Pelletizing Municipal Solid Wastes


See on Scoop.itEnergy Blog

MSW is a poor-quality fuel and its pre-processing is necessary to prepare fuel pellets to improve its consistency, storage and handling characteristics, combustion behaviour and calorific value.

Salman Zafar‘s insight:

RDF production line consists of several unit operations in series in order to separate unwanted components and condition the combustible matter to obtain the required characteristics. The main unit operations are screening, shredding, size reduction, classification, separation either metal, glass or wet organic materials, drying and densification. These unit operations can be arranged in different sequences depending on raw MSW composition and the required RDF quality.

See on www.bioenergyconsult.com

Wastes as Energy Resource


See on Scoop.itFostering Sustainable Development

The tremendous increase in the quantum and diversity of waste materials generated by human activities has focused the spotlight on waste disposal methods. Waste generation rates are affected by sta…

Salman Zafar‘s insight:

The implementation of advanced waste conversion technologies as a method for safe disposal of solid and liquid biomass wastes, and as an attractive option to generate heat, power and fuels, can greatly reduce environmental impacts of a wide array of wastes. 

See on www.ecomena.org

Durban’s closed loop landill site


Originally posted on Sustainability Writer:

I recently wrote this case study about the Mariannhill Landfill Conservancy in KwaZulu-Natal, South Africafor UN Habitat’s 2012 report “Urban Patterns for a Green Economy: Optimizing Infrastructure”.

About 450 tons of waste arrives daily at the Mariannhill Landfill Site, 20 kilometres from Durban, South Africa. Far from an ecological hazard, this CDM project sets new standards for sustainable urban infrastructure by combining natural, robust and low-cost technologies.

The end result might not have been as positive without the dedication of the Mariannhill community, who set up a monitoring committee after discovering the city’s intent to establish a landfill in the area (Winn 2008). Their persistent concern about the ecological impact motivated the engineers at Durban Solid Waste (DSW) and the environmental department at the eThekwini Municipality to pursue a more sustainable design (Parkin 2011). These engineers are equally deserving of praise; they acknowledged the problems associated with conventional…

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What is Waste to Energy


Reduction in the volume and mass of solid waste is a crucial issue especially in the light of limited availability of final disposal sites in many parts of the world. Millions of tonnes of waste are generated each year with the vast majority disposed of in open fields or burnt wantonly. The term “waste-to-energy” has traditionally referred to the practice of incineration of garbage. Today, a new generation of waste-to-energy technologies is emerging which hold the potential to create renewable energy from waste matter, including municipal solid waste, industrial waste, agricultural waste, and industrial byproducts. Waste feedstocks can include municipal solid waste (MSW); construction and demolition debris; agricultural waste, such as crop silage and livestock manure; industrial waste from coal mining, lumber mills, or other facilities; and even the gases that are naturally produced within landfills. Advanced waste-to-energy technologies can be used to produce biogas (methane and carbon dioxide), syngas (hydrogen and carbon monoxide), liquid biofuels (ethanol and biodiesel), or pure hydrogen; these fuels can then be converted into electricity.

A host of technologies are available for realizing the energy potential of wastes, ranging from very simple systems for disposing of dry waste to more complex technologies capable of dealing with large amounts of industrial waste. Conversion routes for wastes are generally thermo-chemical or bio-chemical, but may also include chemical and physical. Besides recovery of substantial energy, these technologies can lead to a substantial reduction in the overall waste quantities requiring final disposal, which can be better managed for safe disposal in a controlled manner while meeting the pollution control standards.

The biochemical conversion processes, which include anaerobic digestion and fermentation, are preferred for wastes having high percentage of organic biodegradable matter and high moisture content. Anaerobic digestion is a reliable technology for the treatment of wet, organic waste.  Organic waste from various sources is composted in highly controlled, oxygen-free conditions circumstances resulting in the production of biogas which can be used to produce both electricity and heat. Anaerobic digestion also results in a dry residue called digestate which can be used as a soil conditioner. Alcohol fermentation is the transformation of organic fraction of biomass to ethanol by a series of biochemical reactions using specialized microorganisms. It finds good deal of application in the transformation of woody biomass into cellulosic ethanol.

Thermochemical conversion systems consist of primary conversion technologies which convert the waste into heat or gaseous and liquid products, together with secondary conversion technologies which convert these products into the more useful forms of energy being heat and electricity. The three principal methods of thermo-chemical conversion corresponding to each of these energy carriers are combustion in excess air, gasification in reduced air, and pyrolysis in the absence of air.

