Mixed Solid Municipal Waste-Based Biochar for Soil Fertility and Greenhouse Gas Mitigation

The overall municipal organic waste in Qatar accounts for 57% of municipal waste generated annually. Organic solid wastes such as food, newspapers, packaging, furniture woods and wood from building demolition have traditionally been placed in landfill, which create issues of sustainability for a country like Qatar with small land mass. While the recently opened Doha solid waste treatment facility contributed to alleviating the pressure on Landfill sites through composting and incineration, new value-added use of solid organic waste are needed for environmental and economic sustainability. Fortunately, biochars from mixed organic solid wastes can be used in soil amendment for food security and long term carbon sequestration for environmental sustainability. We hypothesize that deficiencies in depleted Qatari soils can be remedied by the application of biochars that are custom-designed to possess the right physicochemical characteristics suitable to improve soil fertility. Hence, this study was conducted to (1) Optimize production of biochars from mixed organic waste for desired physicochemical characteristics as soil enhancers. (2) Produce and characterize designer biochars using optimum production conditions for testing in soil incubation experiments. Select municipal organic wastes (newspaper, cardboard, woodchips and landscaping residues) individually and in a 25% blend were used as a precursor for biochar preparation. These residues were chosen due to their commonality in municipal solid waste streams. A complete 5 × 3 × 3 factorial design was used in this study with five biochar precursors (the 4 solid waste materials and a 25% blend/mixture), 3 sets of pyrolysis temperatures (350, 500, and 750°C) and 3 sets of pyrolysis residence time (2, 4 and 6 hrs). Data obtained showed that biochar yield was in the range of 21- 62% across all feedstocks and pyrolysis conditions. The highest yield was observed in newspaper-based biochars pyrolized at 350°C for 2 hrs. Key parameters such as pH, electrical conductivity bulk density and surface area, which positively improve water and nutrient-holding capacity in biochar-amended soil, varied depending on the precursors and production conditions. Bulk density was high in woodchips-based biochars but was similar among all other biochars, irrespective of precursors and pyrolysis conditions. The total surface area of biochars was low but showed dramatic increase in all feedstocks at 700°C pyrolysis temperature. The highest electrical conductivity observed in cardboard-based biochars pyrolized at 700C. Biochars produced from selected waste precursors were acidic except those produced at 700°C temperature where pH became alkaline. The wide range of biochar pH suggests potential tailoring to remediate the specific soil acidity. Cumulatively, biochars showed promising results for improving soil fertility parameters such as better water holding capacity, pH stabilization, and increased electrical conductivity of soil for better aggregation. These findings indicate that solid organic municipal wastes hold promising potential as precursors for manufacturing of value-added biochars with varied physicochemical characteristics allowing them to be used not only as an alternative to bio-waste management and greenhouse gas mitigation but also as means to improve depleted Qatari soil as the country embarks on its ambitious goals of ensuring food security and environmental sustainability.

Effect of biochars produced from solid organic municipal waste on soil quality parameters

Conversion of Organic Municipal Wastes into Biochars and their Effect on Fertility Parameters of Normal and Sabkha Soils of Qatar

Qatar economy has been growing rapidly during the last two decades during which waste generation and greenhouse gas emissions increased exponentially making them among the main environmental challenges facing the country. Production of biochar from municipal solid organic wastes (SOWs) for soil application may offer a sustainable waste management strategy while improving crop productivity and sequestering carbon. This study was conducted to (1) investigate the physicochemical parameters of biochars for SOW, (2) select the best-performing biochars for soil fertility, and (3) evaluate the potential benefits of these biochars in lowering greenhouse gases (GHGs) during soil incubation. Biochars were produced from SOW at pyrolysis temperatures of 300–750 °C and residence times of 2–6 h. Biochars were characterized before use in soil incubation to select the best-performing treatment and evaluation of potential GHG-lowering effect using CO2 emission as proxy. Here, soil–biochar mixtures (0–2%w/w) were incubated in greenhouse settings for 120 days at 10% soil moisture. Soil properties, such as pH, EC, TC, and WHC, were significantly improved after soil amendment with biochar. Two biochars produced from mixed materials at 300–500 °C for 2 h and used at 0.5–1% application rate performed the best in enhancing soil fertility parameters. A significant decrease in CO2 emission was observed in vials with soil–biochar mixtures, especially for biochars produced at 500 °C compared the corresponding raw materials which exhibited an exponential increase in the CO2 emission. Hence, application of biochar to agricultural soils could be beneficial for simultaneously improving soil fertility/crop productivity while sequestering carbon, thereby reducing anthropogenic emissions of GHGs.

