Untreated Municipal Solid Waste Research Articles

A sustainable treatment method to use municipal solid waste incinerator bottom ash as cement replacement

This paper studies the use of municipal solid waste incinerator bottom ash as a supplementary cementitious material in concrete products using an innovative chemical treatment approach. The primary objective is to address emissions associated with waste-to-energy facilities and the heavy reliance on ordinary Portland cement as the primary binder in concrete. The proposed method involves the removal of metallic aluminium from the bottom ash and the subsequent use of the treated bottom ash as a partial cement replacement to produce concrete. Concrete specimens were produced with varying proportions of treated or untreated municipal solid waste incinerator bottom ash, replacing 20%, 35%, and 55% of ordinary Portland cement according to EN 197 European standard for common cement. Moreover, class F fly ash was incorporated in equivalent percentages as a reference supplementary cementitious material, and a control mix was prepared using solely Portland cement. The evaluation encompassed multiple visual and analytical techniques, including scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and setting time analyses on pastes made with Portland cement, fly ash, and bottom ash. All specimens were evaluated in terms of mechanical performance, namely compressive strength. The chemical treatment process facilitated the release of a significant quantity of hydrogen, a by-product of aluminium oxidization. Consequently, this resulted in significantly reduced formation of gas bubbles in concrete in the fresh state and, therefore, diminished expansion during the setting process. As the proportion of cement replacement with bottom ash increased, a decline in strength was observed. However, this decline was less pronounced when using treated bottom ash, particularly with lower levels of incorporation.

Characterization of Leachate and Evaluation of Groundwater Pollution in the Vicinity of the Municipal Solid Waste Landfill in Srinagar, Jammu & Kashmir

Abstract: The most popular way for disposing of municipal solid waste (MSW) throughout India, including Kashmir, is through landfills. However, the discharge of leachate from these facilities has seriously contaminated groundwater. An evaluation was conducted on the groundwater quality near the Srinagar landfill site (Achan). In order to investigate the potential effects of leachate percolation on groundwater quality, samples of leachate and groundwater were taken from the Srinagar dump site and its surrounding areas. Groundwater and leachate samples were used to measure the concentration of various physio-chemical parameters (pH, EC, TDS, COD, BOD, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, NO3-, NH4+, PO43-, Phenol), as well as microbiological parameters (total coliform and faecal coliform) and heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn, and Hg). The relatively elevated levels of NH4+, EC, TDS, BOD, phenol, Cd, and Mg, Cr were above the limits of Indian standard and WHO for drinking water. In addition to this , these also represent heavy pollutant indicators as per the Single Point Pollution Index as well by the Nemero index, as these elements crossed the upper most limit for both these pollution indeces. Assessing the water contamination in depth and distance wise, closer to landfill and shallow wells were characterized as the most polluted and had some additive contaminants ( Cl- ,SO4, Ca , Ni ). This is an indication of pollution transfer and the leachate movement. The presence of total coliform and faecal coliform although in small counts warns for the groundwater quality and thus renders the associated aquifer unreliable for domestic water supply. There is no natural or other possible reason for high concentration of these pollutants, thus it can be concluded that leachate has significant impact on groundwater quality in the area. In the present study, also an attempt has been made to investigate physico-chemical properties, fertilizing potential and heavy metal polluting potentials of the three types of composts including municipal soild waste compost, green waste compost and mixed waste compost. Each of these types were given a treatment with effective micro organisms (EM) to understand the quality of compost so formed by the composting process by its analysis (Laboratory as well as statistical) and the quality of composts was found out using Quality control Indices such as Fertilizing Index and Clean Index. Parameters like, pH, EC, TOC, total nitrogen, total phosphorous, total potassium, C/N ratio, and heavy metals like zinc, copper, cadmium, nickel, lead, and chromium were analyzed and it was found that all the parameters were within the permissible limits prescribed by FCO-2000. Further Fertility Index and Clean Index were determined for the samples and it was found that proper segregation of the solid waste is important from composting point of view because mixed waste affects the quality of compost. From the calculated values for the compost prepared from untreated MSW, FI (3.40) and CI (2.8), for the treated MSW Compost, FI as 3.47 and CI as 3.0, for the untreated mixed waste FI (3.27) and CI (3.0) and for the treated mixed waste FI (3.47), CI (3.2) The determined values indicates that all these compost types belongs to marketable Class D (medium fertilizing potential and medium heavy metal content).The fertility index value was estimated as 2.0 and the Clean Index value as 3.06 for the untreated green waste while for treated green waste FI(2.73) and CI(3.7), which indicates that both compost types belongs to restricted use Class RU-1 (Should not be allowed to market due to low fertilizing potential. However, these can be used as soil conditioner)

