Recovery of plastic packaging from mixed municipal solid waste. A case study from Austria.

Austria must recycle more packaging materials. Especially for plastic packaging waste, significant increases are necessary to reach the EU recycling targets for 2025 and 2030. In addition to improving separate collection and introducing a deposit system for specific fractions, the share of plastic packaging in mixed municipal solid waste (MSW) could be utilized. In Austria, about 1.8milliontonnes of mixed MSW are generated. This includes about 110,000 t/a of plastic packaging waste. Most of the mixed MSW (94 %) is sent directly or via residues from pre-treatment, such as mechanical-biological treatment or waste sorting, to waste incineration. While materials such as glass and metals can also be recovered from the bottom ash, combustible materials such as plastics must be recovered before incineration. This work aims to evaluate the recovery potential of plastic packaging waste in mixed MSW with automated waste sorting. For this purpose, two of the largest Austrian waste sorting plants, with a total annual throughput of about 280,000 t/a, were investigated. The investigation included regular sampling of selected output streams and sorting analysis. The results show that the theoretical recovery potential of plastic packaging from these two plants is 6,500 t/a on average. An extrapolation to Austria results in a potential of about 83,000 t/a. If losses due to further treatment, such as sorting and recycling, are considered, about 30,000 t/a of recyclate could be returned to plastic production. This would correspond to an increase in plastic packaging recycling rate from 25 % to 35 %.

Improving waste management by focussing on goals: A mini review of the publication sector.

The rationale for this article is that often, decision-makers in waste management (wm) tend to neglect goals and confuse them with means like circular economy or waste hierarchy. Because clear goals are crucial for developing effective wm strategies, the objectives of this mini review are (1) to clarify wm goals in a historical context by a literature review, (2) to investigate how (a) these goals have been observed in general scientific publishing and (b) specifically in Waste Management and Research (WM&R) and (3) to recommend measures for better consideration of wm goals by the publication sector. Based on general as well as specific bibliographic analyses of databases in Scopus and Google Scholar, the study confirms that little attention was given to wm goals in scientific publishing. For instance, during the first 40 years of WM&R, 63 publications and eight editorials were found containing terms related to wm goals, but only 14 respectively and eight explicitly discuss wm goals. We recommend focussing more on wm goals. Editors, authors, reviewers and professional associations in the field of wm should become aware of this challenge and react. If WM&R decides to become a strong platform for the issue wm goals, it will be in a unique selling proposition and more authors, articles and readers are likely to result. This article aims at setting a starting signal for such an endeavour.

Comparing the quantity and quality of glass, metals, and minerals present in waste incineration bottom ashes from a fluidized bed and a grate incinerator.

Bottom ash is the primary solid residue arising from municipal solid waste incineration. It consists of valuable materials such as minerals, metals and glass. Recovering these materials from bottom ash becomes evident when integrating Waste-to-Energy within the circular economy strategy. To assess the recycling potential from bottom ash, detailed knowledge of its characteristics and composition is required. The study at hand aims to compare the quantity and quality of recyclable materials present in bottom ash from a fluidized bed combustion plant and a grate incinerator, both located in the same city in Austria and receiving mainly municipal solid waste. The investigated properties of the bottom ash are grain-size distribution, contents of recyclable metals, glass, and minerals in different grain size fractions, and the total and leaching contents of substances in minerals. The study results reveal that most recyclables present are of better quality for the bottom ash arising at the fluidized bed combustion plant. Metals are less corroded, glass contains fewer impurities, minerals contain fewer heavy metals, and their leaching behavior is also favorable. Furthermore, recoverable materials, such as metals and glass are more isolated and not incorporated into agglomerates as observed in grate incineration bottom ash. Based on the input to the incinerators more aluminum and significantly more glass can potentially be recovered from bottom ash from fluidized bed combustion. On the downside, fluidized bed combustion produces about five times more fly ash per unit of waste incinerated, which is currently disposed of in landfills.

