Plastic Wastes and its Management

Plastic seems all pervasive and unavoidable. Since the 1960s our use of plastic has increased dramatically, and subsequently, the portion of our garbage that is made up of plastic has also increased from 1% of the total municipal solid waste stream (household garbage) to approximately 13% (US Environmental Protection Agency). Plastic products range from things like containers and packaging (soft drink bottles, lids, shampoo bottles) to durable goods (think appliances, furniture and cars) and non-durable goods including things from a plastic party tray to medical devices. Sometimes marked with a number and a chasing arrow, there is an illusion that all plastics are recyclable, and therefore recycled. But there are a number of problems with this assumption.

plastic-wastes

While use and consumption of plastic is increasingly high, doubts about viable options for reuse, recycling and disposal are also on the rise. Complications such as the increasing number of additives used alter the strength, texture, flexibility, colour, resistance to microbes, and other characteristics of plastics, make plastics less recyclable. Additionally, there is very little market value in some plastics, leading municipalities to landfill or incinerate plastics as waste. Based on figures from the EPA (2011 data) only 8% of plastic materials are recovered through recycling.

Another major concern about plastics in the waste stream is their longevity and whether or not they are truly biodegrade. It is estimated that most plastics would take 500-1000 years to break down into organic components. Because of this longevity and the low rate of recycling, much of our plastic waste ends up in landfills or as litter. Some of this plastic waste makes its way via rivers and wind to the ocean. Garbage barges, and the trans-continental transport of recyclable materials also lead to an increasing amount of plastics in our oceans and waterways.

Plastic waste directly and indirectly affects living organisms throughout the ecosystem, including an increasingly high impact on marine life at a macro and micro scale. According to United Nations, almost 80% of marine debris is plastic. Policy enforcement remains weak, global manufacture of plastics continues to increase, and the quantity of plastic debris in the oceans, as well as on land, is likely to increase.

With limited sustainable recovery of plastics, there is a growing global movement to reduce the generation of plastic. Certain types of plastic may be ’safer‘ for the environment than others, however, there are troubling issues associated with all of them, leading to the conclusion that action is needed to remove plastic waste, and stricter controls are required to limit new sources of plastic pollution. Efforts such as light weighting of packaging and shifts to compostable plastics are options. Many people use eco-friendly bags for the sake of green living. Policies limiting the use of plastics such as bottle bills and bag bans are other ways to decrease the production and consumption of plastics.

Mining the debris fields in our oceans and turning plastic waste into usable materials, from socks made of fishing line to fuel made from a variety of plastic debris, is one way to mitigate the current situation. You can do your part by using renewable cotton bags.

Note: This excerpt is being published with the permission of our collaborative partner Be Waste Wise. The original excerpt and its video recording can be found at this link

Solid Waste Management – India’s Burning Issue

For the first time in the history of India, the year 2012 saw several public protests against improper solid waste management all across India – from the northernmost state Jammu and Kashmir to the southernmost Tamil Nadu. A fight for the right to clean environment and environmental justice led the people to large scale demonstrations, including an indefinite hunger strike and blocking roads leading to local waste handling facilities. Improper waste management has also caused a Dengue Fever outbreak and threatens other epidemics. In recent years, waste management has been the only other unifying factor leading to public demonstrations all across India, after corruption and fuel prices. Public agitation resulted in some judicial action and the government’s remedial response, but the waste management problems are still unsolved and might lead to a crisis if this continues for too long without any long term planning and policy reforms.

