By Enete Ifeanyi Christian,
Dept. of Geography & Meteorology,
Nnamdi Azikiwe University, Awka
Solid waste management processes and climate change operate at similar timescales, as such; there is a need to understand what the potential climate change impacts may be on waste management. The scope of this study was limited only to municipal and household waste. The paper x-rayed the potential impacts of climate change on solid waste management through the assessment of the risk and impacts of climate change variables to the siting and operations of a wide range of waste management facilities in Nigeria. Definitions of solid waste, correlation between climate change and solid waste management, waste management policies and regulations in Nigeria as well as status of the waste management sector in Nigeria were discussed. Some strategies for reducing green house gases in municipal solid waste such as : product stewardship, paperless office, anaerobic digestion, use of bioreactors, co-firing and biomass pyrolysis/ gasification were recommended.
Key words: Solid waste management, climate change, Green house gases (GHGs), Potential impacts
Solid waste is any solid material which is discarded by its owner, user or producer. Solid wastes are left-over arising from human, animal or plant activities that are normally discarded as useless and not having any consumer value to the person abandoning them (Oyedele, 2009). Timaru District (New Zealand) Consolidated By-Law 2007 defined solid waste as “any material that is primarily not a liquid or gas that is unwanted and/or unvalued and is discarded or discharged by its owner”. Solid waste may include material that may potentially be reused, recycled and composted.
Waste management processes and climate change operate at similar timescales, so there is a need to understand what the potential climate change impacts may be on waste management in order to begin the process of identifying what changes may be needed in waste management operations, regulations, strategy, planning and policy. Climate change is a serious international environmental concern and the subject of much research. Moreover, in international scientific circles, a consensus is growing that the buildup of C02 and other Green House Gases(GHGs) in the atmosphere will lead to major environmental changes such as (1) rising sea levels that may flood coastal and river delta communities; (2) shrinking mountain glaciers and reduced snow cover that may diminish fresh water resources; (3) the spread of infectious diseases and increased heat-related mortality;(4) possible loss in biological diversity and other impacts on ecosystems; and (5) agricultural shifts such as impacts on crop yields and productivity (McCarthy, 2001).
“Climate change could result in changes in temperatures, cloud cover, rainfall patterns, wind speeds, and storms: all factors that could impact future waste management facilities’ development and operation. The time scales for climate change and waste management are similar. For instance, landfill sites can be operational for decades and still remain active for decades following their closure. There is, therefore, a need to consider potential changes in waste management over significant timescales and respond appropriately.”
Although reliably detecting the trends in climate due to natural variability is difficult, the most accepted current projections suggest that the rate of climate change attributable to GHGs will far exceed any natural climate changes that have occurred during the last 1,000 years (Houghton, 2001). Many of these changes appear to be occurring already. Global mean surface temperatures already have increased by about 1 degree Fahrenheit over the past century. A reduction in the Northern hemisphere’s snow cover, a decrease in Arctic Sea Ice, a rise in sea level, and an increase in the frequency of extreme rainfall events all have been documented (Houghton, 2001).
Climate change could result in changes in temperatures, cloud cover, rainfall patterns, wind speeds, and storms: all factors that could impact future waste management facilities’ development and operation. The time scales for climate change and waste management are similar. For instance, landfill sites can be operational for decades and still remain active for decades following their closure. There is, therefore, a need to consider potential changes in waste management over significant timescales and respond appropriately.
In most developed and developing countries with increasing population, prosperity and urbanization, it remains a major challenge for municipalities to collect, recycle, treat and dispose of increasing quantities of solid waste, especially in a changing climate. A cornerstone of sustainable development is the establishment of affordable, effective and truly sustainable waste management practices in developing countries. It must be further emphasized that multiple public health, safety and environmental co-benefits accrue from effective waste management practices which concurrently reduce GHG emissions and improve the quality of life, promote public health, prevent water and soil contamination, conserve natural resources and provide renewable energy benefits.
The scope of impact of climate change on waste management techniques and activities addressed within this paper is focused on the management of municipal and household waste. The management of other waste streams will also be impacted by climate change but not specifically addressed here. The aim of this paper is to x-ray the potential impacts of climate change on solid waste management through the following objectives:
a. To make an assessment of the risk and impact of climate change variables to the siting and operations of a wide range of waste management facilities in Nigeria.
b. To make recommendations for further research and actions.
Status of Waste Management Sector in Nigeria
The availability and quality of annual data are major problems for the waste sector. Solid waste data is lacking for many countries, data quality is variable, definitions are not uniform and inter-annual variability is often not well quantified. There are three major approaches that have been used to estimate global waste generation:
i) data from national waste statistics or surveys including IPCC methodologies (IPCC, 2006);
ii) estimates based on population (NBSC, 2006)
iii) the use of a proxy variable linked to demographic or economic indicators for which national data are annually collected (US EPA, 2008).
Global solid waste generation rates range from <0.1 t/cap/yr (tons per capita per year) in low income countries to >0.8 t/cap/yr (table 1). Overall, the waste sector contributes <5% of global GHG emissions (US EPA, 2003).
