Controlling sludge removal from water - by using capillary suction time measurements to control amount of polyelectrolyte coagulant to be added

摘要

To control the water removal from sludge, the capillary suction time of the filtrate is measured successively. The amt. of added polyelectrolyte coagulation agent, to coagulate the solids in the sludge, is set to hold the capillary suction time of the filtrate as short as possible. Pref. amt. of coagulant to be added, according to the measured capillary suction times, uses a multiplication factor of 0.7-1.0 as defined: additive volume ratio (%) = volume of coagulant/solids in the sludge X 100. The capillary suction times of the sludge and filtrate are measured successively, and the coagulant is added at a rate to achieve a max. extraction ratio of: extraction ratio (%) of CST =(sludge CST - filtrate CST)/(sludge CST) X 100. In the appts. for controlling water removal a measurement unit gives successive readings of the capillary suction times at the filtrate and the sludge. The capillary suctions times are used by the control system to set the amount of coagulant to be added according to the readings, to coagulate the solids according to the water removal pattern. ADVANTAGE - Method ensures that the water rate is controlled and measured coagulant additive reduces the water content in the final solid matter to a min..