Hunger Strike in Kerala

The President of Vilappilsala Village Panchayat went on a hunger strike recently, against her counterpart, the Mayor of Thiruvananthapuram. Thiruvananthapuram is the state capital of Kerala, and Vilappilsala is a village 22 km away. Since July 2000, about 80% of the waste generated in Thiruvananthapuram is being transported to a waste composting plant and a dumpsite in Vilappilsala village. Since the same month, respiratory illnesses reported in Vilappil Primary Health Center increased by 10 times from an average of 450 to 5,000 cases per month. People who used to regularly swim in the village’s aquifer started contracting infections; swarms of flies have ever since been pervasive; and a stigma of filth affected households throughout the community. This was a source of frustration as locals who, as Indians, prize the opportunity to feed and host guests, found them unwilling to even drink a glass of water in their homes. Currently, there is not a single household which has not experienced respiratory illnesses due to the waste processing plant and the adjoining dumpsite.

On the other hand, Thiruvananthapuram’s residents had to sneak out at night with plastic bags full of trash to dispose them behind bushes, on streets or in water bodies, and had to openly burn heaps of trash every morning for months. This was because the waste generated was not being collected by the City as it could not force open the composting plant and dumpsite against large scale protests by Vilappilsala’s residents. This is why in August – 2012, about 2,500 police personnel had to accompany trucks to the waste treatment plant as they were being blocked by local residents lying down on the road, and by some, including the village’s President, by going on an indefinite hunger strike.

Municipal Commissioner Replaced in Karnataka

In response to a similar situation in Bengaluru, the state capital of Karnataka, where the streets were rotting with piles of garbage for months, the municipal commissioner of the city was replaced to specifically address the waste management situation. Against the will of local residents, a landfill which was closed following the orders issued by the state’s pollution control board in response to public agitation had to be reopened soon after its closure as the city could not find a new landfill site.

Mavallipura landfill in Bangalore

Population density and the scale of increasing urban sprawl in India make finding new landfill sites around cities nearly impossible due to the sheer lack of space for Locally Unwanted Land Uses (LULUs) like waste management.

Dengue Outbreak in West Bengal

Even if partially because of improper waste management, Kolkata, state capital of West Bengal and the third biggest city in India experienced a Dengue Fever outbreak with 550 confirmed cases and 60 deaths. This outbreak coincides with a 600% increase in dengue cases in India and 71% increase in malarial cases in Mumbai in the last five years. Accumulation of rain water in non biodegradable waste littered around a city act as a major breeding environment for mosquitoes, thus increasing the density of mosquito population and making the transmission of mosquito related diseases like dengue, yellow fever and malaria easier.

Rabies in Srinagar

Rabies due to stray dog bites already kills more than 20,000 people in India every year. Improper waste management has caused a 1:13 stray dog to human ratio in Srinagar (compared to 1 per 31 people in Mumbai and 1 per 100 in Chennai), where 54,000 people were bitten by stray dogs in a span of 3.5 years. Municipal waste on streets and at the dumpsite is an important source of food for stray dogs. The ultimate solution to controlling stray dogs is proper waste management. The public has been protesting about this stray dog menace for months now with no waste management solutions in sight, but only partial short term measures like dog sterilization.

Waste Management Progress in Nigeria’s Delta State

waste-nigeriaWaste management is a serious problem in Nigeria, and Delta State is no exception. It is a problem that starts at a cultural level: many of the populace believe that once they remove waste from their homes it is no longer their concern. It is a problem that starts at a cultural level: many of the populace believe that once they remove waste from their homes it is no longer their concern, and you often see people disposing of their household waste in the streets at night. Once the waste gets out into the streets, it’s perceived as the duty of the government to handle it.

However, I have never yet heard of any Nigerian politician making waste management a feature of his or her manifesto during the election campaign process. Having said that, a few of Nigeria’s political leaders deserve to be commended for coming to terms with the fact that waste has to be managed properly, even if such issues were far from their minds when they entered political office.

Legislation and Framework

Nigeria does have a waste legislation framework in place. Its focus has been on the most toxic and hazardous waste: partly in response to some major pollution incidents in the 1980s, the government took powers in relation to Hazardous Waste in 1988. In the same year, the Federal Environmental Protection Agency was established – and was subsequently strengthened by the addition of an inspectorate and enforcement department arm in 1991, with divisions for standard regulation, chemical tracking and compliance monitoring. These laws have since given rise to regulations and guidelines pertaining to environmental and waste management issues.

