Landfill operation and waste management procedures in the reduction of methane and leachate pollutant emissions from municipal solid waste landfills

Jokela, Jari Landfill operation and waste management procedures in the reduction of methane and leachate pollutant emissions from municipal solid waste landfills Jyväskylä: University of Jyväskylä, 2002, 63 p. (Jyväskylä Studies in Biological and Environmental Science, ISSN 1456-9701; 113) ISBN 951-39-1282-5 Yhteenveto: Kaatopaikan operoinnin ja jätteen esikäsittelyn vaikutus yhdyskuntajätteen biohajoamiseen ja typpipäästöjen hallintaan Diss. The objective of the present research was to find ways of minimising emissions from municipal solid waste (MSW) landfills by means of laboratory experiments. During anaerobic incubation for 237 days, the grey waste components produced between 120 and 320 m3CH4 tTS-1 and between 0.32 and 3.5 kg NH4-N tTS-1 and the first-order rate constant of degradation ranged from 0.021 and 0.058 d-1. High amounts of COD and NH4-N were observed in the leachate of grey waste in all the procedures tested during lysimeter experiments lasting 573 days. In the 10year-old landfilled MSW, a high rate of methanisation was achieved with rainwater addition and leachate recirculation over 538 days, whereas initially pre-wetted grey waste and landfilled MSW were rapidly acidified, thus releasing a high amount of COD into the leachate. In batch assays, the grey waste produced a methane potential amounting to 70-85 % of the total methane potential of the grey waste plus putrescibles. In low moisture conditions, i.e. below 55%, methane production was delayed in the old landfill waste and prevented in the grey waste. In the emission potential study with five waste types, putrescibles produced 410 m3CH4 tTS-1 and 3.6 kgNH4-N tTS-1, whereas composted putrescibles produced 41 m3CH4 tVS-1, and 2.0 kgNH4-N tTS-1. The remains of putrescibles probably caused the leaching potential of 2.1 kgNH4-N tTS-1 in the grey waste. Aeration for 51 days in lysimeters reduced the CH4 potential of putrescibles by more than 68 % and of the lysimeter landfilled grey waste by 50 %, indicating the potential of aeration for CH4 emission reduction. Nitrogen removal of landfill leachate was studied in the laboratory as well as on-site. Over 90 % nitrification of leachate was obtained with loading rates between 100 and 130 mgNH4-N l-1 d-1 at 25oC. Nitrified leachate was denitrified with a loading rate of 3.8 gT.O. N t-TS-1wasted-1 without adverse effects on the methanation of waste. In an on-site pilot study a leachate nitrification level of above 90 % was achieved in a crushed brick biofilter with a loading rate of 50 mgNH4-N/l d even at 5 10°C. The effective separation and biological treatment of putrescibles is important in minimising the emission potential of MSW and thus environmental impacts of MSW management. The amount and the rate of release of methane as well as organic matter and nitrogen into leachate can be controlled by active landfill operation. Rapid methanation of MSW by controlling waste moisture and inoculation seems to be the key to achieve low emissions in modern landfills. The controlled access of water and/or leachate can be recommended during the post-closure operation of a landfill. Nitrification in a low-cost biofilter followed by denitrification in a landfill body appears to be feasible method for the removal of nitrogen in landfill leachate in colder climates.