Spatial Distribution of Heavy Element in Erbil's Municipal Landfills by Using GIS

Untreated municipal solid waste (MSW) release onto land is prevalent in developing countries. To reduce the high levels of harmful components in polluted soils, a proper evaluation of heavy metal concentrations in Erbil's Kani Qrzhala dump between August 2021 and February 2022 is required. The purpose of this research was to examine the impact of improper solid waste disposal on soil properties within a landfill by assessing the risks of contamination for eight heavy elements in two separate layers of the soil by using geoaccumulation index (I-geo) and pollution load index (PLI) supported. The ArcGIS software was employed to map the spatial distribution of heavy element pollution and potential ecological risks. The I-geo values in summer varied from -1.700 to 3.560 for Zn, 5.045 to 8.175 for Cd, 2.318 to 4.329 for Pb, 0 to 3.374 for Mn, 1.439 to 3.880 for Ni, 0.638 to 2.278 for Cu, -0.541 to 2.665 for Cr, and -2.495 to 0.778 for Hg. Based on the I-geo categorization, the contamination levels of Zn, Cd, Pb, Mn, Ni, Cu, and Hg ranged from uncontaminated to extremely contaminated. However, all metals were assessed as uncontaminated throughout winter, except I-geo (Cd) and I- geo (Ni) varied from -0.467 to 3.966 and -5.720 to 2.015 were classified from as uncontaminated to strong and uncontaminated to moderately/strongly contaminated respectively. According to the PLI category, most samples were rated as "highly polluted" during summer, but during the rainy season, all samples were rated as "unpolluted".

Untreated municipal solid waste incineration ashes for cement replacement

This paper characterised the two different ashes, namely Boiler Ash (BOA) and Residue Ash (RA), collected from Qatar's Municipal Solid Waste Incineration (MSWI) plant through a range of detailed analyses (chemical, physical and morphological). The potential utilisation of these raw MSWI ashes as supplementary cementitious material (SCM) in cement-based composites has been investigated by replacement with 0%, 10%, 20%, and 30% by weight of cement. The effect of the replacement levels on workability, setting time, and strength was investigated. Test results showed that setting time increased and workability decreased with the increase of BOA content. On the contrary, RA substitution decreased the setting time and increased the workability. The highest compressive strength was obtained in RA-incorporated mortars at a 10% replacement ratio. Beyond the 10% replacement ratio, RA incorporation significantly reduced the strength. Due to BOA's high unburned carbon content, BOA substitutions reduced the strength of the mortars. However, the impact of the replacement ratio was not as strong as those in RA mortars. Considering setting time, workability, and compressive strength, BOA and RA's optimum percentage of cement replacement was 20% and 10%, respectively. Heavy metal and salt leaching from MSWI ash-incorporated mortars were evaluated by the monolithic tank test. Results indicated that most toxic metals and salts, except Ba and Cl-, were stabilised in the cement matrix.

EFFECT OF MUNICIPAL SOLID WASTE TREATMENT TECHNIQUES ON SOIL CHEMICAL PROPERTIES IN SUDAN SAVANNAH, KANO STATE, NORTHERN NIGERIA

The objective of this study was to determine the impact of municipal solid waste (MSW) treatment techniques on the soil Chemical properties of Sudan Savannah, Nigeria. MSW was collected from multiple metropolitan sites and mixed together. The composite sample was used to produce biochar and compost treatments. The effect of MSW treatment techniques on the qualities of soil was assessed by applying treatments and controls (untreated MSW) to soil at various rates. Soil samples were collected four weeks after treatment application, processed and analyzed in the laboratory. Results showed significant difference (*P≤0.05) in soil Mg and Zn, as well as highly significant difference at (**P≤0.01) in soil EC and K values. Biochar is recommended for acidic soil to improve soil pH, whereas compost is suggested for increasing soil organic matter and microbial activity. The use of untreated MSW is primarily advised for long-term soil deterioration solutions.

