Biogas facility in Lewe, Germany
Collecting, recycling, treating and disposing of increasing quantities of solid waste and wastewater remains a major challenge for developed and developing countries alike.
Growing landfills around the world mirror the global trends of increasing population, prosperity and urbanization. What is more worrying is excessive waste generation itself: finite resources are transformed into single-use, GHG-emitting goods that all too quickly end up in landfills. At the same time, there is a growing realization that waste can be a resource, too.
Overall, the waste sector contributes less than 5 per cent of global GHG emissions. The largest source is landfill methane (CH4), followed by wastewater CH4 and nitrous oxide (N2O). Nitrous Oxide (N2O) contributes to climate change and a major source is human sewage and further emissions occur during the wastewater treatment process. Methane is also emitted during wastewater transport, sewage treatment processes and leakages from anaerobic digestion of waste or wastewater sludges.
In addition, minor emissions of carbon dioxide (CO2) emerge when waste containing fossil carbon is burnt (e.g. plastics; synthetic textiles) and the non-biomass portion of incinerated waste. Open burning of waste in developing countries is a significant local source of air pollution, constituting a health risk for nearby communities. Composting and other biological treatments emit very small quantities of GHGs. It is worth noting that landfill emission continues several decades after the waste is disposed in them, which makes it difficult to estimate emission trends.
Another emerging issue with regard to waste management is ‘e-waste’ – discarded electrical and electronic products that are an essential part of today’s lifestyle. The amount of appliances put on market every year is increasing both in developed countries and developing ones. This problem is aggravated by rapid product innovations and replacements.
In China alone, about 14 million PC were sold in 2005, as well as more than 48 million televisions. Nearly 20 million of refrigerators and 7.5 million air conditioners were sold in 2001. Some 20 to 50 million metric tonnes of e-waste – which includes lead, cadmium, mercury and other hazardous substances – are generated worldwide every year as a result of the growing demand for computers, mobile phones, TVs, radios and other consumer electronics.
The carbon impacts of e-waste can be minimized by diverting appliances which have reached the end of their life from landfills, and recycling/recovering materials, in particular those having a huge impact in terms of primary mining or production (e.g. gold, aluminium).
Food waste constitutes a significant part of waste management. Over half of the food produced today is either lost, wasted or discarded as a result of inefficiency in the human-managed food chain. In Australia it is estimated that food waste makes up half of that country's landfill. At the other end of the spectrum, the freeganism movement amongst the North American middle class (www.freegan.info) makes an interesting statement on recycling, waste and anti-consumerism. Among other radical acts of refusal to subdue themselves to the dominant economic laws of our societies, they feed themselves on meals prepared from food found in urban waste bins.
In most developed and developing countries with increasing population, prosperity and urbanization, it remains a major challenge to collect, recycle, treat and dispose of increasing quantities of solid waste and wastewater.
Overall, the waste sector contributes less than 5 per cent of global GHG emissions, with total emissions of approximately 1300 MtCO2-eq in 2005. The largest source is landfill methane (CH4), followed by wastewater CH4 and nitrous oxide (N2O). In addition, minor emissions of carbon dioxide (CO2) result from incineration of waste containing fossil carbon (e.g. plastics; synthetic textiles). Landfill emissions continue several decades after waste disposal, thus estimating emission trends is complex and requires models that include temporal trends. Methane is also emitted during wastewater transport, sewage treatment processes and leakages from anaerobic digestion of waste or wastewater sludges. The major sources of N2O are human sewage and wastewater treatment. The CO2 from the non-biomass portion of incinerated waste is a small source of GHG emissions. Open burning of waste in developing countries is a significant local source of air pollution, constituting a health risk for nearby communities. Composting and other biological treatments emit very small quantities of GHGs.
The Electronic Industry over last decades has revolutionized the world: electrical and electronic products are an essential part of today's life around the planet. Such appliances include many domestic devices like refrigerators, washing machines, mobile phones, personal computers, printers, TVs and so on.
The amount of appliances put on market every year is increasing both in developed countries and developing ones. In the EU the total weight of electronic appliances put on market in 2005 ranged up to more than 9.3 million tons and in China about 14 million PCs have been sold in 2005, as well as more than 48 million of TV, nearly 20 million of refrigerators and 7.5 million of air conditioners in 2001. Every year the amount of appliances sold globally increases. This problem is aggravated by rapid product innovations and replacement.
Solutions
The marsh gas produced during wastewater treatment is used for power generation (Rizhao, China)
The mitigation of GHG emissions from waste must be addressed in the context of integrated waste management. Most technologies for waste management are mature and have been successfully implemented for decades in many countries. Nevertheless, there is significant potential for accelerating both the direct reduction of GHG emissions from waste as well as extended implications for indirect reductions within other sectors.
A wide range of mature, environmentally-effective technologies are available to mitigate emissions and provide public health, environmental protection and sustainable development benefits. Collectively, these technologies can directly reduce GHG emissions (e.g. through landfill gas recovery, improved landfill practices, engineered wastewater management) or avoid significant GHG generation (e.g. through controlled composting of organic waste, state-of-the-art incineration and expanded sanitation coverage). In addition, waste minimization, recycling and re-use represent an important and increasing potential for indirect reduction of GHG emissions through the conservation of raw materials, improved energy and resource efficiency and fossil fuel avoidance.
Under the Kyoto Protocol’s Clean Development Mechanism (CDM), a landfill operator from a developing country can receive carbon credits from a methane capturing project and enter into emission reductions purchase agreements with a buyer from an industrial country. The buyer typically agrees to pay the landfill operator in return for GHG emission reductions achieved through methane capturing and destruction, and may then retain the certified emission reductions (CERs)to meet compliance objectives to reduce GHGs, or sell them to a third party.
Through its capacity building activities for the CDM, UNEP is currently supporting a number of landfill projects in the developing world, such as the Yaoundé and Douala municipal landfill projects developed by HYSACAM, a Cameroonian landfill management enterprise. The projects, which will capture and flare landfill gas produced at both landfills, consist of collection systems, gas extraction wells, piping, mechanical blowers, landfill gas condensate and flaring installations, as well as leachate drainage and treatment equipment. Both projects will reduce emissions by capturing and flaring more than 50 per cent of methane emissions or the equivalent of more than 100,000 tons of CO2 that is annually released into the atmosphere at each site.
Solving the e-waste problem helps in terms of climate change actions. Carbon impacts and opportunities of e-waste depends on two concurrent effects:
Diverting end-of-life appliances from landfill, and then ensuring a proper control over greenhouse gas emissions (GHGs) and;Recovery of materials, in particular those having a huge impact in terms of primary mining or production (e.g. gold, aluminium,…).
Proper treatment of end of life appliances represents the fundamental step in closing the loop in terms of life cycle management. In the case of refrigerators, there’s a straight and outstanding link with GHGs. Diverting from landfill and recovering the ozone depleting substances is crucial to tackle climate change issue. For other categories of e-waste , the recovery of precious metals or other metals with a high GHGs and other environmental impacts in the production or mining stage play a relevant role (e.g. for the ICT sector and appliances like mobile phones or PCs).