MSW Treatment Research Articles

Characterization of SRF from MBT plants: Influence of the input waste and of the processing technologies

Mechanical and biological treatments are the widespread treatments of mixed waste and organic waste in order to enable recovering recyclable materials from MSW. However, a large portion of mixed waste ends up as rejects, which can provide a remarkable energy content. Rejects can therefore become a solid recovered fuel (SRF) for incineration or co-incineration plants that meet the classification and specification requirements laid down in standard CEN/TS 15359 (2012). In this work, different flows of reject have been studied and identified, and different rejects have been characterized. The most important differences exist between rejects from the stages of recovery of recyclable materials and rejects from the stages of compost/bio-stabilized matter refinement. Rejects are composed mainly of combustible material, with low S, C and Hg contents, although rejects from the material recovery stage have a higher chlorine content than the others, due to their higher plastics content. Nevertheless, rejects from the material recovery stage have the most favourable SRF class code. Therefore, to take advantage of the fuel contained in the SRF it is necessary to examine the different reject flows from MSW treatment plants separately in order to improve the quality of SRF obtained from rejects.

Hydrothermal Carbonization of Autoclaved Municipal Solid Waste Pulp and Anaerobically Treated Pulp Digestate

In this study, the autoclaved organic fraction of municipal solid waste pulp (OFMSW) and the digestate from OFMSW pulp after anaerobic digestion (AD) were processed by hydrothermal carbonization (HTC) at 200, 250, and 300 °C for 30 min and 2 h. The focus of this work was to evaluate the potential for producing an energy-dense solid hydrochar from either OFMSW or digestate by HTC. The fate of inorganics, especially the heavy metals in hydrochar is discussed. In addition, the aqueous products were analyzed to identify the chemicals produced and the chemical changes during HTC. A carbon balance was performed from the solid and liquid phase analyses. Moreover, two conceptual MSW treatments consisting of autoclaving with or without AD, but including HTC, were proposed and mass and energy balances were performed. From the proximate, ultimate, FTIR, and fiber analyses, the hydrochar becomes increasingly energy and inorganic dense with the increase of HTC temperature.

Effects of moisture content or particle size on the in situ degradability of maize silage and alfalfa haylage in lactating dairy cows.

A study using four Holstein cows with ruminal cannulas was conducted to evaluate the degradability of different moisture content or particle size of maize silage and alfalfa haylage. The maize silage (MS; 20-mm length) and alfalfa haylage (AH; 40-mm length) samples were wet (wet maize silage, MSW; wet alfalfa haylage, AHW), dried (dried maize silage, MSD; dried alfalfa haylage, AHD), or ground to pass through a 2.5-mm screen (dried ground maize silage, MSG; dried ground alfalfa haylage, AHG). Samples were incubated in the rumen for 2, 6, 12, 24, 36, 48, and 72 h. Cows were fed ad libitum and allowed free access to water. High moisture content treatment of MSW expressed a lower rinsing NDF and ADF degradability at 2 h (P < 0.05) compared with dried samples (MSD and MSG). Different moisture content and particle size had a significant impact (P < 0.05) on the NDF degradability at 72 h, ADF degradability at 36, 48, and 72 h, and ruminally degradable ADF. All of the highest values were observed in small particle size and low moisture content AHG treatment. Based on this study, sample processing, such as drying and grinding, should be considered when evaluating nutritive values of forages.

Mobile Platform of SRF Production and Electricity and Heat Generation

The technological frontier is ripe for action on the cycle of municipal waste at local level through the optimization of existing treatment processes, adapting to European Union directives. The study concerns the analysis of the waste cycle in order to rationalize the current paths of the waste by adapting to EU directives, with a view of the entire supply chain - from the delivery to the energy production (WtE, Waste to Energy) – with a intermediate stage of SRF (Solid Recovered Fuel) production. The DIMA has developed an innovative platform for MSW treatment (unsorted and not), based on newly developed technologies that enables its weight and volume reduction and the transformation in SRF high quality, by achieving consistent chemical-physical and particle size parameters through the innovative technology of mechanochemical micronization. This standardized fuel product is therefore suitable for energy recovery within the platform using the most advanced gasification process. The study aims at developing a mobile demonstration plant of 100-200 kWe for energy recovery from waste in cogeneration by conversion of MSW into SRF through a system of characterization, treatment and recycling based on a highly innovative mechanochemical refining system. The SRF is enhanced through more advanced gasification process and it can used for the production of electricity and thermal energy. The production, the gasification and the syngas combustion take place in modular units arranged in appropriate mobile units (containers) appropriately configured, to fully meet the objectives of a sustainable policy management and security of waste. b Unit 1 (waste treater - SRF producer) is developed to operate the transformation of industrial waste in SRF for subsequent gasification inside unit 2 (Boiler Gasifier). It carries out a pre-treatment and mechanochemical micronization waste treatment. The SRF is reduced into pellets to be introduced into the 2 (boiler gasifier) to its gasification (syngas production). The pellet (auxiliary unit 4, pellettizer) is gasified in the unit 2 and enriched in order to obtain synmethan gas for producing electricity in the cogeneration unit 3 (energies production).

