The study of Na2SiO3 as conditioner used to deep dewater the urban sewage dewatered sludge by filter press

In this paper, Na2SiO3 as new conditioner were used to adjust the urban sewage-dewatered sludge (UDSS). By observing the changes of the dehydrate rate of UDSS with Na2SiO3 and without Na2SiO3, the dewatering effect of Na2SiO3 was studied. The results showed when Na2SiO3 was used alone, it had no effect on improving the UDSS's dewatering performance. However, under the effect of FeCl3, Na2SiO3 can improve the dewaterability of UDSS. Besides, in order to determine the optimal conditions of Na2SiO3 and FeCl3 used in UDSS dewatering, the influence factors in the process of dehydration were all systematically studied, including the dosage of FeCl3, molar ratio of Si/Fe, the sequence of adding conditioner. The compound use of FeCl3, Na2SiO3 and fly ash was also investigated, which could further reduce the moisture content of the filter cakes to about 45%. At last, to analyze the role of Na2SiO3 in adjusting the UDSS, the Zeta potential and inner structure of UDSS conditioned by Na2SiO3 and FeCl3 were both studied. The results indicated that the networks structure produced by PAM in the UDSS was destroyed and a new kind of new networks structure was generated by Na2SiO3, which could improve the dewaterability of UDSS. (C) 2016 Elsevier B.V. All rights reserved.