MSW to Energy at a Glance

MSW-to-Energy is the use of thermochemical 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 MSW-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.

Components of MSW-to-Energy Systems

  1. Front-end MSW preprocessing
  2. Conversion unit (reactor or anaerobic digester)
  3. Gas cleanup and residue treatment plant
  4. Energy recovery plant (optional)
  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 biochemical technology for organic fraction of MSW and domestic sewage.
  • Biological conversion of biodegradable organic materials in the absence of oxygen at mesophilic or thermophilic temperatures.
  • Residue is stabilized organic matter that can be used as soil amendment
  • Digestion is used primarily to reduce quantity of sludge for disposal / reuse
  • Methane gas is generated which is used for heat and power generation.

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
  •  

MSW-to-energy technologies can address a host of environmental issues, such as land use and pollution from landfills, and increasing reliance on fossil fuels. In many countries, the availability of landfill capacity has been steadily decreasing due to regulatory, planning and environmental permitting constraints. As a result, new approaches to waste management are rapidly being written into public and institutional policies at local, regional and national levels.

Anaerobic Digestion of Tannery Wastes

The conventional leather tanning technology is highly polluting as it produces large amounts of organic and chemical pollutants. Wastes generated by tanneries pose a major challenge to the environment. Anaerobic digestion of tannery wastes is an attractive method to recover energy from tannery wastes.

According to conservative estimates, more than 600,000 tons per year of solid waste are generated worldwide by leather industry and approximately 40–50% of the hides are lost to shavings and trimmings. Everyday a huge quantity of solid waste, including trimmings of finished leather, shaving dusts, hair, fleshing, trimming of raw hides and skins, are being produced from the industries. Chromium, sulphur, oils and noxious gas (methane, ammonia, and hydrogen sulphide) are the elements of liquid, gas and solid waste of tannery industries.

Biogas from Tannery Wastes

Anaerobic digestion (or biomethanation) systems are mature and proven processes that have the potential to convert tannery wastes into energy efficiently, and achieve the goals of pollution prevention/reduction, elimination of uncontrolled methane emissions and odour, recovery of biomass energy potential as biogas, production of stabilized residue for use as low grade fertilizer.

Anaerobic digestion of tannery wastes is an attractive method to recover energy from tannery wastes. This method degrades a substantial part of the organic matter contained in the sludge and tannery solid wastes, generating valuable biogas, contributing to alleviate the environmental problem, giving time to set-up more sustainable treatment and disposal routes. Digested solid waste is biologically stabilized and can be reused in agriculture.

Until now, biogas generation from tannery wastewater was considered that the complexity of the waste water stream originating from tanneries in combination with the presence of chroming would result in the poisoning of the process in a high loaded anaerobic reactor.

When the locally available industrial wastewater treatment plant is not provided by anaerobic digester, a large scale digestion can be planned in regions accommodating a big cluster of tanneries, if there is enough waste to make the facility economically attractive.

In this circumstance, an anaerobic co-digestion plant based on sludge and tanneries may be a recommendable option, which reduces the quantity of landfilled waste and recovers its energy potential. It can also incorporate any other domestic, industrial or agricultural wastes. Chrome-free digested tannery sludge also has a definite value as a fertilizer based on its nutrient content.

Potential Applications of Biogas

Biogas produced in anaerobic digesters consists of methane (50%–80%), carbon dioxide (20%–50%), and trace levels of other gases such as hydrogen, carbon monoxide, nitrogen, oxygen, and hydrogen sulfide.  Biogas can be used for producing electricity and heat, as a natural gas substitute and also a transportation fuel. A combined heat and power plant (CHP) not only generates power but also produces heat for in-house requirements to maintain desired temperature level in the digester during cold season.

CHP systems cover a range of technologies but indicative energy outputs per m3 of biogas are approximately 1.7 kWh electricity and 2.5kWh heat. The combined production of electricity and heat is highly desirable because it displaces non-renewable energy demand elsewhere and therefore reduces the amount of carbon dioxide released into the atmosphere.

AD Plant at ECCO’s Tannery (Netherlands)

A highly advanced wastewater treatment plant and biogas system became fully operational in 2012 at ECCO’s tannery in the Netherlands. A large percentage of the waste is piped directly into the wastewater plant to be converted into biogas. This biogas digester provides a source of renewable fuel and also helps to dispose of waste materials by converting waste from both the leather-making processes, and the wastewater treatment plant, into biogas. All excess organic material from the hides is also converted into biogas.

This project enables ECCO Tannery to reduce waste and to substitute virtually all of its consumption of non-renewable natural gas with renewable biogas. The aim is to use more than 40% of the total tannery waste and replace up to 60% of the total natural gas consumption with biogas.

