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WF21 Treatment Process: Lime Recalcination and Solids Handling



Solids that have settled to the bottom of the settling basins - about 30 tons per day - are transported to the sludge thickening basin, then sent to one of two centrifuges in the lime building for further dewatering and sludge separation. Sludge removed in the centrifuge is fed into a 1700° F. furnace for recovery and reuse. Nearly 75 percent of this material is recoverable.

The lime building contains a six-hearth lime recalcining furnace, lime storage bins, centrifuges for dewatering of thickened sludge from the sludge thickener, lime feeders and slakers, carbon dioxide compressors, and a control room. The lime recalcination furnace can recover up to 24 tons of lime per day. Furnace stack gases are cooled and compressed to recover carbon dioxide to be used in the recarbonation process. Dry lime is made into a wet slurry and added to the rapid mix basins.