Mechanical-biological Waste Treatment Research Articles

Hydrothermal Carbonization of the Wet Fraction from Mixed Municipal Solid Waste: A Fuel and Structural Analysis of Hydrochars

One of the by-products of a mechanical-biological waste treatment plant is the under-sieve fraction, which requires separation prior to further processing of municipal mixed waste. This stream usually follows the fate of landfilling. Instead, it could be introduced to the hydrothermal carbonization (HTC) process to improve its fuel properties and become solid recovered fuel. The organic fraction and high moisture content (approximately 26%) of under-sieve fraction are favorable properties for the HTC process. In this study, hydrochars, the solid product of HTC, were produced at 200 and 220 °C with residence times of 1, 4, and 8 h. The main aim of this investigation was to establish the influence of different process parameters on hydrochars’ fuel properties. Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were employed in the analyses. The results confirmed the positive effects of hydrothermal carbonization on the under-sieve fraction of municipal mixed waste properties. The ignition temperature increased from 247 °C to 288 °C and burnout temperature decreased to 443 °C from 489 °C after hydrothermal carbonization, causing a shorter combustion process. The determined key combustion parameters were: S = 12.4 × 10−8%·min−2·°C−3, Hf = 1174.9 °C and Di = 0.0075%·min−3, which in comparison to USF decreased by 44%, increased by 33%, and decreased by 29%, respectively, and became closer to those of coal. Furthermore, the identified structural changes indicate that hydrochars could be successfully used in energy production. The most promising results were found for hydrochar produced at 220 °C for 1 h, leading to a better combustion performance and providing a more stable and a less violent flame.

Microplastics generation and concentration during mechanical-biological treatment of mixed municipal solid waste

Mechanical-biological treatment (MBT) is a popular solution for the processing of mixed municipal solid waste (MSW). However, it is assumed that the treatment processes can lead to the generation of microplastics in large quantities and their concentration in the organic output. Organic outputs from MBT as a source of microplastics are still poorly understood. The current article aims to fill this gap and investigate microplastics formation during MBT and their abundance in ready stabilized organic output. Seasonal samples were taken from the four stages of the possible microplastics pathway in MBT to study changes in microplastics numerical and mass concentration, shape and size. Large microplastics were identified by Fourier transform infrared spectroscopy, and small microplastics by Nile Red dye staining method. The results showed that both mechanical pre-treatment and aerobic treatment had a significant impact on microplastics formation, while mechanical post-treatment only resulted in the enrichment of the output with microplastics. Moreover, microplastics became finer during treatment. Microplastics abundance in ready organic output ranged from 8925 ± 1344 particles/kg in winter 2021 to 17407 ± 4319 particles/kg in summer 2020, and up to 160.5 t of microplastics were emitted from the Kaunas MBT treatment facility during the study year. In addition, a relationship between the microplastics abundance and plastic content of the incoming waste was found by a regression analysis. Therefore, to reduce the formation and emission of microplastics by MBT, the organic fraction of MSW should be collected and treated separately.

Composting of fine fraction after mechanical-biological treatment of municipal solid waste

One of most common types of municipal solid waste treatment is mechanical-biological treatment (MBT), which in practice has many variations depending on the method of conducting the technological process and it is possible to get different output fractions. In this paper is analysed waste generated after the MBT with biodrying, where waste after mechanical treatment undergoes process of biodrying, and then is RDF (recovery derived fuel) separated. Fine fraction remains with a high content of organic matter that without additional processing cannot be disposed of on a landfill. The aim of this research was to determine the possibility of fine fraction composting in different conditions – in the open, in the open and covered area, and indoors. In each area are formed three compost piles: 100% fine fraction (KH1, KH4, and KH7), 70% fine fraction and 30% wood chips (KH2, KH5, and KH8), 50% fine fraction and 50% wood chips (KH3, KH6, and KH9). Moisture content, temperature and dissolved organic carbon (DOC) were monitored. Results show that after 13 weeks samples KH1, KH4, and KH7 (100% content of fine fractions) did not achieve DOC value less than 3 000 mg/l. The most effective composting in terms of reducing the DOC is achieved in samples KH3, KH6, KH9. Based on results obtained, it can be concluded that by adding wood chips in fine fraction in ratio 50:50, the most effective and fastest reduction of organic matter is achieved in the analysed samples.

