Clarifier Enhancements Yield Excellent Performance

The critical role of final clarifiers in meeting effluent permit requirements in indisputable. Poor performance of the final clarification step may adversely affect effluent quality. Experience has shown that effluent quality produced by conventional final clarifiers typically meets the secondary effluent requirements of 30 mg/L BOD and 30 mg/L TSS. However, recent enhancements to final clarifier design have been shown to significantly improve performance over conventional units to the point that filtration may not be required to achieve a high quality effluent. An eight-month full-load demonstration test was conducted at the Jacksonville, Illinois WWTP to establish the capabilities of new final clarifiers to produce an effluent meeting limits of 10 mg/L BOD and 12 mg/L TSS. The test demonstrated that the Black & Veatch clarifier design can produce a high quality effluent which meets stringent effluent limits. As a result, significant cost savings may be realized if effluent filtration can be avoided.