Sludge dewatering pretreatment system and combined recovery system and method adopting same

The invention provides a sludge dewatering pretreatment system and a combined recovery system and method adopting the same. The sludge dewatering pretreatment system comprises a sludge feeding unit, adewatering unit and a tank bottom circulating-atomization unit which are sequentially connected; the sludge dewatering pretreatment system further comprises a water cutting unit connected with a sewage outlet of the dewatering unit; an inlet of the tank bottom circulating-atomization unit is connected with a bottom outlet of the dewatering unit, and an outlet of the tank bottom circulating-atomization unit is connected with a sludge return port of the dewatering unit. By adopting the dewatering pretreatment process, a large amount of oily water-containing sludge such as scum is subjected to appropriate reduction treatment, the treatment load and the technical requirements on the sludge in a large steam blowing stage of a coking device are also met, and harmless treatment and resourceful utilization of the sludge