ABSTRACT
The effects of material filling rate, heat source temperature, and dryer speed on sludge drying characteristics, energy consumption, and pollutant release were studied in the vacuum drying experiment using a vacuum rake dryer. The results show that the drying rate rose with the increase in heat source temperature and dryer speed. Dry exhaust odor concentrations were between 500 and 900. When the temperature of the heat source was higher than 125°C, the odor concentration rose sharply. The concentrations of TP, NH4 +-N, and SS in the dried condensate met the first-level standard B of the discharge standard of pollutants for municipal wastewater treatment plants (GB 18918-2002). The COD concentration in the dried condensate was about 400-700 mg/ L, without an obvious correlation with the temperature. The NH4+-N increased with the heat source temperature. The drying cost per unit mass of water was 0.31 and 0.26 yuan/kg when the moisture contents were 10% and 50%, respectively, and the average energy consumption was 2925kJ/kg.
