Combined organic reagents for co-conditioning of sewage sludge: High performance in deep dewatering and significant contribution to the floc property

In this study, we have examined a new all-organic conditioning method for sewage sludge pretreatment, featuring the combined use of poly dimethyldiallylammonium chloride (PDMD) and tannic acid (TA). The impact of the reagents and the specific dosing order were identified for process optimization. Results showed that TA + PDMD mode (i.e., TA addition followed by PDMD) has better sludge filterability and dewaterability. With the optimal dosage, it decreased specific resistance of filtration by 90.60%, capillary suction time by 65.08%, and reduced moisture content of dewatered sludge cake to 53.46%, giving the highest dewatering performance reported so far. In addition, a significant positive correlation was found between viscosity and dehydration performance (Rp = 0.9898, p