ABSTRACT
This chapter presents a case history describing the process used to upgrade an inadequate pretreatment system to meet new, more stringent discharge standards. The modification of the system includes incorporation of several innovative treatment technologies to achieve program goals. The chapter also presents the technical approach used to identify causes of system failure and potential solutions. The original pretreatment system used lime for pH adjustment and precipitation of metal hydroxides. Polyelectrolyte was used as a flocculation aid prior to clarification. Sodium sulfide precipitation of metals polished the clarifier effluent prior to sand filtration. The inconsistent operation of the pretreatment system prevented Radian Corporation from relying strictly on field observations to evaluate system potential. Initial observations indicated that the chemical addition-flocculation process was a weak link in the existing system. The investigation conducted by Radian Corporation determined that the root cause of permit non-compliance and equipment failure was due to waste specific factors.
