ZHANGYan-ping,ZHENGSong-chao,SUNXue-meng,et al.Heat Modified Sludge from Waterworks Combined with Its Acid Extract Conditioning to Promote Excess Sludge Dewatering[J].China Water & Wastewater,2023,39(13):39-46.
Heat Modified Sludge from Waterworks Combined with Its Acid Extract Conditioning to Promote Excess Sludge Dewatering
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第39卷
Number:
第13期
Page:
39-46
Column:
Date of publication:
2023-07-01
- Keywords:
- sludge dewatering; sludge from waterworks; acid extract; skeleton construction; fractal dimension
- Abstract:
- This paper used heat modified sludge (HMS) from waterworks combined with its acid extract to condition excess sludge, and investigated the effect of the combined conditioning on sludge dewatering performance and its mechanism, so as to improve the dewatering performance of excess sludge. When the dosages of HMS and acid extract were 30% and 8 mg/g, the capillary suction time (CST) and specific resistance to filtration (SRF) of sludge were reduced to 10.3 s and 0.83×109 s2/kg, respectively. Compared with conditioning by FeCl3 combined with HMS, the CST and SRF were further reduced by 48.8% and 37.3%, and the dosage of agent was reduced by 60%. In the conditioning process, HMS served as the skeleton particle, which reduced the sludge compression coefficient from 1.39 to 0.82, and improved the water permeability of the sludge. The cations such as Fe, Al and Ca in the acid extract were conducive to increase the volume and compact the structure of the sludge flocs, and increased the fractal dimension from 1.29 to 1.65. The cations dissolved by the acid extract and HMS neutralized the negative charge on the surface of the sludge, and increased the Zeta potential to 0.15 mV, which was conducive to the agglomeration and dewatering of the sludge flocs. Under the combined action of HMS and acid extract, the total content of extracellular polymer (EPS) decreased (30.9% for polysaccharide and 36% for protein), which was accompanied by the conversion of tightly bounded EPS (TB-EPS) to loosely bounded EPS (LB-EPS) and soluble EPS (S-EPS), indicating that the dewatering property of sludge was greatly improved. After the sludge was conditioned by HMS combined with acid extract, the turbidity and SCOD in supernatant were reduced by 86.9% and 73.2% respectively compared with the raw sludge, which was conducive to subsequent treatment.
Last Update:
2023-07-01