Agricultural Biomass in Malaysia

Malaysia is located in a region where biomass productivity is high which means that the country can capitalize on this renewable energy resource to supplements limited petroleum and coal reserves. Malaysia, as a major player in the palm oil and sago starch industries, produces a substantial amount of agricultural biomass waste which present a great opportunity for harnessing biomass energy in an eco-friendly and commercially-viable manner.

Peninsular Malaysia generates large amounts of wood and’ agricultural residues, the bulk of which are not being currently utilised for any further downstream operations. The major agricultural crops grown in Malaysia are rubber (39.67%), oil palm (34.56%), cocoa (6.75%), rice (12.68%) and coconut (6.34%). Out of the total quantity of residues generated, only 27.0% is used either as fuel for the kiln drying of timber, for the manufacture of bricks, the curing of tobacco leaves, the drying rubber-sheets and for the manufacture of products such as particleboard and fibreboard. The rest has to be disposed of by burning.

Palm Oil Industry

Oil palm is one of the world’s most important fruit crops. Malaysia is one of the largest producers and exporter of palm oil in the world, accounting for 30% of the world’s traded edible oils and fats supply. Palm oil industries in Malaysia have good potential for high pressure modern power plants and the annual power generation potential is about 8,000 GWh. Malaysia produced more than 20 million tonnes of palm oil in 2012 over 5 million hectares of land.

The palm oil industry is a significant branch in Malaysian agriculture. Almost 70% of the volume from the processing of fresh fruit bunch is removed as waste in the form of empty fruit bunches (EFBs), fibers and shells, as well as liquid effluent. Fibres and shells are traditionally used as fuels to generate power and steam. Effluents are sometimes converted into biogas that can be used in gas-fired gensets.

Sugar Industry

The cultivation of sugarcane in Malaysia is surprisingly small. Production is concentrated in the Northwest extremity of peninsular Malaysia in the states of Perlis and Kedah. This area has a distinct dry season needed for cost-efficient sugarcane production. Plantings in the states of Perak and Negri Sembilan were unsuccessful due to high unit costs as producing conditions were less suitable.

The lack of growth in cane areas largely reflects the higher remuneration received by farmers for other crops, especially oil palm. Over the past 20 years while the sugarcane area has remained at around 20 000 hectares, that planted to oil palm has expanded from 600 000 hectares to 5 million hectares.

Other leading crops in terms of planted areas are rubber with 2.8 million hectares, rice with 670 000 hectares and cocoa with 380 000 hectares. Malaysia, the world’s third largest rubber producer, accounted for 1 million tons of natural rubber production in 2012. Like oil palm industry, the rubber industry produces a variety of biomass wastes whose energy potential is largely untapped until now.

Food Waste Management in UK

Food-Waste-UKFood waste in the United Kingdom is a matter of serious environmental, economic and social concern that has been attracting widespread attention in recent years. According to ‘Feeding the 5K’ organisation, 13,000 slices of crusts are thrown away every day by a single sandwich factory which is featured in the figure above. More recently, Tesco, one of the largest UK food retailers, has published its sustainability report admitting that the company generated 28,500 tonnes of food waste in the first six months of 2013. TESCO’s report also state that 47% of the bakery produced is wasted. In terms of GHG emissions, DEFRA estimated that food waste is associated with 20 Mt of CO2 equivalent/year, which is equivalent to 3% of the total annual GHG emissions.

Globally, 1.2 to 2 billion tonnes (30%-50%) of food produced is thrown away before it reaches a human stomach. Food waste, if conceived as a state, is responsible for 3.3 Bt-CO2 equivalent/year, which would make it the third biggest carbon emitter after China and USA. What makes food waste an even more significant issue is the substantially high demand for food which is estimated to grow 70% by 2050 due to the dramatic increase of population which is expected to reach 9.5 billion by 2075. Therefore, there is an urgent need to address food waste as a globally challenging issue which should be considered and tackled by sustainable initiatives.

A War on Food Waste

The overarching consensus to tackle the food waste issue has led to the implementation of various policies. For instance, the European Landfill Directive (1999/31/EC) set targets to reduce organic waste disposed to landfill in 2020 to 35% of that disposed in 1995 (EC 1999). More recently, the European Parliament discussed a proposal to “apply radical measures” to halve food waste by 2025 and to designate the 2014 year as “the European Year Against Food Waste”. In the light of IMechE’s report (2013), the United Nations Environment Programme (UNEP) in cooperation with FAO has launched the Save Food Initiative in an attempt to reduce food waste generated in the global scale.

