Supplying hydrogen vehicles and ferries in Western Norway with locally produced hydrogen from municipal solid waste

Gibbs free energy minimization has been used to estimate the hydrogen production potential of air gasification of the wet organic fractions of municipal solid waste available in the Bergen region in Western Norway. The aim of this work was to obtain an upper limit of the amount of hydrogen that could be produced and to estimate of the number of vehicles: passenger ferries and cars that could be supplied with an alternative fuel. The hydrogen production potential was investigated as function of waste composition, moisture content, heat loss, and carbon conversion factor. The amount of hydrogen annually available for both gasification and gasification combined with water-gas-shift-reaction was calculated for different scenarios. Up to 2700 tonne H₂ per year could be produced in the best case scenario; which would, if only utilised for maritime operations, be enough to supply nine ferries and ten fast passenger boat connections in the Hordaland region in Western Norway with hydrogen.     

Effect of bioaugmentation on hydrogen production from organic fraction of municipal solid waste

In the present study, the effect of bioaugmentation with three bacterial species (i.e. E. coli, Bacillus subtilis and Enterobacter aerogenes) on the hydrogen production from organic fraction of municipal solid waste was evaluated at different bacteria/sludge ratios (0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 and 0.40). Cumulative hydrogen production, lag phases, and maximum hydrogen production rates were analyzed using modified Gompertz model. The highest cumulative and volumetric hydrogen production of 564.4 ± 10.9 mL and 1.61L_H2/L_substrate respectively was achieved for bioaugmentation with Bacillus subtilis at bacteria/sludge ratio of 0.25. The corresponding highest hydrogen yield was 43.68 mLH₂/gCarbo. For bioaugmentation with E. coli and Enterobacter aerogenes, the maximum cumulative hydrogen production of 423.4 ± 10.6 mL and 486.3 ± 10.6 mL respectively was obtained from bacteria/sludge ratio of 0.20. Corresponding highest hydrogen yields were 32.9 mLH₂/gCarbo and 37.1 mLH₂/gCarbo respectively. Bioaugmentation shortened the lag phases and improved COD removal. Volatile fatty acid generation was also improved with the bioaugmentation.     

Hydrogen-rich syngas production from municipal solid waste gasification through the application of central composite design: An optimization study

This study aims to investigate the influence and interaction of experimental parameters on the production of optimum H₂ and other gases (CO, CO₂, and CH₄) from gasification of municipal solid waste (MSW). Response surface method in assistance with the central composite design was employed to design the fifteen experiments to find the effect of three independent variables (i.e., temperature, equivalence ratio and residence time) on the yields of gases, char and tar. The optimum H₂ production of 41.36 mol % (15.963 mol kg-MSW⁻¹) was achieved at the conditions of 757.65 °C, 0.241, and 22.26 min for temperature, ER, and residence time respectively. In terms of syngas properties, the lower heating value and molar ratio (H₂/CO) ranged between 9.33 and 12.48 MJ/Nm³ and 0.45–0.93. The predicted model of statistical analysis indicated a good fit with experimental data. The gasification of MSW utilizing air as a gasifying agent was found to be an effective approach to recover the qualitative and quantitate products (H₂ and total gas yield) from the MSW.     

Thermophilic composting of municipal solid waste

Process of composting has been developed for recycling of organic fraction of municipal solid waste (MSW). The bioreactor design was modified to reduce the composting process time. The main goal of this investigation was to find the optimal value of time period for composting of MSW in thermophilic bioreactor under aerobic condition. The temperature profiles correlated well with experimental data obtained during the maturation process. During this period biological degraders are introduced in to the reactor to accelerate the composting process. The compost materials were analyzed at various stages and the environmental parameters were considered. The final composting materials contained large organic content with in a short duration of 40 days. The quantity of volume reduction of raw MSW was 78%. The test result shows that the final compost material from the thermophilic reactor provides good humus to build up soil characteristics and some basic plant nutrients.     

Energy potential from municipal solid waste in Malaysia

The average amount of municipal solid waste (MSW) generated in Malaysia is 0.5–0.8 kg/person/day and has increased to 1.7 kg/person/day in major cities. This paper highlights the MSW characteristics for the city of Kuala Lumpur. Currently, the waste management approach being employed is landfill, but due to rapid development and lack of space for new landfills, big cities in Malaysia are switching to incineration. A simple evaluation was conducted to establish the amount of energy that would be recovered based on the characteristics of the MSW if it were to be incinerated. From the characterization exercise, the main components of the Malaysian MSW were found to be food, paper and plastic, which made up almost 80% of the waste by weight. The average moisture content of the MSW was about 55%, making incineration a challenging task. The calorific value of the Malaysian MSW ranged between 1500 and 2600 kcal/kg. However, the energy potential from an incineration plant operating based on 1500 ton of MSW/day with an average calorific value of 2200 kcal/kg is assessed to be at 640 kW/day.     

