Municipal solid waste management in Thailand and disposal emission inventory

The increasing municipal solid waste (MSW) generation along with the high fraction of organic waste and a common disposal of open dumping is the current scenario in many areas in Thailand. As a response to this problem, the country’s Pollution Control Department (PCD) aims to reduce the MSW generation rate to less than 1 kg/capita/day, increase the collection efficiency, and improve the recovery of recyclables. For many years, more than 60% of the solid waste disposal system in Thailand has been carried out by open dumping. According to the survey conducted by this study, in 2004 there were 425 disposal sites (95 landfills; 330 open dumps) in Thailand and an estimated methane emission of 115.4 Gg/year was generated based on this practice. It has been estimated that the anticipated methane emission in Thailand will rise from 115.4 Gg/year to 118.5 Gg/year if the largest open dumpsites in provinces with no existing landfill are upgraded to sanitary landfill; and it will increase to 193.5 Gg/year if the existing sanitary landfill is upgraded to integrated waste management facilities. Moreover, Bangkok metropolitan have the highest methane emission (54.83 Gg/year) among all the regions in Thailand. The methane emission forecast of 339 Gg/year by 2020 (based on LandGEM methodology) provides a stimulus to create a comprehensive plan to capture and utilize methane as an energy source.     

Assessment of potential impacts of municipal solid waste treatment alternatives by using life cycle approach: a case study in Vietnam

In Vietnam, most of municipal solid waste (MSW) is disposed of at open dumping and landfill sites, and the methane gas from waste is the un-ignorable source of greenhouse gas (GHG) emission. It is indispensable to explore the possibility for GHG mitigation in MSW management. The objective of this study was to estimate alternative waste treatment practices towards the GHG emission mitigation, energy consumption and generation, reduction of landfill volume, and various benefits for proposing the appropriate selection by scenario analyses for representative Vietnam’s cities. Impacts were calculated by utilizing life cycle assessment (LCA) method. A literature review survey on the current applicability of LCA database for assessing impacts from waste sector in developing countries, especially for Vietnam, was carried out. This study assessed the contribution of alternative solid waste treatment practices. The result showed that, except investment and operation costs, incineration with energy recovery seems the suitable alternative for treating waste from representative cities of Vietnam according to reduction of GHG emission and waste burden to landfill sites and energy recovery and generation. Besides, MSW composition was identified as an important factor directly influencing to impacts as well as other products and benefits of waste treatment alternatives. Reliable data on waste composition are indispensable for assessing to choose, improve, or plan the waste treatment practices towards sustainable development.     

Flux estimates from soil methanogenesis and methanotrophy: Landfills,rice paddies,natural wetlands and aerobic soils

Present and future annual methane flux estimates out of landfills, rice paddies and natural wetlands, as well as the sorption capacity of aerobic soils for atmospheric methane, are assessed. The controlling factors and uncertainties with regard to soil methanogenesis and methanotrophy are also briefly discussed.The actual methane emission rate out of landfills is estimated at about 40 Tg yr^–1. Changes in waste generation, waste disposal and landfill management could have important consequences on future methane emissions from waste dumps. If all mitigating options can be achieved towards the year 2015, the CH₄ emission rate could be reduced to 13 Tg yr^–1. Otherwise, the emission rate from landfills could increase to 63 Tg yr^–1 by the year 2025. Methane emission from rice paddies is estimated at 60 Tg yr^–1. The predicted increase of rice production between the years 1990 and 2025 could cause an increase of the CH₄ emission rate to 78 Tg yr^–1 by the year 2025. When mitigating options are taken, the emission rate could be limited to 56 Tg yr^–1. The methane emission rate from natural wetlands is about 110 Tg yr^–1. Because changes in the expanse of natural wetland area are difficult to assess, it is assumed that methane emission from natural wetlands would remain constant during the next 100 years. Because of uncertainties with regard to large potential soil sink areas (e.g. savanna, tundra and desert), the global sorption capacity of aerobic soils for atmospheric methane is not completely clear. The actual estimate is 30 Tg yr^–1.In general, the net contribution of soils and landfills to atmospheric methane is estimated at 180 Tg yr^–1 (210 Tg yr^–1 emission, 30 Tg yr^–1 sorption). This is 36% of the global annual methane flux (500 Tg yr^–1).     

