TA and CTAB treatment synergistically enhance activated sludge dewatering by lowering proteins and boosting Zeta potential

Waste activated sludge (WAS) is produced by urban sewage treatment plants, which contains pathogenic microorganisms, chemical elements, wiht high moisture content (>99%). To mitigate environmental pollution and reduce the volume of WAS, sludge dewatering are widely needed. The main objective of this study is to investigate the improvement in sludge dewaterability through the combined efficacy of tannic acid (TA) and cetyltrimethylammonium bromide (CTAB). Significant reductions in Capillary Suction Time (CST), Specific Resistance to Filtration (SRF), and moisture content of vacuum-filtered sludge cake (WC) were observed as experimental findings demonstrated the combined use of TA and CTAB. Specifically, CST decreased from 78.6s to 15s, SRF reduced from 1.12×1013m/kg to 2.23×1012m/kg, and WC decreased from 97.98% to 74.80%. The levels of polysaccharides and proteins present in various layers of the extracellular polymeric substances (EPS) within the sludge were reduced due to the interaction and formation of protein complexes with TA and CTAB. Additionally, these additives neutralized surface with a negative electrical potential of EPS, decreasing repulsion among sediment particles. This led to a decrease in the Zeta potential, while the contact angle and particle size of the sludge increased. Additionally, the hydrophobicity of the sludge particles was enhanced. As a result, intracellular moisture was released by disrupting the sludge cells. The findings presented here may assist in the development of sustainable and productive strategies for the management of sludge, ultimately promoting environmental protection and the well-being of urban communities.