Based on the screw dewatering, preconcentration device is added which can concentrate the sludge first. It's usd for the sludge with concentration less than 10000mg/L and can increase the capacity.

With all the advantages that list before, it also can make the secondary sludge directly concentrated rapidly and continuously.

The concentration of sludge after concentration and separation is stable and adjustable in the range of 90% to 95%.