A methodology to determine gaseous emissions in a composting plant

Environmental impacts associated to different waste treatments are of interest in the decision-making process at local, regional and international level. However, all the environmental burdens of an organic waste biological treatment are not always considered. Real data on gaseous emissions released from full-scale composting plants are difficult to obtain. These emissions are related to the composting technology and waste characteristics and therefore, an exhaustive sampling campaign is necessary to obtain representative and reliable data of a single plant. This work proposes a methodology to systematically determine gaseous emissions of a composting plant and presents the results obtained in the application of this methodology to a plant treating source-separated organic fraction of municipal solid waste (OFMSW) for the determination of ammonia and total volatile organic compounds (VOC). Emission factors from the biological treatment process obtained for ammonia and VOC were 3.9 kg Mg OFMSW⁻¹ and 0.206 kg Mg OFMSW⁻¹ respectively. Emissions associated to energy use and production were also quantified (60.5 kg CO₂ Mg OFMSW⁻¹ and 0.66 kg VOC Mg OFMSW⁻¹). Other relevant parameters such as energy and water consumption and amount of rejected waste were also determined. A new functional unit is presented to relate emission factors to the biodegradation efficiency of the composting process and consists in the reduction of the Respiration Index of the treated material. Using this new functional unit, the atmospheric emissions released from a composting plant are directly related to the plant specific efficiency.     

Influence of Traffic Emissions Estimation Variability on Urban Air Quality Modelling

The main objective of this work is to analyse how uncertainties in emission data of nitrogen oxides (NO_x) and volatile organic compounds (VOC), originated from road traffic, influence the model prediction of ozone (O₃) concentration fields. Different methods to estimate emissions were applied and results were compared in order to obtain their variability. Based on these data, different emission scenarios were compiled for each pollutant considering the minimum and the maximum values of the estimated emission range. These scenarios were used as input to the MAR-IV mesoscale modelling system. Simulations have been performed for a summer day in the Northern Region of Portugal. The different approaches to estimate NO_x and VOC traffic emissions show a significant variability of absolute values and of their spatial distribution. Comparison of modelling results obtained from the two scenarios presents a dissimilarity of 37% for ozone concentration fields as a response of the system to a variation in the input emission data of 63% for NO_x and 59% for VOC. Far beyond all difficulties and approximations, the developed methodology to build up an emission data base shows to be consistent and an useful tool in order to turn applicable an air quality model. Nevertheless, the sensitivity of the model to input data should be considered when it is used as a decision support tool.     

Gaseous emissions from ceramics manufactured with urban sewage sludge during firing processes

The re-use of sewage sludge without any treatment as primary material-mixed with clays-in order to obtain structural ceramics for buildings has been successfully improved. In the Ecobrick project, the firing of a mixture of specific percentages of three components (clays, sludges and forest debris) resulted in a lighter and more thermal and acoustic insulating brick, compared with conventional clay-bricks. Volatile organic compounds (VOC) emission from the manufacturing of ceramics is the most important aspect to control. In the Ecobrick project VOC emissions were monitored by using a bench-scale furnace. The study was conducted using an EPA recommended sampling train and portable sampling tubes that were thermally desorbed and analyzed by gas chromatography/mass spectrometry. Drying of raw sewage-sludge and firing processes were considered separately. In this paper, we present VOC emissions coming from the firing step of the Ecobrick production.     

Mechanical–Thermal Properties and VOC Emissions of Natural-Flour-Filled Biodegradable Polymer Hybrid Bio-Composites

The mechanical–thermal properties and volatile organic compound (VOC) emissions of natural-flour-filled, biodegradable polymer bio-composites were investigated according to variation in porous inorganic filler types. At a porous inorganic filler content of 3%, the tensile and flexural strengths of the hybrid bio-composites were not significant changed. However, the coefficient of thermal expansion and thermal expansion of the bio-composites were slightly decreased. Furthermore, the incorporation of the porous inorganic materials into bio-composites slightly increased the E’ values of the hybrid bio-composites over the entire temperature range, although the tan δ_max temperature (T _g) of the hybrid bio-composites was not significantly changed. At a porous inorganic filler content of 3%, the various odor and VOC emissions of the hybrid bio-composites were significantly decreased because the various oxidation and thermal degradation gases of the natural flour and matrix were absorbed in the pore structures of the porous inorganic fillers and thereby prevented the migration into the final products.     

