| Title |
Phosphorus Release from Waste Activated Sludge by Microwave Heating |
| Authors |
양회원 ( Hoiweon Yang ) ; 안조환 ( Johwan Ahn ) ; 김장호 ( Jangho Kim ) ; 민성재 ( Sungjae Min ) ; 김정환 ( Junghwan Kim ) |
| DOI |
https://doi.org/10.15681/KSWE.2017.33.4.387 |
| Keywords |
Crystallization; Magnesium ammonium phosphate (MAP); Microwave heating; Microwave irradiation; Phosphorus release |
| Abstract |
Chemical batch tests were conducted to evaluate if microwave heating enhances phosphorous release from waste activated sludge (WAS) at pH 2.5, 5, 7, 9 and 11. Polyphosphate-accumulating organisms have a unique physiological feature, which releases intracellular polyphosphate granules when they are exposed under high temperature environments. Microwave irradiation was found to encourage large amount of phosphorus release from WAS, depending on pH and temperature conditions. Most of phosphorus was released below 59 °C within 30 min. A marked increase in phosphorus release was observed under alkaline or acidic conditions. However, based on control tests for phosphorus release under different pHconditions without microwave heating, the largest amount of phosphorus released by microwave irradiation was found at pH 7, followed by 5, 9, 11. On the other hand, crystallization was conducted to obtain magnesium ammonium phosphate (MAP) from phosphate released by microwave heating at pH 7. X-ray diffraction analysis confirmed that the recovered crystallinematerials were MAP. MAP is an environmentally friendly fertilizer, which slowly releases ammonia and phosphorus in response to the demand of plant root. Thus, the recovered MAP as a phosphate fertilizer is fully expected to play a important role in the reduction of agricultural non-point pollution. |