Improvement of sludge dewaterability with modified cinder via affecting EPS

Highlights

The organic matters decreased during the conditioning with cinders.

The modified cinder could improve the dewaterability via affecting EPS.

Variation of EPS disintegrated sludge floc especially for ACMC addition.

ACMC promoted the reconstruction of sludge floc as skeleton builder via adsorption.

The reconstruction mechanisms included charge neutralization, adsorption bridging.

Abstract

The relationship between the improvement of sludge dewaterability and variation of organic matters has been studied in the process of sludge pre-conditioning with modified cinder, especially for extracellular polymeric substances (EPS) in the sludge. During the conditioning process, the decreases of total organic carbon (TOC) and soluble chemical oxygen demand (SCOD) were obviously in the supernatant especially for the acid modified cinder (ACMC), which could be attributed to the processes of adsorption and sweeping. The reduction of polysaccharide and protein in supernatant indicated that ACMC might adsorb EPS so that the tightly bound EPS (TB-EPS) decreased in sludge. In the case of ACMC addition with 24 g·L⁻¹, SRF of the sludge decreased from 7.85 × 1012 m·kg⁻¹ to 2.06 × 1012 m·kg⁻¹, and the filter cake moisture decreased from 85% to 60%. The reconstruction of “floc mass” was confirmed as the main sludge conditioning mechanism. ACMC promoted the dewatering performance through the charge neutralization and adsorption bridging with the negative EPS, and provided firm and dense structure for sludge floc as skeleton builder. The passages for water quick transmitting were built to avoid collapsing during the high-pressure process.

Graphical abstract

Keywords

Sludge conditioning / Acid or alkali modified cinder / TB-EPS / Floc mass / Floc reconstruction

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Acknowledgments

Support for this research is provided by the National Science & Technology Pillar Program of China (No. 212BAC05B02), the National Natural Science Foundation of China (Nos. 5117834 and 5378141), Program for New Century Excellent Talents in University, Ministry of Education of China (Grant No. NCET-13-0180), State Key Laboratory of Pollution Control and Resource Reuse Foundation (Grant No. PCRRF13003), Postdoctoral Science-Research Developmental Foundation of Heilongjiang Province (Grant No. LBH-Q12107), and the National Engineer Research Center of Urban Water Resources.

Electronic Supplementary Material

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