Enhanced sludge dewatering and calorific value performance using non-thermal drying with sludge-derived hydrochar

The challenge associated with the deep dewatering process of sludge is a key factor restricting the efficiency of subsequent treatment and disposal processes. The moisture content directly affects the treatment amount, and it is also a mandatory index for primary sludge treatment. This study focuses on the effectiveness of dewatering via the addition of sludge-derived hydrochar (HC) to alter the dewatering performance of the sludge and provide a stable drainage channel. Following the addition of HC450°C, the moisture content of the filtrated sludge cake decreased to less than 50%, and the calorific value increased by 7.26%. Combined with traditional thermal drying prior to incineration, the hydrothermal process + deep dewatering pretreatment resulted in a reduction of 52.88% in energy consumption. Sludge-derived HC addition resulted in a stable and connected drainage gallery, and the colloid stability of the added sludge was deconstructed, contributing to a significant improvement in dehydration performance. The preparation of dehydration aids from the sludge to be treated complies with source reduction and provides a green, efficient, and sustainable option for pretreatment before sludge incineration.