Pyrolysis and char reactivity of a poor-quality refuse-derived fuel (RDF) from municipal solid waste

The present study focuses on analyzing the pyrolysis and combustion behaviors of a refuse-derived fuel (RDF), which is generated in a MSW treatment plant located in Zaragoza (Spain). Pyrolysis experiments were carried out in a TGA apparatus and a fixed-bed reactor at different peak temperatures (400 and 600°C) and heating rates (5 and 40°Cmin−1). The reactivity towards oxygen of produced chars was also measured in the same TGA device at a heating rate of 10°Cmin−1 and a final temperature of 800°C. Pyrolysis results were significantly affected by peak temperature and heating rate. The found effect of peak temperature on char and fixed-carbon yields as well as on measured properties (H:C and O:C ratios, BET surface area and average pore diameter) was in agreement with previous studies. However, the effect of heating rate, especially on the release rate of volatiles, could be explained by a change in the pyrolysis reaction scheme. The RDF-derived chars obtained at the highest heating rate showed a higher reactivity in air. In addition, an increase in peak temperature also led to a higher reactivity. This result can indicate that the carbon present in the RDF-derived char is dispersed within an ash matrix containing a high number of active sites, the distribution of which could be improved when heating rate (and, to a lesser extent, peak temperature) is increased. The addition of 10wt.% RDF to two-phase olive mill waste prior to slow pyrolysis led to an apparent increase in the carbonization efficiency as well as to an enhancement of the resultant char's reactivity in air.

The Relevance of Framework Conditions for Modelling GHG Emissions from rMSW Treatment Systems in EU

Apart from landfilling, there are two main technologies in order to treat residual municipal solid waste (rMSW): thermal treatment, particularly incineration with energy recovery, and mechanical biological treatment (MBT). It is generally accepted that both technologies show the potential to reduce the emission of GHGs when compared to landfilling. However, there is no consensus about whether incineration or MBT is the more climate friendly technology. Within the presented paper, the reasons for the ambivalent evaluation of GHG emissions from rMSW treatment are investigated. It is found that the contradicting positions regarding GHG emissions from rMSW treatment mainly result from (1) different modelling approaches and (2) varying framework conditions, which influence the performance of MSW treatment technologies. Based on these findings, a three step approach is developed to define requirements for a model, which allows a robust comparison of GHG emissions from two MBT technologies and one incineration approach taking into account varying backgrounds. The three step approach reveals numerous demands on material parameters that are driven by background conditions [(1) legal requirements (e.g. thresholds for emissions), (2) markets (e.g. metal separation), (3) the population and (4) climatic conditions]. Many of the background demands call for modifications/extensions of the examined technologies. Finally, a need for (1) a deeper understanding of biological treatment processes as well as (2) models of mechanical unit processes that are adjustable to different input materials are discovered as conditions for implementing robust comparison of MBT and incineration within different contexts.

Update of MSW Treatment Facilities to Maximize Energy Recovery and to String then Disaster Waste Treatment

Update of MSW Treatment Facilities to Maximize Energy Recovery and to String then Disaster Waste Treatment

Optimization the transport and treatment cost of municipal solid waste under the effected of economy, socio and environment

The multi-decision support model is developed and demontrated to minimise the cost of transport and treatment of municipal solid waste under the effected of socio and environment. The tool is simple, easy to upgrade to fit with the local condition, easy and fast running (some minutes). The model is used to compare the operation of MSW system if there are some changes in impact factors. The results of model show: (1) the distribution of amount of MSW from sources to treatment plants, (2) the selected treatment technologies, its capacity and location, (3) cost analysis of transport, treatment of MSW and the income. In the current situation of HCMC (case study 2), the model proposed 2 treatment tecnologies in 20 years planning, called bath anaerobic digestion technology and bioreactor landfill, with the treatment amount of 70% and 30%, respectively. In case of the planned land for treatment zone is not reached as case study 2, incineration technology will be a good choice.