垃圾焚烧的二次污染物排放处理

随着垃圾焚烧技术的不断发展,由此产生的二次污染问题也日益显现出来,主要包括垃圾焚烧所产生的飞灰污染、烟气中二恶英以及重金属的污染,特别是二恶英污染已引起全世界的关注,这对垃圾焚烧工艺的进一步发展提出了新的挑战。污染给人类的生存环境造成了很大的破坏,严重威胁着人类的安全。因而,二次污染物的排放控制问题成为亟待解决的问题。本文就垃圾焚烧所产生的二次污染物的排放处理进行讨论。     

Hydrogen-rich syngas produced from the co-pyrolysis of municipal solid waste and wheat straw

The co-thermochemical conversion of Municipal Solid Waste (MSW) and biomass is a new environmental technology and can produce hydrogen-rich syngas. This study investigated the co-pyrolysis of MSW and wheat straw, using a drop-tube furnace experiment. Using a temperature range of 500 °C–1000 °C, the study assessed pyrolysis gas yield, product distribution, gas low heating value, and carbon conversion of co-pyrolysis MSW with different amounts of wheat straw. Adding wheat straw only slightly increases the gas yield and carbon conversion, but improved the carbon monoxide and carbon dioxide in the syngas. At an experimental temperature below 700 °C, adding wheat straw promoted the cracking reaction of hydrocarbon gas, generated by the pyrolysis of MSW. At a temperature of 600 °C, adding 25% wheat straw improved carbon conversion in the blended sample. This study provides a basis for the application of MSW and WS thermo-chemical conversion.     

Optimizing the operating conditions for hydrogen-rich syngas production in a plasma co-gasification process of municipal solid waste and coal using Aspen Plus

The plasma gasification process is one of the newest and most innovative approaches to meet the needs of waste management but requires assessment and research on operational conditions prior to installation. In this work, a model based on Gibbs free energy minimization was developed and implemented in Aspen Plus®. A combination of municipal solid waste (MSW) and coal has been used as feedstocks. The model's performance was compared with the results of the literature and found to be in good agreement. The effect of various parameters such as temperature, equivalence ratio, MSW/coal blending ratio, and steam-to-feedstock ratio on the composition of syngas and hydrogen production were assessed. Very interesting results were obtained concerning the mixture of the feedstocks that maximize the hydrogen production besides that using steam as a gasifying agent allows higher hydrogen production than using air. When using high amounts of coal in the feedstock mixture, low steam ratios are preferred. When using high amounts of MSW in the feedstock mixture high steam ratios are preferred. The use of pure oxygen as the gasifying agent increases the hydrogen percentage but requires an air separation unit to be included in the process. The results obtained in this study are particularly relevant for countries with coal reserves.     

Effect of particle size on pyrolysis of single-component municipal solid waste in fixed bed reactor

According to the differences in components, three representative components (plastic, kitchen garbage and wood) in municipal solid waste (MSW) were pyrolyzed in a fixed bed reactor to evaluate the influence of particle size on pyrolysis performance of single-component municipal solid waste (MSW). The bed temperature was set at 800°C and each sample was separated into three different size fractions (0–5 mm, 5–10 mm and 10–20 mm). The results show for all the samples particle size has an effect on pyrolysis product yields and composition: smaller particle size results in higher gas yield with less tar and char; the decrease of particle size can increase H₂ and CO contents of gas, as well as the ash and carbon element contents in the char. And the influence is the much more significant for sample with higher fixed carbon and ash contents, such as kitchen garbage, and less for sample with higher volatile content, plastic in the test.     

An experimental study on a novel shredder for municipal solid waste (MSW)

Based on composition and volume-mass properties of MSW (i.e., unit weight, void ratio, and water content), a new way for the breakage of the organic MSW is presented to effectively convert MSW to heat and fuel gas. A lab-scale shredder consisting of compaction and shredding chambers is designed and the breakage process of MSW in the shredder can be divided into three successive phases: deformation, further deformation, compressive shearing. The performances of the shredder, such as the effect of the rotor velocity and hydraulic pressure on product size distribution and specific energy are investigated. The results show that with hydraulic pressure the specific energy is reduced, and size distribution of product is finer. When hydraulic pressure is constant, the specific energy decreases with increasing rotor velocity, while the products size distribution is coarser.     