In the UK, WRAP declared a war on food waste by expanding its organic waste programme in 2008 which was primarily designed to “establish the most cost-effective and environmentally sustainable ways of diverting household food waste from landfill that leads to the production of a saleable product”. DEFRA has also identified food waste as a “priority waste stream” in order to achieve better waste management performance. In addition to governmental policies, various voluntary schemes have been introduced by local authorities such as Nottingham Declaration which aims to cut local CO2 emissions 60% by 2050.

Sustainable Food Waste Management

Engineering has introduced numerous technologies to deal with food waste. Many studies have been carried out to examine the environmental and socio-economic impacts of food waste management options. This article covers the two most preferable options; anaerobic digestion and composting.

In-vessel composting (IVC) is a well-established technology which is widely used to treat food waste aerobically and convert it into a valuable fertilizer. IVC is considered a sustainable option because it helps by reducing the amount of food waste landfilled. Hence, complying with the EU regulations, and producing a saleable product avoiding the use of natural resources. IVC is considered an environmentally favourable technology compared with other conventional options (i.e. landfill and incineration). It contributes less than 0.06% to the national greenhouse gas inventories. However, considering its high energy-intensive collection activities, the overall environmental performance is “relatively poor”.

Anaerobic Digestion (AD) is a leading technology which has had a rapidly growing market over the last few years. AD is a biologically natural process in which micro-organisms anaerobically break down food waste and producing biogas which can be used for both Combined Heat & Power (CHP) and digestate that can be used as soil fertilizers or conditioners. AD has been considered as the “best option” for food waste treatment. Therefore, governmental and financial support has been given to expand AD in the UK.

AD is not only a food waste treatment technology, but also a renewable source of energy. For instance, It is expected that AD would help the UK to meet the target of supplying 15% of its energy from renewable sources by 2020. Furthermore, AD technology has the potential to boost the UK economy by providing 35,000 new jobs if the technology is adopted nationally to process food waste. This economic growth will significantly improve the quality of life among potential beneficiaries and thus all sustainability elements are considered.

Bioenergy Perspectives for Southeast Asia

Southeast Asia, with its abundant bioenergy resources, holds a strategic position in the global biomass energy atlas. There is immense bioenergy potential in Southeast Asian countries due to plentiful supply of diverse forms of biomass wastes such as agricultural residues, woody biomass, animal wastes, municipal solid waste, etc. The rapid economic growth and industrialization in the region has accelerated the drive to implement the latest waste-to-energy technologies to tap the unharnessed potential of biomass resources.

Southeast Asia is a big producer of agricultural and wood products which, when processed in industries, produces large amounts of biomass residues. According to conservative estimates, the amount of biomass residues generated from sugar, rice and palm oil mills is more than 200-230 million tons per year which corresponds to cogeneration potential of 16-19 GW.

Rice mills in the region produce 38 million tonnes of rice husk as solid residue which is a good fuel for producing heat and power. Sugar industry is an integral part of the industrial scenario in Southeast Asia accounting for 7% of sugar production worldwide. Sugar mills in Thailand, Indonesia, Philippines and Vietnam generate 34 million tonnes of bagasse every year.  Malaysia, Indonesia and Thailand account for 90% of global palm oil production leading to the generation of 27 million tonnes of waste per annum in the form of empty fruit bunches (EFBs), fibers and shells, as well as liquid effluent.

Woody biomass is a good energy resource due to presence of large number of forests in Southeast Asia. Apart from natural forests, non-industrial plantations of different types (e.g. coconut, rubber and oil palm plantations, fruit orchards, and trees in homesteads and gardens) have gained recognition as important sources of biomass. In addition, the presence of a large number of wood processing industries also generates significant quantity of wood wastes. The annual production of wood wastes in the region is estimated to be more than 30 million m3.

The prospects of biogas power generation are also high in the region thanks to presence of well-established food-processing and dairy industries. Another important biomass resource is contributed by municipal solid wastes in heavily populated urban areas.  In addition, there are increasing efforts both commercially and promoted by governments to develop biomass energy systems for efficient biofuel production, e.g. bio-diesel from palm oil.

Biomass resources, particularly residues from forests, wood processing, agricultural crops and agro-processing, are under-utilised in Southeast Asian countries. There is an urgent need to utilize biomass wastes for commercial electricity and heat production to cater to the needs of the industries as well as urban and rural communities.

Southeast Asian countries are yet to make optimum use of the additional power generation potential from biomass waste resources which could help them to partially overcome the long-term problem of energy supply. Technologies for biomass utilization which are at present widely used in Southeast counties need to be improved towards best practice by making use of the latest trends in the biomass energy sector.