Heavy metal speciation in the composting process

Composting is one of the more efficient and environment friendly methods of solid waste disposal and has many advantages when compared with landfill disposal on which the UK and Ireland are currently heavily dependent. Composting is a very complicated process involving intensive microbial activity and the detailed mechanisms of the process have yet to be fully understood. Metal speciation information can provide an insight into the metal-microbial interaction and would help in the evaluation of the quality of compost. This would facilitate the exploitation of composts in remediation of heavy metal contaminated land. In this work a systematic approach to metal speciation in compost has been taken by applying the three-step method for operationally defined metal speciation of soils and sediments, developed by the European Commission's Standards, Measurement and Testing Programme to monitor the change in metal speciation with time (up to 106 days) for four different waste composting processes. The results have shown that in general metals become less available for the first extraction step as the composting process proceeds. This implies that composting tends to redistribute the metals from more labile forms to more fixed forms which may explain why the application of composts could be useful for with heavy metal contaminated land. There are exceptions to this trend and in some cases, certain metals appear to behave differently depending on the source of the compost.     

Occurrence of phthalic acid esters in Gomti River Sediment, India

Cadmium and lead are important environmental pollutants with high toxicity to animals and human. Soils, though have considerable metal immobilizing capability, can contaminate food chain via plants grown upon them when their built-up occurs to a large extent. Present experiment was carried out with the objective of quantifying the limits of Pb and Cd loading in soil for the purpose of preventing food chain contamination beyond background concentration levels. Two separate sets of pot experiment were carried out for these two heavy metals with graded levels of application doses of Pb at 0.4–150 mg/kg and Cd at 0.02–20 mg/kg to an acidic light textured alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of 2 months. Upper limit of background concentration levels (C _ul) of these metals were calculated through statistical approach from the heavy metals concentration values in leaves of spinach crop grown in farmers’ fields. Lead and Cd concentration limits in soil were calculated by dividing C _ul with uptake response slope obtained from the pot experiment. Cumulative loading limits (concentration limits in soil minus contents in uncontaminated soil) for the experimental soil were estimated to be 170 kg Pb/ha and 0.8 kg Cd/ha. Based on certain assumptions on application rate and computed cumulative loading limit values, maximum permissible Pb and Cd concentration values in municipal solid waste (MSW) compost were proposed as 170 mg Pb/kg and 0.8 mg Cd/kg, respectively. In view of these limiting values, about 56% and 47% of the MSW compost samples from different cities are found to contain Pb and Cd in the safe range.     

A Comprehensive Numerical Model Simulating Gas,Heat, and Moisture Transport in Sanitary Landfills and Methane Oxidation in Final Covers

A model to simulate gas, heat, and moisture transport through a sanitary landfill has been developed. The model not only considers the different processes that go on in a landfill but also the oxidation of methane in the final cover. The model was calibrated using published results and field data from a pilot scale landfill in Calgary. The model captures the physics of the different processes quite well. Simulations from the model show that waste permeability had a significant impact on the temperature, pressure distribution, and flux from a landfill. The presence of the final and intermediate covers enhanced the gas storage capacity of the landfill. Biodegradation of the waste was enhanced as the final cover minimized the atmospheric influences. In addition, the composition of landfill gas emitted to the atmosphere was significantly different from the composition of gas generated in landfill due to the presence of covers as some of the methane is oxidized to carbon dioxide. There was no significant benefit of using a final cover of higher depth. The presence and number of intermediate covers had an impact on gas flux and temperature distribution within a landfill.     