Organic municipal solid waste (MSW) as feedstock for biodiesel production: A financial feasibility analysis

The pursuit towards an alternative solution to fossil fuel has facilitated science investigation initiatives that compare various options leading to biodiesel production. Besides conventional feedstock derived from vegetable oils, alternative sources that could be produce in large scale at competitive costs are the main scope of research in this field. This paper investigates the financial feasibility using organic solid waste as a feedstock, which results in the production of biodiesel through the conversion of volatile fatty acids into lipids (VFA). As a result, based on existing references of capital and operating costs, production and extraction yields for VFA and lipids and an internal rate of return of 15% in real terms, we concluded that biodiesel production is competitive compared to subsidized biodiesel traded in regions of Europe and the United States. These results encourage research aims to examine this technology at a larger scale. The adoption of public policies for the urban waste's disposal and collection, to reduced municipality's costs associated to the treatment, is also important for the implementation of these technologies.     

Steam catalytic gasification of municipal solid waste for producing tar-free fuel gas

In the paper, a two-region municipal solid waste (MSW) steam catalytic gasification process was proposed. The gasifier was composed of two individual reactors: one is the gasification reactors and the other is the catalytic reactor. The MSW was initially gasified and the produced tar was gasified in the gasification reactor, and further, the tar not gasified entered the catalytic reactor together with the fuel gas and was catalytically decomposed to fuel gas. The influences of the catalysts, steam and temperature on the content of tar, dry gas yield and composition, and carbon conversion efficiency were studied. The results indicated that under the optimum operating conditions, the dry gas yield can be up to 1.97 Nm³/kg MSW and the tar in the product can be completely eliminated. The concentration of hydrogen, carbon monoxide and methane in the fuel gas produced was 50.8%, 9.32% and 13.3%, respectively.     

Evaluation of hydrogen and methane production from municipal solid wastes with different compositions of fat,protein, cellulosic materials and the other carbohydrates

Municipal solid wastes (MSW) collected in Kyoto city were carefully separated, and the waste-type proportion in MSW was surveyed. A hydrogen/methane fermentation batch experiment was conducted under thermophilic condition using twenty different types of MSW components. Biodegradable wastes in the MSW almost consist of vegetable kitchen waste, and the characteristics of hydrogen and methane fermentation of MSW were similar to that of vegetable kitchen waste. Hydrogen production per g VS added was considerably positively correlated with easily degradable carbohydrates concentration and negatively correlated with cellulosic materials concentration. The various feedstocks could be classified into four groups according to nutrient composition (protein, fat, cellulosic materials and easily degradable carbohydrates), and the feedstocks belonging to carbohydrates rich group showed higher hydrogen yields than the other feedstocks. Rough hydrogen yield could be easily predicted by concentration of easily degradable carbohydrates.     

An analysis of power generation from municipal solid waste (MSW) incineration plants in Taiwan

Heavily (about 99%) depending on imported energy, Taiwan, a country in the subtropics, has limited natural resources. In this regard, biomass energy from (MSW) municipal solid waste incineration plants thus became attractive during the 1990s. The objective of this paper is to present a comprehensive analysis of MSW-to-energy in Taiwan. This paper gave a concise summary of current status of domestic energy consumption &; power generation, MSW generation &; MSW incineration treatment, and electricity generation from MSW incineration plants since 2000. Based on the electricity generation in 2008 (i.e., 2967 GWh), the environmental benefit of mitigating CO₂ emissions and the economic benefit of selling electricity were preliminarily calculated to be around 1.9 × 10⁶ tons and US$ 1.5 × 10⁸, respectively. However, since the heat content of incinerated MSW and the methodologies were used on the recommendation of the (IPCC) Intergovernmental Panel on Climate Change, the net emissions of CO₂ equivalent from methane (CH₄) &; nitrous oxide (N₂O) have been estimated to be at around 76,000 and 88,000 tons/year compared to coal and oil, respectively.     

Hydrogen-rich syngas produced from co-gasification of municipal solid waste and wheat straw in an oxygen-enriched air fluidized bed

The gasification characteristics of solid waste and wheat straw were investigated in an oxygen-rich atmosphere by using a laboratory-scale continuous fluidized bed reactor in the range of oxidation equivalent (ER) of 0.2~0.5 and reaction temperature of 600 °C~900 °C. Gasification of biomass and waste is an economical method for hydrogen production. When air is used as a carrier gas to gasify municipal solid waste, increasing the oxygen concentration can effectively increase the hydrogen concentration of the syngas. The product distribution of gasification reaction under different mixing ratios and reaction parameters was obtained. As is shown in the results, first, when the ER is between 0.2 and 0.5, if ER decreases by 0.1, the hydrogen concentration of gas production will increase by about 30%; second, if the oxygen concentration increases by 5%, the hydrogen concentration of gas production will increase by about 14%, and the calorific value of gas production will increase by about 14–18%; third, after adding wheat straw in a ratio of 1:1, due to the reduction of plastics, the overall yield of syngas decreased, but the yield of hydrogen increased, and the concentration of hydrogen in syngas increased by 6.4%.     

