Effects of acid-heat combined treatment on sludge dewatering performance at low temperature

College of Environmental and Energy Engineering, Anhui Provincial Key Laboratory of Huizhou Architecture, Anhui Jianzhu University, 230000 Hefei, Anhui, China

Abstract

The effects of different initial pH value, temperature and heating time on sludge dewatering performance were studied by treating sludge with acid-heat combination at low temperature and taking dewatering rate (amount of filtrate per unit time) and dewatering degree (moisture content of mud cake) as indexes to evaluate the sludge dewatering performance. And the mechanism of action was preliminarily discussed by analyzing the concentration of SCOD, protein and polysaccharide in sludge supernatant, Zeta potential and floc morphology of sludge. The results showed that the concentration of organic matter in sludge supernatant increased significantly when the sludge was treated by acid-heat combination, which indicated that the method promoted the fragmentation and dissolution of sludge flocs, and the internal bound water was released more, at the same time, the decrease of Zeta potential and the increase of temperature were beneficial to the flocculation of sludge, which effectively improved the degree and rate of sludge dewatering. The optimal conditioning conditions were determined as follows: pH 3, temperature 90°C and heating time 40 min. Under such condition, the sludge dewatering rate reached 21.30 ml/min and the moisture content of mud cake decreased to 63.20%.