Filtering industrial sludge - with recovery of filtrate for use as eg cooling water when quality is satisfactory

摘要

A filtration method, esp. for effluents contg. sludge and for thin slurries, using pressure filters of known type with disc filter elements and with blank plates arranged upstream of the first element and/or downstream of the last element, as in the parent patent, is improved so that water is recovered for re-use from the filtrate flow. For this purpose, the salt concn. and/or the turbidity of the filtrate are measured downstream of the filter and the water recovery operation is regulated as a function of these measured parameters. The method is partic. applicable to the recovery of filtrate for use as industrial water, e.g. for cooling or flushing, as an economic substitute for mains' water.