This invention is by mixing red clay and inorganic acid, after passing through simple reaction by immersion, one coagulant containing insoluable complex particles and other effective components is obtained, which can be used to treat PH values from 7 to 13 sewerage for quick sedimentation, easy dehydration of mud and to meet requirements for discharging through the outflow. Thus, problems of existing coagulant, such as complicated in both processing and mfg., high cost and low quality of the mud obtained etc.can be solved. |