Performance evaluation of leachate treatment system using innovative sulfur circulation method.
A pilot-scale experimental study was carried out to evaluate the performance of an innovative method for early stabilization of landfill. This method employs sequential processes of: leachate collection; nitrification through aeration; sulfate addition in effluent tank; and leachate injection back to the landfill. This study focused on: 1) decomposition of recalcitrant organic matters, 2) the characteristics of denitrification, 3) sulfide oxidation for sulfate recovery, and 4) nitrification by aerating discharged leachate. It was found that, when sulfate (SO4(2-)) added leachate was introduced inside the landfill, sulfate-reducing bacteria decomposed recalcitrant organic matters like lignocellulose by using SO4(2-) as an electron acceptor and simultaneously sulfur-oxidizing bacteria denitrified the leachate using sulfides (H2S, HS-, S2-) as electron donors. These two types of bacteria existed not competitively but symbiotically on substrate utilization. Sulfate-reducing bacteria produced S2- while sulfur-oxidizing bacteria oxidized S2- to SO4(2-). During aeration, the concentration of NO3(-)-N increased from near zero up to 925 mg l(-1). Eventual denitrification efficiency in the simulated waste landfill was observed to be approximately 92.3%. Also, S2- present in the discharged leachate was converted to SO4(2-) again in the aeration process. Sulfate needed in this process could be recirculated. Therefore, the amount of sulfate required in the operation of this method could be maintained marginal after the initial addition of sulfate in the effluent tank. Decomposition of recalcitrant organic matters and denitrification hastened the stabilization of landfill. The results of this study indicated that this innovative method was effective and economic.
Kim
S K
SK
Water Resources and Environmental Research Division, Institute of Construction Technology, 2311 Daehwa-dong, Ilsan-gu, Koyang, Kyonggi-do, 411-712, Korea.
Kang
M H
MH
Kim
J O
JO
Kim
J K
JK
Matsui
S
S
Shimizu
Y
Y
D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D012037:Refuse Disposal / Q000379:methods*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D014873:Water Pollutants / Q000378:metabolism
D012989:Soil Pollutants; D014873:Water Pollutants; D013455:Sulfur; D009584:Nitrogen