Waste Management in Surrey

Surrey News

Surrey has saved millions of pounds on its landfill tax bill by more than halving the amount of waste it buries in the ground.

In the three year period from 2007/08, the county council reduced the amount of waste it sent to landfill from 64% to 33%.

That means Surrey buried around 200,000 tonnes less waste* in 2010/11 than it did three years earlier.

Currently landfill tax cost £64 per tonne, so the county council would have to fork out £12.8 million in taxes alone to bury 200,000 tonnes of rubbish in the ground.

The reduction in landfill use is in part down to the good work Surrey has done in reaching a 50% household waste recycling target almost a decade ahead of schedule.

It can also be attributed to the fact Surrey residents threw out almost 76,000 tonnes less rubbish in 2010/11 than they did in 2007/08.

John Furey…

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Food Waste in Singapore

222 million tons

According to the UN study quoted in the first entry on this blog, consumers in sub-Saharan Africa, South Asia and Southeast Asia throw away an average of 13 to 24 pounds of food a year – which, compared to the 210 to 250 pounds of food the average North American or European consumer throws away each year, is amazing.

As I was in Singapore in March, I decided to take advantage of the opportunity to do a little research into food waste there. The first thing I wanted to figure out was if Singapore, with the (by far) highest GDP per capita in Southeast Asia, was typical for the region when it comes to food waste. I wasn’t able to find any rigorous studies on household food waste per capita. What I did find was a two-week study of 150 families that found that the average household food waste…

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Rationale for Decentralized Production of Biogas and Bioethanol

Clean Energy and Water Technologies

We live in a technological world where fuel and power play a critical role in shaping our lives and building our nations. The growth of a nation is measured in terms of fuel and power usage; yet there are many challenges and uncertainties in fuel supply and power generation technologies in recent past due to environmental implications. Fossil fuels accelerated our industrial growth and the civilization . But diminishing supply of oil and gas, global warming, nuclear disasters, social upheavals in the Arabian countries, financial problems, and high cost of renewable energy have created an uncertainty in the energy supply of the future. The future cost of energy is likely to increase many folds yet nobody knows for certain what will be the costs of energy for the next decade or what will be the fuel for our cars.  Renewable energy sources like solar and wind seem to be…

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Introduction to POME

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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 m3per 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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Biomass Energy Developments in Jordan

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Renewable energy systems have been used in Jordan since early 1970s. Infact, Jordan has been a pioneer in renewable energy promotion in the Middle East with its first wind power pilot project in Al-Ibrahemiya as early as 1988. Systematic monitoring of the technological developments and implementation/execution of demonstration and pilot projects has been the hallmark of Jordan’s foray into clean energy sector.

Municipal solid wastes represent the best source of biomass in Jordan. In terms of quantity per capita and constituents, the waste generated in Jordan is comparable to most semi-industrialized nations. The per capita of waste generated in Jordan is about 0.9 kg/day. The total generation of municipal waste in Jordan is estimated at 1.84 million tons per year. The main resources of organic waste in Jordan that can be potentially used to produce biogas are summarized as follows:

  • Municipal waste from big cities
  • Organic wastes from slaughterhouse, vegetable market, hotels and restaurants.
  • Organic waste from agro-industries
  • Animal manure, mainly from cows and chickens.
  • Sewage sludge and septic.
  • Olive mills.
  • Organic industrial waste

According to a study conducted by the Greater Amman Municipality, around 1.5 million tonnes of organic waste was generated in Jordan in 2009. In addition, an annual amount of 1.83 million cubic meter of septic and sewage sludge from treatment of 44 million cubic meter of sewage water is generated in greater Amman area. The potential annual sewage sludge and septic generated in Amman can be estimated at 85,000 tons of dry matter.