Inhalation health risk assessment of incineration and landfill in the Bohai Rim, China.

An inhalation health risks assessment of 96 waste to energy (WtE) plants and 178 landfills in the Bohai Rim, located in northeast China, has been conducted. Based on the latest emission inventories in 2020, WRF/CALPUFF was used to simulate the diffusion of pollutants. Population-weighted hazard index (HI) and carcinogenic risk (CR) of incineration and landfill for each pollutant and each target organ impacted were calculated. The health risks of incineration and landfill were correlated with per capita municipal solid waste (MSW) disposal quantity, emission factors, pollutant toxic effects and local migration and diffusion conditions. The HI of incineration and landfill in the Bohai Rim were 4.07 × 10-3 and 4.79 × 10-3, respectively, which was lower than the acceptable level (HI < 1), while the CR of incineration and landfill were 4.72 × 10-7 and 2.58 × 10-7, respectively, which was also lower than the acceptable level (CR < 1 × 10-6). The non-carcinogenic risks of incineration mainly targeted respiratory system and development system, while the non-carcinogenic risks of landfill mainly targeted nervous system and respiratory system. The carcinogenic risks of incineration mainly targeted respiratory system and digestive system, while the carcinogenic risks of landfill mainly targeted hepatic system and respiratory system. With the trend that incineration phase in, while landfill phase out, the number of patients for 15 target organ diseases caused by the disposal of unit mass MSW would decrease in the Bohai Rim, ranging from 1.8 × 10-8 - 1.8 × 10-2 (pop/t)，especially in developed provinces, such as Beijing and Tianjin. However, the number of patients for 4 target organ diseases caused by the disposal of unit mass MSW would increase, ranging from 1.18 × 10-6 - 5.28 × 10-3 (pop/t). Based on pollutants' pathogenic mechanisms, this study innovatively accessed and compared incineration and landfill's health risks of target organs, and provide technical and policy suggestions based on the changing trend of MSW disposal methods in the future.

Separate collection rates for plastic packaging in Austria - A regional analysis taking collection systems and urbanization into account.

According to the EU Circular Economy Package, recycling of plastic packaging waste (PPW) has to be enhanced significantly by 2025 and 2030. Although a set of measures will be required along the whole value chain of plastic packaging, the process of separate collection remains the backbone. Hence, a detailed understanding of the performance of current separate collection systems is crucial. As a case study, the separate collection of PPW was analyzed within a single country, Austria, where a variety of collection procedures are implemented. By using the method of material flow analysis, separate collection rates in terms of quantities and qualities were analyzed for separate collection systems of different settlement patterns, target fractions, and service levels provided. Results show that the highest performance was achieved in systems that cover mainly rural areas and where all plastic packaging wastes are collected through curbside collection, with separate collection rates of 74-77%. With additional collection via collection centers, these values increased to 78%-83%. In comparison, the results for urban areas showed the lowest separate collection rate of 56%. In the case that separate collection targeted plastic bottles only, maximum collection rates of around 50 % were observed, with the tendency towards higher collection rates if co-mingled with metals. To enhance separate collection, a general shift to the target fraction "all plastic packaging" instead of "plastic bottles only" is crucial. Modelling of optimized collection systems in all Austrian regions would lead to a theoretical total separation collection rate of 74%.

Applying the 15N labelling technique to material derived from a landfill simulation experiment to understand nitrogen cycle processes under aerobic and anaerobic conditions.

