One of the leading manufacturers of flat glass for special applications is grinding glass with a high silicon content. His facilities include 3 beveling machines. The machines aresupplied with coolant water from a central receiving tank with a capacity of 18,000 l; the total water requirement of all the machines is 6,000 l/h. The resulting glass grit makes its way into the coolant water circuit. Previously the grit had been removed using chemical precipitation with a flocculation aid followed by dehydration with a filter press.