[Evolution of leachate quantity and quality in the anaerobic-semiaerobic bioreactor landfill]

The Anaerobic-semiaerobic Bioreactor Landfill (AN-SABL) has been devised combining an Anaerobic Bioreactor Landfill (ANBL) with a Semi-aerobic Aged Refuse Biofilter (SAARB) for reducing the investment and the running expense. It was a novel bioreactor landfill which could accelerate the stabilization of waste obviously. The evolution of leachate quantity and quality for the AN-SABL was studied in order to provide a theoretical basis for the management and treatment of leachate. The results indicated that the quantitative reduction of leachate in the AN-SABL was obvious and the highest reduction could reach by 771 g x kg(-1). Moreover, the quality of leachate varied in phases. The concentration of nitrate including nitrite and ammonium was influenced markedly by Eh and pH. At the end of the experiment, the removal rates of COD for the AN-SABL2 and the AN-SABL3 reached by 98.49% and 97.98% and the concentrations of COD were only 14.5% and 21.1% of that in leachate from the ANBL1 respectively. Therefore, the organic matter could be degraded completely with the AN-SABL. Besides, the AN-SABL could remove the nitrogen pollutant effectively as well. The concentrations of ammonium in leachate from the AN-SABL2 and the AN-SABL3 decreased obviously from the maximum of 1 452 mg x L(-1) and 1 409 mg x L(-1) to 525 mg x L(-1) and 459 mg x L(-1) respectively which only were 36.5% and 31.9% of that in leachate from the ANBL1. For the SAARB unit, the TOC and TC ratio played a vital influence on the removal efficiency of the organic matter and nitrogen pollutant. After the TOC and TC ratio declined to about 0.2, the removal rate of COD and TN for SAARB decreased from over 95% and over 93% to 35.25% -69.56% and 64.53% -77.45% respectively.