Waste Degradation In Landfills Research Articles

Reaction Kinetic Analysis of Manganese Peroxidase Augmented Aerobic Waste Degradation

Abstract Past research has shown that waste degradation in landfills could be affected by augmenting with manganese peroxidase (MnP) enzyme via increased hydrolysis of organic waste. However, at pr...

Ammonia inhibition of waste degradation in landfills - A possible consequence of leachate recirculation in arid climates.

Ammonia inhibition of anaerobic waste degradation has been extensively investigated on a laboratory scale. It is hence well known that at ammonium levels above 2500 mg/l, methanogenic bacteria are inhibited, which leads to both reduced methane (CH4) production and increased organic pollution of the leachate. In the present paper, and for the first time, data on a full-scale landfill indicating ammonia inhibition of waste degradation is presented. The leachate of the landfill is characterized by extremely high concentrations of chloride (up to 70,000 mg/l) and ammonium-nitrogen (up to 20,000 mg/l). These high pollution levels are explained by the following facts: first, the landfill is located in an arid climate (annual precipitation of 200 mm), resulting in low fresh water infiltration; and second, leachate or concentrate resulting from reverse osmosis treatment at the site has been recirculated. The high ammonium levels obviously caused inhibitory effects on the anaerobic degradation, which resulted in chemical oxygen demand concentrations in the leachate of far above 300,000 mg/l. Furthermore, a comparatively low level of landfill gas (LFG) generation and a shift towards higher carbon dioxide and lower CH4 contents in the collected LFG was observed. Based on the gas compositional data, the overall reduction in CH4 generation was assessed to be 50%. In order to reduce organic leachate pollution and to enhance LFG production at the site investigated, fresh (rain) water infiltration should be enhanced and the recirculation of leachate or treatment residues derived thereof should be terminated.

SOFC single cells fed by biogas: Experimental tests with trace contaminants

Biogas from biological treatments and from the waste degradation in landfills generally contains a wide range of trace impurities (e.g., sulphur compounds, siloxanes, halogens, tar compounds, etc.). This paper describes an experimental analysis performed with SOFC single cells fed by a synthetic gas polluted by H2S, HCl, D4 and a mixture of H2S + C2Cl4. The aim is to detect the threshold tolerance limit on different cell performance parameters. Results show how: hydrogen sulphide has a strong impact on the polarization losses due to the nickel sulphide formation on the electrode that causes a mass transfer resistance. Hydrogen chloride particularly limited the electrochemical processes. Octamethylcyclotetrasiloxane (D4) showed a high impact on SOFC performance even at ultra-low level (78–178 ppb(v)) as a consequence of the formation of silicon dioxide covering the anode porous sites. Sulphur added to C2Cl4, accelerated the deterioration of SOFC performance. In addition, current density variations and operating temperature are studied during sulphur poisoning. An opposite behaviour on SOFC performance was revealed by operating temperature and current density.

Impact of vent pipe diameter on characteristics of waste degradation in semi-aerobic bioreactor landfill.

The evolution mechanism of a vent pipe diameter on a waste-stabilization process in semi-aerobic bioreactor landfills was analyzed from the organic-matter concentration, biodegradability, spectral characteristics of dissolved organic matter, correlations and principal-component analysis. Waste samples were collected at different distances from the vent pipe and from different landfill layers in semi-aerobic bioreactor landfills with different vent pipe diameters. An increase in vent pipe diameter favored waste degradation. Waste degradation in landfills can be promoted slightly when the vent pipe diameter increases from 25 to 50 mm. It could be promoted significantly when the vent pipe diameter was increased to 75 mm. The vent pipe diameter is important in waste degradation in the middle layer of landfills. The dissolved organic matter in the waste is composed mainly of long-wave humus (humin), short-wave humus (fulvic acid) and tryptophan. The humification levels of the waste that was located at the center of vent pipes with 25-, 50- and 75-mm diameters were 2.2682, 4.0520 and 7.6419 Raman units, respectively. The appropriate vent pipe diameter for semi-aerobic bioreactor landfills with an 800-mm diameter was 75 mm. The effect of different vent pipe diameters on the degree of waste stabilization is reflected by two main components. Component 1 is related mainly to the content of fulvic acid, biologically degradable material and organic matter. Component 2 is related mainly to the content of tryptophan and humin from the higher vascular plants.

亜熱帯・熱帯地域の廃棄物埋立地における微生物生態系の調査

To understand the behavior of waste degradation in landfills and landfill stabilization in tropical and subtropical climate zones, eubacterial community analysis using waste landfill leachate was conducted. Waste landfills in Thailand, Vietnam and Japan were investigated of the bacterial communities. The waste landfills in Hua Hin (Thailand) and Go Cat (Vietnam) had high concentrations of organics in the leachate and organics in these high amounts of gas generated, indicating the active degradation of organic waste, as well as the disposal of large amounts of landfills. The landfills in the Japanese subtropical zone were suggested to be under going a comparatively stable degradation because of the long — term use of the landfill and the preliminary mineralization of landfill materials. All the bacterial communities isolated from observed in the landfills showed the existence of bacteria phylogenically related to Firmicutes and Bacteroidetes, indicating a highly reducing condition of the waste layer in the landfills. On the other hand, bacteria related to CFB (Cytophaga-Flexibacter-Bacteroidetes) group and ε-Proteobacteria were specifically detected from the Hua Hin landfill and Go Cat landfill but not from the Japanese landfills. The presence of these bacterial groups indicates the regional specificity of waste degradation in landfills under active degradation. Some common bacterial groups such as γ-Proteobacteria in the Hua Hin landfill and Japanese subtropical landfills were also found, suggesting certain similarities between these landfills.

Small-scale simulation of waste degradation in landfills

Biogas production from a mixture of food and paper, with additions of inoculum, buffer and nutrient, began after 24 weeks and reached 0.8 vol/vol.day from Week 40 to 51, at 55-65% (v/v) methane. Methanogenesis from a simulated solid waste has not previously been reported.