Municipal solid waste (MSW) source-classified collection represents an advancement in resource cycling and secondary pollution control in China. Comparative experiments were performed to assess the levels and patterns of polychlorinated biphenyls in bottom ash, fly ash from boiler, and fly ash from bag filter from an MSW incineration plant with source-classified collection of MSW. Polychlorinated biphenyls were concentrated in the bag filter fly ash and in the bottom ash. The total amount of polychlorinated biphenyls was much lower than in fly ashes and bottom ash from traditional mixed waste incineration. Total concentration of coplanar polychlorinated biphenyls and toxic equivalent quantities were also reduced. Due to variations of feed waste, complete combustion, including continuously high incineration temperature, low CO concentrations and high air excess ratio were observed. Incineration temperature showed a negative correlation, while CO concentration showed a positive correlation with total and coplanar polychlorinated biphenyls, indicating that the latter can be reduced by controlling combustion conditions related to properties of feed waste. 相似文献
● A database of municipal solid waste (MSW) generation in China was established.● An accurate MSW generation prediction model (WGMod) was constructed.● Key factors affecting MSW generation were identified.● MSW trends generation in Beijing and Shenzhen in the near future are projected. Integrated management of municipal solid waste (MSW) is a major environmental challenge encountered by many countries. To support waste treatment/management and national macroeconomic policy development, it is essential to develop a prediction model. With this motivation, a database of MSW generation and feature variables covering 130 cities across China is constructed. Based on the database, advanced machine learning (gradient boost regression tree) algorithm is adopted to build the waste generation prediction model, i.e., WGMod. In the model development process, the main influencing factors on MSW generation are identified by weight analysis. The selected key influencing factors are annual precipitation, population density and annual mean temperature with the weights of 13%, 11% and 10%, respectively. The WGMod shows good performance with R2 = 0.939. Model prediction on MSW generation in Beijing and Shenzhen indicates that waste generation in Beijing would increase gradually in the next 3–5 years, while that in Shenzhen would grow rapidly in the next 3 years. The difference between the two is predominately driven by the different trends of population growth. 相似文献
In order to eliminate secondary pollution caused by municipal solid waste (MSW) incineration, a MSW gasification and melting process is proposed. The process is expected to reduce the emission of pollutants, especially heavy-metals and dioxins. In this paper, the combustible components of MSW and simulated MSW were gasified in a lab-scale fluidized bed at 400°C–700°C when the excess air ratio (ER) was between 0.2 and 0.8. The experimental results indicated that the MSW could be gasified effectively in a fluidized bed at approximately 600°C–700°C when excess air ratio was 0.2–0.4. The melting characteristics of two typical fly ash samples from MSW incinerators were investigated. The results indicated that fly ash of pure MSW incineration could be melted at approximately 1,300°C and that of MSW and coal co-combustion could be melted at approximately 1,400°C. When temperature was over 1,100°C, more than 99.9% of the dioxins could be decomposed and most of the heavy-metals could be solidified in the slag. Based on the above experiments, two feasible MSW gasification and melting processes were proposed for low calorific value MSW: (1) sieved MSW gasification and melting system, which was based on an idea of multi-recycle; (2) gasification and melting scheme of MSW adding coal as assistant fuel. 相似文献
Aged municipal solid wastes (MSW) excavated from landfills and dumpsites were characterized to analyze their fraction composition, moisture content, and lower heat value (LHV). The necessity and feasibility of recycling combustibles from aged MSW to improve the incineration of fresh MSW were investigated. The results showed that combustibles in aged MSW were easily separated from other components and than LHV of the separated combustibles are higher than 11000 kJ/kg. The fresh MSW are of high moisture contents with average LHV below 6500 kJ/kg, making their stable combustion difficult to maintain in MSW incinerators. For both fresh MSW and aged MSW, plastics are the main contributor to their LHV. To improve incineration of fresh MSW that are characterized with low LHV, combustibles separated from aged MSW were made into refuse derived fuel (RDF) pellets and were then added to fresh MSW by 2% wt.–5% wt. LHV variation and air supply resistance change of the MSW layer on the incinerator grate caused by the addition of RDF was checked, and no significant changes were found. No obvious difference was observed for the ‘burn-out time’ between RDF pellets and fresh MSW either. RDF made from aged MSW combustibles is found to be a promising auxiliary fuel to improve the incineration of fresh MSW, and aged MSW from old landfill cells and dumpsites can be finally disposed of jointly with fresh MSW by recycling combustible from the former to be coincinerated with the latter in the incineration plants. 相似文献
