Whole Effluent Toxicity Evaluation at Recycled Fiber Paperboard Mill Leads to Indirect Discharge to POTW

Whole effluent toxicity (WET) identification and reduction for NPDES compliance continues to be a complex and costly problem for many industrial direct dischargers to solve. WET can be influenced by the test type and organism and the impact and effect of the resultant industry’s water quality including the background water chemistry. A recycled paperboard mill with an industrial water treatment plant to treat process wastewater from the mill prior to discharging to a surface water body, has experienced transient non-compliance issues with their WET NPDES permit limits. This paper describes the steps taken to identify potential sources of the toxicity, test possible treatment remedies, evaluate alternatives to reduce the toxicity, and implement a solution for long term permit compliance. After considering multiple factors, including cost, the preferred alternative to reduce WET non-compliance issues was to indirectly discharge the treated process wastewater to the local publicly owned treatment works.