Reactive nitrogen (N) species, such as ammonium (NH4+), nitrate (NO3) and gaseous nitrous oxide (N2O), are released into the environment during the degradation of municipal solid waste (MSW), causing persistent environmental problems. Landfill remediation measures, such as in-situ aeration, may accelerate the degradation of organic compounds and reduce the discharge of ammonium via leachate. Nonetheless, the actual amount of N in the waste material remains relatively constant and a coherent explanation for the decline in leachate ammonium concentrations is still lacking. Hence, the present study aimed to elucidate the dynamics of N and its transformation processes during waste degradation. To this end, the gross rates of organic N mineralization and nitrification were measured using 15N pool dilution in waste material derived from a landfill simulation reactor (LSR) experiment. The results revealed a high potential for N mineralization and nitrification, the latter of which declined with the diminishing amount of extractable ammonium (after aeration). The analysis of the concentration and isotopic composition of N2O formed confirmed incomplete denitrification as the main source for N2O. Moreover, the natural abundance of 15N was investigated in various waste N pools to verify the conclusions drawn from the 15N tracing experiment. δ15N values of total waste N increased during aeration, indicating that nitrification is the major driver for N losses from aerated waste. The application of stable isotopes thereby allowed unprecedented insights into the complex N dynamics in decomposing landfill waste, of their response to aeration and their effect on hydrological versus gaseous loss pathways.

Quantitative water content estimation in landfills through joint inversion of seismic refraction and electrical resistivity data considering surface conduction.

The disposal of municipal solid waste (MSW) in landfills is the prevalent method of waste management at the global scale. However, the production of landfill gases due to the methanogenic fermentation of wet MSW is a possible threat to human health and accounts for a substantial contribution to the global greenhouse gas emissions. Accordingly, information regarding water content is critical as it is an important factor triggering methane production in MSW landfills. In this study, we propose a petrophysical joint inversion scheme to quantitatively solve for the water content (WC) in landfills based on seismic refraction as well as electrical resistivity data collected at two different frequencies. In this way, we also take into account the contribution of the surface conductivity to the observed electrical response, which is crucial for a reliable quantification of the WC. Our results reveal a high water content within the MSW unit (WC > 20%) for areas characterized by a strong polarization response (normalized chargeability > 5 Mn mS/m). Such areas can be related to an increased biogeochemical activity as evidenced by the detected methane production. We observe consistent estimates between the water content resolved through the proposed joint inversion scheme and values measured in waste samples with a median percentage error of 17%. Our study demonstrates the possibility to obtain reliable estimates for the WC in MSW landfills through the petrophysical joint inversion of seismic and electrical data when surface conductivity is explicitly considered.

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.

Enduring reduction of carbon and nitrogen emissions from landfills due to aeration?

The objective of the present work is to investigate to what extent emission reductions observed during landfill aeration are permanent. To do so, lab-scale degradation experiments using waste from an old landfill have been conducted under different conditions (anaerobic, (partly) aerobic returning to anaerobic, aerobic) and balances for carbon and nitrogen have been established. For the latter, all emissions of C and N (except N2) and their pools at the start and end of the experiment have been determined. In addition, the chloroform fumigation-extraction method (biocidal treatment) has been applied to determine microbially bound carbon and to estimate nitrogen in microbial biomass accordingly. The results reveal that 18 g TOC·kg DM-1 of the waste material were mineralized during aerobic treatment for 699 days, which is equivalent to about 14% of the initial TOC content. For the anaerobic treatment, only 10 g TOC·kg DM-1 were released. For the aerobic-anaerobic reactors, a slight increase in methane emissions approximately 10 months after termination of aeration was observed. With respect to leachate emissions, the results indicate significantly lower emission levels (factor 1.5 for TOC and factor 4 for TN) for the reactors, which were aerated at least sometimes. The biocidal treatment highlights that this emission reduction is rather based on an increased sorption capacity of aerated waste (higher ion exchange capacity) than a lower overall pollutant potential. It is shown that regardless of the operation mode, most nitrogen remained in solids (83.1-92.6%) and is subject to internal recycling during waste degradation.

Performance impairment of Waste to Energy plants during waste delivery times - An analysis of relevant operating parameter.