Identification,Abundance and Origin of Aliphatic Hydrocarbons in the Fine Atmospheric Particulate Matter of Athens,Greece

The organic chemical composition of the fine fraction of atmospheric particulate matter in Athens has been studied, in order to establish emission sources. The results of the analyses of the aliphatic fraction indicate that all samples contain n-alkanes ranging from C₁₄ to C₃₂, with C₂₅, C₂₆, C₂₇ and C₂₉ being the more abundant congeners. Fossil fuels biomarkers such as extended tricyclic terpanes (hopanes, steranes) and isoprenoid hydrocarbons (pristane, phytane) were observed in our samples on a daily basis. Source reconciliation was conducted using molecular diagnostic ratios (such as the carbon preference index – CPI). The mean CPI value (1.84) indicates the mixed origin of the Athenian fine particles. The notable presence of an unresolved complex mixture or “hump” of hydrocarbons in our gas chromatograms is indicative of petrogenic hydrocarbon inputs. An approximate measure of this kind of contamination is the ratio of the concentrations of unresolved components to the resolved n-alkanes and other major compounds (U:R). The high U:R value of 25.25 further confirmed the major contribution of fossil fuels. Yet, the percent contribution of leaf wax n-alkanes (25.15%) indicated the parallel contribution of biogenic sources. This work supports the conclusion that vehicular emissions were the major source of aliphatic organic compounds with a smaller contribution of biogenic n-alkanes during the study period in Athens.     

Volatilization and Biodegradation of VOCs in Membrane Bioreactors (MBR)

Volatilization and biodegradation are major competitive volatile organic compound (VOC) removal mechanisms in biological wastewater treatment process, which depend on compound specific properties and system design/operational parameters. In this study, a mathematical model was used to determine major removal pathways at various organic loading rates (OLR), solids residence time (SRT) and dissolved oxygen (DO) concentrations in a biological process for vinyl acetate. Model results showed that biological treatment process should be designed with long SRT, high OLR and low DO concentrations to maximize biodegradation and minimize volatilization of VOCs. Unless a VOC is toxic to microorganisms under the given conditions, low VOC emission rates are an inherent advantage of MBRs, which operate at higher OLR and longer SRT compared to conventional activated sludge process. A lab scale membrane bioreactor (MBR) was operated at varying OLR to investigate the relative volatilization and biodegradation rates for acetaldehyde, butyraldehyde and vinyl acetate. Synthetic wastewater containing three VOCs was introduced to the MBR. The DO concentration and SRT was maintained at 2.0 mg L^{− 1} and 100 days, respectively. The overall VOC removal rate was more than 99.7% for three VOCs at all the OLR. For vinyl acetate, the biodegradation rate increased from 93.87 to 99.40% and the volatilization removal rate decreased from 6.09 to 0.59% as OLR was increased from 1.1 to 2.0 kg COD m^{− 3} d^{− 1}. It was confirmed that a MBR can be a promising solution to reduce VOC emissions from wastewater.     

Air Quality Management in Izmir Region of Turkey as Required by Clean Air Plans

As a first step to work out an abatement plan against air pollution, a local emission inventory with 1 hr temporal and 1 km spatial resolution in the city of Izmir and its surroundings was prepared. The study area consisted of a 200 × 170 km² rectangle having the city of Izmir at the centre. The studied pollutants were total particulate matter (PM), sulfur oxides (SO_x), nitrogen oxides (NO_x), volatile organic compounds (VOC) and carbon monoxide (CO). Emissions of these pollutants were determined by estimation methods making use of suitable emission factors. Emission sources were evaluated in three categories; point, area and line sources. For year 2000 total emissions in the study area on an average day were estimated as 173 tons PM, 299 tons SOx, 136 tons NOx, 68 tons VOC and 320 tons CO. At the second part of the study, calculated emissions were transformed into air quality predictions in the area by using the Industrial Source Complex – Short Term (ISCST3) dispersion model. Model results were tested with monitoring data from urban air quality stations obtained during the year 2000. Results of the past, present and future air quality estimates in the region were discussed. In order to do so, future scenarios including various control technology applications were formulated and tested to see their effect on the future air quality.     