Behavior of Per- and polyfluoroalkyl substances (PFAS) in Pilot-Scale vertical flow constructed wetlands treating landfill leachate

This study investigated the behavior of per- and polyfluoroalkyl substances (PFAS) in multiple pilot-scale vertical flow constructed wetlands (VFCW) treating landfill leachate. Eight pilot-scale VFCW columns planted with Typha latifolia or Scirpus Californicus were fed untreated municipal solid waste (MSW) landfill leachate that was diluted with potable water at a 1:10 ratio (1 part leachate to 10 parts total) at a fixed daily hydraulic loading rate of 0.525 m d-1. Ninety-two PFAS were examined and 18 PFAS were detected at quantifiable concentrations (7 precursor species and 11 terminal species). The average concentration of Σ92 PFAS in the influent was 3,100 ng L-1, which corresponded with minimal reduction in the effluents from the four VFCW (decreases ranged from 1% to 12% on average for Σ18 PFAS); however, precursors 6:3 FTCA, 7:3 FTCA, N-MeFOSAA, and N-EtFOSAA concentrations decreased significantly in the VFCW effluents, and significant decreases in the concentrations of these PFAA-precursors were concurrent with a significant increase in concentrations of five PFAAs (PFBA, PFNA, PFBS, PFOS, and PFOSI). This trend indicates that from a regulatory perspective, standalone VFCWs are likely to produce an apparent PFAS increase, which may also be true for many other leachate treatment processes incorporating aerobic biological treatment. Additional treatment to address PFAS should be integrated prior to the use of any system, including VFCWs, for the treatment of constituents of concern in MSW landfill leachate.

Are the vegetables grown in the soil of municipal solid waste dumping sites safe for human health? An assessment from trace elements contamination and associated health risks

Trace elements containing untreated municipal solid waste discharged from improper management impose serious environmental and human health risks. In this work, the extent of trace elements (As, Pb, Cd, Fe, Mn, Zn) pollution in the soils and some common vegetables/food crops grown in the municipal solid waste dumping sites in southwestern Bangladesh (Khulna) were evaluated for the first time. To assess the human consumption’s suitability of the collected vegetables cultivated in the waste dumping sites, health risks were appraised due to the trace elements contamination. The concentration of trace elements in the collected soil and vegetable/food crop samples was analyzed by Atomic Absorption Spectrophotometer. The soil pollution evaluation indices such as geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), and pollution load index (PLI) were used to evaluate the soil pollution level. The results showed that trace element levels in the soils and vegetables/food crops follow the order of Fe > Zn > Pb > Mn > As > Cd. The outcome of the soil pollution indices (Igeo, EF, CF, and PLI) implies potential trace elements pollution in the dumping sites, dominated by Pb and Zn. The multivariate analyses exhibited that the trace element sources are of natural and anthropogenic origin. The estimated daily intake of the trace elements via vegetables was lower than the maximum tolerable daily intake, except for Pb. The target hazard quotients of Pb exceeded the threshold level through the consumption of all cultivated vegetables, indicating significant health risks to the residents of the study area. Hence, effective measures should immediately be taken to control the trace elements pollution due to municipal waste dumping in southwestern Bangladesh to protect the environment and human health.