The Government of Jordan, in collaboration with UNDP, GEF and the Danish Government, established 1MW Biomethanation plant at Rusaifeh landfill near Amman in 1999.  The Plant has been successfully operating since its commissioning and efforts are underway to increase its capacity to 5MW. Infact, the project has achieved net yearly profit from electricity sale of about US $ 100, 000.  The project consists of a system of twelve landfill gas wells and an anaerobic digestion plant based on 60 tons per day of organic wastes from hotels, restaurants and slaughterhouses in Amman. The successful installation of the biogas project has made it a role model in the entire region and several big cities are striving to replicate the model.

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Analyzing Different Waste-to-Energy Technologies

Major components of Waste-to-Energy Processes

  1. Front end MSW pre-processing is used to prepare MSW for treatment and separate any recyclables
  2. Conversion unit (reactor)
  3. Gas and residue treatment plant (optional)
  4. Energy recovery plant (optional): Energy / chemicals production system includes gas turbine, boiler, internal combustion engines for power production. Alternatively, ethanol or other organic chemicals can be produced
  5. Emissions clean up

Incineration

  • Combustion of raw MSW, moisture less than 50%
  • Sufficient amount of oxygen is required to fully oxidize the fuel
  • Combustion temperatures are in excess of 850oC
  • Waste is converted into CO2 and water concern about toxics (dioxin, furans)
  • Any non-combustible materials (inorganic such as metals, glass) remain as a solid, known as bottom ash (used as feedstock in cement and brick manufacturing)
  • Fly ash APC (air pollution control residue) particulates, etc
  • Needs high calorific value waste to keep combustion process going, otherwise requires high energy for maintaining high temperatures

Anaerobic Digestion

  •  Well-known technology for domestic sewage and organic wastes treatment, but not for unsorted MSW
  • Biological conversion of biodegradable organic materials in the absence of oxygen at temperatures 55 to 75oC (thermophilic digestion – most effective temperature range)
  • Residue is stabilized organic matter that can be used as soil amendment after proper dewatering
  • Digestion is used primarily to reduce quantity of sludge for disposal / reuse
  • Methane gas generated used for electricity / energy generation or flared

Gasification

  • Can be seen as between pyrolysis and combustion (incineration) as it involves partial oxidation.
  • Exothermic process (some heat is required to initialize and sustain the gasification process).
  • Oxygen is added but at low amounts not sufficient for full oxidation and full combustion.
  • Temperatures are above 650oC
  • Main product is syngas, typically has net calorific value of 4 to 10 MJ/Nm3
  • Other product is solid residue of non-combustible materials (ash) which contains low level of carbon

Pyrolysis

  • Thermal degradation of organic materials through use of indirect, external source of heat
  • Temperatures between 300 to 850oC are maintained for several seconds in the absence of oxygen.
  • Product is char, oil and syngas composed primarily of O2, CO, CO2, CH4 and complex hydrocarbons.
  • Syngas can be utilized for energy production or proportions can be condensed to produce oils and waxes
  • Syngas typically has net calorific value (NCV) of 10 to 20 MJ/Nm

Plasma Gasification

  • Use of electricity passed through graphite or carbon electrodes, with steam and/or oxygen / air injection to produce electrically conducting gas (plasma)
  • Temperatures are above 3000oC
  • Organic materials are converted to syngas composed of H2, CO
  • Inorganic materials are converted to solid slag
  • Syngas can be utilized for energy production or proportions can be condensed to produce oils and waxes

 

        Net Energy Generation Potential Per Ton MSW

Waste Management Method

Energy Potential*

(kWh per ton MSW)

Recycling

2,250

Landfilling

   105

WTE Incineration

   585

Gasification

   660

Pyrolysis

   660

Anaerobic Digestion

   250

Cost Economics of WTE Processes

Technology

Plant capacity

(tons/day)

Capital cost

(M US$)

O&M cost

(US$/ton)

Planning to commissioning

(months)