Characterizing emissions from open burning of military food waste and ration packaging compositions

Emissions from open burning of military food waste and ration packaging compositions were characterized in response to health concerns from open burning disposal of waste, such as at military forward operating bases. Emissions from current and prototype Meals, Ready-to-Eat (MREs), and material options for their associated fiberboard packaging were quantified to assess contributions of the individual components. MREs account for 67–100% of the particulate matter (PM), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins and -furans (PCDDs/PCDFs) emissions when burned in unison with the current fiberboard container and liner. The majority of the particles emitted from these burns are of median diameter 2.5 µm (PM_2.5). Metal emission factors were similar regardless of waste composition. Measurements of VOCs and PAHs indicate that targeted replacement of MRE components may be more effective in reducing emissions than variation of fiberboard-packaging types. Despite MRE composition variation, equivalent emission factors for PM, PAH, VOC, and PCDD/PCDF were seen. Similarly, for fiberboard packaging, composition variations exhibited essentially equivalent PM, PAH, VOC, and PCDD/PCDF emission factors amongst themselves. This study demonstrated a composition-specific analysis of waste burn emissions, assessing the impact of waste component substitution using military rations.     

Control of volatile organic compound emissions at a landfill site in New York: A community perspective

This paper presents a case study of a Long Island. New York, landfill where methane and VOC gases were migrating off-site. The municipally owned and operated Port Washington Landfill located adjacent to residential housing was opened in 1974 and was placed on the U.S. EPA Superfund (rehabilitation) list in 1982 because of odour complaints. Community concerns have focused on combustible gases, odour control, and exposure to trace contaminants. A comprehensive data base and corrective action program was initiated to determine: (1) the extent of off-site volatile organic compounds (VOC) migration; (2) measures to control migration and emissions; and (3) impacts on VOC concentrations under residential areas. Full data reports and monthly interpretations have been provided to the citizenry. Results to date indicate that start-up and operation of the extraction system have significantly reduced off-site VOC concentrations.     

Processing National CO2 Inventory Emissions Data and their Total Uncertainty Estimates

The uncertainty of reported greenhouse gases emission inventories obtained by the aggregation of partial emissions from all sources and estimated to date for several countries is very high in comparison with the countries’ emissions limitation and reduction commitments under the Kyoto Protocol. Independent calculation of the estimates could confirm or question the undertainty estimates values obtained thus far. One of the aims of this paper is to propose statistical signal processing methods to enable calculation of the inventory variances. The annual reported emissions are used and temporal smoothness of the emissions curve is assumed. The methods considered are: a spline-function-smoothing procedure; a time-varying parameter model; and the geometric Brownian motion model. These are validated on historical observations of the CO₂ emissions from fossil fuel combustion. The estimates of variances obtained are in a similar range to those obtained from national inventories using TIER1 or TIER2. Additionally, some regularities in the observed curves were noticed.     

Extension of EU Emissions Trading Scheme to Other Sectors and Gases: Consequences for Uncertainty of Total Tradable Amount

