Survey on household solid waste sorting at source in developing economies : a case study of Nur-Sultan City in Kazakhstan

The exponential population growth in urban areas makes existing solid waste management policies and strategies challenging. The situation becomes more strenuous in fast-growing cities where increasing waste production can hardly be met by the capacity of existing facilities. Practices like waste prevention, recycling, reuse, and recovery are fundamental elements needed for the reduction of solid waste disposed in landfills, especially in fast-growing cities where more sustainable management practices need to be adopted. This study investigated the behavioral attitudes of citizens of the capital of Kazakhstan, Nur-Sultan (former Astana), towards household solid waste disposal and separation at the source. The survey was conducted through stratified random sampling during April and July of 2018 with the participation of 3281 respondents. It is the first attempt, to our knowledge, of assessing recycling trends in Kazakhstan from the household perspective. The results showed that 24% of respondents were already sorting household solid waste despite the absence of a separation system at the source. The study further demonstrated that separation at source could be effective if the local authorities were to introduce sound public awareness campaigns and install recycling bins in close proximity to residential buildings

Effective photochemical treatment of a municipal solid waste landfill leachate

This work aimed at studying the photochemical treatment of a landfill leachate using ultraviolet light, hydrogen peroxide, and ferrous or ferric ions, in a batch recycle photoreactor. The effect of inorganic carbon presence, pH, initial H2O2 amount (0–9990 mg L-1) as well as Fe (II) (200–600 ppm) and Fe(III) (300–700 ppm) concentrations on the total carbon removal and color change was studied. Prior to the photochemical treatment, a pretreatment process was applied; inorganic nitrogen and inorganic carbon were removed by means of air stripping and initial pH regulation, respectively. The leachate sent subsequently for photochemical treatment was free of inorganic carbon and contained only organic carbon with concentration 1200±100 mg L-1 at pH 5.1–5.3. The most favorable concentrations of H2O2 and ferric ions for carbon removal were 6660 mg L-1 and 400 ppm, respectively. Adjusting the initial pH value in the range of 2.2–5.3 had a significant effect on the organic carbon removal. The photo-Fenton-like process was more advantageous than the photo-Fenton one for leachate treatment. By applying the most favorable operating conditions, 88.7% removal of total organic carbon, 100% removal of total inorganic carbon, 96.5% removal of total nitrogen, and 98.2% color removal were achieved

Characterization of tar generated from the mixture of municipal solid waste and coal pyrolysis at 800 oC

Nowadays, comprehensive perception of the tar characteristics generated from municipal solid waste (MSW) and coal to guide pyrolysis or gasification gas yield upgrading and cleaning has attracted massive research attention. In this study, MSW and coal samples were chosen as principal components. The mixture of these products was pyrolyzed in a horizontal tube furnace at 800 °C with a heating rate of 20 °C/min. The tar derived from the pyrolysis of this mixture was further studied. Gas chromatography–mass spectrometry (GC–MS)coupled with a trace GC and a nuclear magnetic resonance (NMR) spectrometer was applied to investigate the tar composition and characterization along with their molecular chemical structures. 1H and 13C NMR spectra indicated that the functional groups of the tar derived from the mixture of MSW and coal were dominant at the resonances of 0.9–1.8 ppm, 1.5–2.6 ppm and 3.8–4.1 ppm for 1H, 10–40 ppm and 60–80 ppm for 13C. The results from GC–MS showed that the tar derived from the mixture of MSW and coal contained about 20 major chemical compounds such as benzene, methyl isobutyl, toluene, xylene, phenol, cresol, naphthalene and others

CO-FIRING OF REFUSE-DERIVED FUEL WITH EKIBASTUZ COAL IN A BUBBLING FLUIDIZED BED REACTOR: ANALYSIS OF EMISSIONS AND ASH CHARACTERISTICS

Converting municipal solid waste (MSW) into valuable feedstocks, such as refuse-derived fuel (RDF), is a sustainable method according to the concept of waste management hierarchy. A heterogeneous composition with a good calorific value and lower emissions allows RDF to be used for energy recovery purposes. We have earlier analyzed the generation and thermochemical characteristics of the MSW produced in Kazakhstan. This work aims to study the combustion characteristics in terms of emissions and ash composition to evaluate the possibility of RDF co-firing with Ekibastuz coal. In particular, RDF is blended with high ash bituminous coal (Ekibastuz coal) and co-fired in the laboratory scale bubbling fluidized bed reactor (BFB) at a bed temperature of 850 C. The co-firing tests of RDF to coal samples were conducted under various proportions to analyze flue gas compositions. Experiments were carried in the presence of bed material (sand), and the fuel particles were fed in batch mode into the hot riser. The BFB reactor had a height of 760 mm and internal diameter of 48 mm. The gaseous products in the flue gas were analyzed by FTIR spectrometry (Gasmet Dx4000). Ash composition was examined by XRD, XRF, SEM, and PSD. The results showed that a high RDF content decreased SO2 emissions to 28 ppm, while it negatively affected NOx release to 1400 ppm, owing to excess air. The emissions of gases from different blended samples and mineral transformations were investigated and discussed in this study