Selection of MSW landfill site for Konya, Turkey using GIS and multi-criteria evaluation

Landfill is a common solution for the final disposal of municipal solid waste (MSW) in Turkey. Landfill siting is an extremely difficult task to accomplish because the site selection process depends on different factors and regulations. To ensure that an appropriate site is chosen, a systematic process should be developed and followed. Unsuccessful landfill siting is typically the result of strong public opposition. In this study, candidate sites for an appropriate landfill area in Cumra County of Konya City are determined by using the integration of geographic information systems (GIS) and multi-criteria evaluation (MCE). ArcGIS 9.0 software and its extensions were used as the GIS tool since it is able to perform suitability analysis using MCE analysis. To identify appropriate landfill areas in the Cumra district, eight input map layers including proximity to municipal and local wells and irrigational canals, distance from transportation routes and rails, distance from archaeological sites, distance from urban areas, land use/land cover, and land slope are used in constraint mapping. A final map was generated which identifies regions showing suitability for the location of the landfill site. According to the map, 6.8% of the study area is most suitable, 15.7% is suitable, 10.4% is moderately suitable, 25.8% is poorly suitable, and 41.3% is unsuitable. At the end of the analyses, three candidate sites are determined. The selection of the final MSW landfill site, however, requires further field research.     

Resource recovery potential from secondary components of segregated municipal solid wastes

Fermentable components of municipal solid wastes (MSW) such as fruit and vegetable wastes (FVW), leaf litter, paddy straw, cane bagasse, cane trash and paper are generated in large quantities at various pockets of the city. These form potential feedstocks for decentralized biogas plants to be operated in the vicinity. We characterized the fermentation potential of six of the above MSW fractions for their suitability to be converted to biogas and anaerobic compost using the solid-state stratified bed (SSB) process in a laboratory study. FVW and leaf litter (paper mulberry leaves) decomposed almost completely while paddy straw, sugarcane trash, sugarcane bagasse and photocopying paper decomposed to a lower extent. In the SSB process between 50–60% of the biological methane potential (BMP) could be realized. Observations revealed that the SSB process needs to be adapted differently for each of the feedstocks to obtain a higher gas recovery. Bagasse produced the largest fraction of anaerobic compost (fermentation residue) and has the potential for reuse in many ways.     

Spatial distribution and multiple sources of heavy metals in the water of Chaohu Lake,Anhui, China

In this study, a survey for the spatial distribution of heavy metals in Chaohu Lake of China was conducted. Sixty-two surface water samples were collected from entire lake including three of its main river entrances. This is the first systematic report concerning the content, distribution, and origin of heavy metals (Cu, Cr, Cd, Hg, Zn, and Ni) in the Chaohu Lake water. The results showed that heavy metals (Cu, Cr, Zn, and Ni) concentrations in the estuary of Nanfei River were relatively higher than those in the other areas, while content of Hg is higher in the southeast lake than northwest lake. Moreover, Cd has locally concentration in the surface water from the entire Chaohu Lake. The heavy metal average concentrations, except Hg, were lower than the cutoff values for the first-grade water quality (China Environment Quality Standard) which was set as the highest standard to protect the social nature reserves. The Hg content is between the grades three and four water quality, and other heavy metals contents are higher than background values. The aquatic environment of Chaohu Lake has apparently been contaminated. Both the cluster analysis (CA) and correlation analysis provide information about the origin of heavy metals in the Lake. Our findings indicated that agricultural activities and adjacent plants chimneys may contribute the most to Cd and Hg contamination of Chaohu Lake, respectively.     

Study on the law of heavy metal leaching in municipal solid waste landfill

Comparative leaching experiments were carried out using leaching medium with different pH to municipal solid waste in the landfill columns in order to investigate the mobility of heavy metals. The leachate pH and oxidation–reduction potential were measured by oxidation–reduction potential analyzer; the contents of heavy metals were measured by inductively coupled plasma mass spectrometry. It is very different in leaching concentrations of heavy metals; the dynamic leaching of heavy metals decreased with the rise of the leaching amount on the whole. Acid leaching medium had definite influence on the leaching of heavy metals in the early landfill, but it had the obvious inhibition effect on the leaching in the middle and late period of landfill; the neutral and alkaline leaching medium are more beneficial to the leaching of heavy metals. Due to the influence of the environment of landfill, the differences of the results in cumulative leaching amount, leaching rate, and leaching intensity of heavy metals are very big. The calculation results of the release rates of heavy metals prove that the orders of the release rates are not identical under different leaching conditions. Acid rain made heavy metals migrate from municipal solid waste to soil and detain in soil more easily; approached neutral and alkaline leaching mediums are more beneficial to leaching of heavy metals in the municipal solid waste and soil with leachate. The field verification of experimental data showed that the law of heavy metal leaching in municipal solid waste revealed by the experiment has a good consistency with the data obtained by municipal solid waste landfill.     

