Experimental study on sludge dewatering under additives conditioning

Abstract

The water content of sewage sludge is still more than 75% even after thickening and mechanical dewatering. Further water removal should be continued to reduce the volume for the last disposal, so as to weaken sludge harmness and reuse the sludge as resource. It is well known that the sludge mechanical treatment is helpless for further water removal because most of colloid particles in sludge take electric charge, and natural drying needs long period and thermal treatment requires high energy cost. Therefore, to improve the dewatering properties, a new method must be developed. The key difficulty of sludge dewatering is the gelatification among water and solid particles, which leads to the difficult removal of floc water. The way of sludge conditioning can modify the physical and chemical nature of colloid particles, destroy the colloid structure, and reduce the affinity between water and colloid particle. On experiment, it is shown that sludge conditioning by certain additive materials can achieve satisfying result. Important information is obtained from experiments: (1) Additive materials takes an obvious effect on sewage sludge dewatering; (2) the dewatering effect is affected by the temperature, humidity, and ventilation etc around test-bed; (3) the dewatering product properties of conditioning sludge is improved.