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Item type:Publication, Access status: without files , Biogaserzeugung(Springer, 2024); ; ; 18 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Conceptualization of bioreactor landfill approach for sustainable waste management in Karachi, Pakistan(Multidisciplinary Digital Publishing Institute (MDPI), 2022-03-13); ; ; ; Finding a sustainable approach for municipal solid waste (MSW) management is becoming paramount. However, as with many urban areas in developing countries, the approach applied to MSW management in Karachi is neither environmentally sustainable nor suitable for public health. Due to adoption of an inefficient waste management system, society is paying intangible costs such as damage to public health and environment quality. In order to minimize the environmental impacts and health issues associated with waste management practices, a sustainable waste management and disposal strategy is required. The aim of this paper is to present a concept for the development of new bioreactor landfills for sustainable waste management in Karachi. Furthermore, this paper contributes to estimation of methane (CH4) emissions from waste disposal sites by employing the First Order Decay (FOD) Tier 2 model of the Intergovernmental Panel on Climate Change (IPCC) and determining of the biodegradation rate constant (k) value. The design and operational concept of bioreactor landfills is formulated for the study area, including estimation of land requirement, methane production, power generation, and liquid required for recirculation, along with a preliminary sketch of the proposed bioreactor landfill. This study will be helpful for stockholders, policy makers, and researchers in planning, development, and further research for establishment of bioreactor landfill facilities, particularly in the study area as well as more generally in regions with a similar climate and MSW composition.Publicationtype: Journal ArticleScopus© Citations 8 92 262 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Municipal solid waste management through sustainable landfilling: In view of the situation in Karachi, Pakistan(Multidisciplinary Digital Publishing Institute (MDPI), 2022-01-11); ; ; ; Open disposal is the most common technique used for municipal solid waste (MSW) management due to the absence of sanitary landfills in Pakistan. The major cities and small towns in Pakistan have become a showcase of negligence and mismanagement of MSW, which results in deterioration of the environmental and social-life quality. Moreover, research has proved that inefficient handling (disposal) of MSW results in uncontrolled emissions of greenhouse gases (GHGs), mainly methane, and adds a significant share in global climate change. This study aims to estimate methane emissions from MSW disposed of at dumpsites and compare the GHG mitigation potential of different landfill strategies in specific climate and waste compositions in Karachi. The GHG estimations are based on lab-scale investigations conducted by simulating landfill conditions through the landfill simulation reactor (LSR) experiment. The synthetic MSW sample representing the composition of MSW generated in Karachi was used in the LSR experiment. Environmental sustainability and GHG mitigation potential of different landfilling strategies was evaluated by analyzing gas formation potential (GP<sub>21</sub>) and respiration activity (RI<sub>4</sub>) at the end of the experiment. This study revealed that the quantity of solid waste annually disposed of at dumpsites in Karachi possesses the potential to release about 3.9 Mt CO<sub>2</sub>-eq. methane (with specific methane potential of 1.8 tCO<sub>2</sub>-eq./tonne DM disposed) due to the biological decomposition of the organic fraction. Results show that the fresh waste disposed of at landfill sites in Karachi possesses about 92% and 94% higher GP<sub>21</sub> and RI<sub>4</sub>, respectively, than the German allocated criteria for mechanically and biologically treated (MBT) waste for landfills Furthermore, sanitary landfills with post-aeration conditions showed higher GHG mitigation potential and low biological activity in the waste. The second highest GHG mitigation potential and lowest biological activity of the waste was noticed from bioreactor landfills with post-aeration conditions. The third number in GHG mitigation and reduced waste activity was noticed in the waste sampled from bioreactors without aftercare approach. The least GHG mitigation potential was noticed from the uncontrolled waste dumping (existing) approach with high residual gas potential and respiration index level. This lab-scale landfill simulation study can provide baseline data for further research and planning the development of new sustainable landfills in Karachi, Pakistan and in the region.Publicationtype: Journal ArticleScopus© Citations 16 139 223 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of moisture content and leachate recirculation on oxygen consumption and waste stabilization in post aeration phase of landfill operation(2021-06-15); ; Sustainable completion of municipal solid waste landfills requires post-closure care after a time when utilization of landfill gas produced from biodecomposition of organic waste be not possible/or economically feasible. Research proved that in-situ aeration is a promising approach employed for landfill aftercare. The application of post aeration operation is targeted to achieve accelerated waste stabilization to avoid long term environmental and public health impacts from landfills. In in-situ aeration operation, consumption of supplied oxygen has significant influence on biological stabilization of solid waste placed in the landfills. The consumption of oxygen is regulated by operation parameters of landfill – one of the important is presence of moisture in landfill ecosystem. This research aims to assess the influence of moisture content and leachate recirculation on the oxygen consumption during post aeration phase of landfill operation. The effect