Under our laws, waste management in each state is the duty of the local governments that fall within it, but few are taking an active approach to implementing and enforcing the sensible measures that the regulations require. A small number of states have taken over this task from local government, and Delta State’s decision to do this has led to significant new investment in waste management.

One of the fruits of that investment is the Delta State Integrated Waste Management Facility at Asaba for treating both household and clinical waste generated locally. It was developed when the Delta State government decided to put an end to the non-sustainable dumping of waste in Asaba, the state capital.

Integrated Waste Management Facility at Asaba

It is described as an integrated waste management facility because it includes a composting department, a recycling department and a (non-WTE) incineration department. Trucks carrying waste are weighed in as they come into the facility. From the weigh bridge, they move to the relevant reception bay – there are separate ones for household and clinical wastes – to tip their load, and are then weighed again on the way out.

Medical waste is taken directly for incineration, but household wastes are sent along conveyors for sorting. Recyclables and compostable materials are, so far as possible, separated both from other waste and from one another. Each recyclable stream ends up in a chamber where it can be prepared for sale. The compostable materials are moved to the composting section, which uses aerated static pile composting.

The remaining waste is conveyed into the three incinerators – moving grate, rotary kiln and fixed end– for combustion. The resulting ash is recycled by mixing it with cement and sharp sand and moulding it into interlocking tiles. The stacks of the three incinerators are fitted with smoke cleaning systems to reduce emissions. The process produces wastewater, which is channelled to a pit where it is treated and reused. Overall, 30% of the waste is composted, 15% recycled and 55% incinerated.

There are many examples of sophisticated waste infrastructure being built in developing countries, but failing because the necessary collection systems were not in place to support them. To ensure that this problem is avoided at Asaba, the Delta State government is working with a group known as the Private Sector Participants (PSP).

Each member of this group has trucks assigned to them and has been directed to collect household waste from different parts of the city, for delivery to the facility for treatment. The arrangements made by each PSP are different: some collect from outside individual properties, and some from communal sites; most collect waste that is found in the streets; and while each is subsidised by the state, households also have to pay towards the cost.

Before the Asaba facility was developed, most of the wastes generated in Asaba were disposed of at a dumpsite just adjacent to the Delta State Airport. This created a pungent odour, as well as visual disamenity for people nearby. A great deal of remediation work is now taking place at the dumpsite, which is vastly improving the local environmental quality.

War on Waste

Of course, although this is an improvement there remains more to do. First on the list is education. People do not know how sustainable waste management can impact positively in their lives, reducing their exposure to toxins as well as improving their surroundings. Nor do they understand that recycling a beverage can or a plastic bottle will cost less than producing one from virgin materials and will have a lesser environmental impact. There remains a good deal of cultural change and environmental education that is needed before people will stop throwing waste and litter on the streets – but there are few countries where, to some extent, the same would not be true.

Next is the lack of infrastructure. Nigeria has 36 states and a federal capital, yet the facility in Asaba is the first publicly commissioned one of its kind in the country; there are also some privately owned incinerators that a few companies in Port Harcourt use to treat wastes from vessels (ships), hospitals and industries. Lagos state and Abuja are relatively advanced, simply by virtue of having put in place a few managed landfills, but they are still far from having the level of facility that Asaba can now boast.

The backbone of Asaba’s progress is the state government’s commitment to put a proper waste management solution in place. We’ve seen the impact in the form of infrastructure, collections and remediation, and law enforcement work is starting to change people’s perception about waste management in Delta State. At the moment, plans are being concluded to setup another facility in Warri, Delta State’s industrial hub, which will be twice the size of the Asaba facility.?