Local authorities in Palestine are the service providers for solid waste management. Given that the organic fraction is the largest in municipal solid waste, and with ineffective management policies, the study of attitudes and behavioral aspects of personnel involved are very-important parameters in developing an effective waste management system and assisting policymakers in rectifying these policies. This study aims to assess the attitude of local authorities (LAs) in the southern West Bank of Palestine towards organic municipal solid waste composting and the factors that affect their attitude. The data was gathered via a structured questionnaire from all local authorities in the study area. The results showed that the local authorities’ attitude towards organic solid waste composting is low and can be considered dissatisfactory since only 36.5% of the local authorities are planning for composting compared to 63.5% who are not. The results also showed that municipal solid waste composting is significantly affected by nine factors, including financial capacity, proper machinery, enough refuse collection vehicles to collect solid waste fractions separately, availability of area of land to be used for composting, familiarity with composting systems, staff previous-experience in compost production, acceptance of the rapid composting system, staff training in compost production, and believe that solid waste composting is within the LAs’ responsibility. Implications municipal solid waste is growing continuously due to the population growth, increase methane emissions, and add more pressure on the landfills, which faces political and social restrictions for expansion in Palestine. In addition, there is severe restrictions on the import of chemical fertilizers imposed by Israel. Therefore, composting the organic fractions of solid waste can, to a large extent, extend the life of the landfills and compensate the shortage of fertilizers in the market, encourage organic farming and reduce methane emissions as well. Moreover, it can contribute to achieve the objective of the national strategy on solid waste management.

This paper presents a comprehensive economic analysis of recycling organic wastes through composting. A mathematical programming model is developed to examine the optimal level of compost production from sources of organic municipal solid waste, livestock manure and wastewater-treatment sludge. The model incorporates the spatial nature of the problem by referring to the locations of the sources for raw organic matter, of the composting plants and agricultural regions. Agricultural demand for compost is derived using estimated production functions for 42 crops, price elasticity of the vegetative agricultural outputs, and farmers' stated willingness to utilize compost. The model accounts for the costs of waste collection, compost production, transportation and landfilling; all include both direct costs and externalities. The optimal allocation of raw materials and outputs is achieved when the financial contribution of the composting system is maximized relative to the alternative of disposing of these organic wastes in landfills. We apply the model to the case of Israel. Today, despite the relatively high levels of organic material in municipal solid waste, the scarcity of landfill sites, and the low level of organic content in agricultural soils, only 37% of Israel's composting potential is realized. Subject to compliance with new environmental regulations, our analysis points to the possibility of an 89% composting rate, in which all livestock manure and sludge are composted, but only 75% of the organic municipal solid waste is utilized in this manner. This finding supports the strict enforcement of these environmental regulations, and indicates the need for a composting encouraging policy. However, regulations aimed at increasing the rate of municipal solid waste recycling should leave enough freedom for municipalities to select their waste disposal strategies. It is also concluded that, given the high costs of separating municipal waste at the 2 source, the government can increase composting rates by initializing and stimulating the formation of regional cooperation to ensure steady long run consumption of raw organic materials. Moreover, the government can increase agricultural demand for compost by both setting clear standards for high quality compost, and spreading the scientific information on the advantages of composting via the governmental agricultural instruction system. The presented methodology is applicable to other cases, as is the scientific-based data, which include the external costs and the compost production functions. This information is relevant for regions facing the same challenges, particularly where the soil's organic content is less than 2%; e.g., Portugal, Spain, Italy and Greece.

