Waste to worth: A new approach to treat wastewater sludge

Abstract

In response to the difficulty and high cost of wastewater sludge treatment, we proposed a new approach capable of carbon reduction and resource utilization. The approach can carbonize wastewater sludge and corn stalks, synergize their processes, and the sludge carbonization product s (SCP) can be further recycled for sludge dewatering. The results showed that SCP could provide skeleton support in the sludge, established drainage channels and synergistically improved the dewatering performance of wastewater sludge with aluminum salt enhancer (ASR), reducing the moisture content of the sludge cake to 55 %. Moreover, the thermal energy generated by carbonization of the corn stalks maked up for the lack of sludge drying carbonization, with the excess generating 541 kWh of electricity per hour. In addition, straw charcoal can be used for exhaust gas treatment of the system, and can also be sold together with SCP as soil amendment and adsorbent. This co-processing allowed for 1.2 tons of sludge (absolutely dry) to be processed for every 1.5 tons of stalk, fixing 26.7% of the carbon in the sludge. Overall, this approach achieved an 88 % reduction in volume per ton of sludge (80% water content), a 25.35 kg reduction in greenhouse gas emissions and a reduction in disposal costs to less than $20.