Development and application of biodegradation-compression test apparatus for municipal solid waste

To study the relationship between the municipal solid waste biodegradation and the settlement of the landfill, a biodegradation-compression test apparatus for MSW was developed, whose functions include temperature controlling, leachate recirculating, loading and gas collecting. A sample of 5 kg refuse with the height of 320 mm, filled in a 190 mm diameter cylinder, was compressed under 150 kPa and decomposed under different conditions with various temperatures, gas pressure, and leachate recirculation .The test results showed that temperature was the dominant factor influencing the biodegradation rate, and lechate recirculation increased gas production rate. The refuse kept decomposing at 400 kPa (absolute gas pressure ). The biodegradation of the refuse sample nearly completed after 6 months, which was placed in a cylinder maintained 41℃ and operated with leachate recycled; The GC/MS analysis represented that the gas generated from the refuse was mainly composed of CH4, CO2 and H2O. The total deformation of the sample was 142 mm, among which the secondary compression deformation was 77 mm.The gas pressure should be considered to calculate the settlement for landfills.