Emissions trading in the European Union (EU), covering the least uncertain emission sources of greenhouse gas emission inventories (CO₂ from combustion and selected industrial processes in large installations), began in 2005. During the first commitment period of the Kyoto Protocol (2008–2012), the emissions trading between Parties to the Protocol will cover all greenhouse gases (CO₂, CH₄, N₂O, HFCs, PFCs, and SF₆) and sectors (energy, industry, agriculture, waste, and selected land-use activities) included in the Protocol. In this paper, we estimate the uncertainties in different emissions trading schemes based on uncertainties in corresponding inventories. According to the results, uncertainty in emissions from the EU15 and the EU25 included in the first phase of the EU emissions trading scheme (2005–2007) is ±3% (at 95% confidence interval relative to the mean value). If the trading were extended to CH₄ and N₂O, in addition to CO₂, but no new emissions sectors were included, the tradable amount of emissions would increase by only 2% and the uncertainty in the emissions would range from −4 to +8%. Finally, uncertainty in emissions included in emissions trading under the Kyoto Protocol was estimated to vary from −6 to +21%. Inclusion of removals from forest-related activities under the Kyoto Protocol did not notably affect uncertainty, as the volume of these removals is estimated to be small.     

Formation and Transport of Atmospheric Aerosol over Athens, Greece

The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Greater Athens Area during the summer period, was investigated. Measurements of size fractionated anions and cations were made at two sites (inland at Ag. Stefanos and on the coast at Pireas) within the Greater Athens Area. The wind regime exhibited a distinctinfluence such that the sea-breeze circulation strongly enhanced the formation of secondary aerosols. For sulphate the difference in concentration between the two sites was,on average, 8 times greater on sea-breeze days compared with Etesian days (warm days with NE winds). During `normal' days,any differences in concentrations were possibly due to localemissions. Elevated concentrations in the fine mode were detectedat both sites during the sea-breeze days. The sea-breezecirculation enhances the development of secondary aerosolswhich was clearly shown at the inland site. Nitrous acid,hydrochloric acid and particulate nitrate, sulphate andammonium increase during sea-breeze days. Elevated levelsof nitrate, 4 m diameter, were particularly observedon the days with a strong sea-breeze circulation. Sulphatewas well correlated with both sulphur dioxide and ammoniumsuggesting the production of NH₄HSO₄/(NH₄)₂SO₄ aerosols, formedthrough the neutralisation of NH₃ with sulphuric acids.Ammonium sulphate was found to be the major ammoniumcomponent in Athens.     

Mitigating methane emissions and air intrusion in heterogeneous landfills with a high permeability layer

Spatially variable refuse gas permeability and landfill gas (LFG) generation rate, cracking of the soil cover, and reduced refuse gas permeability because of liquid addition can all affect CH₄ collection efficiency when intermediate landfill covers are installed. A new gas collection system that includes a near-surface high permeability layer beneath the landfill cover was evaluated for enhancing capture of LFG and mitigating CH₄ emissions. Simulations of gas transport in two-dimensional domains demonstrated that the permeable layer reduces CH₄ emissions up to a factor of 2 for particular spatially variable gas permeability fields. When individual macrocracks formed in the cover soil and the permeable layer was absent, CH₄ emissions increased to as much as 24% of the total CH₄ generated, double the emissions when the permeable layer was installed. CH₄ oxidation in the cover soil was also much more uniform when the permeable layer was present: local percentages of CH₄ oxidized varied between 94% and 100% across the soil cover with the permeable layer, but ranged from 10% to 100% without this layer for some test cases. However, the permeable layer had a minor effect on CH₄ emissions and CH₄ oxidation in the cover soil when the ratio of the gas permeability of the cover soil to the mean refuse gas permeability ?0.05. The modeling approach employed in this study may be used to assess the utility of other LFG collection systems and management practices.     

Influence of aeration on CH4, N2O and NH3 emissions during aerobic composting of a chicken manure and high C/N waste mixture

Co-composting of chicken manure, straw and dry grasses was investigated in a forced aeration system to estimate the effect of aeration rates on NH₃, CH₄ and N₂O emissions and compost quality. Continuous measurements of gas emissions were carried out and detailed gas emission patterns were obtained using an intermittent-aeration of 30 min on/30 min off at rates of 0.01 (A1), 0.1 (A2) and 0.2 (A3) m³ min⁻¹ m⁻³. Concentrations of CH₄ and N₂O at the low aeration rate (A1) were significantly greater than those at the other two rates, but there was no significant difference between the A2 and A3 treatments. CH₄ and N₂O emissions for this mixture could be controlled when the composting process was aerobic and ammonia emissions were reduced at a lower aeration rate. Comparison of CH₄, N₂O, NH₃ emissions and compost quality showed that the aeration rate of the A2 treatment was superior to the other two aeration rates.     

