Variations in Microbial Flora in Different Phases of Refuse in Response to Dibutyl Phthalate

Simulated municipal solid waste (MSW) based on the actual proportional characteristics of MSW was loaded into a simulated leachate recirculation bioreactor landfill and the abundance of common and tolerant microbes exposed to dibutyl phthalate (DBP) were investigated in the initial, acidic and methanogenic phases. The results showed that the abundance of bacteria was greatest, while that of actinomycetes was smallest. The growth of microorganisms was not significantly inhibited by DBP during the initial phase; however, the growth of actinomycetes and fungi was inhibited during both the acidic and methanogenic phases, and the inhibition of actinomycetes was greater than that of fungi. When the DBP concentration was 5.0 g l, the inhibition ratio against actinomycetes was 89.5% and 80.9% in the refuse from the acidic phase and methanogenic phase, respectively, while it was 86.2% and 51.0%, respectively, against fungi during the same period. The toxic effects of DBP on microorganisms in refuse occurred in the order of actinomycetes > fungi > bacteria. In addition, the populations of bacteria, fungi and actinomycetes were significantly and positively correlated with dehydrogenase activity, but negatively correlated with the VSS and BDM of refuse (P<0.01).