Abstract: A process is for removal of suspended solids including resin and fatty acids from pulp mill effluents including Chemi-Thermo-Mechanical Pulp (CTMP) mill effluents. The process involves filtration of untreated or primary treated effluents through a mat of primary sludge, pulp or woodroom sludge. A sludge mat is formed on a wire screen or punched drum and the effluent to be treated is filtered through the mat. Most of the suspended solids and a part of colloidal material and dissolved solids are retained by the mat. Following the filtration stage, the sludge is dewatered and removed. A portion of the sludge is recycled to form the mat for the next filtration cycle, while the excess sludge is purged. The filtration is achieved by the application of vacuum below the filter mat or pressure over mat.

Abstract: A multi-step method is provided for the purification of waste water, especially pulp mill effluents. It comprises a number of steps carried out in a specific sequence. The first step involves passing an oxygen-containing gas through the waste water while the waste water is in intimate contact with a finely divided activated carbonaceous material, preferably including, as a preliminary step, the addition of the finely divided activated carbonaceous material to the waste water. The second step involves adding a clarification agent selected from one or more of a coagulant, a flocculant, and a polyelectrolyte to the treated waste water provided by the first step. The third step involves recovering a solids-free effluent by known means, e.g.