Qualitative assessment of compost engendered from municipal solid waste and green waste by indexing method

The present study aims at quantification of the quality of three varieties of composts made from municipal solid waste, green waste and combined waste by critically evaluating their physicochemical attributes, effect on soil fertility and metal pollution risk. Each waste type was treated with effective micro-organisms to compare the compost quality using Quality Control Indices. The effect of microbial consortia on the wastes was prominent resulting in decreased pH levels and increased electrical conductivity. C/N ratio ranged between 14-24 for waste composts without microbial treatment, and 8-11 for microbial treated wastes. The fertility parameter was observed to be more in microbial treated waste composts. Also, heavy metals concentration in waste compost without effective microbial treatment was higher than the types given EM. Based on the fertility and clean indices, the treated and untreated municipal solid waste and combined waste compost belonged to class RU-1 and class D, respectively. Moreover, compost prepared from treated and untreated green waste belonged to classes B and C respectively. In general, the prepared CW and GW composts have medium to high fertilizing potential and are fit for domestic as well as commercial use. However, MSW compost is not fit for agricultural purposes as it didn’t improve soil fertility to a greater extent but can be used as a soil conditioner in limited quantity as it can cause metal toxicity. For this reason, proper segregation of inputs at the start of a composting process is necessary to improve its quality before being put to agricultural use as any unbalanced or unchecked content of mixed waste will affect the overall compost quality.

Screening of untreated municipal solid waste incineration fly ash for use in cement-based materials: chemical and physical properties

The environmental impact during concrete manufacturing can be reduced by using less cement or using types of cement with high amounts of secondary cementitious materials (SCMs) and fillers. Fly ash from municipal solid waste incineration (MSWI) is an unused material, which could potentially be used as an SCM or filler. The applicability of MSWI fly ash samples in cement-based materials was investigated through an indirect determination based on the chemical composition, toxic metal content and particle size distribution of the samples. Furthermore, how the samples compared to each other and how representative the samples were for MSWI fly ash, in general, were investigated by multivariate modelling. MSWI fly ash samples were obtained from Denmark, Sweden and Greenland. Comparing the chemical composition of the MSWI fly ash samples with the chemical requirements for coal fly ash to be used in concrete, specified in EN 450-1 2012, indicated a low potential as SCMs. Additionally, the MSWI fly ash contained and leached more toxic metals than the allowed limits. The particle size distributions were larger than cement and indicated limited potential as filler. A principal component analysis showed that the obtained samples were chemically different materials compared to each other and would have different effects if used in cement-based materials. Additionally, the samples from Denmark were unrepresentative of MSWI fly ash, while the Greenlandic and Swedish samples were comparable to previously studied MSWI fly ash samples.

Waste type, incineration, and aeration are associated with per- and polyfluoroalkyl levels in landfill leachates

Per- and polyfluoroalkyl substances (PFAS) are found in many consumer products which will be ultimately disposed in landfills. Limiting environmental contamination and future exposures will require managing leachates from different types of landfills, each with different PFAS levels depending upon the source of the waste. The objective of this study was to evaluate the influence of waste type and on-site treatment on PFAS levels in landfill leachates. Eleven PFAS species (7 carboxylic acids, 3 sulfonic acids, and 5:3 fluorotelomer carboxylic acid) were evaluated in leachates from municipal solid waste (MSW), construction and demolition (C&D), MSW ash (MSWA), and a mixture of MSWA and MSW with landfill gas condensate (MSWA/MSW-GC). Leachates were also analyzed before and after on-site treatment at two of these facilities. Results indicate that MSWA leachate had significantly lower PFAS levels relative to other leachate types. Lower total PFAS concentrations in MSWA leachates were correlated with an increase in incineration temperature (R2 = 0.92, p = 0.008). The levels of PFAS in untreated C&D and untreated MSW leachate were similar. The levels of targeted PFAS species in MSW leachate for one of the facilities evaluated increased after on-site landfill treatment presumably due to the conversion of PFAS precursors in the untreated leachate sample.

Effectiveness of aerobic pretreatment of municipal solid waste for accelerating biogas generation during simulated landfilling