Disposal of solid waste poses great challenges to city managements. Changes in solid waste composition and disposal methods, along with urbanisation, can certainly affect greenhouse gas emissions from municipal solid waste. In this study, we analysed the changes in the generation, composition and management of municipal solid waste in Beijing. The changes of greenhouse gas emissions from municipal solid waste management were thereafter calculated. The impacts of municipal solid waste management improvements on greenhouse gas emissions and the mitigation effects of treatment techniques of greenhouse gas were also analysed. Municipal solid waste generation in Beijing has increased, and food waste has constituted the most substantial component of municipal solid waste over the past decade. Since the first half of 1950s, greenhouse gas emission has increased from 6 CO2-eq Gg y(-1)to approximately 200 CO2-eq Gg y(-1)in the early 1990s and 2145 CO2-eq Gg y(-1)in 2013. Landfill gas flaring, landfill gas utilisation and energy recovery in incineration are three techniques of the after-emission treatments in municipal solid waste management. The scenario analysis showed that three techniques might reduce greenhouse gas emissions by 22.7%, 4.5% and 9.8%, respectively. In the future, if waste disposal can achieve a ratio of 4:3:3 by landfill, composting and incineration with the proposed after-emission treatments, as stipulated by the Beijing Municipal Waste Management Act, greenhouse gas emissions from municipal solid waste will decrease by 41%.

In Uganda, the municipal solid wastes are generally a menace to the environment, ranging from indiscriminate dumping, open burning, and landfills, which would be utilized to augment agricultural fields through organic manure. The National Environment Management Authority (NEMA) of Uganda, however from 2009 to 2012 initiated and implemented a Clean Development Mechanism project. This project was established and conducted in nine urban centers with the key objective of reducing methane and other environmental nuisances while generating compost manure. The in-coming fresh municipal wastes at composting facilities were sorted into six categories; i) wood and wood products, ii) food and food wastes, iii) textiles, iv) garden, yard and park wastes, v) paper and pulp, and vi) glass, plastics, and metals. These were laboratory analyzed based on standard procedures, characterized and investigated for the pH, total organic carbon (TOC), total nitrogen (TN), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) (g kg−1). Statistical analyses were performed based on One-Way ANOVA, implemented in the SPSS program. The results indicate that the municipal fresh solid wastes were mainly dominated by biodegradable organic matter; garden, yard, and park wastes (49%), food and food wastes (43.2%), and the other wastes falling below 5.4%. Overall, the pH was 7.7 ± 0.02, TOC 318.2 ± 2.90, TN 12.1 ± 0.10, C/N 26.7 ± 0.20, P 4.4 ± 0.04, K 35.0 ± 0.49, Ca 38.9 ± 0.51, and Mg 5.8 ± 0.09. The concentration of the fresh wastes and macro-nutrients varied per municipality and were congruent with the economic activities and population lifestyles. We detected the effect of season/month on the concentration of wastes which corresponded with the various agronomical activities. The results from this study suggest that the notion of composting is potentially a viable organic waste management strategy in the country which can ultimately generate sufficient organic manure for agricultural input and thus enhanced carbon sequestration. Implications: In this study, we characterized the in-coming fresh municipal solid wastes and investigated the pH, total organic carbon (TOC), total nitrogen (TN), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) (g kg−1). We found that the municipal fresh solid wastes were mainly dominated by biodegradable organic matter (>90%). The results from this study suggest the notion of composting to be potentially a viable organic waste management strategy in Uganda which can ultimately generate sufficient organic manure for agricultural input. This is typically vital for enhancing carbon sequestration towards minimizing greenhouse gas emissions.

The objective of this study was to estimate the potential of organic municipal solid waste generated in an urban setting in a tropical climate to produce biogas. Five different categories of wastes were considered: fruit waste, food waste, yard waste, paper waste, and mixed waste. These fractions were assessed for their efficiency for biogas production in a laboratory-scale batch digester for a total period of 8weeks at a temperature of 15-30°C. During this period, fruit waste, food waste, yard waste, paper waste, and mixed waste were observed to produce 0.15, 0.17, 0.10, 0.08, and 0.15m(3) of biogas per kilogram of volatile solids, respectively. The biogas produced and caloric value of each feedstock was in the range of 1.25 × 10(-3)m(3) (17kWh)/cap/day (paper waste) to 15 × 10(-3)m(3) (170kWh)/cap/day (mixed waste). Paper waste produced the least (<1×10(-3)(<17.8kWh)/cap/day), and mixed waste produced the highest methane yield (10 × 10(-3)m(3) (178kWh)/cap/day). Thus, mixed waste was found to be more efficient than other feedstocks for biogas and methane production; this was mainly related to the better C/N ratio in mixed waste. Taking the total waste production in Jimma into account, the total mixed organic solid waste could produce 865 × 10(3)m(3) (5.4m(3)/capita) of biogas or 537 × 10(3)m(3) (3.4m(3)/capita) of methane per year. The total caloric value of methane production potential from mixed organic municipal solid waste was many times higher than the total energy requirement of the area.