Relations between drying efficiency and parameters in bio-drying process for MSW treatment: A review

Relations between drying efficiency and parameters in bio-drying process for MSW treatment: A review

Plasma Arc Gasification for Waste Management and Sustainable Renewable Clean Energy Generalization

Plasma gasification in waste to energy is one of the novel applications that were introduced many years ago. Landfill sites and incineration continue to be the primary methods used to dispose wastes with significant negative impact on the environment. Landfill releases methane which is 21 times more dangerous as a greenhouse gas than carbon dioxide. Incineration is often pushed as an alternative to land filling. However, it is a known fact that incinerator ashes are contaminated with heavy metals, unburned chemicals and new chemicals formed during the burning process. These ashes are then buried in landfill or dumped in the environment. Rather than making waste disappear, incinerators create more toxic waste that pose a significant threat to public health and the environment. Sustainable and successful treatment of MSW should be safe, effective, and environmentally friendly. In this application, plasma arc gasifies the carbon-containing materials in the waste to produce synthesis gas (syngas) composed primarily of carbon monoxide and hydrogen, which can be used to produce energy through reciprocating engine generators - gas turbines and steam boilers in integrated gasification combine circle (IGCC), and/or liquid fuels. The in-organic waste materials are vitrified and runs out of the vessel’s bottom as glass-like slag and reusable metal. The double benefit of waste management and energy production is realized from plasma gasification process

Optimization for MSW logistics of new Xicheng and new Dongcheng districts in Beijing based on maximum capacity of transfer stations

It is necessary to achieve the optimization for MSW logistics based on the new Xicheng (combining the former Xicheng and the former Xuanwu districts) and the new Dongcheng (combining the former Dongcheng and the former Chongwen districts) districts of Beijing. Based on the analysis of current MSW logistics system, transfer station's processing capacity and the terminal treatment facilities' conditions of the four former districts and other districts, a MSW logistics system was built by GIS methods considering transregional treatment. This article analyzes the MSW material balance of current and new logistics systems. Results show that the optimization scheme could reduce the MSW collection distance of the new Xicheng and the new Dongcheng by 9.3 x 10(5) km x a(-1), reduced by 10% compared with current logistics. Under the new logistics solution, considering transregional treatment, can reduce landfill treatment of untreated MSW about 28.3%. If the construction of three incineration plants finished based on the new logistics, the system's optimal ratio of incineration: biochemical treatment: landfill can reach 3.8 : 4.5 : 1.7 compared with 1 : 4.8 : 4.2, which is the ratio of current MSW logistics. The ratio of the amount of incineration: biochemical treatment: landfill approximately reach 4 : 3 : 3 which is the target for 2015. The research results are benefit in increasing MSW utilization and reduction rate of the new Dongcheng and Xicheng districts and nearby districts.

Public perception of odour and environmental pollution attributed to MSW treatment and disposal facilities: A case study

If residents’ perceptions, concerns and attitudes towards waste management facilities are either not well understood or underestimated, people can produce strong opposition that may include protest demonstrations and violent conflicts such as those experienced in the Campania Region of Italy. The aim of this study was to verify the effects of the closure of solid waste treatment and disposal facilities (two landfills and one RDF production plant) on public perception of odour and environmental pollution. The study took place in four villages in Southern Italy. Identical questionnaires were administered to residents during 2003 and after the closure of the facilities occurred in 2008. The residents’ perception of odour nuisance considerably diminished between 2003 and 2009 for the nearest villages, with odour perception showing an association with distance from the facilities. Post closure, residents had difficulty in identifying the type of smell due to the decrease in odour level. During both surveys, older residents reported most concern about the potentially adverse health impacts of long-term exposure to odours from MSW facilities. However, although awareness of MSW facilities and concern about potentially adverse health impacts varied according to the characteristics of residents in 2003, substantial media coverage produced an equalisation effect and increased knowledge about the type of facilities and how they operated. It is possible that residents of the village nearest to the facilities reported lower awareness of and concern about odour and environmental pollution because the municipality received economic compensation for their presence.