Microbiota Dynamics of Mechanically Separated Organic Fraction of Municipal Solid Waste during Composting.

Mechanical-biological treatment of municipal solid waste (MSW) facilitates reducing the landfill workload. The current research aimed to study general activity parameters, content, functions, and diversity of fungal and prokaryotic microbiota in mechanically separated organic fraction of MSW (ms-OFMSW) composting, without using bulking agents and process-promoting additives. During 35 days of composting, vigorous emission of CO2 (max. 129.4 mg CO2 kg−1 h−1), NH3 (max. 0.245 mg NH3 kg−1 h−1), and heat release (max. 4.28 kJ kg−1 h−1) occurred, indicating intense microbial activity. Immediately following the preparation of the composting mixture, eight genera of lactic acid bacteria and fungal genera Rhizopus, Aspergillus, Penicillium, Agaricus, and Candida were predominant. When the temperature increased to more than 60 °C, the microbial biodiversity decreased. Due to succession, the main decomposers of ms-OFMSW changed. The Bacillaceae family, the genera Planifilum, Thermobifida, and Streptomyces, and the fungal genera Thermomyces and Microascus were involved in the processes of organic matter mineralization at the high-temperature and later stages. The biodiversity of the microbiota increased at the stages of cooling and maturation under conditions of relatively high nitrogen content. Thus, the microbial community and its succession during ms-OFMSW composting were characterized for the first time in this work.

Techno-economic assessment of a novel integrated system of mechanical-biological treatment and valorisation of residual municipal solid waste into hydrogen: A case study in the UK

Resources embedded in the waste streams are often not properly recovered and are mostly ended up in landfills or only recovered as energy via energy-from-waste (EfW) facilities. Innovative resource recovery from waste strategies are urgently needed to maximise resource efficiency, divert waste from landfills and reduce reliance on EfW. This study proposes a novel mechanical-biological treatment with valorisation concept (MBT-v) that combines material recovery and fuel production, as alternatives to EfW for residual municipal solid waste (MSW) treatment. The polygeneration feature exhibited by the MBT-v system enhances resource efficiency and product diversification. The proposed MBT-v system involves valorisation of rejected materials from MBT into hydrogen by incorporating an additional gasification system. A comprehensive techno-economic assessment is conducted for the proposed MBT-v system and compared against a conventional MBT. The results reveal that the conventional MBT strongly relies on gate fees to be economically viable while it is heavily impacted by the rejects disposal cost. The analysis also shows that higher economic potential (36.4 M£/y) for MBT-v can be obtained compared to that of conventional MBT (3.4 M£/y) for a 100 kt/y residual MSW system. The minimum hydrogen selling price (MHSP) from the Gasification-H2 system is estimated to be at 3.4 £/kg (28.3 £/GJ), with potential for further reduction through upscaling the facility. This study concludes that producing high value product such as hydrogen (with the current assumed market price of hydrogen of 10 £/kg) can significantly improve the economic performance and minimise financial instability of the facilities. It is recommended that the scale and optimal configuration of MBT-v to be designed based on local conditions.