of oxygen consumption on the extent of waste stabilization achieved after experiment was also assessed. Three lab-scale landfill simulation reactors (LSRs) were used – in two of three reactors (LSR-1 and LSR-3) operation was carried out in two phases: Anaerobic and post-aeration. One reactor (LSR-2) was operated under anaerobic condition throughout the experiment and used as control. To compare the oxygen consumption, conventional landfill (CLF) conditions without excess water addition and leachate recirculation were simulated in LSR-1 and the bioreactor landfill conditions (BRLF) with excess water injection and leachate recirculation were simulated in LSR-3. In CLF 46.4% of supplied oxygen was consumed during post aeration phase while in BRLF only 0.96% of oxygen consumption was noticed. In result of higher oxygen consumption, biostabilization rate of waste in CLF was 7% higher than BRLF at the end of experiment. This study demonstrated that, in presence of low moisture in landfill ecosystem optimal air distribution can be realized which results in enhanced waste oxidization and stabilization.Publicationtype: Journal Article115 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Estimation of methane production and electrical energy generation from municipal solid waste disposal sites in Pakistan(Multidisciplinary Digital Publishing Institute (MDPI), 2021-05-01); ; ; ; This work aimed to estimate the annual methane production from the municipal solid waste disposal sites in Pakistan. In this study, the Intergovernmental Panel on Climate Change (IPCC) default methodology was used to estimate theoretical methane formation potential of the waste disposal sites in major cities of Pakistan. The estimates of this study are based on the last population census conducted in the year 2017 and latest available data regarding the waste generation and management practices in the cities considered in the study. Results showed that 31.18 million tonnes of municipal solid waste (MSW) is generated annually. The top 10 major populated cities in Pakistan (with 20% share in country’s population) contributing 31% share in the total quantity of MSW generated in overall country. On average 50–60% of the MSW generated is collected and openly dumped at the designated waste disposal sites. After analyzing the data, we estimate that annually 12.8 MtCO2-eq of methane is emitted from the waste disposal sites in major cities considered in this study. The methane produced from the waste disposal sites can be sustainably utilized as a source of energy through transforming MSW disposal sites (open dumps) to sanitary landfills with methane capturing and utilization facilities. In the present scenario of waste management and methane formation potential, sanitary landfills would generate 62.35 MWh of electric power if 25% of the methane was recovered and utilized in power generation.Publicationtype: Journal ArticleScopus© Citations 14 183 139 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Biochemical methane potential assessment of municipal solid waste generated in Asian cities: A case study of Karachi, PakistanMunicipal solid waste (MSW) generation rate in Asian cities is exponentially increasing with rise in urbanization and commercial activities. Beside this, the cities in developing Asia are deficient in adequate waste management and facing energy shortage as well. The ineffectual waste management practice is one of the main causative factors behind the negative repercussions on public health and environment. This paper provides an estimation of power generation potential along with economic and environmental benefits of biochemical methane production from MSW. The biochemical methane potential (BMP) test of the MSW generated in Karachi, Pakistan was conducted by using the fresh synthetic waste sample. Through the analysis of the results obtained in this study and available data of the MSW generation (quantity, organic fraction and moisture content) in Karachi it is estimated that, every year about 5600 tons of methane are being wasted to atmosphere adding enormous share in global climate change. This study estimated that, about 63 MWe electric power can be generated by establishing biowaste digestion plants with power generation facilities in the city. The generated power can contribute 2.1% share in daily power supply and 21% power shortage can be reduced as well. Additionally, about 401.3 million-PKRs (2.6 million-US) revenue can be earned every year by selling the power generated by utilizing the MSW in waste to energy plants. Moreover, 0.13 Mt CO2-eq/annum greenhouse effect caused by methane emissions from open disposal of MSW can be eliminated.Publicationtype: Journal Article166 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Environmental sustainability enhancement of waste disposal sites in developing countries through controlling greenhouse gas emissions(Multidisciplinary Digital Publishing Institute (MDPI), 2021-01-01); ; ; Sustainable management of municipal solid waste is one of the major challenges for authorities in developing countries. Current waste disposal methods in Pakistan and other developing countries are not meeting standards of any proper waste management system opted for in the developed world. This mismanagement of waste is leading to serious environmental problems at local as well as global levels. This study aims to investigate the methane emissions from waste dumpsites in the city of Karachi, Pakistan, and to propose an effective approach to enhance their environmental sustainability. The methane emissions from waste disposal sites were assessed by simulating four different landfill situations during the landfill simulation reactor experiment. The residual methane reduction potential of each waste disposal approach was assessed by a biochemical methane test of waste after the experiment. It is estimated that in the present situation, about 11,500 tons of CO2-eq methane is released annually from waste disposal sites in Karachi. The convectional anaerobic landfill with methane capturing