Source Apportionment Of Groundwater Pollution Around Landfill Site In Nagpur, India

The present work attempts statistical analysis of groundwater quality near a Landfill site in Nagpur, India. The objective of the present work is to figure out the impact of different factors on the quality of groundwater in the study area. Statistical analysis of the data has been attempted by applying Factor Analysis concept. The analysis brings out the effect of five different factors governing the groundwater quality in the study area. Based on the contribution of the different parameters present in the extracted factors, the latter are linked to the geological setting, the leaching from the host rock, leachate of heavy metals from the landfill as well as the bacterial contamination from landfill site and other anthropogenic activities. The analysis brings out the vulnerability of the unconfined aquifer to contamination.     

Heavy metal concentrations in groundwaters and soils of Thane Region of Maharashtra, India

Thane district is one of the most industrialized districts in Maharashtra. The heavy industrialization and the increasing urbanization are responsible for the rapidly increasing stress on the water and soil environment of the area. Therefore, an attempt has been made through comprehensive study on the groundwater contamination and soil contamination due to heavy metals in Thane region of Maharashtra. The area undertaken for the study was Thane and its suburbans Kalwa, Divajunction, Dombivali, Kalyan, and Ulhasnagar. Industrialization and urbanization lead to generation of large volumes of wastewater from domestic, commercial, industrial, and other sources, which discharged in to natural water bodies like river and creek in this region. Groundwater samples and soil samples were collected from residential, commercial, agriculture, and industrial areas. Groundwater samples were analyzed for various water quality parameters. The analytical data shows very high concentration of total dissolved solids, total hardness, total alkalinity, chemical oxygen demand, chloride etc. Groundwater and soil samples were analyzed for ten heavy metals by inductively coupled plasma (ICPE-9000) atomic emission spectroscopy. The analytical data reveal that, very high concentration level of arsenic, cadmium, mercury, and nickel throughout the industrial area. The random dumping of hazardous waste in the industrial area could be the main cause of the groundwater and soil contamination spreading by rainwater and wind. In the residential areas the local dumping is expected to be the main source for heavy metals. A comparison of the results of groundwater with WHO guidelines show that most of the groundwater sampling station are heavily contaminated with organic matter and heavy metals. Groundwater samples are heavily contaminated by arsenic, cadmium, mercury, and nickel. Similarly, the results of heavy metals in soil compared with Swedish soil guideline values for polluted soil show that soil samples collected from residential, commercial and industrial areas are heavily contaminated by arsenic, cadmium, mercury, and nickel.     

Trace metals in the bottom sediments of the harbour of Lagos,Nigeria

A study has been made of the heavy metal contents of sediments in the harbour of Lagos which receives a variety of human and industrial wastes. The results indicate three areas with low, medium and high pollution by heavy metals. The harbour in which most shipping activities are concentrated has a low level of pollution. Both other areas with medium and high pollution by heavy metals are located at the entrance and in northwest sections of the harbour respectively, which receive effluents from industries and communities.     

Assessment of the impact of landfill on groundwater quality: A case study of the Pirana site in western India

In present study focus has been given on estimating quality and toxicity of waste with respect to heavy metals and its impact on groundwater quality, using statistical and empirical relationships between different hydrochemical data, so that easy monitoring may be possible which in turn help the sustainable management of landfill site and municipal solid waste. Samples of solid waste, leachate and groundwater were analyzed to evaluate the impact of leachates on groundwater through the comparison of their hydrochemical nature. Results suggest the existence of an empirical relationship between some specific indicator parameters like heavy metals of all three above mentioned sample type. Further, K/Mg ratio also indicates three groundwater samples heavily impacted from leachate contamination. A good number of samples are also showing higher values for and Pb than that of World Health Organization (WHO) drinking water regulation. Predominance of Fe and Zn in both groundwater and solid waste samples may be due to metal plating industries in the area. Factor analysis is used as a tool to explain observed relation between numerous variables in term of simpler relation, which may help to deduce the strength of relation. Positive loading of most of the factors for heavy metal clearly shows landfill impact on ground water quality especially along the hydraulic gradient. Cluster analysis, further substantiates the impact of landfill. Two major groups of samples obtained from cluster analysis suggest that one group comprises samples that are severely under the influence of landfill and contaminated leachates along the groundwater flow direction while other assorted with samples without having such influence.     