Gasification of wastes takes place in a restricted supply of oxygen and occurs through initial devolatilization of the biomass, combustion of the volatile material and char, and further reduction to produce a fuel gas rich in carbon monoxide and hydrogen. This combustible gas has a lower calorific value than natural gas but can still be used as fuel for boilers, for engines, and potentially for combustion turbines after cleaning the gas stream of tars and particulates. Pyrolysis enables wastes to be converted to a combination of solid char, gas and a liquid bio-oil. Using fast pyrolysis, bio-oil yield can be as high as 80 percent of the product on a dry fuel basis. Bio-oil can act as a liquid fuel or as a feedstock for chemical production.

Waste-to-Energy Market Trends


Teesside Waste to Energy Power Station at Have...

The global market for WTE technologies was valued at US$19.9bn in 2008. This has been forecasted to increase to US$26.2bn by 2014. While the biological WTE segment is expected to grow more rapidly from US$1.4bn in 2008 to approximately US$2.5bn in 2014, the thermal WTE segment is nonetheless estimated to still constitute the vast bulk of the entire industry’s worth. This segment was valued at US$18.5bn in 2008 and is forecasted to expand to US$23.7bn in 2014.

The global market for waste to energy technologies has shown substantial growth over the last five years, increasing from $4.83 billion in 2006, to $7.08 billion in 2010 with continued market growth through the global economic downturn. Over the coming decade, growth trends are expected to continue, led by expansion in the US, European, Chinese, and Indian markets. By 2021, based on continued growth in Asian markets combined with the maturation of European waste management regulations and European and US climate mitigation strategies, the annual global market for waste to energy technologies will exceed $27 billion, for all technologies combined.

Asia-Pacific’s waste-to-energy market will post substantial growth by 2015, as more countries view the technology as a sustainable alternative to landfills for disposing waste while generating clean energy. In its new report, Frost & Sullivan said the industry could grow at a compound annual rate of 6.7 percent for thermal waste-to-energy and 9.7 percent for biological waste-to-energy from 2008 to 2015.

The WTE market in Europe is forecasted to expand at an exponential rate and will continue to do so for at least the next 10 years. The continent’s WTE capacity is projected to increase by around 13 million tonnes, with almost 100 new WTE facilities to come online by 2012. In 2008, the WTE market in Europe consisted of approximately 250 players due in large to the use of bulky and expensive centralized WTE facilities, scattered throughout Western Europe.

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Palm Oil Mill Effluent (POME)


Palm oil mill

Palm Oil processing gives rise to highly polluting waste-water, known as Palm Oil Mill Effluent (POME), which is often discarded in disposal ponds, resulting in the leaching of contaminants that pollute the groundwater and soil, and in the release of methane gas into the atmosphere. POME is an oily wastewater generated by palm oil processing mills and consists of various suspended components. This liquid waste combined with the wastes from steriliser condensate and cooling water is called palm oil mill effluent (POME). On average, for each ton of FFB (fresh fruit bunches) processed, a standard palm oil mill generate about 1 tonne of liquid waste with biochemical oxygen demand (BOD) 27 kg, chemical oxygen demand (COD) 62 kg, suspended solids (SS) 35 kg and oil and grease 6 kg

POME has a very high Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), which is 100 times more than the municipal sewage. POME is a non-toxic waste, as no chemical is added during the oil extraction process, but will pose environmental issues due to large oxygen depleting capability in aquatic system due to organic and nutrient contents. The high organic matter is due to the presence of different sugars such as arabinose, xylose, glucose, galactose and manose. The suspended solids in the POME are mainly oil-bearing cellulosic materials from the fruits. Since the POME is non-toxic as no chemical is added in the oil extraction process, it is a good source of nutrients for microorganisms.

Currently, recovery of renewable organic-based product is a new approach in managing POME. The technology is aimed to recover by-products such as volatile fatty acid, biogas and poly-hydroxyalkanoates to promote sustainability of the palm oil industry. In addition, it is envisaged that POME can be sustainably reused as a fermentation substrate in production of various metabolites through biotechnological advances. In addition, POME consists of high organic acids and is suitable to be used as a carbon source

Anaerobic digestion is widely adopted in the industry as a primary treatment for POME. Biogas is produced in the process in the amount of 20 m3 per ton FFB. This effluent could be used for biogas production through anaerobic digestion. At many Palm-oil mills this process is already in place to meet water quality standards for industrial effluent. The gas, however, is flared off. Liquid effluents from Palm Oil mills in Southeast Asia can be used to generate power through gas turbines or gas-fired engines.

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