The Air and Sewage Pollutants from Biological Waste Treatment

The mechanical-biological waste treatment plants (MBTP), which include the municipal waste biogas plants, have an important role in sustainable urban development. Some plants are equipped with a sewage pre-treatment plant, which is then directed to the sewerage system and the treatment plant. Others, on the other hand, have only a non-drainage tank. The parameters of technological sewage (TS) or processing technology could reduce sewage contamination rates. In addition to the quality of sewage from waste treatment plants, the emission of odours is also an important problem, as evidenced by the results obtained over the sewage pumping station tank. The conducted statistical analysis shows a significant positive correlation between odour concentration (cod) and volatile organic compounds (VOCs). Analysing the individual compounds, a high positive correlation was also found—the strongest being between H2S, NH3 and VOCs. In the case of sewage compounds, the insignificant correlation between P total and other parameters was found. For the rest of the compounds, the highest positive correlation was found between COD and BOD and N-NO2 and N-NH3 as well as COD and N-NO2. The dilution of sewage is only an ad hoc solution to the problem. Further work should be aimed at reducing sewage pollution rates. The obtained results indicate large pollution of technological sewage and a high level of odour and odorants concentration. The novelty and scientific contribution presented in the paper are related to analyses of various factors on technological sewage parameters and odour and odorant emission from TS tank at biogas plant processing municipal waste, which may be an important source of knowledge on the management of TS, its disposal and minimisation of emitted compound emissions.

Prospects for environmentally safe mechanical biological treatment of municipal solid waste in Ukraine

Improving waste management is currently one of the priorities for Ukraine in the environmental safety. EU experience in the use of mechanical biological waste treatment technologies should be applied now in connection with the development and implementation of Regional Waste Management Plans in Ukrainian regions. The aim of the paper is to analyse the benefits and the preconditions of using mechanical biological waste treatment technologies in Ukraine, as well as barriers that may hinder the construction of mechanical biological waste treatment plants. The analysis of the eight drafts of the Regional Waste Management Plans showed that the mechanical biological waste treatment technologies market is free in Ukraine and the best option for the regions where there are cement plants operating is production of solid recovered fuel. Such types of projects could be affordable for Ukrainians with the cost recovery period more than 8 years. On the other hand there are significant obstacles of economic, organizational and technological nature to their immediate implementation i.e. low rates on waste disposal tax, partly compliance on air emissions monitoring system, absence of necessary standards etc. The priority actions to speed up mechanical biological waste treatment technologies implementation have been defined.

Impact of Implementing a Deodorization System on the Functioning of a Waste Management Plant

This article is an analysis of the impact of implementing technical and technological solutions in the form of a deodorization system, which was carried out on the basis of a case study in the years 2015 and 2019 of an existing waste management plant named located in the region of Lower Silesia. The method for determining the impact was based on an analytical method for estimating changes in plant operation parameters in relation to the emission of odor compounds, determined at selected reference points, during a period of normal operation before and directly after the implementation of the deodorization system. The purpose of this work is the evaluation of the impact of the deodorization system on the parameters determining the functioning of the plant—a mechanical-biological waste treatment facility in order to determine sustainability factors and their relative changes.

The correlations of the particle size, calorific value, moisture- and ash content of waste derived fuel, and examination of its heavy metal content

Significant development has taken place in the field of waste management recently in the preparation of the energetic exploitation of recyclable, non-hazardous municipal solid waste. With mechanical-biological waste treatment, 35-40% of the weight of this waste can be made appropriate for energetic exploitation, mainly for co-incineration in cement factories and power plants.
 The recoverability of waste derived fuel produced in mechanical-biological waste treatment plants highly depends on the burning and combustion technological properties of the mixture, and on its compounds influencing burning and different emissions. Waste recovery facilities do not take over fuel below a specific calorific value and over a given heavy metal, halogen and pollutant content.
 In our research we were looking for correlations in the particle size, calorific value, moisture-, ash- and heavy metal content of waste derived fuel. On the basis of the measurement results, the connection between the particle size fractions and the fuel properties can clearly be stated. The fractions of smaller particle size have higher moisture-, ash- and heavy metal content, while the fractions of bigger particle size have higher calorific value.