Analysis of mercury, selenium, and tin concentrations in canned fish marketed in Iran

The presence of heavy metals in the environment could constitute a hazard to food security and public health. These can be accumulated in aquatic animals such as fish. In the present paper, three heavy metals (mercury, selenium, and tin) in canned products produced and sold in Iran were studied: longtail tuna, Kawakawa, Kilka, and yellowfin tuna were determined using inductively coupled plasma–optical emission spectrometer and a direct mercury analyzer. Analytical results were validated by spiking the samples with various concentrations of these metals to test recovery. The metal contents, expressed in micrograms per gram, wet weight, varied depending upon the species studied. The levels of Hg ranged from 0.0003 to 0.408 μg/g, the levels of Sn ranged from 0.036 to 0.480 μg/g, while the levels of Se ranged from 0.130 to 4.500 μg/g. Comparative evaluation of these metals in different brands of canned fish showed that the average concentrations of Hg, Sn, and Se of all species is significantly lower than adverse level for the species themselves and for human consumption when compared with FAO/WHO permissible limits. Therefore, their contribution to the total body burden of these heavy metals can be considered as negligibly small.     

Characterization of landfill leachates and studies on heavy metal removal

This study covers a thorough characterisation of landfill leachates emerging from a sanitary landfill area. The landfill leachates were obtained in the acidic stage of landfill stabilisation. Their organic content was high as reflected by the high BOD5 (5 day biological oxygen demand) and COD (chemical oxygen demand) values. They were also highly polluted in terms of the parameters TKN (total Kjeldahl nitrogen), NH4-N, alkalinity, hardness and heavy metals. Nickel was present in these wastewaters at a significant concentration. With regard to the high heavy metal content of these wastewaters, several physicochemical removal alternatives for the heavy metals Cu, Pb, Zn, Ni, Cd, Cr, Mn and Fe were tested using coagulation, flocculation, precipitation, base addition and aeration. Additionally, COD removal and ammonia stripping were examined. Co-precipitation with either alum or iron salts did not usually lead to significantly higher heavy metal removal than lime alone. The major methods leading to an effective heavy metal removal were aeration and lime addition. Nickel and cadmium seemed to be strongly complexed and were not removed by any method. Also lead removal proved to be difficult. The results are also discussed in terms of compliance with standards.     

Solid waste characteristics and their relationship to gas production in tropical landfill

Solid waste characteristics and landfill gas emission rate in tropical landfill was investigated in this study. The experiment was conducted at a pilot landfill cell in Thailand where fresh and two-year-old wastes in the cell were characterized at various depths of 1.5, 3, 4.5 and 6 m. Incoming solid wastes to the landfill were mainly composed of plastic and foam (24.05%). Other major components were food wastes (16.8%) and paper (13.3%). The determination of material components in disposed wastes has shown that the major identifiable components in the wastes were plastic and foam which are resistant to biodegradation. The density of solid waste increased along the depth of the landfill from 240 kg m⁻³ at the top to 1,260 kg m⁻³ at the bottom. Reduction of volatile solids content in waste samples along the depth of landfill suggests that biodegradation of solid waste has taken place to a greater extent at the bottom of the landfill. Gas production rates obtained from anaerobic batch experiment were in agreement with field measurements showing that the rates increased along the depth of the landfill cell. They were found in range between 0.05 and 0.89 l kg⁻¹ volatile solids day⁻¹. Average emission rate of methane through the final cover soil layer was estimated as 23.95 g⁻²day⁻¹ and 1.17 g⁻²day⁻¹ during the dry and rainy seasons, respectively.     

