The microbial metabolic activity on carbohydrates and polymers impact the biodegradability of landfilled solid waste

Biological waste degradation is the main driving factor for landfill emissions. In a 2-year laboratory experiment simulating different landfill in-situ aeration scenarios, the microbial degradation of solid waste under different oxygen conditions (treatments) was investigated. Nine landfill simulation reactors were operated in triplicates under three distinct treatments. Three were kept anaerobic, three were aerated for 706 days after an initial anaerobic phase and three were aerated for 244 days in between two anaerobic phases. In total, 36 solid and 36 leachate samples were taken. Biolog® EcoPlates™ were used to assess the functional diversity of the microbial community. It was possible to directly relate the functional diversity to the biodegradability of MSW (municipal solid waste), measured as RI4 (respiration index after 4 days). The differences between the treatments in RI4 as well as in carbon and polymer degradation potential were small. Initially, a RI4 of about 6.5 to 8 mg O2 kg−1 DW was reduced to less than 1 mg O2 kg−1 DW within 114 days of treatment. After the termination of aeration, an increase 3 mg O2 kg−1 DW was observed. By calculating the integral of the Gompertz equation based on spline interpolation of the Biolog® EcoPlates™ results after 96 h two substrate groups mainly contributing to the biodegradability were identified: carbohydrates and polymers. The microbial activity of the respective microbial consortium could thus be related to the biodegradability with a multilinear regression model.

Gas monitoring station in hazardous environment with gases containing

Landfill sites collect tons of municipal solid waste (MSW) using an open dump mechanism, causing gases to emerge, which may cause disease and the greenhouse effect. Mainly, landfill environments are observed using a portable system that does not continuously monitor and measure emitted gas levels. It is also difficult to evaluate changes in landfill emissions over the long term unless they are monitored at regular intervals according to a detailed plan. This paper presents a new monitoring method to measure gas levels in landfill sites, which documents dynamic changes in gas composition concentrations over the long term. The system was placed in the middle area of the landfill and was charged using solar panels for convenience and greater efficiency during monitoring. While the instruments that are currently available are used for a specific parameter, this system can measure eight parameters, i.e., ambient concentration of methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), temperature, humidity, wind direction, wind speed, and voltage level. The system was evaluated regarding its ability to monitor gas parameters continuously.

Evaluation of Occupational Exposure Risk for Employees Working in Dynamic Olfactometry: Focus on Non-Carcinogenic Effects Correlated with Exposure to Landfill Emissions

This work aims to evaluate the non-carcinogenic health effects related to landfill odor emissions, therefore focusing on workers involved in dynamic olfactometry. Currently, the most common technique to quantify odor emissions is dynamic olfactometry, a sensorial analysis involving human assessors. During the analysis, assessors are directly exposed, at increasing concentrations, to odor samples, and thus to the hazardous pollutants contained therein. This entails the need to estimate the associated exposure risk to guarantee examiners’ safety. Therefore, this paper evaluates the exposure risk for olfactometric examiners to establish the minimum dilution level to be adopted during the analysis of landfills’ odorous samples to guarantee panelists’ safety. For this purpose, an extensive literature review regarding the pollutants emitted by landfill odor sources was conducted, comparing compounds’ chemical concentrations and threshold limit values (TLVs) to calculate the Hazard Index (HI) and thus establish a minimum dilution value. The data collected indicate that a non-negligible non-carcinogenic risk exists for all landfill emissions considered. However, from the data considered, the minimum dilution factor to be adopted is lower than the typical odor concentration observed for these sources. Therefore, the olfactometric analysis of landfill samples can be generally conducted in safe conditions.