My hope is that the progress made by Delta State will be a beacon for other states’ governments. The example we are providing of cleaner, hygienic, more environmentally responsible waste management, and the positive changes that is bringing about, should inspire new development elsewhere in the country, which could equal or even exceed Delta State’s results. So whilst Nigeria’s track record on waste may leave a lot to be desired, the path ahead could be a great deal more promising.

Note: The article is being republished with the kind permission of our collaborative partner Isonomia. The original article can be found at this link.

Waste Disposal Methods: Perspectives for Africa

Waste disposal methods vary from city to city, state to state and region to region. It equally depends on the kind and type of waste generated. In determining the disposal method that a city or nation should adopt, some factors like type, kind, quantity, frequency, and forms of waste need to be considered.

For the purpose of this article, we will look at the three common waste disposal methods in Africa and the kind of waste they accept.

Open Dumping/Burning

This is the crudest means of disposing of waste and it is mostly practiced in rural areas, semi-urban settlements, and undeveloped urban areas. For open dumping or open burning, every type and form of waste (including household waste, hazardous wastes, tires, batteries, chemicals) is dumped in an open area within a community or outside different homes in a community and same being set on fire after a number of days or when the waste generator or community feels it should be burnt.

There is no gainsaying that the negative health and environmental impact of such practice are huge only if the propagators know better.

Controlled Dumping

This is apparent in most States in Nigeria, if not all and some cities in Africa like Mozambique, Ghana, Kenya, Cameroon, to mention but a few. It is a method of disposing of all kinds of waste in a designated area of land by waste collectors and it is usually controlled by the State or City Government.

Opening burning of trash is a common practice across Africa

Controlled dumps are commonly found in urban areas and because they are managed by the government, some dumps do have certain features of a landfill like tenure of usage, basic record keeping, waste covering, etc. Many cities in Nigeria confuse the practice of controlled dumping as landfilling but this not so because a landfill involves engineering design, planning, and operation.

Sanitary Landfill

A sanitary landfill is arguably the most desired waste management option in reducing or eliminating public health hazards and environmental pollution. The landfill is the final disposal site for all forms and types of waste after the recyclable materials must have been separated for other usages and other biodegradables have been extracted from the waste for use as compost, heat, or energy; or after incineration. These extractions can be done at household level or Material Recovery Facilities (MRFs) operated by the government or private individuals.

As desirable as a landfill is, so many factors need to be put into consideration in its siting and operation plus it requires a huge investment in construction and operation. Some of these factors include but not limited to distance from the residential area, proximity to water bodies, water-table level of the area the landfill is to be sited, earth material availability, and access road.

Note: The original version of the article was published on Waste Watch Africa website at this link.

A Primer on Waste-to-Energy

Waste-to-Energy (also known as energy-from-waste) is the use of thermochemical and biochemical technologies to recover energy, usually in the form of electricity, steam and fuels, from urban wastes.These new technologies can reduce the volume of the original waste by 90%, depending upon composition and use of outputs.

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 household wastes are generated each year with the vast majority disposed of in open fields or burnt wantonly.

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.

The three principal methods of thermochemical conversion are combustion in excess air, gasification in reduced air, and pyrolysis in the absence of air. The most common technique for producing both heat and electrical energy from wastes is direct combustion. Combined heat and power (CHP) or cogeneration systems, ranging from small-scale technology to large grid-connected facilities, provide significantly higher efficiencies than systems that only generate electricity.

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. Cellulosic ethanol can be produced from grasses, wood chips and agricultural residues by biochemical route using heat, pressure, chemicals and enzymes to unlock the sugars in biomass wastes.

Waste-to-energy plants offer two important benefits of environmentally safe waste management and disposal, as well as the generation of clean electric power.  The growing use of waste-to-energy as a method to dispose of solid and liquid wastes and generate power has greatly reduced environmental impacts of municipal solid waste management, including emissions of greenhouse gases.