Behavioral Drivers Behind Food Wastes

food-waste-behaviorBy 2075, the United Nations estimates the global population will peak at 9.5 billion, an extra 3 billion mouths to feed by the end of the century. Meanwhile, while we produce about four billion tonnes of food annually, it is estimated that 30-50% of this never reaches our plates. Of the food that does reach us, some western societies throw away up to a third of all food purchased. This has enormous implications for the global environment, from wasting the water used to grow the food to adverse effects on climate, land and biodiversity.

The drivers behind these phenomenal levels of food waste are complex and include food pricing, logistical and storage issues. However, given the significant level of waste that happens within the households of societies like the UK and US, it is useful and informative to consider those behaviours that drive this level of waste.

The quality of data around food waste, as with much of waste data, has historically been poor. To this end, WRAP commissioned groundbreaking research in the UK in 2006/7 to act as a baseline to their Love Food Hate Waste campaign. This came up with the alarming statistic that 1/3 of food bought by a UK household was thrown away. Until this time, there had been no comprehensive research, either by food manufacturers, retailers or interest groups, suggesting the importance of government, or some other dis-interested party, taking a lead on the issue.

Back to Basics

There may be a link between the amount of time spent preparing food, and the skill and effort that goes into this, and the amount of food waste produced. This has led to a loss of confidence in the kitchen, with individuals losing basic skills that allow them to cook with leftovers, understand food labeling, including Best Before and Use By, even basic storing. WRAP had found little evidence of best practice storage advice so carried out the research themselves – leading the (surprising for many) conclusion that fruit such as apples and pears are best stored in the fridge wrapped in a plastic cover. However, this has masked a larger trend of less time spent in the kitchen, due to demographic changes. This of course begs the question – how should we use this when trying to reduce food waste? Should we encourage people to cook from scratch as a principle?

Although waste prevention and recycling are clearly separated within the waste hierarchy, there are apparent links between the two when considering food waste. There is an urgent need for legislation to enforce separate food waste collections, not only to ensure it was diverted to anaerobic digestion or composting, but also as it led to greater self awareness around food waste. WRAP research has clearly showed a fall in food waste when separate food waste collections were introduced.

Role of Packaging

Historically, packaging has always been a high priority to the public when asked about priorities for reducing waste. However, as awareness of food waste has grown, a more nuanced position has developed among waste managers. While excess packaging is clearly undesirable, and, within the UK for instance, the Courtauld Commitment  has helped reduced grocery packaging by 2.9 million tonnes of waste so far, there is a realization of the importance of food packaging in preserving food and hence reducing food waste.

Making food easily accessible and affordable by many, it could be argued, is one of the crowning achievements of our age. Over the last century, the proportion of household income that is spent on food has plummeted, and there is a direct link to malnutrition and food prices, particularly for children. But does cheap food mean that it is less valued and hence greater wastage? Is the answer expensive food? The evidence from WRAP in the UK is that food waste is still a serious economic issue for households, and underlining the economic case for reducing food waste a major incentive for households, especially as food prices are not entering an era of increase and instability, providing added economic urgency

Political Persuasions

Different political persuasions often differ in the approaches they take to changing behaviours and food waste is no different. In the UK, the Courtauld Commitment is a voluntary agreement aimed at encouraging major retailers to take responsibility mainly for packaging, later growing to encompass food waste, voluntary and so far has seen a 21% reduction in food waste post-consumer.

Meanwhile Wales (in the UK) effectively banned food waste from landfill. Scotland has ensured that businesses make food waste available for separate collection – again it’s only once you see it, you can manage it. Campaigns like the UK’s Love Food Hate Waste have been successful but measuring food waste prevention, as with all waste prevention, is notoriously difficult. But, people are now widely aware of food waste as an issue – we even see celebrity chefs actively talking about food waste reduction and recipes involving leftovers or food that is about to go off.

There is clearly a balance between food waste and food safety, with a commitment to reducing food waste throughout the retail and catering world, not just at home. By engaging environmental health officers to help deliver this, a potentially conflicting message can be delivered in a nuanced and balanced way. Indeed, environmental health officers in Scotland will be responsible for ensuring that Scottish food businesses present their food waste for separate collection.

Role of Communication

It is worth considering how the message should be communicated, and by whom. The community sector are more trusted by the public than government and the private sector are more effective at imparting personal, deeply held beliefs – the sort of beliefs that need to change if we are to see long term changes in attitudes towards consumption and hence waste production.

Furthermore, communications can engage wider audiences that hold an interest in reducing food waste that is perhaps not primarily environmental. The health and economic benefits of issues and behaviours that also result in food waste prevention may be the prevalent message that fits with a particular audience. So whilst the main aim of a training session might be food waste prevention, this is may not be the external message. And this has wider implications for waste prevention, and how we engage audiences around it.

