Aerobic Municipal Solid Waste Compost Quality According to Different Layers of Composting Bioreactor
Composting is one of the methods of solid waste management (SWM) where the organic component of solid waste stream is biologically decomposed under controlled conditions. A bioreactor tank was designed to contain 59.2 kg of mixed organic municipal solid waste, the organic matter was degraded under aerobic condition for 30 days. The tank was 45 cm in diameter, 130 cm total height and a 0.2 cm wall thickness. Three circular openings with screwed cover having diameter of 12 cm were leveled at (20, 40 and 80) cm respectively to withdraw samples. Temperature, moisture and pH were measured for three layers as process guideline indicators. Maximum temperature ranged between (34.79 to 46.91) ºC. Initial pH value was 6.53, ended within a range of (7.4 to 7.44). Chemical analysis for the composts in the three levels proved that the final C/N ratio ranged between (13.8 to16.1), TOC ended within a range of (17.33% to 25.24 %), final nitrification index (N-NH4/N-NO3) ranged between (0.22 to0.31), final of P% ranged between (0.89% to 1.23%), final of K% ranged between (1.69% to 1.81%) and results of germination index (GI %) ranged between (76.54%, to 88.35%) for three layers respectively. At the close of the experiment results proved that aerobic in-vessel composting could reduce the large amounts of wastes by 40% as a total mass. A satisfactory degree of decomposition was apparent in all levels, and the material was characterized by a pleasant earthy odor, and the obtained compost can be classified as mature compost. In conclusion, the three different layers do not have much effect on the quality indices of the final product.