PREVIOUS CROPS AND ORGANIC FERTILIZERS IN LETTUCE: EFFECTS ON YIELDS AND SOIL PROPERTIES

The use of organic amendments in agriculture could sustain crop production and preserve the agroecosystem, due to their importance in the conservation of organic matter in soil. The objective of this research was to evaluate the effects of differing organic fertilizers and of previous crops on lettuce growth, nutritional status and yields. The effects on soil characteristics were further investigated. The research was carried out during two years (2006 and 2007) at Metaponto (MT) in southern Italy, on lettuce crops cultivated after eggplant and melon to avoid their continuous cropping. The effects of application of a mineral fertilizer (MF), and of three treatments with organic fertilizers (commercial stable manure - OM; anaerobic digestate based on wine distillery wastewater - AD; composted municipal solid organic wastes coming from the separate collection - MSW) were studied. Head average weight, leaf area index, nitrate content and SPAD readings during the cropping cycles did not show significant differences among fertilizer treatments. On the contrary, marketable yield and head average weight at the harvest presented significantly different among the three organic fertilizers. The average marketable yield and head average weight of organic fertilizers experimental (AD and MSW treatments) decreased of 16 and 17%, respectively, compared to OM treatment. The previous melon crop influenced positively all analyzed parameters of the lettuce compared with previous eggplant crop. The previous melon crop reached the highest marketable yield with an increase of 59% compared with previous eggplant crop. Compared to the mineral fertilizer, the organic ones significantly increased the extracted fraction of soil organic carbon (6.9, 10.7 and 14.9% for OM, AD and MSW, respectively), without significant changes for the humic and fulvic content.

Investigations of Bio-Drying Process of Municipal Solid Waste

Operation analysis of the mechanical-biological stabilization reactor was presented. Minicipal waste undergoes mechanical pretreatment and then the fraction 0–80 mm rich in organic matter is treated by oxidic method in the reactor. Results of investigations of raw MSW (0–80 mm) and stabilat (0–20 mm, 20–80 mm) which are the resulting material after the 7 days bio-drying processes, were discussed. The loss of ignition (LOI), humidity, pH, the amount of sulfur, chlorides, heavy metals and the biologically stable state are the main investigated parameters. To evaluate the material stabilization, the determination of the O2 uptake and CO2 production was measured. The results allowed to evaluate the work effectiveness of the industrial reactor constructed for MSW treatment. The experiments were led using an OXYMAX respirometer ER-10 (Columbus Instruments), an ion chromatograph 883 Basic IC plus, spectrometer with plasma ICP.

The Formation and Control of Secondary Pollutants during Thermal Treatment of Municipal Solid Waste

With government-depth recognition of scientific development and improvement of people’s living environment, treatments of MSW has become one of the key points of environmental protection. Herein, the formation paths of dioxins and heavy metals during the thermal treatment of MSW were presented detailed, the countermeasures including source control, thermal treatment technology and gas and ash terminal-treat for the emissions control were proposed either.

Metals in RDF and other high calorific value fractions from mechanical treatment of MSW: analysis and sampling errors

RDF and other high calorific value fractions derived from MSW by mechanical treatment processes contain goods such as cans, cables, zippers or batteries which are highly concentrated in metals. The objective of this study was to investigate the importance of these metal carriers (i) for total metal loads and (ii) for sampling errors. Six different products derived from MSW were analysed for carrier bound and total loads of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn. Sophisticated sample preparation procedures were applied in order to quantify the separate analyte loads from metallic carriers. Typical values for total metal contents and shares of carrier bound loads were found as follows: Al, 20 g kg(-1) (30%); Cr, 0.4 g kg(-1) (50%); Cu, 5 g kg(-1) (80%); Fe, 40 g kg(-1) (80%); Ni, 0.15 g kg(-1) (70%); Pb, 0.4 g kg(-1) (40%); and Zn, 2 g kg(-1) (30%). NiCd-batteries were found in three materials representing 30-70 % of total Cd contents (total 6-20 mg kg(-1)). Sampling errors related to the distribution of analyte carriers were in most cases found in the range of 50-150 % relative standard deviation in spite of the large sample masses of 200-800 kg. The results demonstrate: (1) metal carriers are responsible for significant analyte loads; if they are not adequately considered, total metal contents may be severely underestimated; (2) sampling errors are dominated by the distribution of carriers; (3) correct analysis of total metal contents including loads from metallic components requires expensive sample preparation.