Municipal authorities tasked with waste prevention will need to engage with new groups, in new ways. They will have to consider approaches previously considered to be beyond their powers to engage new audiences – should they be partnering with public health authorities with an interest in nutrition, or social housing providers that are focused on financial inclusion.

Should waste prevention even be a discipline in itself? After all, across material streams it is a motley assortment of behaviours with different drivers. Furthermore, with the knots that one can tie oneself in trying to measure waste that doesn’t get generated, – therefore doesn’t exist – should we integrate waste prevention in to other socio-economic programmes and position it as an “added benefit” to them?

Note: The article is being republished with the permission of our collaborative partner be Waste Wise. The unabridged version can be found at this link. Special thanks to the author Mike Webster.

Municipal Solid Waste Management in Oman

Municipal solid waste management is a challenging issue for the Sultanate of Oman because of its adverse impacts on environment and public health. With population of almost 3 million inhabitants, the country produces about 1.9 million tons of solid waste each year. The per capita waste generation in Oman is more than 1.5 kg per day, among the highest worldwide.

Prevalent Scenario

Solid waste in Oman is characterized by very high percentage of recyclables, primarily paper (26%), plastics (12%), metals (11%) and glass (5%). However the country is yet to realize the recycling potential of its municipal waste stream.

The predominant waste disposal method in Oman is landfilling. Most of the solid waste is sent to authorized and unauthorized dumpsites for disposal which is creating environment and health issues. There are several dumpsites which are located in the midst of residential areas or close to catchment areas of private and public drinking water bodies.

Solid waste management scenario in Oman is marked by lack of collection and disposal facilities, as well as lack of public awareness about waste in the country. Solid waste, industrial waste, e-wastes etc are deposited in very large number of landfills scattered across the country. Oman has around 350 landfills/dumpsites which are managed by municipalities. In addition, there are numerous unauthorized dumpsites in Oman where all sorts of wastes are recklessly dumped.

Al Amerat Sanitary Landfill

Al Amerat landfill is the first engineered sanitary landfill in Oman which began its operations in early 2011. The landfill site, spread over an area of 9.6 hectares, consists of 5 cells with a total capacity of 10 million m3 of solid waste and spread over an area of over 9.6 hectares. Each cell has 16 shafts to take care of leachate (contaminated wastewater).

All the shafts are interconnected, and will help in moving leachate to the leachate pump. The project is part of the government’s initiatives to tackle solid waste in a scientific and environment-friendly manner. Being the first of its kind, Al Amerat sanitary landfill is expected to be an example for the future solid waste management projects in the country.

The Way Forward

Solid waste management is among the top priorities of Oman government which has chalked out a robust strategy to resolve waste management problem in the Sultanate. The country is striving to establish 16 engineered landfills, 65 waste transfer stations and 4 waste treatment plants in different parts of the country.

Modern solid waste management facilities are under planning in several wilayat, especially Muscat and Salalah. The new landfills will eventually pave the way for closure of authorized and unauthorized garbage dumps around the country. However investments totaling Omani Rial 2.5 billion are required to put this waste management strategy into place. Oman is also seriously exploring waste-to-energy as a tool to manage garbage in a sustainable manner.

Medical Waste Management in Developing Countries

medical-waste-managementHealthcare sector is growing at a very rapid pace, which in turn has led to tremendous increase in the quantity of medical waste generation in developing countries, especially by hospitals, clinics and other healthcare establishments. The quantity of healthcare waste produced in a typical developing country depends on a wide range of factors and may range from 0.5 to 2.5 kg per bed per day.

For example, India generates as much as 500 tons of biomedical wastes every day while Saudi Arabia produces more than 80 tons of healthcare waste daily. The growing amount of medical wastes is posing significant public health and environmental challenges across the world. The situation is worsened by improper disposal methods, insufficient physical resources, and lack of research on medical waste management. The urgent need of the hour is to healthcare sustainable in the real sense of the word.

Hazards of Healthcare Wastes

The greatest risk to public health and environment is posed by infectious waste (or hazardous medical waste) which constitutes around 15 – 25 percent of total healthcare waste. Infectious wastes may include items that are contaminated with body fluids such as blood and blood products, used catheters and gloves, cultures and stocks of infectious agents, wound dressings, nappies, discarded diagnostic samples, swabs, bandages, disposal medical devices, contaminated laboratory animals etc.

