Three-dimensional modelling of leachate recirculation using vertical wells in bioreactor landfills.
Bioreactor landfills use leachate recirculation to enhance the biodegradation of municipal solid waste and accelerate landfill stabilisation, which can provide significant environmental and economic benefits. Vertical wells are operated as a major method for leachate recirculation systems. The objectives of this article are to analyse the leachate migration in bioreactor landfills using vertical wells and to offer theoretical basis for the design of leachate recirculation systems. A three-dimensional numerical model was built using FLAC-3D, and this model can consider the saturated and unsaturated flow of leachate within anisotropic waste to reflect the actual conditions. First, main influence factors of leachate migration were analysed, including the vertical well height, hydraulic conductivity, and anisotropic coefficient, in a single-well recirculation system. Then, the effects of different configurations of a group-well system were studied and the optimal well spacing was obtained. Some key design parameters (e.g. the recirculation flow rate, volume of impact zone, radius of impact zone and time to reach steady state) were also evaluated. The results show that the hydraulic conductivity has a great impact on the optimal height of vertical wells and uniform configuration is the best option in terms of both volume of impact zone and time to reach steady state.
Department of Geotechnical Engineering, Tongji University, Shanghai, China fsjgly@tongji.edu.cn.|Key Laboratory Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai, China.
Shi-Jin
SJ
Feng
Department of Geotechnical Engineering, Tongji University, Shanghai, China.
Zheng-Wei
ZW
Chen
Department of Geotechnical Engineering, Tongji University, Shanghai, China.
Ben-Yi
BY
Cao
D016880:Anisotropy; D019149:Bioreactors; D004867:Equipment Design; D062070:Hydrology / Q000379:methods; D008962:Models, Theoretical; D012037:Refuse Disposal / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D064091:Waste Disposal Facilities; D014874:Water Pollutants, Chemical
D014874:Water Pollutants, Chemical
Bioreactor landfills; group-well configurations; leachate recirculation system; three-dimensional model; vertical wells