In this study, waste landfill site was used as a bioreactor landfill for the treatment of anaerobically digested foodwastewater, and a basic study on waste landfill injection of anaerobically digested food wastewater was conducted. To studythe effect of different operating condition on the quality of lysimeter leachate, 3 lysimeters were operated at differentcondition (i.e., Lys 1=no recirculation, Lys 2=leachate recirculation, Lys 3=leachate recirculation after one day aeration),and the results of leachate quality were as followings. pH Level of leachate became similar to the digested food wastewaterafter 63 days of operation(equivalent to the 11.2% of bed volume) and Cl- concentration of leachate was higher than injectedfood wastewater during whole 6 months of operation period. Leachate COD showed stable values after 70 days of operation,and reduction rate of COD concentration after 6 months was 86%, 89, and 90% for Lys 1, Lys 2, and Lys 3, respectively.The reduction rates of TKN concentration were 19, 28, and 65% for Lys 1, Lys 2, and Lys 3. Lys 3 showed the mosteffective TKN reduction. Leachate recirculation after one day aeration resulted effective reduction of cumulative COD andTKN mass, which were 61% and 40% respectively, compared to the no recirculation case.

In order to accelerate the biodegradation of easily organic materials in landfilled waste before excavating a closed solid waste landfill and prevent to be dried the landfilled wastes at the same time, this study has suggested the Dual Step Biostabilization System (DSBS), which could inject air with dry fog into its body. In addition, the applicability of the DSBS was estimated by means of field test at a closed landfill. As a result of field test, the reduction of oxygen consumption rate for landfilled wastes (48%) stabilized by air with dry fog was higher than that of landfilled wastes (38%) stabilized by only air. Three lysimeter experiments were, also, performed for the landfilled wastes sampled from the closed landfill. The production of cumulative carbon dioxide for landfilled wastes stabilized by air with dry fog was estimated to be highest (1,144.8 mL). In case of lysimeter that moisture was not introduced was found to be 1,051.9 mL, while another lysimeter that moisture was introduced through horizental trenches was 1,095.8 mL. It is clear that the DSBS can accelerate the biodegradation of organic compounds. In terms of volatile solids, the reduction amount of volatile solids for air with dry fog was higher than that of the other conditions.

The objective of this research was to suggest the estimation method of air injection quantity for pre-stabilization of landfilled wastes in a sustainable landfill. A study on the determination of oxygen demand quantity of landfilled wastes, therefore, was conducted in two different experiments. Firstly, a batch test was performed in order to measure the oxygen quantity required to oxidize easily degradable organic matter under aerobic conditions. Secondly, a lysimeter experiment was carried out to assess the air injection period according to moisture content (20%, 30%, 40%, 50%) and to validate the oxygen demand quantity obtained by the batch test. This study assumed that landfilled wastes contain two different organic matters and two matters are sequentially utilized by microorganism. The first one provides the faster oxygen uptake rate that called the “easily degradable organics”. During the second phase of the aerobic decomposition, the other one provides the slower oxygen uptake rate that called the “moderately degradable organics”. Also, in this study, a modified logistic equation divided two terms (fractions of easily degradable organic and moderately degradable organic) was suggested to determine the oxygen demand quantity for easily degradable organic of landfilled solid waste. As a result, the oxygen demand quantity obtained by the batch test led to similar results compared with that of lysimeter experiment. Therefore, it showed that the modified logistic equation and batch test were appropriate for determination of oxygen demand quantity for decomposition of easily degradable organic matter. Also, air injection period for decomposition of easily degradable organic decreased with the increase of moisture content.

A field research at Sudokwon landfill was carried to analyse the effect of leachate and organic waste water injection on decomposition characteristics of landfill waste. The moisture content after leachate (79,783 m3) addition into block 3A for 1 year increased from 27.4% to 34.1%. As a result of moisture increasement, Cellulose and Lignin proportions as indicators of waste degradability changed from 1.45 to 1.18. It is also illustrated that TOC as an indicator of CH4 production potential reduced from 22.0% to 19.5%. Comparison results of TOC after 4 months of each leachate, digested waste water, food waste water injection into block 4A shows reduction of 3.5%, 4.7% and 3.7%, respectively. Hence, it is indicated that injection of leachate and organic waste water into landfill enhances the rate of CH4 production as well as the speed of landfill stabilization.

Landfill gas (LFG) has received considerable attention to produce a renewable energy source from waste because LFG contains about 45 ~ 55% methane. In order to improve LFG, the concept of bioreactor landfill is applied to Sudokown Landfill site. In landfill field test, the research area 3A (300 m × 300 m) and reference area 2A (300 m × 300) are prepared to compare the effect of leachate recirculation. Using injection wells, leachate is injected into the research area in the 2nd Landfill site and the distribution of moisture content in the research area is homogeneously saturated by the injected leachate. Leachate characteristics such as Alkalinity, BOD, COD, TKN, and TOC are increased with the input of the injected leachate because wastes are decomposed by the injected leachate but pH of leachate is almost not affected by the injected leachate. The production of LFG in the reseach area is improved by about 40% comparing with that in the reference area and the content of CH4 in LFG is consistently higher than 50%. Hence, it can be summarized that the production and the quality of LFG can be improved by the injection of leachate into landfill site.