Evaluation of urban solid waste degradation processes in landfill. A case study GC5 Landfilling

Prediction of biodegradation processes for the organic fraction of municipal solid waste is an issue of paramount interest for efficient landfill design and management. This paper presents the results obtained from an extended field work developed in a time period of ten years. Solid waste samples from a landfill were collected at different depths in 5 holes with depth of 17 m, and analyzed in laboratory for the determination of total organic matter, raw cellulose, humic acid, volatile solids, total organic carbon, total nitrogen, and C/N ratio. These parameters were used to estimate the efficiency of waste disposed degradability. This research also aimed the determination of the total period of organic matter degradation and the end of leachate and gas production in a landfill, in order to establish accurate post-closure and monitoring policies. Landfill of Matosinhos, a Portuguese municipality with 165 000 inhabitants, and located in the metropolitan area of Oporto, was used as case study for applying the planned methodologies. Approximate 700 000 tonnes of solid waste have been disposed on the studied landfill since 1978, occupying, in 1993, a volume of more than 10 m, to which a daily deposition of more than 200 tonnes of municipal solid waste have been added until 2003. From the results obtained, it was concluded that total organic matter, raw cellulose, humic acid, volatile solids, and C/N appear to be adequate parameter indicators of solid waste degradability.