The Fundamental Research On The Biosorption Of Lead Ions By Aerobic Composting Products And Related Biomaterials

Based on the systemic study to literatures, the effects of lead ions on aerobic composting of municipal organic solid waste was analyzed and discussed according to the biochemical reaction mechanism, the biology characteristics of microorganisms and so on. The transition of chemical form of lead ions was also studied during aerobic composting of municipal organic solid waste. Two kinds of biosorbent - Spent Mushroom Compost and Lentinus edodes were evaluated through removal of lead ions in aqueous solutions.The character and kinetic for the growth of microorganism were investigated in aerobic composting process. It was considered that the growth of microorganism was affected largely by temperature. It showed wave change of growth of microorganism alone with temperature change. Meanwhile, a kinetic model of microorganism growth in the aerobic composting was established based on Logistic model and Malthus model. The model was scientific according to its numerical simulation results being consistent with experiment results and rightly reflected the growth rule of microorganism in the aerobic composting.On condition that the content of lead ions exceeded 600mg/kg, the bioactivity of microorganism in composting was restrained, the process of fermentation was slowed down, however, municipal organic solid waste could decay in a longer time. Chemical form of lead ions varied according to pH of composting products. The bioavailability of lead decreased when pH value increased.A fundament investigation on removal of lead ions from aqueous solutions by the spent mushroom compost was conducted in batch conditions. The Fourier transform infrared spectrometry showed that the functional groups of carboxyl, phosphoryl and phenolic were the main binding sites. The biosoption kinetics followed pseudo-second-order Lagergren model. The experimental parameters such as time contact, pH, biomass dosage and initial lead concentration played important roles on biosorption. The best pH values varied from 4.09-7.00 and the maximum uptake estimated with the Langmiur isotherm model was 714.29 mg/g. The suitable agitation speed and temperature were 150r/min and 30℃,coexisting ions restrained Pb2+ biosorption but Mg2+,Al3+ and Cd2+ benefited Pb2+ biosorption in some range of low concentrations.HCl could be used to desorb laden Pb2+ on the spent mushroom compost.