低速搅拌球磨破解剩余污泥高效释放碳源

High Efficient Release of Carbon Source from Excess Sludge Disintegrated by Low-speed Stirring and Ball-milling

针对传统污泥厌氧消化技术停留时间较长、能耗较高的缺点,采用低速搅拌带动玻璃珠相互挤压、碰撞的方法对剩余污泥进行物理破解,考察了玻璃珠粒径、破解时间、转速、泥珠体积比等对碳源释放的影响。结果表明,SCOD的溶出率随破解时间与转速的增加而增加,但破解时间或转速增加到一定值后,SCOD溶出率增加非常缓慢。当玻璃珠粒径为1~1.5 mm、泥珠体积比为1∶2时剩余污泥的破解效果最佳,在搅拌器边缘线速度仅为1.44 m/s的低速条件下破解3 h,上清液SCOD浓度可达3 770mg/L,氨氮与硝酸盐氮浓度则分别达到25.2、43.7mg/L;相同条件下,延长破解时间至7 h或增加线速度至2.02 m/s后,SCOD浓度仅分别上升10.3%和2.5%,可知污泥碳源释放已接近极限。经粒径分析,污泥破解前、后中值粒径分别为28.114、2.233μm,扫描电镜结果显示,污泥絮体与污泥细胞均被破坏。低速旋流搅拌球磨破解可在较低能耗下实现剩余污泥的碳源充分释放,可为解决剩余污泥处置及低碳氮比污水处理问题提供新思路。

Traditional sludge anaerobic digestion technology has the disadvantages of a long residence time and high energy consumption. Therefore, excess sludge was physically disintegrated by a method of low speed stirring driving glass beads to squeeze and collide with each other, and effects of glass bead size, disintegration time, rotating speed and sludge/bead ratio on carbon source release were investigated. The dissolution rate of SCOD increased with the increase of disintegration time and rotating speed. However, the increase of SCOD was very slow when the disintegration time or speed reached a certain degree. The best excess sludge disintegration performance was obtained when glass bead particle size was 1-1.5 mm and sludge/bead ratio was 1 ∶2. After disintegrated for 3 hours with agitator edge linear speed of only 1.44 m/s, SCOD in the supernatant could reach 3 770 mg/L, and ammonia nitrogen and nitrate nitrogen could reach 25.2 mg/L and 43.7 mg/L, respectively. Under the same reaction conditions, the SCOD only increased by 10.3% and 2.5% after prolonging the disintegration time to 7 hours or increasing the linear velocity to 2.02 m/s, indicating that the carbon source release of the sludge was close to the maximum. Particle size analysis indicated that the sludge median particle size before and after disintegration was 28.114 μm and 2.233 μm, respectively. SEM showed that both the flocs and the cells were destroyed. Low-speed stirring and ball-milling disintegration method can fully release the carbon source of excess sludge at a lower energy consumption, which provides a new idea for solving the problem of excess sludge disposal and low carbon to nitrogen ratio sewage treatment.