Characterization of PM10 and PM2.5 and associated heavy metals at the crossroads and urban background site in Zabrze, Upper Silesia, Poland, during the smog episodes

The concentrations of seven heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, and Pb) associated with PM10 and PM2.5 at the crossroads and the background sites have been studied in Zabrze, Poland, during smog episodes. Although the background level was unusually elevated due to both high particulate emission from the industrial and municipal sources and smog favorable meteorological conditions, significant increase of the concentration of PM2.5 and PM10 as well as associated heavy metals in the roadside air compared to the urban background has been documented. The average daily difference between the roadside and corresponding urban background aerosol concentration was equal to 39.5 μg m^???3 for PM10 and 41.2 μg m^???3 for PM2.5. The highest levels of the studied metals in Zabrze appeared for iron carried by PM10 particles: 1,706 (background) and 28,557 ng m^???3 (crossroads). The lowest concentration level (in PM10) has been found for cadmium: 7 and 77 ng m^???3 in the background and crossroads site, respectively. Also the concentrations of heavy metals carried by the fine particles (PM2.5) were very high in Zabrze during the smog episodes. Concentrations of all studied metals associated with PM10 increased at the roadside compared to the background about ten times (one order) while metals contained in PM2.5 showed two to three times elevated concentrations (except Fe—five times and Cr—no increase).     

Distribution of heavy metals in agricultural soils near a petrochemical complex in Guangzhou, China

The aim of the study was to investigate influence of an industrialized environment on the accumulation of heavy metals in agricultural soils. Seventy soil samples collected from surface layers (0-20 cm) and horizons of five selected pedons in the vicinity area of petrochemical complex in Guangzhou, China were analyzed for Zn, Cu, Pb, Cd, Hg and As concentrations, the horizontal and vertical variation of these metals were studied and geographic information system (GIS)-based mapping techniques were applied to generate spatial distribution maps. The mean concentrations of these heavy metals in the topsoils did not exceed the maximum allowable concentrations in agricultural soil of China with the exception of Hg. Significant differences between land-use types showed that Cu, Pb, Cd, Hg and As concentrations in topsoils were strongly influenced by agricultural practices and soil management. Within a radius of 1,300 m there were no marked decreasing trends for these element concentrations (except for Zn) with the increase of distance from the complex boundary, which reflected little influence of petroleum air emission on soil heavy metal accumulation. Concentrations of Zn, Cu, Pb, Cd, Hg and As in the five pedons, particularly in cultivated vegetable field and orchard, decreased with soil depth, indicating these elements mainly originated from anthropogenic sources. GIS mapping was a useful tool for evaluating spatial variability of heavy metals in the affected soil. The spatial distribution maps allowed the identification of hot-spot areas with high metal concentration. Effective measures should be taken to avoid or minimize heavy metal further contamination of soils and to remediate the contaminated areas in order to prevent pollutants affecting human health through agricultural products.     

Enhanced uptake of heavy metals in municipal solid waste compost by turfgrass following the application of EDTA

Enhancement of multiple heavy metal uptake from municipal solid waste (MSW) compost by Lolium perenne L. in a field experiment was investigated with application of EDTA. EDTA was added in solution at six rates (0–30 mmol kg^???1) after 50 days of plant growth. Two weeks later, plants were harvested for the first crop and then all the turfgrasses were mowed. After another 30 days of growth, EDTA was added again at above six rates to the corresponding sites and the second crop was harvested 2 weeks later. The results showed that EDTA significantly increased heavy metal accumulation in both crops of L. perenne. For the first crop, the concentrations of Mn, Ni, Cd, and Pb in the shoots increased remarkably with increasing EDTA supply, peaked at 25 mmol kg^???1 EDTA, and shoots of 0–5 cm height (shoots from medium surface to 5 cm height) had higher metal concentrations than 5–10 cm and >10 cm shoots. The highest concentration of Mn, Ni, Cd, and Pb was 2.3-, 2.3-, 2.6-, and 3.2-fold, respectively, in 0–5 cm shoots higher than control. For the second crop, the concentrations of Mn, Cu, and Pb in shoots were, in general, less than those in the first crop. However, the second crop was significantly higher (P?< 0.05) than the first crop in dry biomass, so the total amount of metals removed by the second crop was more than the first crop. In addition, EDTA significantly increased the translocation ratios of most heavy metals from roots to shoots. For the first crop, 38% of the total Zn, 51% of Cd, 49% of Pb, 60% Mn, 55% Ni, and 45% Cu taken up by the plant was translocated in the shoots of 0–5 cm height. Turfgrass would have potential for use in remediation of heavy metals in MSW compost or contaminated soils.