facilities and post-aeration operation was found to be the most environmentally sustainable approach with controlling 65% of residual methane emissions in comparison with the present scenario. For the development of new landfill sites, we recommend the bioreactor landfill approach with methane recovery and post-care (in-situ aeration).Publicationtype: Journal ArticleScopus© Citations 22 196 187 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Evaluation of behavior of waste disposal sites in karachi, pakistan and effects of enhanced leaching on their emission potentialThis study aims to assess the efficiency of enhanced leaching on biodegradation of residual waste and gas emissions from waste disposal sites. The investigation simulated the waste disposal conditions in the landfill sites of Karachi, Pakistan in terms of waste composition, moisture content, and climatic conditions. For this purpose, a lysimetric analysis method was applied. Landfill sites in Karachi have typically no cover and the waste degrades in relatively dry conditions due to the lower moisture content of the waste as well as due to the low annual rainfall. Decomposition of organic waste with low moisture content and limited water introduction is causing prolonged emissions in the form of gas and leachate due to the slow biodegradation process. This paper focuses on the comparison of gaseous emissions from waste disposal sites in two different circumstances by applying two different experimental approaches. In the first approach, the actual dry conditions were simulated by means of limited water addition and without leachate recirculation.In the second approach, enhanced leaching conditions were provided with process water addition and leachate recirculation. The results from 100 days of experimental operation revealed that an enhanced leaching is able to increase gas formation in comparatively short periods and prolongs gaseous emissions from waste disposal sites can be controlled.This lab scale study can provide baseline data for further research and planning to transform waste dumpsites to sanitary landfills in the region.Publicationtype: Journal ArticleScopus© Citations 8 307 323 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Aeration of the teuftal landfill: Field scale concept and lab scale simulation(2016-09-01); ; ; ; Long lasting post-closure care (PCC) is often the major financial burden for operators of municipal solid waste (MSW) landfills. Beside costs for the installation and maintenance of technical equipment and barriers, in particular long term treatment of leachate and landfill gas has to be paid from capital surplus. Estimations based on laboratory experiments project time periods of many decades until leachate quality allows for direct discharge (i.e. no need for further purification). Projections based on leachate samples derived from the last 37 years for 35 German landfills confirm these assumption. Moreover, the data illustrate that in particular ammonium nitrogen concentrations are likely to fall below limit values only after a period of 300 years. In order to avoid long lasting PCC the operator of Teuftal landfill, located in the Swiss canton Bern, decided to biologically stabilize the landfill by means of a combined in situ aeration and moisturization approach. In December 2014 the aeration started at a landfill section containing approximately 30% of the total landfill volume. From summer 2016 onwards the remaining part of the landfill will be aerated. Landfill aeration through horizontal gas and leachate drains is carried out for the first time in field scale in Europe. The technical concept is described in the paper. Parallel to field scale aeration, investigations for the carbon and nitrogen turnover are carried out by means of both simulated aerated landfills and simulated anaerobic landfills. The results presented in this paper demonstrate that aeration is capable to enhance, both carbon mobilization and discharge via the gas phase. This effect comes along with a significant increase in bio-stabilization of the waste organic fraction, which positively affects the landfill emission behavior in the long run. In terms of leachate pollution reduction it could be demonstrated that the organic load decrease fast and widely independent of the adjusted aeration rates whereby ammonium nitrogen load efficiently decrease later and only under higher aeration rates.Publicationtype: Journal Article94 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Landfill aeration within the scope of post-closure care and its completionThe time frame required for post-closure care of Municipal Solid Waste (MSW) landfills is often assessed over several decades or centuries. One possibility to significantly shorten this period and, at the same time, improve the emission behavior exists with in situ aeration. Positive effects in connection with this method for biological stabilization have been investigated and published elsewhere. However, until today neither generally accepted monitoring guidelines nor completion criteria have been defined. With the paper on hand the authors propose a methodology for the assessment of both, total and remaining stabilization periods for aerated landfills. The central component of this methodology is a carbon balance. The latter is based on a detailed waste characterization in combination with online monitoring of the emissions (gas and leachate). The methodology is exemplarily demonstrated by means of data derived from a full scale project in Northern Germany. Here it could be shown that the predicted aeration period of approximately 6.4. years was sufficient to bio-stabilize the landfill. Furthermore, proposals for the completion of landfill aeration are presented. In this connection, carbon balance is of particular importance since the amount of biodegradable organic carbon mainly determines the emission potential. Additional parameters, aiming at a validation of the state of biological stabilization achieved during aeration are proposed and described.Publicationtype: Journal Article157