Influences of different inoculation methods on fluorescence characteristics of DOM in solid waste composting

In order to determine better inoculation methods of compound microorganisms in solid waste composting, biochemical parameters and dissolved organic matter (DOM) during the process of composting with five different inoculation methods were tested and analyzed. The results show that temperature, pH value, and synchronous fluorescence spectra of DOM in the composting piles of the five deals exhibits a certain trend with composting time increasing, in which macromolecules with complex structures and humic substances gradually increase. Overall, the temperature increases first and then decreases, and pH value is nearly stable at slightly alkaline range by the end of composting. Complex macromolecules and humic substances increase, and DOM properties tend to stabilize. Meanwhile, humification index (IA/IC, %PLF, and %HLF) of the five deals of compost also experienced significant changes. With the decrease of protein-like substances, the content of humus correspondingly increase, i.e. with composting time increasing, low-molecular-weight organic matter in the compost gradually transforms into stable high-molecular-weight humic substances, which suggests increasing aromaticity and distinctive complexity of DOM. From a comprehensive comparison of the relevant parameters and indicators, the deal of inoculating compound microorganisms at the start time or after the high-temperature phase could notably speed up the humification process in solid waste composting.