Removal of Phosphorus from Swine Wastes Using Calcium Carbonate

News source: National Institute of Agro-Environmental Sciences, Japan
For further information: JARQ 32, 23-30, 1998, 2001-01-01

Clam Shells Most Effective Material

For the treatment of swine wastes, an attempt was made to develop a phosphorus removal technique, using natural calcareous materials. These can be applied to farmland as phosphate materials with minimal waste, at a low cost and with easy management. The results of tests on packed materials passing through a water column under the same conditions revealed that the efficiency of phosphorus removal was in the order of Sakhalin surf clam > oyster seashell > scallop seashell > coral sand > fossilized seashell > dolomite, for twice the daily amount of passed water. In brief, recent calcareous materials originating from marine Conchifera were superior as dephosphorization materials.

Materials Can Be Used As Fertilizer

The mechanism involved in phosphorus removal of natural calcareous materials was neither absorption to materials nor crystallization, but a direct replacement reaction from carbonates to phosphates. Since the produced salts were CaHCO3 and Ca4H(PO4)3 with low Ca/P and OH/P ratios, highly valuable phosphates for fertilizer were obtained. The pH of the effluent was a maximum of 8.5, which lies within the legal standard range. The total cost is low.

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