The Effect of Digester Stability and PAD-THP on Dewatering

Biosolids handling cost can be a significant part of the overall budget at a wastewater treatment plant. An efficient dewatering is of importance for reducing the amount of water in the final biosolids product, hence reducing the quantity of product that needs to be handled. Bound extracellular polymeric substances (EPS) was assessed by microscopic evaluation and compared to dewatering performance. Disturbance in anaerobic digestion (AD) performance showed an increase the production of bound EPS, and a reduction in the amount of free water. Both factors lead to deterioration of final dewatering performance. Digestion of hydrolysed raw sludge reduced the dewatering potential compared to direct dewatering of hydrolysed raw sludge. Application of Post-AD THP (PAD-THP) regained this potential, significantly improving dewaterability of the digestate.

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