Pyrolysis

70-270

16 – 90

80 – 150

12 – 30

Gasification

900

15 – 170

80 – 150

12 – 30

Incineration

1300

30 – 180

80 – 120

54 – 96

Plasma gasification

900

50 – 80

80 – 150

12 – 30

Anaerobic digestion

300

20 – 80

60 – 100

12 – 24

In vessel composting

500

50 – 80

30 – 60

9 – 15

Sanitary landfill

500

5 – 10

10 – 20

9 – 15

Bioreactor landfill

500

10 – 15

15 – 30

12 – 18

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Composting

Composting
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The composting process is a complex interaction between the waste and the microorganisms within the waste. The microorganisms that carry out this process fall into three groups: bacteria, fungi, and actinomycetes.Actinomycetes are a form of fungi-like bacteria that break down organic matter. The first stage of the biological activity is the consumption of easily available sugars by bacteria, which causes a fast rise in temperature. The second stage involves bacteria and actinomycetes that cause cellulose breakdown. The last stage is concerned with the breakdown of the tougher lignins by fungi.

Central solutions are exemplified by low-cost composting without forced aeration, and technologically more advanced systems with forced aeration and temperature feedback. Central composting plants are capable of handling more than 100,000 tons of biodegradable waste per year, but typically the plant size is about 10,000 to 30,000 tons per year. Biodegradable wastes must be separated prior to composting: Only pure foodwaste, garden waste, wood chips, and to some extent paper are suitable for producing good-quality compost.

 The composting plants consist of some or all of the following technical units: bag openers, magnetic and/or ballistic separators, screeners (sieves), shredders, mixing and homogenization equipment, turning equipment, irrigation systems, aeration systems, draining systems, bio-filters, scrubbers, control systems, and steering systems. The composting process occurs when biodegradable waste is piled together with a structure allowing for oxygen diffusion and with a dry matter content suiting microbial growth. The temperature of the biomass increases due to the microbial activity and the insulation properties of the piled material. The temperature often reaches 65 degrees C to 75 degrees C within a few days and then declines slowly. This high temperature hastens the elimination of pathogens and weed seeds.

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Trends in Waste-to-Energy Industry

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Around 130 million tonnes of municipal solid waste (MSW) are combusted annually in over 600 waste-to-energy (WTE) facilities globally that produce electricity and steam for district heating and recovered metals for recycling. Since 1995, the global WTE industry increased by more than 16 million tonnes of MSW. Incineration, with energy recovery, is the most common waste-to-energy method employed worldwide. Over the last five years, waste incineration in Europe has generated between an average of 4% to 8% of their countries’ electricity and between an average of 10% to 15% of the continent’s domestic heat.

Currently, the European nations are recognized as global leaders of the SWM and WTE movement. They are followed behind by the Asia Pacific region and North America respectively. In 2007 there are more than 600 WTE plants in 35 different countries, including large countries such as China and small ones such as Bermuda. Some of the newest plants are located in Asia.

The United States processes 14 percent of its trash in WTE plants. Denmark, on the other hand, processes more than any other country – 54 percent of its waste materials. As at the end of 2008, Europe had more than 475 WTE plants across its regions – more than any other continent in the world – that processes an average of 59 million tonnes of waste per annum. In the same year, the European WTE industry as a whole had generated revenues of approximately US$4.5bn. Legislative shifts by European governments have seen considerable progress made in the region’s WTE industry as well as in the implementation of advanced technology and innovative recycling solutions. The most important piece of WTE legislation pertaining to the region has been the European Union’s Landfill Directive, which was officially implemented in 2001 which has resulted in the planning and commissioning of an increasing number of WTE plants over the past five years.

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A Primer on Waste-to-Energy

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Energy is the driving force for development in all countries of the world. The increasing clamor for energy and satisfying it with a combination of conventional and renewable resources is a big challenge. Accompanying energy problems in different parts of the world, another problem that is assuming critical proportions is that of urban waste accumulation. The quantity of waste produced all over the world amounted to more than 12 billion tonnes in 2006, with estimates of up to 13 billion tonnes in 2011. The rapid increase in population coupled with changing lifestyle and consumption patterns is expected to result in an exponential increase in waste generation of upto 18 billion tonnes by year 2020.