In Nigeria, accurate data on the quantities of municipal solid waste generated in Nigeria are not easy to come by. Nevertheless, Rushbrook and Pugh (1999) outlined the range of per capita waste generation as well as waste densities (on net weight basis) from low and middle income neighborhood of Nigerian cities (see table 2).
In Nigeria, recycling activities are not popular and non-existent. However, the recovery of materials from wastes (scavenging) is practiced on a large scale. This type of recovery takes place at both legal and illegal dump sites where scavengers search continually for valuable metals, plastics, and bottles to be reused or for sale to buyers of different type of scraps. In general, treatment of solid wastes is not often carried out in Nigeria. Incineration of wastes or use of approved sanitary landfill is non-existent. The most common practice is open dumping and burning of waste within residential areas and at illegal and legal dumps. Other strategies employed in disposing waste in the country include:
1. Composting: Composting is a biological process that uses micro-organisms to degrade organic matter using atmospheric oxygen. The stabilized end product occupies a reduced volume compared with the starting materials. The principal emissions are C02 and water vapor, bio-aerosols and odor. It is estimated that nearly a quarter of all household waste is organic and can be composted. In Nigeria, compositing is undertaken in the open. The end product is used in farms.
2. Collection and Transfer: Waste transfer points are used by waste management companies as a means of increasing the efficiency of their waste collection service through the bulking up of waste into larger consignments prior to transfer to dump and disposal sites. At the transfer points, waste is loaded directly into large bulk container vehicles and transferred by road to the dump site. The environmental impacts commonly cited are: odor, dust, bio-aerosols, attraction of bird, noise and surface water pollution and surface water runoff management. Waste transfer stations are often located along the streets, while the dump sites are usually away from the city centers.
3. Combustion: Combustion of MSW results in emissions of C02 (because nearly all of the carbon in MSW is converted to C02 under optimal conditions) and N20. C02 from burning biomass sources (such as paper products and yard trimmings) is not courted as a GHG because it is biogenic.
Waste Management Policies and Regulations in Nigeria
The discovery of a major toxic waste dumped by a foreign company at Koko Town near Warri in Delta State, Nigeria in 1987 led to the establishment of Federal Environmental Protection Agency (FEPA) by Decree No. 58 of 1988. In June, 1999, the Federal Government of Nigeria created the Ministry of Environment and as a result, FEPA’s function was absorbed by the new ministry.
The Federal Ministry of Environment has the following instruments of intervention in place to tackle the problem of environmental degradation including waste management:
– the revised policy on environment, 1999.
– the National Agenda 21 (published in 1999), which touches on the various cross-sectoral areas of environmental concern and map out strategies on how to address them.
These instruments complement what existed in the form of guidelines and standards for environmental pollution control in Nigeria and other regulations that deal with effluents, industrial pollution, waste management and environmental impact assessments (FME, 2003).Among FEPA’s instructions in combating environmental degradation are the waste management Regulation S.1.9 of 1991 and Environmental Impact Assessment (EIA) Decree No. 86 of 1992. FEPA policies regulate the collection, treatment and disposal of solid and hazardous waste for municipal and industrial sources and makes EIA mandatory for any major development project likely to have adverse impact on the environment.
There is also in existence an environmental sanitation edict of 1997 that declared the last Saturday of every month to be used for cleaning the environment for three (3) hours (7am – 10am). This edict is still in force and still being observed all over Nigeria. Every last Saturday of the month, between the hours of 7am and 10am, people are required by law to clean their surroundings and offenders are apprehended and punished as stipulated by the act. The post-1988 environmental laws and regulations continue to prevail without any change.
Climate Change and Solid Waste Management
Climate change traditionally refers to any change in climate over time, whether due to natural variability or as a result of human activity. The United Nations Framework Convention on Climate Change (UNFCCC) defines climate change as a change of climate which is attributable directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over a comparable time periods (IPCC, 2001).
The Earth’s atmosphere contains many types of gases, including those known as “greenhouse gases” which hold in the sun’s warmth. Scientists call this naturally occurring phenomenon the “greenhouse effect”. Greenhouse gases help regulate global temperatures. Certain human activities such as burning fossil fuels and dumping solid waste, however, produce additional greenhouse gases and upset the natural balance by raising global temperatures. Global temperature has risen by about 0.60C over the last 100 years and 1998 was the single warmest year in the 142 – year global instrumental record (Hulme et al, 2002). Climate change could have an impact on the waste management industry, and given the operational time frame for many waste management sites, there is a need to examine whether the issues that arise are of such significance that policy or operational changes are required. This paper concentrates on the issues that are likely to arise from the management of municipal and household waste. However, many of the issues will also apply to the management, treatment and disposal of industrial, commercial, agricultural and construction and demolition wastes.