Fly ash from municipal solid waste incineration is a toxic waste due to the presence of toxic heavy metals. Here, a new method for metal stabilization based on the use of silica gel extracted from rice husk ash is presented. This method is sustainable because of the use of only waste materials to produce a final inert product, and because the inertization procedure occurs at room temperature. The estimated maximum Pb adsorption capacity of extracted silica, of about 36 mg/g, is found to be far greater than the adsorption capacity of other known absorbers used for municipal solid waste incineration fly ash. 相似文献
Polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (Co‐PCBs) were determined in fly ash samples from municipal solid waste (MSW), medical waste (MW), and electricity power plant incinerators in Taiwan. The average concentrations of PCDD/DFs and Co‐PCBs are 7.02 ng‐TEQ/g and 1.06 ng‐TEQ/g, respectively. The contributions to total TEQ are 24% from PCDDs, 64% from PCDFs, and 12% from Co‐PCBs, indicating that PCDFs generate the highest environmental impact and MSW and MW incinerators are potential Co‐PCBs contaminating sources. The levels of PCDD/DFs and Co‐PCBs found in ash samples increase from petroleum‐fired, coal‐fired, large municipal solid waste, small medical waste, to small municipal solid waste incinerators, and are generally lower than those from incinerators built earlier. All fly ash samples analyzed in this study were considered hazardous materials. More research is suggested to establish the relationship between the amounts of PCDD/DFs and Co‐PCBs in fly ash and in flue gas. 相似文献
Municipal solid waste management was studied for 1 year in a representative urban area of Lahore city for environmental sustainability. The effects of financial status of the household and the seasonal variations on generation rate and compositions of municipal solid waste (MSW) were determined. MSW generation rate and the economic status of the households were positively correlated (p < 0.05). Seasonal variations observed were significant only for organics (p = 0.001), plastics (p = 0.008) and food waste fractions (p = 0.009) in MSW. Response surface regression model developed and analysed by Minitab-15® showed that the interaction of season and different economic zones of the town on the MSW generation rate was non-significant (p = 0.334). Elemental and heating value analyses of the mixed organic fractions in kitchen waste had carbon 47.93%, hydrogen 6.20%, nitrogen 2.24%, sulphur 0.23%, oxygen 39.01%, and C and N ratio 27.78. Findings concluded that food waste was 56% of total MSW with 71.03% moisture content and a modest heating value of 5566 J/g. Existing temporary storage capacity of MSW is 51% of the total MSW generated considering the weighted MSW generation rate of 0.57 kg/person/day calculated in this study. Composting could be a possible final disposal option due to high moisture and organic content and can be studied in future research. Development of a transfer station, introduction of home composting programmes and awareness towards proper segregation and reduction of waste at the household level is suggested to attain sustainability in the MSW management system. 相似文献
This first nationwide survey was conducted to evaluate the overall performance of the circulating fluidized bed (CFB) incineration of municipal solid waste (MSW) in 2014-2015 in China. Total 23 CFB incineration power plants were evaluated. The data for monthly average flue gas emission of particles, CO, NOx, SO2 and HCl were collected over 12 consecutive months. The data were analyzed to assess the overall performance of CFB incineration by applying the Mahalanobis distance as a multivariate outlier detection method. Although the flue gas emission parameters had met the Chinese national emission standards, there were 11 total outliers (abnormal behavior) detected in 6 out of 23 CFB incineration power plants from the perspective of the MSWincineration performance. The results demonstrate that it is more important for a better performance of CFBs to reduce the frequencies of the MSW load changes, rather than the magnitudes of the MSW load changes, particularly reducing the frequencies in the range of 10% and more of the load changes, under the same and stable conditions. Furthermore, the overloading occurs more often than the underloading during the operation of the CFB incineration power plants in China. The frequent overloading is 0% to 30% of the designed capacity. To achieve the stable performance of CFBs in practice, an appropriately designed MSW storage capacity is suggested to build in a plant to buffer and reduce the frequency of the load changes.