Fixed-bed gasification and pyrolysis of organic fraction of MSW blended with coal samples

Buildup of vast quantities of municipal solid waste (MSW) including refuse derived fuel, organic fraction around the urban areas has negative environmental consequences. Gasification and pyrolysis of municipal solid waste could be an attractive option to utilize or convert to a valuable product. This study investigates the thermochemical properties of refuse derived fuel (RDF), organic fraction of MSW (Org MSW) and coal samples. Along with proximate and elemental analysis, calorific values were provided for RDF, MSW organic fraction, and coal samples. This followed by the thermogravimetric analysis of the same samples. In addition, Org MSW MSW and coal samples were blended in a proportion of 0.5/0.5 and 0.25/0.75 and then thermally treated in horizontal tube furnace both under air and inert gases to investigate the pyrolysis and gasification processes. TGA tests revealed that volatile content from Org MSW and RDF begin to be emitted at temperatures above 180-200 °C. Org MSW and RDF lose all their volatile contents at 500 °C and 700 °C. Pyrolysis experiments revealed that below 500 °C mostly tars are formed from Org MSW. Organic MSW and coal 0.5/0.5 blends yielded higher methane concentrations than coal or MSW alone, reaching 35-37 % at 800 °C. It could be concluded that both fixed bed and thermogravimetric method analysis have provided a good result to investigate the gasification and pyrolysis processes

Characterization of solid char produced from pyrolysis of the organic fraction of municipal solid waste, high volatile coal and their blends

In this study, the organic fraction of municipal solid waste (Org-MSW) was blended with high-volatile coal (HVC) in proportions of 25/75%, 50/50%, 75/25% by weight. Pyrolysis of these mixtures was then investigated in a thermogravimetric analyzer (TGA) and a horizontal tube furnace under a nitrogen environment. The mass loss rate of samples, differential thermogravimetry (DTG) curves and kinetic analysis of the samples were compared for both blended and non-blended samples. Higher gas yields were seen with increasing pyrolysis temperature for both samples. In addition, the kinetic analysis indicated that the apparent activation energy values of org-MSW samples varied from 535 to 5284 kJ/kmol (over the temperature range of 100–887 °C), while the values for HVC were 247–962 kJ/kmol. The activation energy for HVC varied with temperature and the highest value of 2036 kJ/kmol was found in the temperature range of 336–490 °C. Comparable results were obtained between the TGA and fixed bed tests on the residual char fraction. The findings of this work will be very important in developing a co-firing technology for solid waste residuals and coal for energy production

Detailed municipal solid waste composition analysis for Nur-Sultan City, Kazakhstan with implications for sustainable waste management in Central Asia

A detailed characterization of municipal solid waste (MSW) beyond a standard compositional analysis may offer insights useful for improving waste management systems. The present paper contributes to the scarce literature in the field by presenting new data from a rapidly developing Central Asian city, the capital of Kazakhstan, Nur-Sultan. Three sampling campaigns (each 1 week long) have been conducted at the city landfill over a 1-year period (2018–2019), and a detailed characterization for selected waste components and sub-components has been performed. The major fractions of MSW were organics (46.3%), plastics (15.2%), paper (12.8%), and diapers (5.9%). The detailed composition analysis showed high LDPE (low-density polyethylene) content (5.5%) mostly comprised of plastic bags (4.5%), transparent glass (3.2%), pharmaceuticals (0.4%), and fine (i.e., < 12 mm) organic fraction content (29%). The MSW generation rate of Nur-Sultan was estimated as 1.47 kg capita−1 day−1 based on the field collection as well as literature data. Among sustainable waste management recommendations addressed for Nur-Sultan and applicable to other cities in Central Asia, composting is recommended due to high organics fraction in MSW and its great potential to reduce the landfilled waste volume and to help valorizing the waste

Municipal solid waste management and greenhouse gas emissions at international airports : a case study of Astana International Airport

The steady expansion of the city of Astana and the increase of airport capacity is leading to an increase in municipal solid waste generation. The purpose of this study was to perform compositional analysis of the municipal solid waste produced at the Astana International Airport and evaluate different waste management scenarios in terms of greenhouse gas emissions. Recyclable and combustible fractions were found to be the major fractions (over 50%) of the total municipal solid waste generated in the Astana International Airport. Four base greenhouse gas emissions scenarios were proposed in this study, namely scenario-1 describing the current municipal solid waste management case, scenario-2 with integration of 29% recycling and 71% of municipal solid waste landfilling, scenario-3 for 100% of airport municipal solid waste being incinerated and scenario-4 for recycling 29% and the remaining waste being processed for energy recovery purposes. The proposed scenario 2 demonstrated significantly reduced net greenhouse gas emissions (t CO2 eq/year) over the existing scenario 1, while scenarios 3 and 4 showed negative net greenhouse gas emissions. The experimental data provided and the scenarios discussed in this work are useful tools for decision makers for environmental waste management at airports