Reaction mechanisms and rate constants of waste degradation in landfill bioreactor systems with enzymatic-enhancement.

Augmenting leachate before recirculation with peroxidase enzymes is a novel method to increase the available carbon, and therefore the food supply to microorganisms at the declining phase of the anaerobic landfill bioreactor operation. In order to optimize the enzyme-catalyzed leachate recirculation process, it is necessary to identify the reaction mechanisms and determine rate constants. This paper presents a kinetic model developed to ascertain the reaction mechanisms and determine the rate constants for enzyme catalyzed anaerobic waste degradation. The maximum rate of reaction (Vmax) for MnP enzyme-catalyzed reactors was 0.076 g(TOC)/g(DS).day. The catalytic turnover number (k(cat)) of the MnP enzyme-catalyzed was 506.7 per day while the rate constant (k) of the un-catalyzed reaction was 0.012 per day.

Waste degradation and gas production with enzymatic enhancement in anaerobic and aerobic landfill bioreactors.

The presence of lignin is the limiting factor at later stages of biodegradation of municipal solid waste under aerobic or anaerobic conditions. Supplying enzymes into the system could facilitate lignin degradation, thereby aiding anaerobic and aerobic waste degradation processes. A comprehensive set of laboratory experiments were conducted under both anaerobic and aerobic conditions to evaluate the feasibility of using enzymes in accelerating lignin-rich waste degradation. After 30 days of anaerobic operation, MnP and LiP enzyme treated reactors produced 36 and 23 times higher cumulative methane (CH4), respectively, compared to that of the control reactor devoid of enzyme treatments. The carbon dioxide (CO2) yield of MnP enhanced aerobic reactor showed more than two-fold increase.

Effect of enzyme additions on methane production and lignin degradation of landfilled sample of municipal solid waste.

Operation of waste cells as landfill bioreactors with leachate recirculation is known to accelerate waste degradation and landfill gas generation. However, waste degradation rates in landfill bioreactors decrease with time, with the accumulation of difficult to degrade materials, such as lignin-rich waste. Although, potential exists to modify the leachate quality to promote further degradation of such waste, very little information is available in literature. The objective of this study was to determine the viability of augmenting leachate with enzymes to increase the rate of degradation of lignin-rich waste materials. Among the enzymes evaluated MnP enzyme showed the best performance in terms of methane yield and substrate (lignin) utilization. Methane production of 200 mL CH(4)/g VS was observed for the MnP amended reactor as compared to 5.7 mL CH(4)/g VS for the control reactor. The lignin reduction in the MnP amended reactor and control reactor was 68.4% and 6.2%, respectively.