An economic evaluation and assessment of environmental impact of the municipal solid waste management system for Taichung City in Taiwan

Municipal solid waste management (MSWM) is an important environmental challenge and subject in urban planning. For sustainable MSWM strategies, the critical management factors to be considered include not only economic efficiency of MSW treatment but also life-cycle assessment of the environmental impact. This paper employed linear programming technique to establish optimal MSWM strategies considering economic efficiency and the air pollutant emissions during the life cycle of a MSWM system, and investigated the correlations between the economical optimization and pollutant emissions. A case study based on real-world MSW operating parameters in Taichung City is also presented. The results showed that the costs, benefits, streams of MSW, and throughputs of incinerators and landfills will be affected if pollution emission reductions are implemented in the MSWM strategies. In addition, the quantity of particulate matter is the best pollutant indicator for the MSWM system performance of emission reduction. In particular, this model will assist the decision maker in drawing up a friendly MSWM strategy for Taichung City in Taiwan. Implications: Recently, life-cycle assessments of municipal solid waste management (MSWM) strategies have been given more considerations. However, what seems to be lacking is the consideration of economic factors and environmental impacts simultaneously. This work analyzed real-world data to establish optimal MSWM strategies considering economic efficiency and the air pollutant emissions during the life cycle of the MSWM system. The results indicated that the consideration of environmental impacts will affect the costs, benefits, streams of MSW, and throughputs of incinerators and landfills. This work is relevant to public discussion and may establish useful guidelines for the MSWM policies.

On the pre-treatment of municipal organic waste towards fuel production: a review

Lignocelluloses are the main constituents of municipal organic waste (MOW). In order to increase the production of fuels, via fermentations, the enzymatic hydrolysis is the first step towards a valorisation process. It is well-known that the hydrolysis of lignocelluloses is not very effective because of the high stability of the constituents. In this respect the pre-treatment of MOW is necessary to increase the efficiency of the biological processes. Several pre-treatment processes are reviewed and analysed in the paper and the drawbacks are pointed out. The fundamental scientific features are highlighted and details are given on the technological parameters. The increase in the availability of sugars after pre-treatment seems to be rather high. The necessity of setting up a design procedure and defining scale-up criteria for the full scale pre-treatment of MOW are problems that still need to be overcome in order to extend the technology to MSW treatment field. A pilot plant of adequate potentiality is shown in an attempt to cover this gap.

Analyses on Carbon Emission from Municipal Solid Waste Treatment in China

The carbon emissions from China’s MSW management are evaluated with the mass balance model. According to the MSW generation and treatment trends, the future carbon emission and sink are also predicted. The results show that the net equivalent CO2emission is maintaining at about 150 million tons at recent years, although the MSW generation is growing slowly. MSW incineration for energy production and Landfill gas utilization in landfill sites are the main ways of carbon emission reduction. China’s MSW generation will reach 166 million tons, while the equivalent CO2emission will decease to 144 million tons due to more energy recovery from MSW treatment.

The best MSW treatment option by considering greenhouse gas emissions reduction: a case study in Georgia

The grave concern over climate change and new economic incentives such as the clean development mechanism (CDM) have given more weight to the potential of projects for reducing greenhouse gas (GHG) emissions. In the Adjara solid waste management project, even though the need for reductions in GHG emissions is acknowledged, it is not one of the key factors for selecting the most appropriate treatment method. This study addresses the benefit of various solid waste treatment methods that could be used in the Adjara project in terms of reducing GHG emissions. Seven different options for solid waste treatment are examined: open dumping as the baseline case, four options for landfill technology (no provision of landfill gas capture, landfill gas capture with open flare system, with enclosed flare system and with electricity generation), composting and anaerobic digestion with electricity production. CDM methodologies were used to quantify the amount of reductions for the scenarios. The study concludes sanitary landfill with capture and burning of landfill gas by an enclosed flare system could satisfy the requirements, including GHG reduction potential. The findings were tested for uncertainty and sensitivity by varying the data on composition and amount of waste and were found to be robust.