Despite long-term practical experience with waste incineration plants, their operation under the conditions for which they were designed pose challenges, mainly due to the heterogeneous composition of the waste feed. Within the framework of the present paper, the operation of 6 waste incineration plants (five grate and one fluidized bed incinerator) have been analysed in terms of hourly steam production, waste throughput, auxiliary fuel consumption and air surplus over one year. The results reveal that the operation of the majority of the plants was negatively influenced during times of waste delivery. Reductions in steam production and waste throughput of up to 3% were observed for these times in comparison to periods without any delivery of waste. Furthermore, an increase in air surplus and auxiliary fuels consumption (up to a factor of 2) was noticed, both resulting in lower environmental performance. The results further indicate that incineration plants receiving their waste via trucks are more prone to impairments of performance than plants supplied via train delivery. This observation might be explained by the fact that train delivery requires a transfer of the waste from truck to train, which is typically associated with a mixing of the waste. Based on the observed impairment of the operation during waste delivery times, the related economic loss for plant operators is estimated to be several 100,000 Euros per year. Hence, in order to improve the performance of waste incineration plants, a better mixing of the waste, in particular during times of waste delivery, is recommended.

How to increase recycling rates. The case of aluminium packaging in Austria.

The recycling of aluminium (Al) packaging as a single fraction is a new obligation within the Circular Economy Package of the EU, with mandatory recycling rates of 50% for 2025 and 60% for 2030. The case study of Al packaging in Austria has been chosen to assess if and what measures need to be taken to achieve these recycling rates and what costs arise from these measures. In particular, the following options of Al recovery, and combinations thereof, have been investigated: bottom ash (BA) treatment; material recovery facilities (MRF) for mixed municipal solid waste; and changes to the selective collection system. The results of the study reveal that the present recycling rate of 55% for A1 packaging in Austria might be improved most significantly by MRF (up to 94%) and advanced BA treatment (up to 72%). Only minor improvements in the recycling rate (+2%) are achievable via a change in the collection system from selective metal to a mixed selective collection (joint collection of metal and lightweight packaging). If the only aim were to increase the recycling rates for Al packaging beyond the future target of 60%, an improvement in the Al recovery rates from BA treatment would be sufficient. With regard to increased recycling quantities of all recyclables, plastics in particular, the implementation of complex systems such as MRF makes sense, even if this results in higher costs for Al recovery (increasing from the current 480 to 640 € t-1 of recycled Al).

Recycling rate - The only practical metric for a circular economy?

The paper is related to the suggestion of metrics for measuring and fostering circular economy. Besides a recycling rate based evaluation, the author recommend to include also a subsitution factor describing the share of primary resources subsituted by the establishment of a circular economy.

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.

Performance assessment of landfill in-situ aeration - A case study.

The assessment of landfill in-situ aeration eludes standardization as its application highly depends on varying local conditions. The prevailing work tries to assess the procedure performance by using typically available data. In the here presented case study the aeration pipes were applied horizontally. To evaluate the air-distribution and its effect on the landfill solid body, two monitoring fields with 10 × 10 m were created. From there in total 60 solid and 336 gaseous samples were taken over five years. As the material from the landfill was rather old and characterized by comparatively low reactivity, "new" material from a mechanical biological treatment (MBT) plant was introduced in the landfill. Additionally online gas data from eight technically separated landfill sections were analyzed during in-situ aeration. In total, about 46 Mm3 (0.27 m3/kg waste) air was introduced into the landfill body. The eight sections showed differences in reactivity (overall C-discharge was 8 g C kg-1 dry weight, ranging from 4.5 to 11). With solid sampling we could not show a significant decrease in landfill TOC but for the introduced MBT-material. Ammonium in solid samples was significantly reduced (to 14.7% initial) and NO3 significantly increased (2.1% initial). The reduction of the initial TOC (4.58%) was on average 11%. The application of horizontal landfill aeration led to a widespread air-distribution in a rather shallow landfill. Monitoring fields allowed for a screening of the impact of the measures on the solid body with reduced sampling costs.

