Why Do We Need Solid Waste Management?

Some countries have achieved considerable success in solid waste management. But the rest of the world is grappling to deal with its wastes. In these places, improper management of solid waste continues to impact public health of entire communities and cities; pollute local water, air and land resources; contribute to climate change and ocean plastic pollution; hinder climate change adaptation; and accelerate depletion of forests and mines.

Garbage_Bangalore

Compared to solid waste management, we can consider that the world has achieved significant success in providing other basic necessities like food, drinking water, energy and economic opportunities. Managing solid wastes properly can help improve the above services further.

Composting of organic waste can help nurture crops and result in a better agricultural yield. Reducing landfilling and building sanitary landfills will reduce ground and surface water pollution which can help provide cleaner drinking water. Energy recovery from non-recyclable wastes can satiate significant portion of a city’s energy requirement.

Inclusive waste management where informal waste recyclers are involved can provide an enormous economic opportunity to the marginalized urban poor. Additionally, a good solid waste management plan with cost recovery mechanisms can free tax payers money for other issues. In the case of India, sustainable solid waste management in 2011 would have provided

  • 9.6 million tons of compost that could have resulted in a better agricultural yield
  • energy equivalent to 58 million barrels of oil from non-recyclable wastes
  • 6.7 million tons of secondary raw materials to industries in the form of recyclable materials and livelihood to the urban poor

Solid waste management until now has only been a social responsibility of the corporate world or one of the services to be provided by the municipality and a non-priority for national governments. However, in Mumbai, the improperly managed wastes generate 22,000 tons of toxic pollutants like particulate matter, carbon monoxide, nitrous and sulfur oxides in addition to 10,000 grams of carcinogenic dioxins and furans every year. These numbers are only for the city of Mumbai. This is the case in cities all across the developing world. There are numerous examples where groundwater is polluted by heavy metals and organic contaminants due to solid waste landfills.

Solid waste management expenditure of above $ 1 billion per year competes with education, poverty, security and other sustainable initiatives in New York City. Fossil fuels for above 500,000 truck trips covering hundreds of miles are required to transport NYC’s waste to landfills outside the city and state. Similarly, New Delhi spends more than half of its entire municipal budget on solid waste management, while it is desperate for investments and maintenance of roads, buildings, and other infrastructure.

Solid waste management is not just a corporate social responsibility or a non-priority service anymore. Improper waste management is a public health and environmental crisis, economic loss, operational inefficiency and political and public awareness failure. Integrated solid waste management can be a nation building exercise for healthier and wealthier communities. Therefore, it needs global attention to arrive at solutions which span across such a wide range of issues.

Generating Electricity from Municipal Solid Waste

We live in a throwaway society that accumulates vast quantities of waste every day. While this comes with pressing challenges, there are also opportunities for professionals including electrical engineers to process at least some of the waste to produce much-needed renewable energy.

According to the U.S. Energy Information Administration (EIA), in 2018 a total of 68 U.S. power plants generated around 14 billion kilowatt-hours of electricity from 29.5 million tons of combustible municipal solid waste (MSW). Biomass, which comes from plants and animals and is a source of renewable energy, was responsible for more than half (about 51%) of the electricity generated from waste. It also accounted for about 64% of the weight of the MSW used. The rest of the waste used was from other combustible materials including synthetic materials made from petroleum and plastics. Glass and metal are generally not noncombustible.

WTE_Plant_Belgium

Waste-to-Energy is now widely accepted as a part of sustainable waste management strategy.

Municipal Solid Waste in the U.S.

Burning MSW is not only a sustainable way to produce electricity, it also reduces the volume of waste that would inevitably end up in landfills. Instead, the EIA estimates that burning MSW effectively reduces waste volumes by about 87%.

But, while more than 268 million tons of MSW are generated in the United States every year, in 2017, only 12.7% of it was burned to recover energy. More than half (52.1%) went to landfill, about a quarter (25.1%) was recycled, and the rest (10.1%) was used to generate compost.

According to a U.S. Environmental Protection Agency (EPA) fact sheet on sustainable materials management published in November 2019, the total MSW generated in 2017 by material, comprised:

  • Paper and paperboard, primarily containers and packaging 25%
  • Food 15.2% (see below)
  • Plastics 13.2% (19.2% of the total materials that ended up in landfill were plastics)
  • Yard trimmings 13.1% (most of this type of waste is composted)
  • Rubber, leather and textiles 9.7%
  • Metals 9.4%
  • Wood 6.7%
  • Glass 4.2%
  • Other 3.5%

Indicating tremendous human waste in its worst form, 22% of the material that ended up in landfill was classified as food. Trashed food was also the product category with the highest landfill rate, at an alarming 75.3%. Nearly a quarter (22%) of materials that were combusted with energy recovery were food, and overall, food was also the highest product category to recover energy, with a rate of 18.4%.

The total MSW combusted to generate energy was made up of the following materials:

  • Food 22%
  • Plastics 16.4%
  • Rubber, leather, and textiles 16.1%
  • Paper and paperboard 13.2%
  • Wood 8.4%
  • Metals 8.6%
  • Yard trimmings 6.2%
  • Glass 4.3%
  • Other 4.3%

Generating Electricity from MSW

There are a variety of technologies for generating electricity from municipal solid waste, but in the US the most common system involves mass burning of MSW in a large incinerator that has a boiler that produces steam, and a generator that produces electricity. Another entails processing MSW into fuel pellets for use in smaller power plants.

Waste materials destined to be processed to generate electricity

Generating electricity in mass-burn WTE plants is remarkably straightforward and follows seven basic steps:

  1. The MSW is dumped out of garbage trucks into a large pit.
  2. A crane with a giant claw attachment is used to grab the waste and dump it into a combustion chamber.
  3. The waste, which now becomes the fuel, starts to burn, releasing heat.
  4. The heat that is released turns water in the boiler into high-pressure steam.
  5. The steam turns the turbine generator’s blades and produces electricity.
  6. The mass-burn plant incorporates an control system to prevent air pollution by removing pollutants from the combustion gas before it is released through a smoke-stack.
  7. Ash is inevitably produced in the boiler and the air pollution control system, and this has to be removed before another load of waste can be burned.

While the volumes burned as fuel in different plants vary, for every 100 pounds of MSW produced in the US, potentially, more than 85 pounds could be burned to generate electricity.

Of course, the USA isn’t the only country that uses waste-to-energy plants to generate electricity from MSW. And in fact, when compared to a lot of other countries, the percentage of MSW burned with energy recovery in the U.S. is minimal. At least nine countries are named by the EIA as bigger producers of electricity from municipal waste. In Japan and some European countries, for instance, there are fewer energy resources and not much open space available for landfills. So generating electricity from MSW is an obvious opportunity.

The four leading nations identified by the EIA as burning the most MSW with energy recovery are:

  • Japan 68%
  • Norway 54%
  • Switzerland 48%
  • France 35%
  • The United Kingdom 34%

One thing’s for certain, the percentages are all set to continue increases globally as the move towards sustainability gains momentum. And U.S. percentages are going to increase too.