This study evaluates the effectiveness of aerobic pretreatment of municipal solid waste (MSW) on reducing lag phase and accelerating biogas generation. Aerobic pretreatment degree (APD) was determined on the basis of reduction in volatile solids (VS) on a wet weight basis. In this study, intermittent aeration (IA) was applied to three reactors as a main aeration mode; since a single reactor was operated under continuous aeration mode. However, the purpose of the experiment was to reduce VS content of waste, irrespective of the comparison between aeration modes. Fresh MSW was first pretreated aerobically with different aeration rates (10, 40, 60 and 85 L/min/m3) for the period of 30–50 days, resulting in VS-loss equivalent to 20%, 27%, 38% and 53% on w/w basis for the wastes A1, A2, A3 and A4, respectively. The cumulative biogas production, calculated based on the modified Gompertz model were 384, 195, 353, 215, and 114 L/kg VS for the wastes A0, A1, A2, A3 and A4, respectively. Untreated waste (A0) showed a long lag phase; whereas the lag phases of pretreated MSW were reduced by more than 90%. Aerobically pretreated wastes reached stable methanogenic phase within 41 days compared to 418 days for untreated waste. The waste mass decreased by about 8% to 27% compared to untreated MSW, indicative that even more MSW could be placed in the same landfill. The study confirmed the effectiveness of aerobic pretreatment of MSW prior to landfilling on reducing lag phase and accelerating biogas generation.

Municipal solid waste management and greenhouse gas emission control through an inexact optimization model under interval and random uncertainties

ABSTRACTRapid increases in the amounts of untreated municipal solid waste (MSW) and discharged greenhouse gases (GHGs) from waste treatment processes have caused great challenges to urban development and environmental protection. This study aimed to develop an integrated interval-stochastic optimization model to support regional MSW management in China, where the parameters which show large variations were expressed as birandom variables, whereas the parameters with small fluctuation were assumed to be interval numbers. The main objective of this optimization model was to minimize the total cost with simultaneous considerations of MSW treatment and GHG control requirements. The stochastic equilibrium-based chance constrained programming technique and interactive two-step algorithms were used to solve this model. Among many types of solutions with various constraint-violation levels, the solutions with balanced characteristics were recommended as the decision basis. Compared with existing management schemes, the model solutions showed advantages in cost reduction and climate-change impact mitigation.

Application of thermally activated municipal solid waste incineration (MSWI) bottom ash fines as binder substitute

Untreated municipal solid waste incineration (MSWI) bottom ash fines (0–2 mm) have poor pozzolanic properties, and contain substances which can pose an environmental risk (e.g. heavy metals and salts). This study investigates combined treatments applied on bottom ash fines (BAF) to increase their reactivity. The treated BAF is compared with both untreated BAF and cement, and its contribution to cement hydration is investigated. Additionally, the utilization of the treated BAF in mortar as cement replacement is tested. Finally, the leaching properties of mortars containing treated and untreated BAF are estimated. According to the results obtained, the 28-day compressive and flexural strengths of mortar with 30% treated bottom ash are about 16% and 6% lower than the reference mortar, respectively. The leaching of contaminants from the crushed mortars with BAF are well under the limit values imposed by Dutch legislation.

Application of continuous normal–lognormal bivariate density functions in a sensitivity analysis of municipal solid waste landfill

The variability of untreated municipal solid waste (MSW) shear strength parameters, namely cohesion and shear friction angle, with respect to waste stability problems, is of primary concern due to the strong heterogeneity of MSW. A large number of municipal solid waste (MSW) shear strength parameters (friction angle and cohesion) were collected from published literature and analyzed. The basic statistical analysis has shown that the central tendency of both shear strength parameters fits reasonably well within the ranges of recommended values proposed by different authors. In addition, it was established that the correlation between shear friction angle and cohesion is not strong but it still remained significant. Through use of a distribution fitting method it was found that the shear friction angle could be adjusted to a normal probability density function while cohesion follows the log-normal density function. The continuous normal–lognormal bivariate density function was therefore selected as an adequate model to ascertain rational boundary values (“confidence interval”) for MSW shear strength parameters. It was concluded that a curve with a 70% confidence level generates a “confidence interval” within the reasonable limits. With respect to the decomposition stage of the waste material, three different ranges of appropriate shear strength parameters were indicated. Defined parameters were then used as input parameters for an Alternative Point Estimated Method (APEM) stability analysis on a real case scenario of the Jakusevec landfill. The Jakusevec landfill is the disposal site of the capital of Croatia – Zagreb. The analysis shows that in the case of a dry landfill the most significant factor influencing the safety factor was the shear friction angle of old, decomposed waste material, while in the case of a landfill with significant leachate level the most significant factor influencing the safety factor was the cohesion of old, decomposed waste material. The analysis also showed that a satisfactory level of performance with a small probability of failure was produced for the standard practice design of waste landfills as well as an analysis scenario immediately after the landfill closure.