Legal situation and current practice of waste incineration bottom ash utilisation in Europe.

Almost 500 municipal solid waste incineration plants in the EU, Norway and Switzerland generate about 17.6 Mt/a of incinerator bottom ash (IBA). IBA contains minerals and metals. Metals are mostly separated and sold to the scrap market and minerals are either disposed of in landfills or utilised in the construction sector. Since there is no uniform regulation for IBA utilisation at EU level, countries developed own rules with varying requirements for utilisation. As a result from a cooperation network between European experts an up-to-date overview of documents regulating IBA utilisation is presented. Furthermore, this work highlights the different requirements that have to be considered. Overall, 51 different parameters for the total content and 36 different parameters for the emission by leaching are defined. An analysis of the defined parameter reveals that leaching parameters are significantly more to be considered compared to total content parameters. In order to assess the leaching behaviour nine different leaching tests, including batch tests, up-flow percolation tests and one diffusion test (monolithic materials) are in place. A further discussion of leaching parameters showed that certain countries took over limit values initially defined for landfills for inert waste and adopted them for IBA utilisation. The overall utilisation rate of IBA in construction works is approximately 54 wt%. It is revealed that the rate of utilisation does not necessarily depend on how well regulated IBA utilisation is, but rather seems to be a result of political commitment for IBA recycling and economically interesting circumstances.

Complete determination of the material composition of municipal solid waste incineration bottom ash.

Bottom ash from waste incineration is heterogeneous and contains different materials. Previous studies on the material composition of bottom ash provide only limited information as to composition, because large pieces present in bottom ash were not investigated nor were all materials were separated and analysed. The objective of the present study is to provide the complete and detailed composition of bottom ash encompassing and extensive range of different materials. Altogether, nine bottom ash samples with a mass of 3000 kg each were sieved to eight size fractions, whereby small particles adhering to larger pieces were separated by water and added to the respective size fractions. In the sorting analysis of all size fractions, the materials enclosed in molten mineral material and materials present as composites (e.g. transformers and batteries) were considered. The material characterisation revealed that the size fraction > 50 mm contains most of the iron (up to 50% of the total iron) and copper (about 20% of the total copper), while batteries, coins, silver and gold are almost exclusively present between 16 and 50 mm. The fractions between 8 and 16 mm show the highest share of aluminium (up to 50% of the total aluminium) and glass (up to 60% of the total glass). While the metal content is underestimated, if large pieces of material are disregarded, the multi-step approach applied in this study enables a complete determination of materials in bottom ash, which is essential for optimising material recovery in bottom ash treatment.

A new thermoanalytical method for the quantification of microplastics in industrial wastewater.

Plastics are crucial for our modern lifestyle and yet pose a major threat to our environment. Rising levels of microplastics (MP) in rivers and oceans are a big challenge for our economy and regulatory institutions as well as from a scientific point of view. Smaller microplastic particles, in particular, are especially hard to identify and even harder to quantify in environmental samples. Hence, we present a novel and inexpensive approach to quantify microplastics (MP) on a weight basis, relying on a thermoanalytical method. The Elemental Analysis combined with Overdetermined Equation Method (EA-OEM) was originally developed for determining the plastic content of refuse-derived fuels. It makes use of the distinct differences in the organic elemental composition (C, H, N, S, O) of plastics, biogenic and inorganic materials to calculate the (micro)plastic content on a detailed weight base. The study presented provides the first experimental results yielded from the application of the EA-OEM and two different laboratory approaches to the analysis of polyethylene (PE) and polypropylene (PP) MP content in industrial effluent samples from one source. In this way, it was possible to ensure that the polymer composition was known and the MP content therein (10-29%) could be derived. Further, the study reveals good MP recovery rates when applying the methodology to PE/PP-spiked samples.

Chemical composition and leachability of differently sized material fractions of municipal solid waste incineration bottom ash.