Comparison of a Traditional Landfill and a Mechanically-Biologically Treated waste Landfill (Case study; Kirkuk landfill)

Owing to the increasing population in Kirkuk, Iraq and the consequent rise in the production of waste, alongside with global warming caused by an increase in the greenhouse gases concentrations, a high level of emissions was observed at the landfill site near Kirkuk. These emissions can be transmitted by the wind over considerable distances and adversely affect the environment and individual health. In this study, two pilot scale columns were built to investigate different options for achieving sustainability by reducing long-term landfill emissions. Each reactor was packed with (8.5) kg of shredded synthetic solid waste (less than 5 cm) that was prepared according to an average composition of domestic solid waste in the city of Kirkuk. The main result of this study was that the pretreatment of the waste may shorten the transition time for active methane development and increase the methanogenesis of the landfill site and also affects COD removals efficiencies which were 19.11% and 66.53% for columns A and B respectively.

Accumulation of airborne microplastics in lichens from a landfill dumping site (Italy)

The aim of this study was to assess if lichens (Flavoparmelia caperata) surrounding a landfill dumping site in Italy accumulated higher amounts of microplastics compared with lichens at more distant sites. Lichen samples were collected at three sites along a transect from the landfill: close (directly facing the landfill), intermediate (200 m), and remote (1500 m). Anthropogenic microparticles (fibres and fragments) were determined visually after wet peroxide digestion of the samples, and microplastics were identified based on a hot needle test; the type of plastic was identified by micro-Raman analysis. The results showed that lichens collected in the vicinity of the landfill accumulated the highest number of anthropogenic microfibres and fragments (147 mp/g dw), and consequently microplastics (79 mp/g dw), suggesting that the impact of landfill emissions is spatially limited. The proportion of fibres and fragments identified as microplastics was 40% across all sites and the most abundant polymer type was polyester or polyethylene terephthalate (68%). These results clearly indicated that lichens can effectively be used to monitor the deposition of microplastics.

Evaluating landfill leachate treatment by organic municipal solid waste-derived biochar

Transforming the organic fraction of municipal solid waste (OFMSW) into biochar to reduce fugitive landfill emissions and control organic micropollutants (OMP) during landfill leachate treatment could provide a new circular...

Emission from Uyo Main Refuse Dumpsite and Potential Impact on Health

This paper presents potential impact on health of emission from landfill site on Uyo village road, Uyo local government area of Akwa Ibom State, Nigeria. Three sampling points were assessed for particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), hydrogen sulphide H2S, ammonia (NH3), total volatile organic carbon (TVOC) and hydrogen cyanide (HCN) using highly sensitive digital portable meters. The data obtained were expressed in terms of an air quality index. Air quality index indicates that the ambient air can be described as unhealthy for sensitive groups for NO2, unhealthy for SO2 and PM2.5 and moderate for CO, respectively. H2S, NH3, TVOC, HCN, PM10 were not indicated in USEPA air quality standards. It recommended that stringent and proper landfill emissions management together with appropriate burning of wastes should be considered in the study area to ease the risks associated with these pollutants on public health.

OPTIMISED MANAGEMENT OF SEMI-AEROBIC LANDFILLING UNDER TROPICAL WET-DRY CONDITIONS

The processes involved in semi-aerobic landfills are heavily influenced by local climate conditions and waste composition. In particular, when considering rainfall seasonality in a tropical climate, the lack of moisture during the dry season and heavy rainfalls during the wet season may negatively affect biodegradation processes and landfill emissions. The aim of the present study was to investigate the performance of semi-aerobic landfill under tropical dry-wet climate conditions and to assess the potential benefits afforded by appropriate management of water input when operating the landfill by overlaying a new layer of waste in each climate season. Six lab-scale lysimeters were operated in two phases to reproduce, on two subsequent waste layers, a sequence of dry and wet tropical seasons: two with an initial dry phase, two with an initial dry phase under controlled watering and two with an initial wet phase, during which leachate was stored to allow recirculation during the subsequent dry phase. In each pair of lysimeters one was filled with low putrescible content waste and the other with high putrescible content waste. Although appropriate management of water input significantly improved landfill performance under dry climate conditions, the overlaying of a new layer of waste in each climate season played a fundamental role in ensuring good stabilisation over the one year simulation period; following stabilisation, the landfill bottom layer acts as an internal attenuating biological filter. In particular, under initial dry conditions, final BOD COD and ammonia values detected were below 20mgO2/L, 200mgO2/L, and 30mgN/L, respectively.