Waste Management in Global North and Global South

Waste management is highly context specific. Therefore it is important to distinguish between the conditions in the Global North and the Global South. Recent ILO figures suggest that 24 million people around the world are involved in the informal waste recycling sector, 80% of whom are waste pickers. Some estimates say that 1% of urban population in developing countries makes their primary household income through informal sector waste management activities.  In Latin America alone, 4-5 million waste pickers earn their livelihood by being a part of the global recyclables supply chain.

waste-management-latin-america

Municipal budgets in the Global South are often limited and only a small percentage of that budget is assigned to waste management as compared to other municipal services. In the Global North waste management is recognized as a necessary public good and there is a greater willingness to pay for this service. Solid waste management (e.g. waste collection, transportation and recycling) is generally more labour intensive than in North America and Europe.

Urbanization in the Global South is often haphazard and unplanned; creating pockets of high and low income neighbourhoods. This creates logistical issues for the waste management service provision limiting options for viable waste collection and transportation. It is often the informal sector that steps in to fill this service gap.

The maturity and strength of the legal framework differs between the Global South and Global North. In North America and Europe the legal framework of waste management actively promotes and provides incentives for waste reduction, reuse and recovery whereas, despite recent developments in some countries, in Latin America legal frameworks remain focused upon mixed waste collection, transportation and disposal.

Recycling rates in Argentina are at 11% of the total waste stream with 95% of this material is recovered by the informal sector. This situation is replicated in many other countries. The informal sector recovers between 50% (e.g. Mexico) and 90% (e.g. Nicaragua) of the waste recovered and in the different countries of the region. Resource recovery and recycling is driven by market conditions. Materials that have a value are diverted from landfill through an informal network of recyclers and waste collectors.

The composition of waste is also very different in the Global South where organic waste is a much larger percentage of the waste stream. Because of the high percentage of organics in the waste stream in many cities in the Global South, innovations in decentralised composting and small scale biogas have been seen across the Global South (particularly in India) and can be used effectively by the informal sector, making a zero waste future a real possibility.

Role of Informal Recycling Sector

The informal sector can be highly effective at collecting and diverting garbage from landfill. When empowered with a facilitating legal framework, and collectively organized, the informal sector can be a key part of a sustainable resource recovery system. Using people power to increase recycling and diversion rates decreases the need for expensive, fixed, high technology solutions.

Understanding that the context for waste management is different between the Global North and Global South, and even in different areas within a city or region, means that no two situations will be the same. However, if there is one principle to follow it may well be to consider the context and look for the simplest solution. The greenest cities of the future may well be those that use flexible, adaptable solutions and maximize the work that the informal sector is already doing.

Note: This excerpt is being published with the permission of our collaborative partner Be Waste Wise. The original excerpt and its video recording can be found at this link

Recycling Outlook for Latin America

Latin America has one of the highest rates of urbanization in the world (80% urban population). By 2050, 90% of Latin America’s population will live in urban areas. This high rate of urbanization coupled with the global economic crisis has resulted in a waste management crisis. Municipalities find themselves unable to keep up with providing services and infrastructure to the urban populations.

recycling-latin-america

Some cities in Latin America are facing this challenge by integrating the informal sector recyclers who are already active in their cities into the municipal solid waste management systems. In many cities, these “recicladores”, “cartoneros” or “catadores” (a few of the many names used for these workers in the region) are responsible for up to 90% of the recyclable waste recovered from the waste stream. Their work reduces municipal waste transportation costs, increases landfill lifetimes and supports the recycling chain throughout the region.

State of the Affairs

Every location presents its own challenges–there is no one-size-fits-all solution for integrated solid waste management systems–but relevant lessons can be drawn from both failed attempts and successful examples of informal sector integration in recycling systems in Latin America.

There are often two very different contexts within cities. In low-income neighborhoods waste collection services are often not provided and individuals and families accumulate and then sell their recyclables for additional income. In contrast, residents in high income neighborhoods do receive a waste collection service and their motivation for recycling is often related to greater levels of environmental awareness. It is important to consider these differences when designing waste management solutions.