Improper management of healthcare wastes from hospitals, clinics and other facilities in developing nations pose occupational and public health risks to patients, health workers, waste handlers, haulers and general public. It may also lead to contamination of air, water and soil which may affect all forms of life. In addition, if waste is not disposed of properly, ragpickers may collect disposable medical equipment (particularly syringes) and to resell these materials which may cause dangerous diseases.

Inadequate healthcare waste management can cause environmental pollution, growth and multiplication of vectors like insects, rodents and worms and may lead to the transmission of dangerous diseases like typhoid, cholera, hepatitis and AIDS through injuries from syringes and needles contaminated with human.

In addition to public health risks associated with poor management of biomedical waste, healthcare wastes can have deleterious impacts on water bodies, air, soil as well as biodiversity. The situation is further complicated by harsh climatic conditions in many developing nations which makes disposal of medical waste more challenging.

The predominant medical waste management method in the developing world is either small-scale incineration or landfilling. However, the WHO policy paper of 2004 and the Stockholm Convention, has stressed the need to consider the risks associated with the incineration of healthcare waste in the form of particulate matter, heavy metals, acid gases, carbon monoxide, organic compounds, pathogens etc.

In addition, leachable organic compounds, like dioxins and heavy metals, are usually present in bottom ash residues. Due to these factors, many industrialized countries are phasing out healthcare incinerators and exploring technologies that do not produce any dioxins. Countries like United States, Ireland, Portugal, Canada and Germany have completely shut down or put a moratorium on medical waste incinerators.

Alternative Treatment Technologies

The alternative technologies for healthcare waste disposal are steam sterilization, advanced steam sterilization, microwave treatment, dry heat sterilization, alkaline hydrolysis, biological treatment and plasma gasification.

Nowadays, steam sterilization (or autoclaving) is the most common alternative treatment method. Steam sterilization is done in closed chambers where both heat and pressure are applied over a period of time to destroy all microorganisms that may be present in healthcare waste before landfill disposal. Among alternative systems, autoclaving has the lowest capital costs and can be used to process up to 90% of medical waste, and are easily scaled to meet the needs of any medical organization.

Advanced autoclaves or advanced steam treatment technologies combine steam treatment with vacuuming, internal mixing or fragmentation, internal shredding, drying, and compaction thus leading to as much as 90% volume reduction. Advanced steam systems have higher capital costs than standard autoclaves of the same size. However, rigorous waste segregation is important in steam sterilization in order to exclude hazardous materials and chemicals from the waste stream.

Microwave treatment is a promising technology in which treatment occurs through the introduction of moist heat and steam generated by microwave energy. A typical microwave treatment system consists of a treatment chamber into which microwave energy is directed from a microwave generator. Microwave units generally have higher capital costs than autoclaves, and can be batch or semi-continuous.

Chemical processes use disinfectants, such as lime or peracetic acid, to treat waste. Alkaline digestion is a unique type of chemical process that uses heated alkali to digest tissues, pathological waste, anatomical parts, or animal carcasses in heated stainless steel tanks. Biological processes, like composting and vermicomposting, can also be used to degrade organic matter in healthcare waste such as kitchen waste and placenta.

Plasma gasification is an emerging solution for sustainable management of healthcare waste. A plasma gasifier is an oxygen-starved reactor that is operated at the very high temperatures which results in the breakdown of wastes into hydrogen, carbon monoxide, water etc. The main product of a plasma gasification plant is energy-rich syngas which can be converted into heat, electricity and liquids fuels. Inorganic components in medical wastes, like metals and glass, get converted into a glassy aggregate.

Solid Waste Management in Kuwait

Kuwait, being one of the richest countries, is among the highest per capita waste generators in the world. Each year more than 2 million tons of solid waste is generated in the tiny Arab nation. High standards of living and rapid economic growth has been a major factor behind very high per capita waste generation of 1.4 to 1.5 kg per day.

Waste Disposal Method

The prevalent solid waste management method in Kuwait is landfill burial. Despite being a small country, Kuwait has astonishingly high number of landfills. There are 18 landfills, of which 14 sites are closed and 4 sites are still in operation. These landfills act as dumpsites, rather than engineered landfills.

Menace of Landfills

Infact, landfill sites in Kuwait are notorious for causing severe public health and environmental issues. Besides piling up huge amounts of garbage, landfill sites generate huge amount of toxic gases (methane, carbon dioxide etc) and plagued by spontaneous fires. Due to fast paced urban development, residential areas have expanded to the edges of landfill sites thus causing grave danger to public health.

The total land area of Kuwait is around 17,820 sq. km, out of which more than 18 sq. km is occupied by landfills. Area of the landfill sites ranges from tens to hundreds of hectares with waste deposition depth varying from 3 to 30 meters.

