Simple model of sludge thickening process in secon

Authors: Yuankai Zhang Hongchen Wang Lu Qi Guohua Liu Zhijiang He Songzhu Jiang

Publish Date: 2014/11/22

Volume: 10, Issue: 2, Pages: 319-326

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Abstract

In wastewater treatment plants WWTPs a secondary settler acts as a clarifier sludge thickener and sludge storage tank during peak flows and therefore plays an important role in the performance of the activated sludge process Sludge thickening occurs in the lower portions of secondary clarifiers during their operation In this study by detecting the hindered zone from the complete thickening process of activated sludge a simple model for the sludge thickening velocity u s = aX b a = 09925SSVI 35 b = 3541lnSSVI 35+12973 describing the potential and performance of activated sludge thickening in the hindered zone was developed However sludge thickening in the compression zone was not studied because sludge in the compression zone showed limited thickening This empirical model was developed using batch settling data obtained from four WWTPs and validated using measured data from a fifth WWTP to better study sludge thickening To explore different sludge settling and thickening mechanisms the curves of sludge thickening and sludge settling were compared Finally it was found that several factors including temperature stirring initial depth and polymer conditioning can lead to highly concentrated return sludge and biomass in a biologic reactor

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