Evaluation of Heavy Metals Content in Simulated Solid Waste Food Compost

Abstract

Composting is one of the solid waste management (SWM) methods where the organic component decomposed biologically under controlled conditions. In this study, a 0.166 m³ bioreactor tank was designed to compose 59.2Kg of simulated common municipal solid food waste having a bulk density, organic matter, organic carbon, pH, nitrogen content, C/N and nitrification index (NH₄-N/ NO₃-N) of 536.62 kg/m³, 62.34%, 34.76%, 6.53, 1.86%, 23 and 0.34 respectively. The bioreactor operated aerobically for 30 days, and anaerobically for 70 days, until the end of the composting process. Results proved that the composting process could reduce the mass of the waste by 69%.  Nitrogen content, C/N, nitrification index, NPK, and germination index (GI) were found to be 1.52%, 14.54, 0.31, 1.52%, 1.53%,0.85 % and 85.5% indicating that the obtained compost is stable and mature according to the standards. Twelve heavy metals of Zinc (Zn), Cupper (Cu), Molybdenum (Mo), Zirconium (Zr), Strontium (Sr), Rubidium (Rb), Manganese (Mn), Scandium (Sc), Iron (Fe), Titanium (Ti), Calcium (Ca) and Potassium (K) were detected by using Niton (XRF) device. Results of Cu and Zn were within the limits of the standards, while the rest were considered acceptable as standards did not restrict them.