PHOSPHORUS REMOVAL FROM HOGGERY SEWAGE USING NATURAL CALCIUM-CARBONATE

For the treatment of hoggery sewage, an attempt was made to develop a phosphorus removal technique by using natural calcareous materials who se products can be restored to farmland as phosphate materials with mi nimal waste, at a low cost and with easy management. The results of te sts on packed materials passing through a water column under the same conditions revealed that the efficiency of phosphorus removal characte ristics was in the order of Sakhalin surf clam > oyster seashell, scal lop seashell > coral sand > fossilized seashell > dolomite for twice t he daily amount of passed water. In brief, young calcareous sources or iginating from marine Conchifera were superior as dephosphorization ma terials. The mechanism involved in phosphorus removal of natural calca reous materials was neither absorption to materials nor crystallizatio n but a direct replacement reaction from carbonates to phosphates. Sin ce the produced salts were CaHCO3 and Ca4H(PO4)(3) With low Ca/P and O H/P ratios, highly valuable phosphates for fertilizer were obtained. S ince the pH of effluents was 8.5 at the maximum and lies within the le gal standard range, the dissolution of carbonates and the production o f phosphates prevent clogging and the total cost is low. If the TOC an d TIC concentrations of influents are high, the TIP concentration in t he effluents easily increases. However, it was demonstrated that 24 h aeration in the presence of sludge results in a decrease of the pH due to accelerated nitrification and that the release of supersaturated C O2 into the atmosphere can lower the TIC significantly.