The chemical composition and leachability of municipal solid waste incineration bottom ash are important parameters determining its suitability for utilisation. The objective of the present study is to investigate the chemical composition of individual size and material fractions and their contribution to the total elemental contents of bottom ash. Nine bottom ash samples with a mass of 3000 kg each were sieved to eight size fractions and sorted into different materials. The materials (mineral material, glass, batteries) were separately analysed by inductively coupled plasma optical emission spectrometry after acid digestion. Additionally, x-ray fluorescence measurements and leaching tests were performed. Metals were further analysed by sorting analysis. The chemical analysis revealed that large particles have higher contents of Fe and Si, but lower contents of Ca and S compared to smaller particles. All mineral fractions exceed the legal limit values for utilisation in Austria mainly because of the total contents of Pb and Tl and the leachate contents of Cr and Sb. Glass from bottom ash is enriched in As, Na, Si and Tl compared to the mineral material. Although battery contents contribute only 0.2% to the total mass of bottom ash, they contribute at least 30% to the total content of Cd. Most previous studies neglected large metallic pieces and batteries, which contain most of the Cd, Cr, Cu and Ni present in bottom ash. This practice can result in an underestimation of the total contents of these elements by up to about 70%.

Integrating High-Resolution Material Flow Data into the Environmental Assessment of Waste Management System Scenarios: The Case of Plastic Packaging in Austria.

The environmental performance of the waste management system of plastic packaging in Austria was assessed using a combination of high-resolution material flows and input-dependent life cycle inventory data. These data were used to evaluate different configurations of the waste management system, reflecting the system structure as it was in 1994 in Austria and still is in some of the new EU member states, as well as a situation achieving the increased circular economy targets to be met by 2030. For the latter, two options, namely single-polymer recycling and mixed-polymer recycling, were investigated. The results showed that the status quo achieves net benefits for 15 out of 16 impact categories evaluated. Regarding the alternative scenarios, for most impact categories these benefits increased with increasing recycling rates, although for four impact categories the highest net benefit was achieved by the status quo. For many impact categories the marginal environmental benefit decreased at higher recycling rates, indicating that there is an environmentally optimal recycling rate below 100%. The results also highlight the importance of high-quality single-polymer plastics recycling from an environmental perspective because utilizing mixed polymer recycling to achieve circular economy targets would result in lower environmental benefits than the status quo.

Theoretical analysis of municipal solid waste treatment by leachate recirculation under anaerobic and aerobic conditions.

Long-term emissions of Municipal Solid Waste (MSW) landfills are a burden for future generations because of the required long-term aftercare. To shorten aftercare, treatment methods have to be developed that reduce long-term emissions. A treatment method that reduces emissions at a lysimeter scale is re-circulation of leachate. However, its effectiveness at the field scale still needs to be demonstrated. Field scale design can be improved by theoretical understanding of the processes that control the effectiveness of leachate recirculation treatment. In this study, the simplest and most fundamental sets of processes are distilled that describe the emission data measured during aerobic and anaerobic leachate recirculation in lysimeters. A toolbox is used to select essential processes with objective performance criteria produced by Bayesian statistical analysis. The controlling processes indicate that treatment efficiency is mostly affected by how homogeneously important reactants are spread through the MSW during treatment. A more homogeneous spread of i.e. oxygen or methanogens increases the total amount of carbon degraded. Biodegradable carbon removal is highest under aerobic conditions, however, the hydrolysis rate constant is lower which indicates that hydrolysis is not enhanced intrinsically in aerobic conditions. Controlling processes also indicate that nitrogen removal via sequential nitrification and denitrification is plausible under aerobic conditions as long as sufficient biodegradable carbon is present in the MSW. Major removal pathways for carbon and nitrogen are indicated which are important for monitoring treatment effectiveness at a field scale. Optimization strategies for field scale application of treatments are discussed.