A novel approach to calcium removal from calcium-rich industrial wastewater.

Calcium-rich wastewater is a problem for industries due to calcification during downstream processing. The potential for Ca2+ removal from industrial wastewater through ureolytic microbiological carbonate precipitation was investigated for the first time. Batch experiments were used to determine feasible urea concentrations and hydraulic retention times. These results were applied in a semi-continuous reactor system, where the emphasis was placed on the development of a calcifying sludge. Calcium removal in excess of 90% was achieved throughout the experimental period, while the effluent pH remained at a reasonable level.