Development of An Adsorbent Derived From Concrete Sludge for Phosphorus Recovery From Waste Water

A solid adsorbent for phosphorus recovery was prepared from concrete sludge. Concrete sludge was diluted with water with dilution ratios ranging from 1 to 15. The diluted concrete sludge was then filtered and dried. Two types of drying methods were examined: natural drying under atmospheric conditions and forced drying in an oven at 105^oC. The phosphorus recovery performances of prepared adsorbents were examined using a potassium dihydrogen phosphate (KH₂PO₄) solution containing 100 mg-P/L as a model of wastewater, which is close to the water effluent produced in the sewage sludge dewatering process. All the adsorbents prepared showed phosphorus recovery performance. The forced drying treatment at 105^oC significantly increased the phosphorus recovery rate from the solution. The adsorbent prepared with dilution ratio 10 and forced drying showed the highest phosphorus recovery rate. The final phosphorus concentration in solution was 0.83 mg/L at 4 h from the addition of the optimized adsorbent. These results indicate that the phosphorus adsorbents prepared from concrete sludge are applicable for practical and inexpensive phosphorus recovery processes.