When the treatment plant handles small volumes of sludge, the most common dewatering system is by means of filter bags. It is a stainless steel structure that supports the aforementioned filter bags. The previously decanted sludge reaches the bags by gravity. The function of the bags is to contain the sludge and let the water they contain pass through, the pressure exerted by the weight of the sludge facilitates this filtering. Once the bags are full, the equipment will be replaced with new ones.