Imported systems, and even locally derived systems based on examples from the Global North, generally focus on only one waste management scenario, making it difficult to manage the multiple competing scenarios in many cities in Latin America. There is often a bias towards the automation of waste management services, with the application of the high technology solutions used in the Global North. Regardless of the practicality or scientific evidence against certain high tech solutions, these are often sought after, thought to raise the bar of the city, to make it appear more sophisticated and modern. This leads to a misconception that working with informal sector is a step backwards in terms of urban development and modernization.

Conflicts between private waste management companies, the municipality and informal recyclers are common. The waste management companies do not want pickers on the landfill and wastepickers then go to the municipality for help. However, municipalities usually have very little experience to support the integration of formal and informal waste sectors. There are opportunities for new systems to emerge within this conflict. For example, during a similar conflict in Mexicali, Mundo Sustentable, with the help of Danone, intervened to help a private company work with the informal waste sector and improve recycling rates.

The Way Forward

In Latin America, there is a great opportunity to increase recycling rates by using labour-intensive solutions, which create jobs and support the development of a better urban environment in the cities. Municipal governments should be an integral part of these processes as they are usually responsible for solid waste management at local level. The key to catalyzing informal recycling sector integration will be the development and dissemination of successful examples.

Informal recyclers provide important a range of services to municipalities (such as waste collection and recovery in communities that would not otherwise have access to them), as well as cost savings (for example, the extension of landfill life and reduced transport costs), yet are rarely compensated for these benefits. Informal recyclers further form the foundation of an entire recycling supply chain, which ultimately benefits formal businesses, and often aliment entire local economies.

Challenges to Overcome

Municipal governments are often hesitant to work with informal actors, who are frequently seen as an unknown quantity. Yet often in the process of working and developing relations with informal recycler groups, their concerns diminish and they may actually exhibit enthusiasm. Likewise, the recyclers may gain in confidence and professionalism in their experience of formalization.

One major challenge facing efforts to integrate the informal sector in developing countries is the desire of some local governments to adopt technological solutions that appear more “modern.” In much of Latin America, however, low-cost, low-tech solutions tend to be more viable and sustainable.

The main difference between Latin America and the countries of the Global North is that solid waste management is a labor intensive system. It is made up of workers and hence has an important social component. The ILO estimated there is 24 million of people working in the global recycling supply chain, but those at the bottom of the pyramid, the wastepickers, make up 80%. They remain the lowest paid even though they make an enormous contribution to their cities.

It is important to understand that highly sophisticated, high technology systems are not required for effective resource recovery. In many cities in Latin America between 80-90% of everything that is recycled is recovered by the informal recycling sector.

Despite the fact that there is little or no public investment in waste management or recycling infrastructure, cities with an active informal sector reach twice the rate of fully formalized municipal solid waste management systems. As an example, the recycling rate is 60% in Cairo, while in Rotterdam (and other cities in the Global North) recycling levels only reach 30%, even with a high public investment in the system (UN Habitat, 2010).

When designing infrastructure and waste management systems we must consider not only the waste management and resource recovery needs but also the social side of the system. In order to be effective, efforts to upgrade waste management services should go hand in hand with efforts to formalise and integrate the informal sector.

Bogota – A Success Story

An example of a recent success story is that after 27 years of struggle, the waste pickers in Bogota, Colombia have managed to change the government’s outlook on their work and their existence. They are now included in the system and are paid per tonne of waste collected, just like any other private sector collection and waste management company would be. They have become recognized as public service providers, acknowledged for their contribution to the environment and public health of the city.

The key challenge is to be much more creative and understand that in order to improve the working conditions of waste pickers and in order to increase recycling rates, we don’t need high technology. We need a systemic approach and this can be very simple sometimes infrastructure as simple as a roof [on a sorting area] can be effective in improving working conditions.

