Improving Quality of Municipal Solid Waste Compost through Mg-Modified Zeolite

Developing materials to improve the efficiency of fertilizers and increase their performance is one of the main areas of research in the agricultural science. To the best of our knowledge, this is the first time that Mg-modified zeolite is used for modification of composting process of urban organic solid waste. Natural zeolite was clinoptilolite with a particle size smaller than 250 μm modified with MgCl2.6H2O salt. Different ratios (i.e. 5, 10, and 15% , on a weight basis) of natural and/or Mg-modified zeolite were used to modify the Municipal Solid Waste (MSW) compost. Experimental results revealed that the pH of the final compost product with the Mg-modified zeolite was effectively buffered at 7.7. Furthermore, in comparison to the control treatment (without zeolite), the compost with natural and Mg-modified zeolite showed 32.13 and 41.25% reduction in electrical conductivity, respectively. Ammonium retention of the compost containing 15% natural and Mg-modified zeolite was increased by 64.51 and 110.10%, respectively. Metals mobility test of the matured composts also revealed that adding zeolite, especially the Mg-modified zeolite, could decrease the mobility of Cu, Pb, Zn, Fe, Ni, and Mn metals. The most decrease in the mobility of metals was observed in Cu, which was about 44.16 and 47.82%, in the compost with the natural and Mg-modified zeolite, respectively.