How Solid Waste Impacts Climate Change
Even before a material or product becomes a solid waste, it goes through a long cycle that involves removing and processing raw materials, manufacturing the product, transporting the materials and products to markets, and using energy to transform the product. Each of these activities has the potential to generate greenhouse gas emissions through one or more of the following means:
a. Energy Consumption: Extracting and processing raw materials, manufacturing products, and transporting materials and products to markets all generate greenhouse gas emissions by consuming energy from fossil fuels.
b. Methane Emissions: When organic waste decomposes in landfills and dumps, it generates methane, a greenhouse gas.
c. Carbon Storage: Trees absorb carbon dioxide, a greenhouse gas, from the air and store it in wood through carbon sequestration. Waste prevention and recycling of wood and paper products allow more trees to remain standing in the forest, where they can continue to remove carbon dioxide from the air, which helps minimize climate change impacts.
Different wastes and waste management activities have varying impacts on energy consumption, methane emissions, and carbon storage. For example, recycling reduces greenhouse gas emissions by preventing methane emissions from landfills or open dumps and by preventing the consumption of energy for extracting and processing raw materials.
Climate Change Impacts on Waste Management Processes
In order to give some indication of how climate change and waste management could interact, table 3 presents a general assessment of what climate change could mean for waste management.
Specific Impacts on Waste Management Processes
Table 4 applies these potential impacts to various waste management process in detail.
Strategies for Reducing Green House Gases in Municipal Solid Waste
Product Stewardship: More and more companies are moving toward redesigning their products to reduce their environmental foot print. By necessity, this trend involves rethinking how their products are managed at end-of-life so that valuable materials can be recovered and reused. The electronics industry is reducing the energy usage of their products as well as reducing reliance on toxic inputs in their products. They are also redesigning their products to make them easier to recycle. The packaging industry is moving towards package designs that use less material (reducing GHG emissions from transportation) and are more easily recyclable (reducing GHG emissions and energy investments in processing virgin materials). Many other industries, such as the carpet, office furniture, and textile industries, are in the process of developing sustainability standards for their products. Companies committed to this kind of change are very interested in metrics that will help them measure the environmental benefits of the changes they are making to their products.
Paperless Office: The rise of computer technology for research, communications, and other everyday workplace functions has presented a major opportunity for source reduction in the modern office. Today’s offices are commonly equipped with all the necessary technologies to bypass paper entirely and rely instead on electronic communication. This form of “comprehensive” source reduction comes with significant GHG benefits.
Anaerobic Digestion: Several facilities are using this technique to produce CH4 from mixed waste, which is then used to fuel energy recovery. The approach generates CH4 more quickly and captures it more completely than in a landfill environment and thus, from a GHG perspective offers a potentially attractive waste management option (Environment Canada, 2001).
Bioreactors: Bioreactors are a form of controlled land filling with the potential to provide reliable energy generation from solid waste, as well as significant environmental and solid waste management benefit. The concept is to accelerate the decomposition process of landfill waste through controlled additions of liquid and leachate recirculation, which enhances the growth of the microbes responsible for solid waste decomposition. The result is to shorten the period of landfill gas generation, thereby rendering projections of landfill gas generation rates and yields that are much more reliable for landfill gas recovery.
Compost as Landfill Cover: Using compost as landfill cover on closed landfills provides an excellent environment for the bacteria that oxidize CH4. Under optimal conditions, compost covers can practically eliminate CH4 emissions. Furthermore, the covers offer the possibility of controlling these emissions in a cost-effective manner. This technology is particularly promising for small landfills, where landfill gas collection is not required and the economics of landfill gas-to-energy projects are not attractive. Ancillary benefits also might arise in the compost market from this technique if using compost as a landfill cover becomes a widespread practice. An increase in composting could reduce the quantity of organic waste disposed of at MSW landfills, thereby reducing CH4 emissions.
Biomass Pyrolysis/Gasification: Pyrolysis and gasification are similar technologies in which waste is thermally decomposed in an oxygen- poor environment. In pyrolysis, organic matter is vaporized and the vapor is condensed and collected as “bio-oil”, which can then be burned for energy (The Biomass Technology Group, “Flash Pyrolysis”). The advantage of pyrolysis over normal waste-to energy incineration is that pyrolysis produces a liquid fuel that can be stored and used in a number of applications (similar to biodiesel), whereas waste-to-energy (WTE) produces only electricity for immediate consumption. Biomass gasification is similar except that a gas rather than a liquid is produced.
Co-firing Waste Biomass: For utilities and power generating companies with coal-fired capacity, co-firing involves replacing a portion of the coal with biomass at an existing power plant boiler. This replacement can be achieved by either mixing biomass with coal before fuel is introduced into the boiler or by using separate fuel feeds for coal and biomass. Specific biomass feedstocks include agricultural and wood waste, MSW, and industrial wastes.
This study has begun the process of understanding what climate change could mean for waste management in Nigeria. As it is a new area, it is recommended that more research is carried out into specific impacts. The selection of truly sustainable waste strategies is very important for both the mitigation of GHG emissions and for improved urban infrastructure.
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