Methane and leachate pollutant emission potential from various fractions of municipal solid waste (MSW): Effects of source separation and aerobic treatment

Abstract

The effects of source-separation of putrescibles as well as aerobic pre-treatment and landfill aeration on the pollutant emission potential of methane and leachate pollutants were studied in the fresh (PFMSW) and composted (CPFMSW) source-separated putrescible fraction of municipal solid waste, and in the grey waste, and in lysimeter landfilled grey waste and ten-year-old unsorted MSW from our landfill lysimeter study. After 0, 23 and 51 days, an aerobic lysimeter experiment, an elution test and biochemical methane potential (BMP) test was done on samples. PFMSW had high methane (CH4) potential (410 m(3) CH4 t(-1)TS) as well as a high amount of ammonium-nitrogen (3.6 kg NH4-N) was eluted, whereas CPFMSW produced 41 m(3) CH4 t(-1)TS and 2.0 kg NH4-N t(-1)TS. A high nitrogen elution potential was found in the grey waste (2.1 kg NH4-N t(-1)TS). Aeration for 51 days in lysimeters reduced CH4 potential by more than 68% for the PFMSW and CPFMSW samples, whereas for the lysimeter landfilled grey waste the reduction was 50% indicating the potential of aeration for CH4 emission reduction. The effective separation and biological treatment of the PFMSW are important in reducing the environmental impacts of waste management, especially for minimising the methane potential of MSW fractions.

Detailed internal characterisation of two Finnish landfills by waste sampling

“…The highest BMPs (160-180 m 3 /t TS) in Ä mmässuo were approximately half that of food waste (301 m 3 /t TS, Eleazer et al, 1997), and higher than reported for grey waste (46-101 m 3 /t TS; Jokela et al, 2001Jokela et al, , 2002, suggesting high methane potential despite the fact that the waste was mainly from a period (1995 onwards) when source segregation was increasingly being implemented in this region. As expected, the BMPs were lowest in both landfills in the bottom layer, close to or below the water table, also suggesting that at that level waste had probably biodegraded, that biodegradable compounds had leached from the waste, or that little biodegradable material had originally been landfilled (Kujala).…”

“…Leachable COD decreased slightly from top to bottom in both landfills except at the top layer in Kujala, where the leaching was close to that of the bottom layer, probably due to the introduction of source segregation of biowaste. The COD leaching of fresh biowaste is several-fold (8.2 kg COD/t TS) higher than that of grey waste (approximately 0.7 kg COD/t TS) (Jokela et al, 2002), while in the present study mean leaching was 19 kg COD/t TS in Ä mmässuo and 6 kg COD/t TS in Kujala, thus indicating that the leaching potential of COD had increased during landfilling. Both landfills contained leachable COD in all layers, even in the bottom layer in Kujala where low organic material content was assumed (VS/TS ratio, 16%).…”

“…Sampling before or in conjunction with the construction of gas recovery wells or leachate recirculation, especially at sites with limited existing information, may have economic benefits to optimise the gas extraction or liquid recirculation methods. Landfills have been previously sampled to estimate the rate of degradation of MSW and its different waste components (e.g., Hartz and Ham, 1983;Bogner, 1990;Gurijala and Suflita, 1993;Baldwin et al, 1998;Jokela et al, 2002;Gardner et al, 2003) while -to our knowledge -only a few studies have been published on vertical profiles of pH, temperature, moisture, organics, cellulose, lignin, or BMP (Bookter and Ham, 1982;Jones et al, 1983;Attal et al, 1992;Ham et al, 1993;Wang et al, 1994;Townsend et al, 1996;Chen et al, 2004;Ö stman et al, 2006) and even fewer studies (Ettala et al, 1988;Ham et al, 1993;Ö stman et al, 2006) on landfill nitrogen content. These earlier studies showed MSW landfills to be heterogeneous with respect to the stages of degradation and conditions within the landfill body with wastes in the top layers usually less degraded than in the deeper layers.…”

“…The major fractions (Table 1) of discarded MSW are paper and cardboard, kitchen biowaste, plastics and garden waste (Golder Associates, 1999;YTV, 2004;US EPA, 2005b), and major portions of the methane potential can be attributed to cellulose and hemicellulose (Barlaz et al, 1989;Baldwin et al, 1998). The emission (and energy) potential of different MSW fractions vary greatly; e.g., the source segregated residual fraction of MSW (termed ''grey waste'' in Finland) and biowaste may have a biological methane potential (BMP) of 46 m 3 /t total solids (TS) (grey waste) and 410 m 3 /t TS (biowaste) and contain 2.1 kg NH 4 -N/t TS (grey waste) and 3.6 kg NH 4 -N/t TS (biowaste) of leachable nitrogen (Jokela et al, 2002). Furthermore, in addition to waste, landfills often contain soil of variable properties, which is used as daily cover.…”

Influence of alkalinity on the stabilization of municipal solid waste in anaerobic simulated bioreactor

“…Therefore, a balance between acid production and acid consumption is essential for a stable anaerobic process for optimized methanogesis and waste stabilization. Some of the operational techniques such as two-phase process (acidogenic process and methanogenic process) [11][12][13][14]22], aeration [12,[15][16][17][18]28], pH control/buffer addition [19,20] have been presented in recent years.…”