With rapid urban development, municipal solid waste (MSW) has become a pressing issue. Estimation of carbon discharge through municipal solid waste provides a way to assess environmental load of solid waste from the viewpoint of the carbon cycle. With few studies on carbon research and provides insights into human impacts on the carbon cycle. Based on a comprehensive fieldwork investigation of a typical Chinese tourist city – Haikou City, Hainan Island – the characteristics of MSW carbon discharge and human activities that influenced it were analysed. The results indicated that, in 2001, the total carbon discharge from 261.9 Gg of MSW was 105.1 GgC per year, and 174.6 kgC per capita per annum. Carbon is discharged in the form of food scraps (24%), plastics (20%), wood (17%), fabrics (14%), paper (13%), and dust and stone (12%). If landfill received all the waste, 4.7% of MSW carbon would be transformed into methane, with a value of 4.9 GgC. Between 1991 and 1999, Haikou's per capita MSW carbon discharge increased by 59.9%, and total MSW carbon discharge increased by 124.9%. MSW carbon discharge in Haikou is significantly affected by the growth of residential expenditure and urbanisation. Local characteristics of tourism also influence Haikou's MSW carbon discharge, not only in terms of its yearly variation, but also its monthly variation. Integrating data on carbon discharge with carbon consumption will provide a systematic view of the carbon metabolism in urban ecosystems, and further insights into the generation of urban environmental pollution. 相似文献
The fast growing of urban areas in developing countries has brought serious problems on municipal solid waste (MSW) management. It will be rational to adopt an integrated approach to deal with such a challenge so that the overall eco-efficiency of MSW management could be improved. To better examine how attributes of integrated MSW management are being interpreted and put into practice, and to explore what changes should be made to improve the application of integrated MSW management, we employ a case study method so that lessons learned could be used to inform initiatives in other cities and the potential solution may offer feasible strategies. The case study city is Dalian, a typical seaport city with fast growing rate in economy. The outcomes of this case study show us that fragmented management structure, ineffective and inefficient enforcement of relevant regulations, backward technologies, limited financial resources and lack of public participation are main barriers for the implementation of integrated MSW management. Consequently, in order to overcome these barriers, we propose an integrated management framework on MSW management, aiming to maximize the overall eco-efficiency of MSW management. 相似文献
Considering high-moisture municipal solid waste (MSW) of China, a steam dried MSW gasification and melting process was proposed, the feasibility was tested, and the mass and energy balance was analyzed. Preliminary experiments were conducted using a fixed-bed drying apparatus, a 200 kg per day fluidized-bed gasifier, and a swirl melting furnace. Moisture percentage was reduced from 50% to 20% roughly when MSW was dried by slightly superheated steam of 150°C?C350°C within 40 min. When the temperature was less than 250°C, no incondensable gas was produced during the drying process. The gasifier ran at 550°C?C700°Cwith an air equivalence ratio (ER) of 0.2?C0.4. The temperature of the swirl melting furnace reached about 1240°C when the gasification ER was 0.3 and the total ER was 1.1. At these conditions, the fly ash concentration in the flue gas was 1.7 g·(Nm3)?1, which meant over 95% fly ash was trapped in the furnace and discharged as slag. 85% of Ni and Cr were bound in the slag, as well as 60% of Cu. The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97% when MSW is dried by steam of 200°C. The boiler heat efficiency is sensitive to three important parameters, including the temperature of preheated MSW, the moisture percentage of dried MS Wand the fly ash percentage in the total ash. 相似文献
• Municipal solid waste (MSW) was fermented, screened, gasified, then co-processed.• Co-processing MSW in cement kilns could cause excessive pollutant emissions.• Bypass flue gas can be disposed of through the main flue system.• Popular MSW co-processing methods do not affect cement quality. Cement kiln co-processing techniques have been developed in the past 20 years in China, and more than 60 factories now use fermentation, screening, and gasification pre-treatment techniques to co-process municipal solid waste (MSW). There three complete MSW pre-treatment techniques, co-processing procedures, and environmental risk assessments have been described in few publications. In this study, we assessed the effectiveness of each technique. The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard. To reveal the mechanisms of pollutant migration and enrichment, the substances in the kiln and kiln products are investigated. The input of co-processing materials (Co-M) produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/Fs) in the bypass flue gas (By-gas) in excess of the regulatory standard. The Co-M input produced by the screening and gasifier technologies caused the total organic carbon (TOC) concentration to exceed the standard. In addition, the NOx, TOC, and PCDD/Fs in the By-gas exceeded the regulatory standard. Raw meal was the primary chlorine and heavy metals input stream, and clinker (CK) and cement kiln dust (CKD) accounted for>90% of the total chlorine output stream. Flue gas and CKD were the primary volatile heavy metal (Hg) output streams. Greater than 70% of the semi-volatile heavy metals (Cd, Pb, Tl and Se) distributed in hot raw meal and bypass cement kiln dust. The low-volatility heavy metals were concentrated in the CK. These results indicated that co-processing techniques used in China still require improvement. 相似文献