TPA is the main priority in handling municipal solid waste in Indonesia, with many problems and challenges. TPST is one of other alternatives in handling solid waste in accordance with Solid Waste Management Law No. 18 year 2008, therefore it has an important role in reducing heavy burden of TPA. Activities that can be done in TPST are collecting, sorting, re-using, re-cycling, treatment of fi nal processing, either for organic solid waste or for inorganic solid waste. However, based on characteristic of municipal waste, it’s better the stressing activities are pointed to organic solid waste treatment that make composting as the main alternative activity. Government support and help are much needed in order that TPST activity can be optimally done.Keywords : municipal solid waste, integrated treatment facility, composting

Determinants of municipal solid and hazardous waste management in the occupied Palestinian territory: a cross-sectional study

Municipal solid waste is still a big problem in the cities of Indonesia especially in the Capital and capital of province. Open dumping in TPA is operated through all of Indonesian cities, this bring to consequences a bad influence to the environment. Conversion of Organic solid waste either to energy or biofertilizer is one of the best choices on the solid waste management. These methods will create a good manageable of cities environment, producing fertilizer for the farmer, energy for the communal and jobs for the people. Municipal organic wastes were grinded andfermented in anaerobic aerobic conditions. Anaerobic conditions produce rrydrogen or methane as bioenergy meanwhile aerobic fermentation was used to get either compost or liquid oiofertilizer. The result of Bioenergy and biofertilizer production showed that Municipal organic waste has a great potential as substrate for bioenergy such as hydrogen and methane or substrate for biofertilizer. The biofertilizer could be either as compost or liquid biofertilizer which are rich with growth promoting substances produces by specific bacteria during municipal organic solid waste fermentation. Key words: Municipal, organic solid waste, management, bioenergy, bioJertilizer

This research aims to develop a systematic life cycle assessment approach for alternative technologies for converting UK’s municipal solid waste (MSW) to energy and chemicals. The study focuses on seven scenarios, which are combustion, gasification, methanol synthesis, indirect dimethyl ether (DME) synthesis, direct DME synthesis, solid oxide fuel cell (SOFC) and methanation. The LCA model is developed based on one ton of MSW where three waste compositions are considered. The environmental impacts are evaluated by SimaPro software using IMPACT 2002+ method and Ecoinvent 3 as database. This work does not consider on the MSW collection and transportation, the plant construction and uncertainty of the MSW. The syngas composition employed in this study is predicted from a non-stoichiometric equilibrium gasification model using Lagrange multiplier and Gibb’s free energy minimisation approach, which is simulated in MATLAB software. Moreover, a dynamic kinetic model based on the reactions in the gasification is also developed and simulated. The model output is compared to the experimental results and the parameters enhanced using two estimability analysis approaches. The environmental impact results show that the SOFC process has the least impact on most end-point categories for the base case of the waste composition (MSW 1) because it can generate the highest amount of electricity. The other two waste compositions are also compared and found that in case of the second MSW composition (MSW 2), SOFC is in the most environmentally friendly based on the end-point impact categories. For the third composition (MSW 3), the direct DME synthesis becomes the top technology in the human health, whereas SOFC is still the top in the climate change and resource categories. The methanation always has the lowest ecosystem quality impact. A sensitivity analysis is performed by increasing the total yields for methanol, indirect and direct DME synthesis. It appears that when the total yield increases from 0.4 to be 0.6, all three processes have lower global warming (GW) impact, because there are more carbon atoms converted to methanol and DME in the process, but still more than SOFC process. A techno-economic analysis is also carried out for each scenario. It is found that the net present value (NPV) from SOFC process are always higher than other process when the waste capacity is more than 160 kilotons per annum for MSW 1 and MSW 2. However, the direct DME synthesis has higher NPV than the SOFC in case of MSW 3. Lastly, a multi-objective optimisation is performed to help achieve a more holistic decision making on these scenarios by using ϵ-constraint method that consists in maximising the NPV and minimising the global warming potential (GW). The results confirm that the SOFC is the optimal technology for both MSW 1 and MSW 2 (in the capacity ranges of 84-481 kton MSW 1 per year and 92-602 kton MSW 2 per year). For MSW 3, SOFC is the optimal process in the range between 36-103 kton CO2 eq. per year (capacity 59-168 kton MSW 3 per year) and the direct DME synthesis is the optimal technology in the range between 214-678 kton CO2 eq. per year (capacity 218-691 kton MSW per year).

