Comprehensive Approach to Minimizing Paper Mill Effluent Total Suspended Solids, 1993 Environmental Conference Proceedings

A corrugating medium mill in central Ohio was experiencing serious solids carryover from their secondary clarifiers, resulting in high effluent Total Suspended Solids (TSS) levels. The mill’s waste treatment plant consisted of a primary clarifier, followed by two single pass aeration basins operated in series, two secondary clarifiers operated in parallel, and a sludge dewatering system. Following an annual maintenance outage in October, 1991, the effluent quality gradually deteriorated to the point of impending permit non-compliance in May, 1992.

In late May, 1992, a comprehensive systems management plan was implemented with the immediate goal to meet permit compliance during June. A secondary goal was to obtain TSS levels to meet a self-imposed plant goal of 65% of the permitted value. The program was designed to address all aspects of the wastewater treatment plant operation. Specific action areas included:

1) Optimization of primary clarifier operation.

2) Improve twin-belt press performance to reduce filtrate solids recycled to primary clarifier.

3) Improve control of nutrient addition.

4) Optimization of bacterial population via bioaugmentation.

5) Evaluate efficacy of polymer addition to secondary clarifiers.

6) Conduct biological tracer study to verify system retention time.

For the four months prior to May, 1992, the average daily TSS was at 97.4% of permit level. Compliance was re-established in June, despite high TSS levels early in themonth. Four weeks after implementing the total system management program, the average TSS level for July was 40% of permit.