Abstract: A novel synergistic conditioning process using microwave and electron beam irradiation was proposed to solve the problems of low dewatering efficiency and easy secondary pollution in traditional municipal sludge conditioning technologies. Municipal sludge with a moisture content of 87.04% from Sijiqing Sewage Treatment Plant in Huai’an City was used as the test material. Single-factor tests and orthogonal tests were carried out to investigate the effects of microwave power, microwave time, electron beam irradiation dose and irradiation sequence on sludge dewatering performance. The performance of different conditioning methods were compared by pressure filtration tests. The results show that electron beam irradiation dose and microwave time are significant factors affecting sludge dewatering performance (P<0.05). Under the optimal conditions of microwave followed by electron beam irradiation, microwave power of 200 W, microwave time of 30 s and electron beam irradiation dose of 9 kGy, the capillary suction time and specific resistance of the sludge are significantly decreased, and the moisture content of the filter cake is as low as 49.06%. This synergistic conditioning process does not require the addition of chemical reagents and generates no secondary pollution. It exhibits better dewatering performance than traditional chemical conditioning methods and can serve as a technical reference for the deep dewatering of municipal sludge.

Key words: sludge conditioning, microwave irradiation, electron beam irradiation, dewatering performance