All kind of wastes, including municipal wastes, food wastes, industrial wastes, construction and demolition debris etc are dumped at these sites. Infact, about 90 percent of the domestic waste is sent to landfills which imply that more landfills will be required to tackle rapidly increasing volumes of solid wastes.

Most of the landfill sites have been closed for more than 20 years due to operational problems and proximity to new residential, commercial and industrial areas. These sites include Sulaibiyah, Kabed, Al Qurain, Shuaiba, Jleeb AI Shuyoukh, West Yarmouk, AI Wafra among others. Migration of leachate beyond landfill site boundaries is a frequent problem noticed across Kuwait. Groundwater contamination has emerged as a serious problem because groundwater occurs at shallow depths throughout the country.

The major landfill sites operated by municipality for solid waste disposal are Jleeb AI Shuyoukh, Sulaibiyah and Al-Qurain. The Qurain landfill, with area of 1 sq. km, was used for dumping of municipal solid waste and construction materials from 1975 until 1985 with total volume of dumped waste being 5 million m3.

The Sulaibiyah landfill site received more than 500 tons of waste per day from 1980 to 2000 with area spanning 3 sq. km. Jleeb AI Shuyoukh, largest landfill site in Kuwait with area exceeding 6 sq. km, received 2500 tons per day of household and industrial waste between 1970 and 1993. Around 20 million m3 of wastes was dumped in this facility during its operational period.

Over the years, most of the dumpsites in Kuwait have been surrounded by residential and commercial areas due to urban development over the years. Uncontrolled dumpsites were managed by poorly-trained staff resulting in transformation of dumpsites in breeding grounds for pathogens, toxic gases and spontaneous fires.

Most of the landfill sites have been forced to close, much before achieving their capacities, because of improper disposal methods and concerns related to public health and environment. Due to fast-paced industrial development and urban expansion, some of the landfills are located on the edges of residential, as is the case of Jleeb Al-Shuyoukh and Al-Qurain sites, endangering the lives of hundreds of thousands of people.

The Problem of Shipping Wastes

garbage-oceanShipping wastes, long a neglected topic, has started to attract worldwide attention, thanks to the mysterious and tragic disappearance of flight MH370. During the search for MH370, a succession of items floating in the sea were identified as possible wreckage, but later confirmed to be simply pieces of marine litter. Whilst it was large pieces of debris that complicated the search, marine debris of all sizes causes problems for users of marine resources. In the most polluted areas, around 300,000 items of debris can be found in each square kilometre.

Up to 80% of ocean debris originates from land based sources, including beach litter, litter transported by rivers, and discharges of untreated municipal sewage, while ocean based sources (merchant shipping, ferries, cruise liners, fishing and military vessels) account for the remainder. Whilst typically this may be only 20% of marine litter, in areas of high shipping activity such as the North Sea it rises closer to 40%.

Wastes from commercial vessels seems like an area that could be effectively tackled with regulation. However, it is difficult for individual nations or regions to take action when ships operate in international waters and the debris in our oceans is constantly on the move.

So how is it addressed through international legislation?

Law of the Seas

In fact, a good many laws are already in place. The key piece of legislation preventing ‘the disposal of garbage at sea’ is Annex V of the International Convention for the Prevention of Marine Pollution from Ships (MARPOL). Amongst the numerous other relevant laws are the London Convention and Protocol, the Basel ConventionUNCLOS, and the Convention on Biological Diversity.

In addition, many more laws exist at regional and national levels. In the EU, laws directly related to marine debris include the Marine Strategy Framework Directive and the Directive on Port Reception Facilities. Laws indirectly related to marine debris include the Common Fisheries Policy, the Water Framework Directive, the Waste Framework Directive, the Habitats Directive…. The list goes on.

Fathoming the Legislation

Despite the profusion of legislation, the scale of the current and potential problems caused by marine debris, it is clear that implementation and enforcement is lagging behind. Why so?

Ratification

As yet, not all coastal or flag states have ratified international instruments such as MARPOL Annex V. This means that ships registered with a non-ratified state under a‘flag of convenience’ may legally continue to discharge garbage in international waters. However, even if the current suite of international legislation was universally ratified, this would serve to expose the remaining gaps in the framework.

Discharge provisions

MARPOL Annex V includes specific requirements regarding the discharge of different types of waste and location of discharges. For instance, ground food waste can be discharged up to 3 nautical miles from land, but if it is not ground it may only be discharged at a distance of 12 nautical miles or more. Although the discharge of ‘all other garbage including plastics’ is prohibited, compliance relies upon good waste management practices on board vessels.