Note: This excerpt is being published with the permission of our collaborative partner Be Waste Wise. The original excerpt and its video recording can be found at this link

Biogas from Slaughterhouse Wastes

slaughterhouse-wasteSlaughterhouse waste (or abattoir waste) disposal has been a major environmental challenge in all parts of the world. The chemical properties of slaughterhouse wastes are similar to that of municipal sewage, however the former is highly concentrated wastewater with 45% soluble and 55% suspended organic composition. Blood has a very high COD of around 375,000 mg/L and is one of the major dissolved pollutants in slaughterhouse wastewater.

In most of the developing countries, there is no organized strategy for disposal of solid as well as liquid wastes generated in abattoirs. The solid slaughterhouse waste is collected and dumped in landfills or open areas while the liquid waste is sent to municipal sewerage system or water bodies, thus endangering public health as well as terrestrial and aquatic life. Wastewater from slaughterhouses is known to cause an increase in the BOD, COD, total solids, pH, temperature and turbidity, and may even cause deoxygenation of water bodies.

Anaerobic Digestion of Slaughterhouse Wastes

There are several methods for beneficial use of slaughterhouse wastes including biogas generation, fertilizer production and utilization as animal feed. Anaerobic digestion is one of the best options for slaughterhouse waste management which will lead to production of energy-rich biogas, reduction in GHGs emissions and effective pollution control in abattoirs. Anaerobic digestion can achieve a high degree of COD and BOD removal from slaughterhouse effluent at a significantly lower cost than comparable aerobic systems. The biogas potential of slaughterhouse waste is higher than animal manure, and reported to be in the range of 120-160 m3 biogas per ton of wastes. However the C:N ratio of slaughterhouse waste is quite low (4:1) which demands its co-digestion with high C:N substrates like animal manure, food waste, crop residues, poultry litter etc.

Slaughterhouse effluent has high COD, high BOD, and high moisture content which make it well-suited to anaerobic digestion process. Slaughterhouse wastewater also contains high concentrations of suspended organic solids including pieces of fat, grease, hair, feathers, manure, grit, and undigested feed which will contribute the slowly biodegradable of organic matter. Amongst anaerobic treatment processes, the up-flow anaerobic sludge blanket (UASB) process is widely used in developing countries for biogas production from abattoir wastes.

Slaughterhouse waste is a protein-rich substrate and may result in sulfide formation during anaerobic degradation. The increased concentration of sulfides in the digester can lead to higher concentrations of hydrogen sulfide in the biogas which may inhibit methanogens. In addition to sulfides, ammonia is also formed during the anaerobic digestion process which may increase the pH in the digester (>8.0) which can be growth limiting for some VFA-consuming methanogens.

Concept of Zero Waste and Role of MRFs

zero-waste-MRFCommunities across the world are grappling with waste disposal issues. A consensus is emerging worldwide that the ultimate way to deal with waste is to eliminate it. The concept of Zero Waste encourages redesign of resource life cycles so that all products are reused, thereby systematically avoiding and eliminating the volume and toxicity of waste and materials.

The philosophy of Zero Waste strives to ensure that products are designed to be repaired, refurbished, re-manufactured and generally reused. Among key zero waste facilities are material recovery facilities, composting plants, reuse facilities, wastewater/biosolids plants etc.

Material recovery facilities (MRFs) are an essential part of a zero waste management program as it receives separates and prepares recyclable materials for marketing to end-user manufacturers. The main function of the MRF is to maximize the quantity of recyclables processed, while producing materials that will generate the highest possible revenues in the market. MRFs can also process wastes into a feedstock for biological conversion through composting and anaerobic digestion.

A materials recovery facility accepts materials, whether source separated or mixed, and separates, processes and stores them for later use as raw materials for remanufacturing and reprocessing. MRFs serve as an intermediate processing step between the collection of recyclable materials from waste generators and the sale of recyclable materials to markets for use in making new products. There are basically four components of a typical MRF: sorting, processing, storage, and load-out. Any facility design plan should accommodate all these activities which promote efficient and effective operation of a recycling program. MRFs may be publicly owned and operated, publicly owned and privately operated, or privately owned and operated.

