Compositing of municipal sewage sludge using semifermented solid waste and grass cuttings

Composting is more beneficial compared to that of other disposal methods likeincineration, land filling ? dumping because the sludge volume decrease by 40 ? 50 % andis sterile due to reductions in pathogenic microorganisms.The objective of this study was to examine the capability (and possibility) of sewagesludge and further its agricultural use. Aerobic composting of the sewage sludge wasinvestigated by two different mechanisms in three different experiments. In the regard,grass cuttings from university gardens, sewage sludge from zmir ? Çigli WastewaterTreatment Plant, and semi fermented solid waste which were taken from zmir ? UzundereCompost Plant were used. In 1st and 3rd studies, semi fermented solid waste and sewagesludge were mixed in different rates and systems. In 2nd study, sewage sludge, semifermented solid waste and grass cutting were mixed.During the study, moisture, organic matter, temperatures, C/N ratio, pHs were determined.Primary macro (P, K), and secondary plant nutrients (Fe, Cu, Zn, Mn), heavy metals (Cr,Ni) were also measured to investigate for agricultural use of final product.Results revealed that the method used in Experiment 1 did not end with the expectedcompost product. However, Experiment 2 and Experiment 3 resulted with a better compostwhile Experiment 2 being the best in this respect. Effect grass cuttings used in Experiment2 on composting was positive. Heavy metal contents of the final products were also belowthe standard values given in the Turkish Regulation of Soil Pollution Control.