METHOD OF CONTROLLING SLUDGE YIELD AND PROPERTIES IN A PROCESS FOR SELENIUM REMOVAL FROM WASTE WATER

摘要

Disclosed is a method of controlling the properties and yield of sludge in a process for removing selenium from a selenium-contaminated water stream to yield treated water having an ultra-low selenium concentration. The process includes two iron addition steps. The first step includes mixing ferric salt with the contaminated water that is followed by a second step of mixing ferrous salt with the mixture from the first step. The pH of the second step mixture is controlled within a range to give iron precipitate sludge having certain desired settling and compaction properties. The second step mixture then undergoes separation of the iron precipitate sludge from the treated water.