There are two types of MRFs – dirty and clean. A dirty MRF receives mixed waste material that requires labor intense sorting activities to separate recyclables from the mixed waste. A clean MRF accepts recyclable materials that have already been separated from the components in municipal solid waste (MSW) that are not recyclable. A clean MRF reduces the potential for material contamination.

A typical Zero Waste MRF (ZWMRF) may include three-stream waste collection infrastructure, resource recovery center, reuse/recycling ecological part, residual waste management facility and education centers.

The primary objective of all MRFs is to produce clean and pure recyclable materials so as to ensure that the commodities produced are marketable and fetch the maximum price. Since waste streams vary in composition and volume from one place to another, a MRF should be designed specifically to meet the short and long term waste management goals of that location. The real challenge for any MRF is to devise a recycling strategy whereby no residual waste stream is left behind.

The basic equipment used in MRFs are conveyors & material handling equipment to move material through the system, screening equipment to sort material by size, magnetic separation to remove ferrous metals, eddy current separation to remove non-ferrous metals, air classifiers to sort materials by density, optical sorting equipment to separate plastics or glass by material composition, and baling equipment to prepare recovered material for market. Other specialized equipment such as bag breakers, shredders and sink-float tanks can also be specified as required by application.

Biomass Wastes to Energy for MENA

The high volatility in oil prices in the recent past and the resulting turbulence in energy markets has compelled many MENA countries, especially the non-oil producers, to look for alternate sources of energy, for both economic and environmental reasons. The significance of renewable energy has been increasing rapidly worldwide due to its potential to mitigate climate change, to foster sustainable development in poor communities, and augment energy security and supply.

The Middle East is well-poised for waste-to-energy development, with its rich feedstock base in the form of municipal solid wastes, crop residues and agro-industrial wastes. The high rate of population growth, urbanization and economic expansion in the Middle East is not only accelerating consumption rates but also accelerating the generation of a wide variety of waste. Bahrain, Saudi Arabia, UAE, Qatar and Kuwait rank in the top-ten worldwide in terms of per capita waste generation. The gross urban waste generation quantity from Arab countries is estimated at more than 80 million tons annually. Open dumping is the most prevalent mode of municipal solid waste disposal in most countries.

Waste-to-energy technologies hold the potential to create renewable energy from waste matter, including municipal solid waste, industrial waste, agricultural waste, and industrial byproducts. 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. Waste-to-energy systems can contribute substantially to GHG mitigation through both reductions of fossil carbon emissions and long-term storage of carbon in biomass wastes.

Modern waste-to-energy systems options offer significant, cost-effective and perpetual opportunities for greenhouse gas emission reductions. Additional benefits offered are employment creation in rural areas, reduction of a country’s dependency on imported energy carriers (and the related improvement of the balance of trade), better waste control, and potentially benign effects with regard to biodiversity, desertification, recreational value, etc. In summary, waste-to-energy can significantly contribute to sustainable development both in developed and less developed countries. Waste-to-energy is not only a solution to reduce the volume of waste that is and provide a supplemental energy source, but also yields a number of social benefits that cannot easily be quantified.

Biomass wastes can be efficiently converted into energy and fuels by biochemical and thermal conversion technologies, such as anaerobic digestion, gasification and pyrolysis. Waste-to-energy technologies hold the potential to create renewable energy from waste matter.  The implementation of waste-to-energy 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 significantly reduce environmental impacts of wastes. In fact, energy recovery from MSW is rapidly gaining worldwide recognition as the fourth ‘R’ in sustainable waste management system – Reuse, Reduce, Recycle and Recover. A transition from conventional waste management system to one based on sustainable practices is necessary to address environmental concerns and to foster sustainable development in the region.