Toward the implementation of new regional biowaste management plans: Environmental assessment of different waste management scenarios in Catalonia

In the present work, different scenarios for the treatment of the organic fraction of municipal waste at regional scale are proposed and assessed by means of LCA. The geographical area under study is Catalonia (Spain). The current Catalan waste management scenario treating 1218Gg of organic waste is analyzed and compared to a new scenario treating the same amount of waste but fulfilling the European Landfill Directive and the new recently approved Catalan waste management plan. As final disposal (incineration and sanitary landfill) of untreated municipal solid waste is not permitted, the new scenario includes increasing anaerobic digestion treatment of source selected organic fraction of municipal solid waste while maintaining the existing composting plants for this type of waste. Gaseous emissions treatment equipment will be provided when not installed in composting plants. Home composting is also included. Non-source selected organic fraction of municipal solid waste will be treated by composting. Different scenarios for sensitivity analysis have also been proposed dealing with the influence of transport, fugitive methane emissions from anaerobic digestion plants and the use of compost among other issues. The new scenario proposed decreases the impact in five out of the six impact categories studied (from a 49% in eutrophication potential to a 9% in ozone depletion potential). The inclusion of methane fugitive emissions in anaerobic digestion installations in impacts calculation impairs the environmental benefits of this type of treatment facilities (increasing global warming potential value up to a 31%). Improvement of landfill gas collection is of utmost importance in decreasing global warming potential.

Aerobic biological pretreatment of municipal solid waste with a high content of putrescibles: effect on landfill emissions

The objective of this work was to study the effect of aerobic biological pretreatment on the emissions of municipal solid waste (MSW) with a high content of putrescibles after landfilling. For this purpose, the organic fraction of MSW was simulated by a mixture of food waste and office paper at a 2.4:1 wet weight ratio. MSW was first pretreated aerobically for three different time periods (8, 45 and 90 days) resulting in organic matter reductions equal to 15%, 45% and 81% respectively. MSW were then placed in 160-L air-tight anaerobic bioreactors. The control anaerobic bioreactors contained untreated MSW. Anaerobic experiments lasted from 300 to 550 days. Results showed that the biogas production from untreated MSW was 372 NL dry kg(-1) (average of two replications) after 530 days. The MSW that was pretreated aerobically for 45 days and 90 days yielded 130 and 62 NL dry kg(-1) of biogas after 310 days and 230 days respectively. However, the 8-day (very short-term) pretreatment period led to an increase of the biogas yield (550 NL dry kg(-1) after 340 days) compared with that of raw refuse. All three runs with aerobically pretreated MSW reached the steady methanogenic phase faster than raw MSW. Leachate emissions were significantly lower in the aerobically-pretreated MSWthan the untreated ones. The leachate ammonium concentrations had an increasing trend in all anaerobic reactors and reached a plateau of between 2 and 3.5 g L(-1) at the end of the process.

PREDICTING SETTLEMENT OF CHEMICALLY STABILISED LANDFILLS

This paper presents the findings of numerical analyses to predict the vertical and horizontal displacements of closed landfills under surcharge load with and without treatment by chemical admixtures. The finite element program, PLAXIS, has been used to evaluate the settlement of a landfill model. The soft soil creep model is used for this analysis. Five layers of solid waste are considered for the landfill to evaluate the effect of depth of stabilisation on settlement of landfill model. Treated and untreated municipal solid waste (MSW) parameters are obtained from the results of an extensive laboratory program performed on MSW samples in this research. The settlement of the landfill model 10 and 20 years after applying the surcharge load for different fly ash-quicklime contents and various depths of improvement is estimated. Results indicate that treatment of MSW reduces the vertical displacement of the landfill model under surcharge load significantly. This reduction is more with higher depths of improvement. The finite element results have been validated based on results of triaxial tests conducted in the laboratory on the treated municipal solid waste.

