Comparison of physicochemical parameters during the forced-aeration composting of sewage sludge and maize straw at different initial C/N ratios.

The composting of sewage sludge and maize straw was investigated in forced-aeration composting systems at initial C/N ratios of 14, 20, and 25, respectively. The temperatures of composting mixture with initial C/N ratios of 25 and 20 could meet the requirement of destroying pathogens. The final electrical conductivity (EC) of composting mixture with initial C/N ratios of 20 and 25 did not exceed the limit value of 3000 microS cm(-1), and the NH4(+)-N content of composting mixture with an initial C/N ratio of 14 did not meet the limit value of 400 mg kg(-1). The final NO3(-)-N and germination index (GI) of composting mixture with an initial C/N ratio of 25 were higher than those of composting mixtures with initial C/N ratios of 14 and 20. The Fourier transform infrared (FTIR) spectra of composting mixtures in the three composting mixtures showed the same changing pattern during the composting.