If waste streams are contaminated, this may result in plastics and other debris being discharged into the sea. The current approach may have been developed to accommodate shipping activity, but in practice it is somewhat confusing and it would perhaps make more sense to issue a blanket ban on discharges.

Scope

Another gap within MARPOL Annex V is the scope of the requirements for ‘garbage management plans’ and ‘garbage record books’. Vessels of 100 gross tonnes or more are required to have a garbage management plan, while vessels of 400 gross tonnes or more are required to have a garbage record book. Smaller vessels are not obliged to comply with the requirements.

Less than 1% of vessels in the world fishing fleet have a gross tonnage of over 100 tonnes, the majority has no obligation to implement and maintain a plan or book; with no planning or record keeping, the risk of illegal disposal is increased. Small fishing vessels may not be considered ‘commercial’ shipping vessels at all – thereby avoiding legislation – but they still contribute towards the problem of marine debris. Most notably, abandoned, lost or otherwise discarded fishing gear has a considerable impact on marine species through ‘ghost fishing’.

Port waste reception facilities

MARPOL Annex V requires the government of each ratified nation to provide facilities at ports for the reception of ship generated residues and garbage that cannot be discharged into the sea. The facilities must be adequate to meet the needs of ships using the port, without causing undue delay to ships. However, MARPOL does not prescribe any set standards or provide for certification. The term ‘adequate’ is instead defined in a qualitative (rather than quantitative) manner in Marine Environment Protection Committee (MEPC) resolution 83 (44).

Furthermore, MARPOL does not set any requirements regarding how waste delivered to port reception facilities should be managed. Only the non-mandatory MEPC resolution 83 (44) requires that facilities should allow for the ultimate disposal of ships’ wastes to take place in an environmentally appropriate way.

Cruise ships

Cruise ships operate in every ocean worldwide, often in pristine coastal waters and sensitive marine ecosystems. Operators provide amenities to their passengers similar to those of luxury resort hotels, generating up to 14 tonnes of waste per day. Worldwide, the cruise industry has experienced a compound annual passenger growth rate of 7% since 1990, and the number of passengers carried is expected to increase from approximately 21 million in 2013 to 23.7 million in 2017.

The majority of current legislation on pollution and ship waste was developed prior to the rapid growth of the cruise market; as a consequence, there is no international legislation addressing the particular issues surrounding pollution and waste management on these vessels.

Although there is not yet data to support this, intuitively the amount of waste produced by ships would be linked to the number of people on board, rather than the vessel’s gross tonnage (which determines whether MARPOL rules apply). If the industry grows as forecasted, cruise ships may be responsible for a significant proportion of waste generated by ships, particularly if unmanned are the future.

To address this, onboard waste management systems that implement zero disposal of solid waste at sea are needed for cruise ships, together with a requirement that they only dispose of their waste at ports with reception facilities adequate to handle the type and volume of waste produced.

Taking the Helm

Where international and regional legislation is found lacking a number of voluntary mechanisms have been devised, indicating an appetite to improve the current waste disposal practices of the shipping industry.

  • The indirect fee system aims to remove the disincentive for ships to dispose of waste at port rather than at sea by including the cost of waste disposal services in the port fees paid by visiting ships, irrespective of whether ships use the facilities
  • The Clean Shipping Index is an easy to use, transparent tool which can be used by cargo owners to evaluate the environmental performance of their sea transport providers. The information is entered on a ship-by-ship basis but is also added to a total carrier fleet score for an overall ranking. Questions on waste relate to garbage handling and crew awareness, and scores can only be obtained for measures that go beyond existing regulations.
  • One commercial container operator (Matson Navigation) has introduced a zero solid waste discharge policy. The ‘greentainer’ programme uses containers specifically designed for storing solid waste. Since 1994, this programme has prevented over 10,000 tonnes of garbage being disposed of at sea.

Currently, international legislation does not properly support a closed loop system for waste management onboard ships. Despite legislative progress and improvements in practice, the monitoring of waste from shipping remains problematic. ‘Policing the seas’ to verify what a ship discharges and where, and whether this follows recommended best practice, remains one of the most challenging aspects of waste management practice at sea, but critical to making the legal framework effective.

The United Nations Environment Programme neatly summarised the issue in 2005:“… marine litter is not a problem which can be solved only by means of legislation, law enforcement and technical solutions. It is a social problem which requires efforts to change behaviours, attitudes, management approaches and multi-sectoral involvement.” 

The limitations of international legislation governing the case of marine litter disposed of at sea do need to be addressed; but unless legislation is accompanied by environmental education for seafarers, and improved monitoring, our attempts to tackle this source of marine litter will remain all at sea.

Note: The article has been republished with the permission of our collaborative partner Isonomia. The original version of the article can be found at this link.