Closing the gaps for a circular economy
Cities provide great opportunities for connectivity, jobs, and culture. The proximity of everything allows for increased efficiency and maximized profits. However, one issue has always haunted urban areas – the issue of waste. With so many people concentrated in one relatively small area, waste can become a serious environmental hazard and health threat. Human excrement can carry pathogens, cause eutrophication and degrade the natural environment. Furthermore, depending on the conditions at which the waste is disposed, it can release harmful gasses such as hydrogen sulfide, nitrous oxide, and methane. To make matters worse, modern sewage contains increased levels of chemicals previously foreign to any water body, such as drugs, micro-plastics, hydrocarbons, and high quantities of detergents.
Historically, cities have been densely polluted areas with poor water and air quality. The main way that we have, and often still do attempt, to minimize the problems is by physically removing our waste to a satisfactory distance. In some cases this meant throwing it out of the window and in more civilized times, we developed sub-terrenial canals that brought human excrement out of the city and into local water bodies. The latter provided a temporary solution to human health concerns but nothing in terms of environmental protection. This has resulted in large ecological footprints related to urbanization. Since then many cities have become more advanced in their methods of disposing of not only excrement but also other forms of waste. However, for most this historical attitude and fear of waste has unfortunately made waste into something that has to be gotten rid of, not as a potential opportunity.
Some cities have begun to realize the potential of sewage as biogas and even fertilizer for crops. Utilizing biogas and fertilizer potential has both economic incentive as well as reduces dependence on fossil fuels. Take the Newtown Creek wastewater treatment plant in Brooklyn, New York for example. It is the largest of 14 wastewater treatment plants in New York City. It is a state of the art facility that mixes both art and tech, with massive egg-shaped bio-digesters that decorate the skyline and generate natural gas, fertilizer, and water. Everyday this plant produces 1,200 tons of biosolids for fertilizer…. that’s a lot of shite, but can it make a difference? How much CO2 emissions could that mitigate? Assuming we use 7.35 tons of biosolids per ha of farmland in place of synthetic fertilizer, with a savings rate of 0.77 tons of CO2 per ha (when transport is considered), that would save us 45,885.7 tons of CO2 per year! The natural gas produced is injected into the grid and heats roughly 2500 homes, reducing the annual CO2 emissions by about 16,000 tons annually. This is the equivalent of removing about 3,000 cars off the road! So all in all we are talking about a reduction of about 61,885 tons of CO2 emissions for 1,000,000 people. If that doesn’t sound like a great opportunity to close the loop between waste and resources I don’t know what does.
Another Fantastic example of a city attempting to close the holes in their economy is San Francisco. However, San Francisco has focused mainly, not on what goes down the drain but on what goes in the can. San Francisco already diverts 80% of its waste from landfills into composting or recycling programs and by 2020 it aims to be a zero waste city. Despite dealing with a similar problem, San Francisco chose a very different approach than New York. While NYC employed an infrastructural and technological approach, San Francisco took a more interdisciplinary approach that involved law, economics, and education. SF was the first city to pass a mandatory composting laws and ban a variety of environmentally unfriendly items such as styrofoam and plastic bags. They simultaneously used economic incentives such as higher collection rates for non recyclable non-compostable items. Furthermore, unlike in NYC where there are countless decentralized private companies managing trash, there is one waste collection company (Recology) in SF, allowing for smooth implementation and realization of goals. Finally, they had effective educational campaigns that promoted these programs and gained widespread public support. The cherry on top is that this program is run fully on collection fees and does not have any substantial difference in cost to neighboring programs! Sounds like a win-win situation.
These two cities are an inspiring example of how the traditional pitfalls of cities can be flipped into collective benefits. I think it is also a sign that it is about time that we change our perspectives about waste to an arguably more simplistic one. Let’s put it back into our economy and not let it destroy the environment. Let’s design products and infrastructure that accommodates the reality that our waste has to go somewhere. It doesn’t just disappear. Or in other words lets try to remember the old saying “One man’s trash is another man’s treasure”.
Brigham K. July 14 2018. How San Francisco sends less trash to the landfill than any other U.S city. CNBC. [Internet] [cited 2019 March 30]. Available from: https://www.cnbc.com/2018/07/13/how-san-francisco-became-a-global-leader-in-waste-management.html
Brown S, Leonard P. 2004. BIOSOLIDS AND GLOBAL WARMING : MANAGEMENT IMPACTS.
Chahbazpour D. 2017. EPA Renewable Natural Gas Technology Transfer Workshop National Grid ’ s Journey.
NYC DEP (New York City Department of Environmental Protection). 2019. Wastewater. March 30.