Purpose – This paper examined the current status of municipal solid waste management across Nigeria. The core aspects covered are generation, characterization, collection, scavenging, open dumping, disposal and environmental implications of poor solid waste management. The purpose of this paper is to present a comprehensive overview of the current state of municipal solid waste management in Nigeria. Design/methodology/approach – This study was executed by a combination of an extensive literature search and field study. Solid waste generation rates for 31 Nigerian cities were obtained from literature. In addition, characteristics of municipal solid waste from 26 Nigerian cities were also obtained from literature. Other aspects such as characterization of solid waste obtained from final dumpsite and heavy metals accumulation in solid waste dumpsites were undertaken first hand. Findings – Solid waste generation rate was found to vary from 0.13 kg/capita/day in Ogbomosho to 0.71 kg/capita/day in Ado-Ekiti. Factors affecting solid waste generation rates were identified. Typically, food waste was found to constitute close to 50 percent of overall municipal solid waste in Nigerian cities. This study shows that the rate of generation of plastics, water proof materials and diapers has assumed an upward trend. Due to the dysfunctional state of many municipal waste management authorities, many cities have been overrun by open dumps. For instance, more than 50 percent of residents of Maiduguri in northern Nigeria and Ughelli in southern Nigeria dispose of their waste in open dumps. Indiscriminate disposal of waste has also resulted in the preponderance of toxic heavy metals in agricultural soils and consequent bioaccumulation in plants as well as groundwater contamination. Research limitations/implications – The main limitation of this research is municipal waste management authorities do not have relevant data. Hence, there was heavy reliance on published materials. The status of waste management in Nigeria is very deplorable and therefore poses serious threats to public and environmental health. There is urgent need for both government and individuals to adopt holistic and sustainable waste management strategies in order to safeguard public/environmental health. Practical implications – Findings from this paper can form a veritable resource for the formulation and implementation of sustainable municipal solid waste management framework and strategies in Nigeria. Originality/value – While most studies on municipal solid waste management in Nigeria are focussed on selected cities of interest, this particular study cuts across most cities of Nigeria in order to present a broader and holistic view of municipal solid waste management in Nigeria. The paper has also unraveled core municipal solid waste management challenges facing Nigerian cities.

Accurate estimation of emissions of greenhouse gases (GHGs) is required for making effective climate change mitigation policies at the national level. Among major sources, municipal solid waste (MSW) is an important source of GHGs, such as methane (CH4), generated during the anaerobic decomposition of organic matter. In Viet Nam, the emissions of GHGs are not well quantified, in particular from the MSW management system. In this study, we estimated emissions of GHGs from the MSW management system of Ho Chi Minh City (HCMC), considering the current waste management practices. In HCMC, landfilling has been a common practice of solid waste management. About 85 percent of the total MSW generated in the city has been landfilled at two landfill sites. Our estimates show that landfilling was the significant source of GHGs in HCMC, with a net contribution of 781.05 kg CO2-equivalent (CO2-eq.) per tonne of MSW landfilled. From the whole MSW management system, the direct GHG emission was 768.61 (kg CO2-eq. per tonne of MSW) with avoided emissions of 72.47 (kg CO2-eq. per tonne of MSW) through composting and recycling of MSW. The net GHG emission from the MSW management system was 696.14 kg CO2-eq. per tonne of MSW (≈1.665 million tonnes of CO2-eq. per year). The GHG emission data of this study may be useful to policymakers for making effective climate change mitigation policies.