Waste generation rates are affected by socio-economic development, degree of industrialization, and climate. Generally, the greater the economic prosperity and the higher percentage of urban population, the greater the amount of solid waste produced. 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.

Waste-to-Energy (WTE) is the use of modern combustion and biochemical technologies to recover energy, usually in the form of electricity and steam, from urban wastes. These new technologies can reduce the volume of the original waste by 90%, depending upon composition and use of outputs. The main categories of waste-to-energy technologies are physical technologies, which process waste to make it more useful as fuel; thermal technologies, which can yield heat, fuel oil, or syngas from both organic and inorganic wastes; and biological technologies, in which bacterial fermentation is used to digest organic wastes to yield fuel. Waste-to-energy technologies can address a host of environmental issues, such as land use and pollution from landfills, and increasing reliance on fossil fuels.

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Rationale for Aluminium Recycling

Shredded aluminium beverage cans.
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Aluminium is used extensively in aircraft, building construction, electrical transmission and consumer durables such as fridges, cooking utensils and air conditioners as well as in food processing equipment and cans. Infact, the use of aluminum exceeds that of any other metal except iron. Aluminium is the second most widely used metal whereas the aluminum can is the most recycled consumer product in the world. Aluminium exposed to fires at dumps can be a serious environmental problem in the form of poisonous gases and mosquito breeding. Recycled aluminium can be utilized for almost all applications, and can preserve raw materials and reduce toxic emissions, apart from significant energy conservation.

The demand for aluminium products is growing steadily because of their positive contribution to modern living. Aluminium finds extensive use in air, road and sea transport; food and medicine; packaging; construction; electronics and electrical power transmission. Aluminum has a high market value and continues to provide an economic incentive to recycle it. The excellent recyclability of aluminium, together with its high scrap value and the low energy needs during recycling make aluminium lightweight solutions highly desirable.

The contribution of the recycled metal to the global output of aluminium products has increased from 17 percent in 1960 to 34 percent today, and expected to rise to almost 40 percent by 2020. Global recycling rates are high, with approximately 90 per cent of the metal used for transport and construction applications recovered, and over 60 per cent of used beverage cans are collected.

Aluminium does not degrade during the recycling process, since its atomic structure is not altered during melting. Aluminium recycling is both economically and environmentally effective, as it requires a lot less energy to recycle than it does to mine, extract and smelt aluminium ore.  Recycled aluminium requires only 5% of the energy used to make primary aluminium, and can have the same properties as the parent metal. However, in the course of multiple recycling, more and more alloying elements are introduced into the metal cycle. This effect is put to good use in the production of casting alloys, which generally need these elements to attain the desired alloy properties.

The industry has a long tradition of collecting and recycling used aluminium products. Over the years, USA and European countries have developed robust separate collection systems for aluminium packaging with a good degree of success. Recycling aluminium reduces the need for raw materials and reduces the use of valuable energy resources. Recycled aluminium is made into aircraft, automobiles, bicycles, boats, computers, cookware, gutters, siding, wire and cans.

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A Glance at Biomass Energy Technologies

Biomass energy technology is inherently flexible. The variety of technological options available means that it can be applied at a small, localized scale primarily for heat, or it can be used in much larger base-load power generation capacity whilst also producing heat. Biomass generation can thus be tailored to rural or urban environments, and utilized in domestic, commercial or industrial applications.

A wide range of technologies are available for realizing the potential of biomass waste as an energy source, ranging from very simple systems for disposing of dry waste to more complex technologies capable of dealing with large amounts of industrial waste.

Biomass can be converted into energy by simple combustion, by co-firing with other fuels or through some intermediate process such as gasification. The energy produced can be electrical power, heat or both (combined heat and power, or CHP). The advantage of utilizing heat as well as or instead of electrical power is the marked improvement of conversion efficiency – electrical generation has a typical efficiency of around 30%, but if heat is used efficiencies can rise to more than 85%.

