度、提高酸化程度和硫酸根产率。底物元素硫的最佳粒径为165μm,此时沥滤体系pH下降速率为0.85个pH单位/d,硫酸根的产率为454.9 mg/(L.d),沥滤6 d后污泥中高浓度重金属Cu、Zn、Cd的去除率达到70.3%、81.2%、87.8%.

Effect of particle size of elemental sulfur on bioleaching heavy metals from sewage sludge

In this research, surplus sludge taken from a wastewater treatment plant(WWTP) was used as the bioleaching medium, and indigenous AcidithiobaciUus thiooxidans was the main bioleaching microorganism in bioleaching process. The acidification effect of sewage sludge, activity of bioleaching microorganism and removal rate of heavy metals were investigated with various elemental sulfur particle sizes from 150μm to 725μm. This experiment was conducted in sequence batch bioleaching reactor with 3 g/L of S~0 dosage and aeration rate of 1.0 L/(min · L). The results showed that sludge acidification speed, sludge acidification level and sulfate production rate could be improved significantly when sulfur particle size decreased from 215μm to 165μm. And 165 μm was determined as the optimum elemental sulfur particle size for bioleaching process. Under this condition, pH decreasing rate and sulfate ions yield rate was 0.85 pH/d and 454.9 mg/(L · d) respectively, the removal rates of Cu, Zn and Cd were 70.3% 、81.2% and 87.8%, respectively after 6 days' bioleaching.