A novel permeable reactive bio-barrier to remediate interflow from simple landfill
To achieve the in-situ control and remediation of interflow from simple landfills in hilly areas,this study developed a permeable reactive bio-barrier(PRB).The optimization of the adsorption material ratio was conducted through single-factor experiments,orthogonal experiments,and response surface experiments.Additionally,the ratio of fixed materials and supporting materials was further optimized to formulate the PRB material compositions.The ratios of the high and low permeability coefficient PRB for activated carbon∶ceramic∶zeolite∶expanded perlite∶cement∶quartz sand were 4.8∶2.9∶3.8∶2.1∶9.2∶2.7 and 4.8∶2.9∶3.8∶2.1∶9.2∶0,respectively.The effects of layout spacing and number of layers were investigated,leading to the determination that the optimal deployment type of the PRB was four layers(high-high-low-low),with no spacing between the first two layers,consistent last two layers with first two layers,and a spacing/thickness of 6 between the two groups.The removal efficiencies of chemical oxygen demand and total nitrogen was 72.88％±6.91％and 64.30％±13.91％,respectively.Fourier transform infrared spectra demonstrated that the intensity of the nitrogen-related and organic-related absorption peaks of the used PRB increased.Microbiological analyses demonstrated that the first two layers were dominated by bacteria with potential nitrogen metabolism function(40.98％)and refractory organic matter(TRO)-degrading bacteria(22.19％),and the last two layers were dominated by bacteria with potential nitrogen metabolism function(62.58％).In sum,the TRO was mainly removed through microbial metabolism in the first two layers but by adsorption in the last two layers.The nitrogenous pollutants were degraded by microorganisms,and the last two layers had the stronger nitrogen removal effects.
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