 Biochemical processes, like anaerobic digestion, can also produce clean energy in the form of biogas which can be converted to power and heat using a gas engine. In addition, wastes can also yield liquid fuels, such as cellulosic ethanol, which can be used to replace petroleum-based fuels. Algal biomass is also emerging as a good source of energy because it can serve as natural source of oil, which conventional refineries can transform into jet fuel or diesel fuel.

Biomass Combined Heat and Power (CHP) Systems

Combined Heat and Power (CHP) is the simultaneous generation of multiple forms of useful energy (usually mechanical and thermal) in a single, integrated system. In conventional electricity generation systems, about 35% of the energy potential contained in the fuel is converted on average into electricity, whilst the rest is lost as waste heat. CHP systems use both electricity and heat and therefore can achieve an efficiency of up to 90%.

CHP systems consist of a number of individual components—prime mover (heat engine), generator, heat recovery, and electrical interconnection—configured into an integrated whole. Prime movers for CHP units include reciprocating engines, combustion or gas turbines, steam turbines, microturbines, and fuel cells.

A typical CHP system provides:

  • Distributed generation of electrical and/or mechanical power.
  • Waste-heat recovery for heating, cooling, or process applications.
  • Seamless system integration for a variety of technologies, thermal applications, and fuel types.

The success of any biomass-fuelled CHP project is heavily dependent on the availability of a suitable biomass feedstock freely available in urban and rural areas.

Rural Resources Urban Resources
Forest residues Urban wood waste
Wood wastes Municipal solid wastes
Crop residues Agro-industrial wastes
Energy crops Food processing residues
Animal manure Sewage

Technology Options

Reciprocating or internal combustion engines (ICEs) are among the most widely used prime movers to power small electricity generators. Advantages include large variations in the size range available, fast start-up, good efficiencies under partial load efficiency, reliability, and long life.

Steam turbines are the most commonly employed prime movers for large power outputs. Steam at lower pressure is extracted from the steam turbine and used directly or is converted to other forms of thermal energy. System efficiencies can vary between 15 and 35% depending on the steam parameters.

Co-firing of biomass with coal and other fossil fuels can provide a short-term, low-risk, low-cost option for producing renewable energy while simultaneously reducing the use of fossil fuels. Biomass can typically provide between 3 and 15 percent of the input energy into the power plant. Most forms of biomass are suitable for co-firing.

Steam engines are also proven technology but suited mainly for constant speed operation in industrial environments. Steam engines are available in different sizes ranging from a few kW to more than 1 MWe.

A gas turbine system requires landfill gas, biogas, or a biomass gasifier to produce the gas for the turbine. This biogas must be carefully filtered of particulate matter to avoid damaging the blades of the gas turbine.  

Stirling engines utilize any source of heat provided that it is of sufficiently high temperature. A wide variety of heat sources can be used but the Stirling engine is particularly well-suited to biomass fuels. Stirling engines are available in the 0.5 to 150 kWe range and a number of companies are working on its further development.

A micro-turbine recovers part of the exhaust heat for preheating the combustion air and hence increases overall efficiency to around 20-30%. Several competing manufacturers are developing units in the 25-250kWe range. Advantages of micro-turbines include compact and light weight design, a fairly wide size range due to modularity, and low noise levels.

Fuel cells are electrochemical devices in which hydrogen-rich fuel produces heat and power. Hydrogen can be produced from a wide range of renewable and non-renewable sources. A future high temperature fuel cell burning biomass might be able to achieve greater than 50% efficiency.

Conclusions

CHP technologies are well suited for Clean Development Mechanism (CDM) and sustainable development projects, because they are, in general, socio-economically attractive and technologically mature and reliable. In developing countries, cogeneration can easily be integrated in many industries, especially agriculture and food-processing, taking advantage of the biomass residues of the production process. This has the dual benefits of lowering fuel costs and solving waste disposal issues.