Assessment of the Efficiency of Biological Treatment of Gases from Municipal Waste Processing

Abstract The objective of the study is research on a biofilter existing at a mechanical-biological waste treatment plant in Radom. The paper presents results of research on the filling of the analysed biofilter (moisture, organic matter content, nutrient content, pH, grain size composition, and equivalent diameter), process gases (temperature, humidity and pH, concentrations of the main pollutants - ammonia, hydrogen sulphide, volatile organic compounds, acetic acid, ethanol) and operational parameters (flow rate, height of the biofilter layer, surface load, gas residence time in the filter bed). Irregularities were observed related to biofiltration efficiency, particularly resulting from improperly selected filling material and improper biofilter operation. The technological research permitted the identification of problems and determination of the requirement of performing necessary operational changes. Further works will involve the design, manufacture, and installation of an integrated biofilter with two-stage gas purification process (a classic biofilter and a semi-permeable membrane).

Efficiency of waste processing in the MBT system

In the professional literature there is no information on the efficiency of waste treatment in MBT (mechanical-biological waste treatment) systems in Poland. This knowledge is currently particularly important as it will decide on the role of the MBT system in the new reality of the circular economy, and consequently on the direction and necessary scope of modernization of these systems. The article presents a series of technical and technological indicators designated for one of the recently commissioned MBT plants against the background of minimum, maximum and average values of these parameters set for 20 systems with various MBTs covered by the research as part of the review of technological solutions used in Poland, made in 2015. For the system in Marszów, respectively in 2017 and 2018, the average value of the ratio of underscreen to overscreen fraction was 1.4; the losses of mass in the biological treatment process amounted to 28.7 and 29.4%; energy demand – 46.6 and 44.3 kWh/Mg; the aeration index – 16.7 m3/(Mg h); the average waste recycling rate – 15.2 and 17.3%; the share of fuel fraction recovery – 11.6 and 16,6% and the share of waste sent to landfill – 33.2 and 32.3%.

MECHANICAL-BIOLOGICAL TREATMENT OF MUNICIPAL SOLID WASTE IN POLAND - CASE STUDIES

After the entry into force of Landfill Directive 1999/31/EC the member states of European Union (EU) turned towards other technologies for waste treatment and management, such as mechanical-biological treatment of waste (MBT) in order to meet the obligations related to the reduction of the amount of landfilled biodegradable waste. This paper presents an analysis of the waste management in Poland in terms of the current regulations and requirements of the EU and achievement of the mechanical - biological treatment of municipal solid waste based on operational data from two waste treatmend plants with different degrees of segregation and aerobic waste stabilization applied technologies: one MBT plant with aerobic stabilization in open chambers with forced aeration of remaining municipal solid waste after separation at source and a manual sorting line (KKO-100 technology), and the other MBT plant with mechanical and manual sorting and aerobic stabilization of biodegradable waste in a dynamic system in a closed hall in bioreactors (BIOFIX system). Based on the mass balance analysis of the waste and the technological and economic parameters, the efficiency of the mechanical-biological treatment of the waste was determined. The results showed that the waste sorting technology within the framework of MBT had a significant effect on the final efficiency of resource recovery and waste disposal reduction.

Characterization of odorous compounds and odor load in indoor air of modern complex MBT facilities

Gaseous emissions and chemical compounds responsible for odor nuisance are the most common social concerns arising from modern municipal mechanical-biological waste treatment (MBT) facilities. Regarding to this, an inventory of indoor concentrations of hydrogen sulfide and volatile organic compounds (VOCs) along with odor analyses were carried out at three different full-scale MBT facilities. 48-h profiles of total volatile organic compounds (tVOCs) and hydrogen sulfide were performed in selected areas (reception warehouse, pretreatment, anaerobic digestion and composting areas) and a complete gases and odor characterization were performed at two selected moments of the day according to maximum and minimum tVOCs concentrations, which corresponded to day/night variations. Terpenoids, aromatic hydrocarbons and aliphatic hydrocarbons were the families of VOCs more often detected. The average percentage of contribution of these three VOCs families was 32, 21 and 24%, respectively, while the average percentage of contribution of other VOCs families ranged from 0.2 to 5.5%. A multiple regression method was developed as a simple tool for odor modeling and prediction, showing that 98.5% (p<0.001) of the variance in odor concentration could be explained by the concentrations of hydrogen sulfide and tVOCs. Results obtained suggested that optimization of indoor ventilation systems and, concomitantly, operational costs of MBT facilities was possible in certain locations where ventilation could be reduced up to 20–25% during night hours.

