Key Indicators For Municipal Solid Waste Landfill Stabilization Process

There are various parameters used to indicate the stabilization process of MSWlandfill in China and in the world and hasn’t formed a set of unified system. Based onthe indoor-simulation test of MSW landfill and re-analysis of related research datafrom literatures, this paper screened and ascertained the key indicators and criteria forMSW landfill stabilization process. Firstly, through the dynamic variation andcorrelation analysis of stabilization indicators under different operation modes ofsimulation test, key indicators were screened. And then, according to their dynamicvariation characteristics, MSW landfill stabilization process was divided to differentphases and the criteria were presented meanwhile. Furthermore, by means ofre-analysis of related research data from literatures, the criteria proposed in this paperwere confirmed and checked. Finally, the criteria of key indicators for MSW landfillstabilization process were ascertained.The result displayed that volatile solid （VS）, biodegradable matter （BDM）,cellulose （C） and cellulose/lignin （C/L） of waste composition could be the importantindicators to reflect MSW landfill stabilization process. And there were positivecorrelations among them, which were enhanced by bioreactor landfill. BOD5, CODCr,TOC, NH₃-N, TN and B/C of leachate quality could indicate the stabilization processof landfill. There were nice positive correlations among BOD5, CODCrand TOC; ahigh positive correlation between NH₃-N and TN; a good positive correlationbetween B/C and BOD5; a certain correlation between B/C and NH₃-N, which wassubject to the specific operation modes. Thus, dynamic variation of B/C could standfor the attenuation situation of BOD5, CODCrand TOC, and reflect the changeprocess of NH3-N and TN to some extent. Settlement change of surface settlement （S）which reflected the degradation law of waste macroscopically, could not be amacro-indicator to show the stabilization process of landfill. So surface settlementrate （S′） was chosen to be the macro-indicator. In the end, BDM, B/C and S′wereselected to be key indicators for MSW landfill stabilization process, which BDM and B/C belonged to biological indicators and their dynamic variation showedexponential attenuation and corresponded well with first order reaction kinetics.Landfill stabilization process was divided to unstable, semi-stable and stable3-phase, corresponding to the different criteria of key indicators. Criteria of BDMpresented in this paper could represent the degradation situation and stabilizationdegree of waste from different regions and practical landfills in domestic. Criteria ofB/C correlated closely with the characteristic value of B/C from leachate of differentstabilization stages of traditional landfill and dissimilar landfill ages. Moreover, itaccorded with the variation law of leachate organics of practical landfills. Criteria ofS′was similar to the existing criteria. Finally, the criteria of MSW landfillstabilization process were ascertained as follows: when it’s in unstable phase,BDM>16%, B/C>0.4, and S′>40cm·a^-1; when it’s in semi-stable phase, BDM wasbetween4%and16%, B/C was between0.1and0.4, and S′was between2cm·a^-1and40cm·a^-1; when it’s in stable phase, BDM<4%, B/C<0.1, and S′<2cm·a^-1.