Release of non-methane organic compounds during simulated landfilling of aerobically pretreated municipal solid waste

Characteristics of non-methane organic compounds (NMOCs) emissions during the anaerobic decomposition of untreated (APD-0) and four aerobically pretreated (APD-20, APD-39, APD-49, and APD-63) samples of municipal solid waste (MSW) were investigated in laboratory. The cumulative mass of the NMOCs of APD-20, APD-39, APD-49, and APD-63 accounted for 15%, 9%, 16%, and 15% of that of APD-0, respectively. The intensities of the NMOC emissions calculated by dividing the cumulative NMOC emissions by the quantities of organic matter removed (Q(VS)) decreased from 4.1mg/kg Q(VS) for APD-0 to 0.8-3.4mg/kg Q(VS) for aerobically pretreated MSW. The lipid and starch contents might have significant impact on the intensity of the NMOC emissions. Alkanes dominated the NMOCs released from the aerobically pretreated MSW, while oxygenated compounds were the chief component of the NMOCs generated from untreated MSW. Aerobic pretreatment of MSW prior to landfilling reduces the organic content of the waste and the intensity of the NMOC emissions, and increases the odor threshold, thereby reducing the environmental impact of landfills.

Application of various statistical methods to evaluate thermo-analytical data of mechanically–biologically treated municipal solid waste

Resource recovery and stabilization of waste organic matter before landfilling are crucial issues in waste management. These requirements are closely related to efficient separation of recyclables and well operated biological processes. Adequate analytical methods are a prerequisite to verify the realization of these purposes. A large data pool of mechanically–biologically treated (MBT) municipal solid waste originating from different Austrian treatment plants was investigated using simultaneous thermal analysis that comprises thermogravimetry/mass spectrometry (TG/MS) and differential scanning calorimetry (DSC). Biodegradation of MBT-waste is paralleled by decreasing enthalpies. Referring to organic matter enthalpy increases with progressing stabilization. Evaluation of thermal data was supported by multivariate data analysis. The efficiency of the biological pretreatment of municipal solid waste (MSW) compared to untreated MSW in landfills was verified by principal component analysis (PCA) of heat flow (DSC) profiles. Divergent input materials were identified by means of heat flow profiles and discriminant analysis (PLS-DA). Prediction models for the calorific value and the TOC (total organic carbon) based on DSC-profiles and partial least squares regression (PLS-R) resulted in a good correlation ( R 2 = 0.94 in both cases). The root mean square errors of crossvalidation were 413 J g −1 and 1.5% referring to dry matter, respectively. Respiration activity (RA 4) was reflected by thermal analyses. The correlation was based on mass spectra of volatile combustion products and DSC-profiles. The correlation resulted in a coefficient of determination ( R 2) of 0.87 and 0.82 respectively. Thermal analysis in association with multivariate statistical methods has proven to be a reliable method to verify efficient separation of the plastic fraction, stabilization by biological treatment and waste material composition.

Influence of biological pre-treatment of municipal solid waste on landfill behaviour in Sri Lanka

Sri Lanka is an island in the Indian Ocean with an area about 65 610 km(2). The population of the country is around 20.2 million. Hazardous disposal of municipal solid waste (MSW) is a major concern particularly in the most urbanized areas of Sri Lanka. However, the current waste management system does not facilitate any waste pre-treatment techniques before final disposal. As a consequence, there is immense pressure to improve the waste disposal practices in the country. Under the above circumstance, this study is an attempt to examine the influence of biological pre-treatment of MSW on landfill behaviour in Sri Lanka. Field-scale lysimeters with untreated and biologically pre-treated MSW were used for this study. The data was obtained on leachate quantity, quality, and settlement. The ambient parameters were also measured at the experiment site. According to the results, the effect of rainfall incident on leachate generation was visible but the effect on pre-treated waste was comparatively less than untreated waste. The organic pollutant load in leachate of pre-treated MSW was seven times lower than that of untreated MSW. The settlement of the lysimeter with pre-treated MSW was comparatively less. It can be concluded that the process of biological pre-treatment of MSW by composting is an effective method for Sri Lanka and also it reduces the health and environmental risks by improving the behaviour of landfill.