Life cycle assessment of refuse-derived fuel production from mixed municipal waste

ABSTRACTThe aim of this study is to identify and assess the potential environmental impacts caused by refuse-derived fuel (RDF) production from mixed municipal waste, in a mechanical–biological waste treatment plant in Krakow, Poland. The study is based on life cycle assessment methodology, employing EASETECH model. The system boundaries include only those operations which lead to the production of RDF. The adopted functional unit is 1 Mg of mixed municipal waste generated in Krakow, which enters the mechanical–biological waste treatment plant.

Assessment of Range of Olfactory Impact of Plant to Mechanical-biological Treatment of Municipal Waste

Plants (installations) to mechanical-biological treatment (MBT) of municipal solid waste belong to the object group being potential sources of odorants emission. One of the most important parameters of their characteristic is the range of the real olfactory impact. It depends on many factors, such as: the type of emitter (point or surficial) and its characteristics (among other things, height and surface, polluted air stream temperature), emission value and its variability in time, and also topography and land management method and local climatological and meteorological conditions. Assessment of range of olfactory impact of plants is the issue, which may be the subject of theoretical considerations. The search for answers for practical purposes is associated among other things with spatial planning (land use), decision-making on location and land management (improvement of the territory) around the MBT installation and resolving complaints and disputes arising from their nuisance for residents (inhabitants). In Poland, the range of onerous impact of waste management facilities has been, in the past, assessed mainly by the indicator method (based on the widths of the so-called protection zone), and currently is determined using mathematical modelling (especially for of planned undertakings) and direct olfactometric measurements (in the case of existing facilities).In the paper is presented a general outline of the methodology of assessment of a range of olfactory impact of fugitive emission from surficial sources. Theoretical considerations are illustrated on the example of the results of the examinations of large plant (installation) of the mechanical-biological treatment of waste. During the examinations, apart from usual odour emission and dispersion processes, the effect of the convective vertical flow of the odorant-polluted air effect was observed.The research program includes twelve series of direct olfactometric measurements (with field olfactometers) and odorimetric observations in measurement-observation (receptor) points, deployed in and around the MBT installation. In each series has been tagged the background of air polluted with odorants (on the windward side of MBT installation). The olfactometric examinations were carried out by method of identification and with characterizing the trail of the odour emitted from the explored source. The receptor points were determined mainly in the area, in which the odours were uniquely identifiable as to their origin. In addition, has been made one “intervention” series of odorimetric observations. During field examinations, olfactometric measurements were carried out with control of the current meteorological situation – measurements and observations of the weather conditions (wind, temperature and relative humidity of the air, the degree of cloudiness).

Multi criteria option analysis in the technology design of mechanical-biological treatment of waste

The residual waste has a high concentration of recoverable elements, which can be either recycled or recovered into energy in accordance with the waste hierarchy. One option is the implementation of mechanical biological treatment of waste, which has showed a steady progress in the recent two years in Hungary. This paper analysis the relevant factors, which should be considered during the technology planning. The multi criteria analysis involves the economical environmental and external considerations into the technology assessment. Based on the results, the technology plan should be revised and adjusted.

Sorting Tests of Unsorted Municipal Solid Waste from Germany for a Selected Opto-Pneumatic Sorting Machine

Polish waste management systems currently are under development and modernization in order to adjust to European Union standards. Mechanical biological waste treatment systems installed in so-called regional municipal solid waste treatment plants are being developed. This type of plant needs to be operated in order to obtain required levels of recycling and waste recovery and to limit the amount of biodegradable waste directed to landfills. A key element of all these type of devices are sorting plants. This paper presents the results of sorting tests of unsorted municipal solid waste from Koblenz city. Tests were performed in the Research and Test Facility located at TITECH GmbH in Mulheim-Karlich in Germany. The tests made it possible to determine efficiency of the process of automatic separation of plastics and papers using a Titech autosort separator equipped with near infra-red sensor (NIR 1). Test results show differences in the morphological composition of unsorted municipal solid waste from Poland and Germany, and their potential in respect to content of recovered materials.

