摘要 |
For the treatment of wastewaters containing substantial BOD and substantial calcium ion concentrations, e.g., effluents from the washing and flushing cycles of sugar manufacturing plants, by an activated sludge process, under aeration with an O2-containing gas, the improvement which comprises introducing a CO2-containing gas having a concentration of CO2 higher than that of air into liquid present in the activated sludge system to precipitate calcium ion as calcium carbonate thereby lowering the pH of the liquid and facilitating the separation of the activated sludge solids and the bacterial action of the activated sludge process.
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