Greenhouse gases emission from municipal waste management: The role of separate collection

The municipal solid waste management significantly contributes to the emission in the atmosphere of greenhouse gases (e.g. CO₂, CH₄, N₂O) and therefore the management process from collection to treatment and disposal has to be optimized in order to reduce these emissions. In this paper, starting from the average composition of undifferentiated municipal solid waste in Italy, the effect of separate collection on greenhouse gases emissions from municipal waste management has been assessed. Different combinations of separate collection scenarios and disposal options (i.e. landfilling and incineration) have been considered. The effect of energy recovery from waste both in landfills and incinerators has also been addressed. The results outline how a separate collection approach can have a significant effect on the emission of greenhouse gases and how wise municipal solid waste management, implying the adoption of Best Available Technologies (i.e. biogas recovery and exploitation system in landfills and energy recovery system in Waste to Energy plants), can not only significantly reduce greenhouse gases emissions but, in certain cases, can also make the overall process a carbon sink. Moreover it has been shown that separate collection of plastic is a major issue when dealing with global warming relevant emissions from municipal solid waste management.     

Modelling Seasonal Dynamics from Temporal Variation in Agricultural Practices in the UK Ammonia Emission Inventory

Most ammonia (NH₃) emission inventories have been calculated on an annual basis and do not take into account the seasonal variability of emissions that occur as a consequence of climate and agricultural practices that change throughout the year. When used as input to atmospheric transport models to simulate concentration fields, these models therefore fail to capture seasonal variations in ammonia concentration and dry and wet deposition. In this study, seasonal NH₃ emissions from agriculture were modelled on a monthly basis for the year 2000, by incorporating temporal aspects of farming practice. These monthly emissions were then spatially distributed using the AENEID model (Atmospheric Emissions for National Environmental Impacts Determination). The monthly model took the temporal variation in the magnitude of the ammonia emissions, as well as the fine scale (1-km) spatial variation of those temporal changes into account to provide improved outputs at 5-km resolution. The resulting NH₃ emission maps showed a strong seasonal emission pattern, with the highest emissions during springtime (March and April) and the lowest emissions during summer (May to July). This emission pattern was mainly influenced by whether cattle were outside grazing or housed and by the application of manures and fertilizers to the land. When the modelled emissions were compared with measured NH₃ concentrations, the comparison suggested that the modelled emission trend corresponds fairly well with the seasonal trend in the measurements. The remaining discrepancies point to the need to develop functional parametrisations of the interactions with climatic seasonal variation.     

Near-real-time measurement of trace volatile organic compounds from combustion processes using an on-line gas chromatograph

The US EPA's current regulatory approach for combustion and incineration sources considers the use of real-time continuous emission monitors (CEMs) for particulate, metals, and organic compounds to monitor source emissions. Currently, the CEM technologies to support this approach have not been thoroughly developed and/or demonstrated. The EPA's Air Pollution Prevention and Control Division has developed a near-real-time volatile organic compound (VOC) CEM, using an on-line gas chromatograph (OLGC), capable of measuring over 20 VOCs at concentrations typically present in well-operated combustion systems. The OLGC system consists of a sample delivery system, a sample concentrator, and a GC equipped with both flame ionization and electron capture detectors. Application of the OLGC system was initially demonstrated through participation in the 1995 US EPA/DOE CEM demonstration program. Additional work has improved system performance, including increased automation and improved calibration technique. During pilot-scale incineration testing, measurement performance was examined in detail through comparisons to various CEM performance criteria. Specifically, calibration error, calibration drift error, and system bias were examined as a function of full scale (absolute error) and gas concentration (relative error). Although OLGC measurement performance was not able to meet standard EPA CEM measurement performance criteria, measurement performance was encouraging. The system demonstrated the ability to perform hourly trace level VOC measurements (0–100 ppbv) for as many as 23 different VOCs with boiling points ranging from −23.7 to 180.5 °C at a known level of measurement performance. This system is a suitable alternative to VOC reference method measurements which may be performed only intermittently.     