Reducing the Indoor Odorous Charge in Waste Treatment Facilities

Characterising and determining the odorous charge of indoor air through Odour Units (OU) is an advantageous approach to evaluate indoor air quality and discomfort inside municipal solid waste facilities. The assessment of the OU can be done through the determination of Volatile Organic Compounds (VOC) concentrations and their odour thresholds. The aim of the study was to evaluate the differences in the odorous charge in the organic matter pit of a mechanical-biological waste treatment plant with a processing capacity of 287,500 tons year-1. The sampling was carried out during the months of September 2012 (original situation) and October 2012 (after emptying the organic matter pit drain pipe). 150 chemical compounds were determined qualitatively in the studied location, from which 102 were quantified due to their odorous characteristics as well as their potentiality of having negative health effects. The results obtained demonstrated that after a maintenance cleaning operation such as draining the organic matter pit pipe, the odorous charge inside the facility can be diminished in a great way, up to a 95%.

Feasibility of Refuse Derived Fuel 5 Composed of the Mechanical Biological Waste Treatment and Crude Oil Sludge

The main focus of this paper is concerned with the production and properties of refuse derived fuel 5 (RDF-5) for use in energy from waste technologies. The analysis was performed using feedstocks made up of residues from a range of mechanical biological treatment (MBT) plants and crude oil sludge. The RDF-5 was composed of crude oil sludge and mechanical biological waste treatment (MBWT). The ratios of MBWT to crude oil sludge were 5:95, 10:90, 15:85 and 20:80 respectively. The physical and thermal characteristics of RDF-5 were examined. This was further investigated in the context of the parameters required during production and the properties of RDF-5. RDF-5 was produced using a screw compactor. Analysis of the optimal mixing ratios between the crude oil sludge and MBWT were undertaken by testing the thermal value based on ASTM D 240 moisture contents was based on ASTM D 3173, ash was based on ASTM D 3174, and density was based on ASTM E 75 respectively. The results showed that the optimal ratios of MBWT to crude oil sludge were 15:85 and 20:80 have feasibility to produce the RDF-5. Because of the ratios of 15:85 and 20:80 have a high value 10,831 kcal/kg and 11,260 kcal/kg, the percentages of moisture were 2.73% and 5.93% and the density values were 750 kg/m3and 806 kg/m3respectively (RDF-5 has a high heating value (HHV &gt; 5,000 kcal/kg), with the percentage of moisture content not exceeding 10 percent and the density value (D 600 kg/m3) according to production of solid fuels standards). The ash values were 5.10% and 4.74% respectively. Comparing the energy production costs between RDF-5 and other fuels used in Thailand we found that the production costs of RDF-5 were 0.014 /MJ and 0.013 /MJ which are comparable to that of paddy husk and much cheaper than those of fuel lignite and bituminous. This preliminary evaluation reveals that the recovery of energy through RDF-5 production from MBWT with crude oil sludge is cost attractive and it should be considered as a feasible option for utilizing energy from MBWT with crude oil sludge.

CLIMATE PROTECTION POTENTIAL OF WASTE MANAGEMENT IN BOSNIA AND HERZEGOVINA

In order to comply with the EU landfill directive (Bosnia and Herzegovina is a potential candidate for a membership in the European Union) and to reduce greenhouse gas emissions as well as to save important resources, mechanical biological treatment of municipal solid waste is a promising waste treatment option compared to open dumping and in particular large size landfilling. Mechanical biological waste treatment shows high potential to reduce direct GHG emissions through avoiding methane generation in landfills. Besides, indirect GHG can be reduced by replacing primary products or fossil energy by recycling products and renewable energy, which are less greenhouse gas emission intensive. Key words: municipal solid waste management, greenhouse gas emissions, mechanical-biological treatment, landfill gas, material recovery.