Bioaugmentation on hydrogen production from food waste

The aim of this work was to evaluate the effect of two hydrolytic (Paenibacillus polymyxa and Bacillus subtilis) and two fermentative (Clostridium saccharobutylicum and Clostridium beijerinckii) strains on hydrogen (H₂) production in dark fermentation by batch testing. Food waste was used as a substrate, pretreated anaerobic sludge was used as the inoculum, and different concentrations of the evaluated microorganisms were used. Bioaugmentation with 3.5 × 10⁹ CFU/mL/L_reactor B. subtilis showed the best performance, obtaining a production of 84.5 mL H₂/g SV and a reduction in the lag phase (from 7.9 h in control to 3.5 h). Bioaugmentation with B. subtilis in an anaerobic sequencing batch reactor exhibited a significant effect on volumetric productivity, reaching a maximal increase of 344% of H₂ production in comparison with that obtained without the addition of the strain. The increase in H₂ was observed in a short period of time (4 cycles), after which H₂ production returned to the original H₂ production baseline. During all reactor operations, the main volatile fatty acids produced were acetic acid and butyric acid. Microbial community analysis when bioaugmentation was applied showed an importance of lactic acid bacteria abundance, such as that of Bifidobacterium and Lactobacillus, whose metabolic activity was crucial in reactor performance. The added concentration of microorganisms is a critical parameter for the bioaugmentation process.     

Hydrogen-rich gas production by steam gasification of municipal solid waste (MSW) using NiO supported on modified dolomite

NiO on modified dolomite (NiO/MD) catalysts were developed for hydrogen-rich gas production from steam gasification of municipal solid waste (MSW). The catalysts were prepared through deposition-precipitation method and characterized by various characterization methods. The activity of NiO/MD on the steam gasification of MSW was investigated in a lab-scale fixed bed. The results indicated that the catalysts could significantly eliminate the tar in the gas production and increase the hydrogen yield. In addition, higher temperature contributed to higher hydrogen production and gas yield, meanwhile, the optimal ratio of steam to MSW (S/M) was found to be 1.23. In the experimental conditions, the NiO/MD catalysts showed a good performance over a long lifetime test.     

Assessing the power generation,pollution control,and overall efficiencies of municipal solid waste incinerators in Taiwan

This paper evaluates the productivity of municipal solid waste incinerators (MSWIs) by addressing the following questions: (1) to what extent should one further increase the production of power generation while maintaining the emission of noxious air at the current level?; (2) To what extent should one further decrease the emission of noxious air while maintaining the production of power generation at the current level?; and (3) To what extent should one increase the production of power generation and decrease the emission of noxious air simultaneously? To effectively address these questions to improve performance, the power generation and pollution control efficiencies are evaluated using TODEA (two-objective data envelopment analysis), as well as the overall efficiency evaluated using Tone’s NS-overall model (slacks-based measure with non-separable desirable and undesirable outputs for evaluating overall efficiency). A MSWI case study in Taiwan with the panel data covering the period of 2004–2008 reveals that the power generation and overall efficiencies of build-operate-transfer are more efficient, on average, than those of public-own-operate and build-own-operate. However, the three building and operation types do not significantly differ in pollution control efficiency.     

Effect of sulfate on hydrogen production from the organic fraction of municipal solid waste using co-culture of E. coli and Enterobacter aerogenes

In the present study, the effect of sulfate on the hydrogen production from the organic fraction of municipal solid (OFMSW) waste using co-culture of Enterobacter aerogenes and E. coli has been studied under varying pH conditions. The presence of sulfate in the feedstock declines hydrogen production efficiency. To evaluate the effect of sulfate on hydrogen production from OFMSW, COD/sulfate ratio of 17.5, 15.0, 12.5, 10.0, 7.5, 5.0 and 2.5 were applied at different pH conditions (i.e. pH 5.5, 6.0 and 6.5). The hydrogen production continuously declined with the decreasing COD/sulfate ratio and increase in pH. The cumulative hydrogen production decreased from 220.8 ± 10.5 mL in control to a minimum of 98.3 ± 10.5 mL, 74.4 ± 10.4 mL, and 44.6 ± 2.6 mL at pH 5.5, 6.0 and 6.5 respectively. The major content of gaseous composition included hydrogen and CO₂ at higher COD/sulfate ratio and low pH, while H₂S formation started with the decrease in COD/sulfate ratio and increase in the pH. Similarly, sulfate removal efficiency was found to be influenced by COD/sulfate ratio and pH condition. Soluble metabolite analysis revealed that total volatile fatty acid concentration was not affected by sulfate addition. Thus, Sulfate removal is essential prior to fermentation in order to improve hydrogen yield.