Greenhouse gases emissions from solid waste: an analysis of Expo 2010 Shanghai,China

The management of greenhouse gases (GHGs) emissions is currently a very important environmental issue. Mega-event organizers and host cities have attached great importance to GHGs emissions associated with event-related activities. However, GHGs emissions from event solid waste have never been thoroughly discussed. This study investigated GHGs emissions of major event’s solid waste using life cycle assessment, based on Shanghai Expo case. The results showed that GHGs from collecting and sorting, transportation and landfill treatment amount to 9790 t CO₂e. And the emission intensity is estimated to be 134 g CO₂e per event service. GHGs reduction from recycling amounts to 48 kt CO₂e, with 78 % of these the result of construction waste recycle. It illustrates that waste recycle plays a vital role in GHGs mitigation. Finally, the study suggests that the concept of waste avoidance, waste reuse and waste recycle is an effective waste management to mitigate climate change and should be implemented in major event to achieve the goal of green event.     

Generating CO2-credits through landfill in situ aeration

Landfills are some of the major anthropogenic sources of methane emissions worldwide. The installation and operation of gas extraction systems for many landfills in Europe and the US, often including technical installations for energy recovery, significantly reduced these emissions during the last decades. Residual landfill gas, however, is still continuously produced after the energy recovery became economically unattractive, thus resulting in ongoing methane emissions for many years. By landfill in situ aeration these methane emissions can be widely avoided both, during the aeration process as well as in the subsequent aftercare period. Based on model calculations and online monitoring data the amount of avoided CO_2-eq. can be determined. For an in situ aerated landfill in northern Germany, acting as a case study, 83–95% (depending on the kind and quality of top cover) of the greenhouse gas emission potential could be reduced under strictly controlled conditions. Recently the United Nations Framework Convention on Climate Change (UNFCCC) has approved a new methodology on the “Avoidance of landfill gas emissions by in situ aeration of landfills” (UNFCCC, 2009). Based on this methodology landfill aeration projects might be considered for generation of Certified Emission Reductions (CERs) in the course of CDM projects. This paper contributes towards an evaluation of the potential of landfill aeration for methane emissions reduction.     

Uncontrolled methane emissions from a MSW landfill surface: Influence of landfill features and side slopes

Sanitary landfills for Municipal Solid Waste (MSW) disposal have been identified as one of the most important anthropogenic sources of methane (CH₄) emissions; in order to minimize its negative effects on the environment, landfill gas (LFG) recovery is a suitable tool to control CH₄ emissions from a landfill site; further, the measurement of CH₄ emissions can represent a good way to evaluate the effectiveness of LFG recovering systems. In general, LFG will escape through any faults in the landfill capping or in the LFG collection system. Indeed, some areas of the capping can be more permeable than others (e.g. portions of a side slope), especially when considering a temporarily capped zone (covered area that is not expected to receive any further waste for a period of at least 3 months, but for engineering reasons does not have a permanent cap yet). These areas, which are characterized by abnormal emissions, are usually defined as “features”: in particular, a feature is a small, discrete area or an installation where CH₄ emissions significantly differ from the surrounding zones. In the present study, the influence that specific features have on CH₄ emissions has been investigated, based on direct measurements carried out in different seasons by means of a flux chamber to the case study of Palermo (IT) landfill (Bellolampo). The results showed that the flux chamber method is reliable and easy to perform, and the contoured flux maps, obtained by processing the measured data were found to be a suitable tool for identifying areas with abnormal (high) emissions. Further, it was found that a relationship between methane emission rates and landfill side slope can be established. Concerning the influence of the temporary HDPE cover system on CH₄ recovery efficiency, it contributed to a significant decrease of the free surface area available for uncontrolled emissions; this aspect, coupled to the increase of the CH₄ volumes collected by the LFG recovery system, led to a significant increase of the recovery efficiency.