Conventional clarifiers are generally limited in their performance by the settling characteristics of the biological sludge and hydraulic conditions in the clarifier. In general, secondary clarifier effluent total suspended solids less than 10 mg/L are difficult to achieve consistently. The Hydrograv Adapt variable inlet structure changes that. Unlike traditional inlet structures, mixed liquor is introduced near the bottom of the clarifier below the sludge blanket. In addition the inlet elevation and opening height adapts to the load thus always operating in ideal hydraulic conditions. Embedded in the functioning principal is blanket filtration. Since MLSS is introduced near the bottom of the sludge blanket, all flow has to travel (filter) through the blanket. The results are impressive. At Moers-Gerdt the average annual turbidity for 2015 was 1.5 NTU. To investigate the performance of an HA clarifier under peak load conditions a full scale stress test was conducted at the Moers-Gerdt facility Nov 14th 2017. Pushing 100% of the plant through one of three clarifiers, effluent turbidity never exceeded 1.0 NTU and was closer to 0.5 most of the time.
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