93-05: Chemical Approaches to Zero Blowdown Operation

Complying with increasingly stringent water discharge limitations has forced a re-examination of current cooling water treatment practices. Plants faced with severe effluent restrictions have looked to high cycle or zero-blowdown is discussed in light of current phosphonate/polymer technology and a newly developed non-phosphorus scale control additive. Experiences with treatment programs operating with (pH 7.5-8.0) and without (pH 8.8-9.2) pH control at 40+ cycles of concentration are documented. Field-testing over an 18-month period has identified two viable approaches to zero-blowdown (high eyolo) operation.