METHOD FOR MINIMISING THE NEW WATER USE IN THE WATER CIRCULATION SYSTEM OF A TREATMENT PLANT

摘要

The invention relates to a method for minimising the new water use in the water circulation system of a treatment plant. The material to be treated is purified and/or disintegrated by means of water in a treatment step. The suspension containing the remaining components is subjected to mechanical purification and the mechanically purified suspension is separated into two process water streams. The first process waters stream is supplied back into the treatment step and the second process water stream is subjected to a chemical-physical clarification. The chemically-physically clarified process water stream is separated into two clear water streams. The first clear wate r stream is led into one of the two process water streams and/or into the suspension and the second clear water stream is subjected to a biological clarification. The biologically clarified clear water stream being a fresh water stream is led in one or two clear water stream/s. The ratio between th e process water streams and the clear water streams has been determined before according to the material that is supplied to the treatment step and the kin d of the mechanical purification and the kind of the chemical-physical clarification.