UN Sustainable Development Goals Addressed

  • Goal 3: Good Health & Wellbeing

  • Goal 11: Sustainable Cities & Communities

  • Goal 12: Responsible Production & Consumption

  • Goal 17: Partnerships for the Goals

2021 Global Design Challenge Finalist

This design concept was developed by participants in the Institute’s Global Design Challenge. The descriptions below are from the team’s competition entry materials.

Location: Utrecht, Netherlands
Team members: Rutger Remmers, Beth Dodds, Jiska Vaarwerk, Stefano Roccio

Glass tube with liquid sloshed out of it supporting jar of ethanol and flora and fauna
Image: Project Team / PURAERA / Copyright © - All rights reserved

Innovation Details

Inspired by the mucous of the human respiratory system and the net-like feeding structures of marine organisms called salps, the Puraera team designed a hydrogel to capture pollutants from the air in metro transit systems such as the London Underground. The biodegradable hydrogel would be placed on the sides of train tracks inside stations to allow for the best capture of pollutants harming human health. While specifically designed for the conditions of the London Underground, a few small adjustments can recreate the solution for other air quality issues and point source pollution.

Define the problem being solved. All over the world, public transport is promoted as a means of sustainable transport. Unsurprisingly, trains are also implemented increasingly in cities, often poured in the form of metro networks. Trains, especially older models, also produce a lot of pollution, which accumulates in the underground platforms and tracks. Its users, including commuters, students, and travelers, are exposed on a daily basis to particulate matter, PM2.5. This negatively affects their health, specifically the respiratory system. Short term exposure can lead to throat and lung irritation, whereas long term exposure increases the chance of getting lung cancer, heart disease, and other problems. PM 2.5 is prevalent in the London Underground, despite all the implemented measures that reduce air pollution. Here, tackling the hazardous pollution is most difficult, due to the old age of the tunnels and the limited manpower available for cleaning.

 

What organisms/natural systems helped inform this design? The biological model that has acted as prime inspiration is mucus, a slippery secretion produced by certain membranes. In many mammals, it is found in the digestive tract, the respiratory tract, and the reproductive organs. Mucus consists of 95% water, and the rest is made up by lipids, inorganic salts, s, and antimicrobial enzymes. Its composition allows it to act as a protector of the cells by inhibition of bacterial proliferation and capturing pollutants. Humans are only one example of utilizing mucus as a defense mechanism. Salps, a marine example, depend on it for its survival as salps use mucus to catch food. These organisms own an efficient filter made of mucus filaments. Through this netlike structure, they capture organisms including viruses and bacteria. This allows the macroscopic salps to survive on a diet of some of the tiniest forms of life.

 

What does this design do? The design uses a mucus-inspired hydrogel to capture air pollutants from the air in metro systems. The small particles in the air will stick to the hydrogel, which prevents pollution to be inhaled by passengers. This hydrogel will be produced using a waste product from growing the fungus schizophyllum commune in laboratory conditions, called schizophyllan. This substance will be precipitated using ethanol, although other chemicals are also being researched. This way, a highly viscous gel-like substance will be created. This hydrogel can easily be turned into a slab that can be placed on a wall. Within the London Underground, the placement of the hydrogel is important. The pollution comes from the wear and tear of the rails, which is a result of braking. The placement of the hydrogel closest to this source will bind the maximum amount of pollutants from the air. Therefore, the best places for the design are the walls on the sides of the track inside the stations. In the stations, most of the braking takes place, which means that pollution production is the highest here. This is also a place where health concerns are very high, as all passengers need to pass through stations in order to board trains. Notably, air filtering systems are (mostly) absent here. Furthermore, the walls on the sides of the tracks are the closest place possible to the tracks, which allows for maximized binding of pollutions. Once the hydrogel has captured the maximum amount of pollutants, it can either be washed and reused, or sold as fertilizer for plants. The components of the hydrogel are completely biodegradable and the pollutants in the London Underground can be taken up by plants and used for growth. If the hydrogels are washed for reuse, the pollutants may be used for other purposes.

 

How does this solution address the problem or opportunity? This model captures pollutants at the source, thereby creating better air quality in underground environments. PM2.5 poses the greatest health risk to individuals with pre-existing health conditions, in particular those that affect lung function, (asthma, COPD, etc) but also in healthy individuals in the development of these diseases, cancers, and even Alzheimer’s disease. Thus, by reducing the exposure of these particles to passengers, the hope is to reduce the occurrence and severity of these diseases. Additionally, the model aims to be circular by reducing the amount of waste produced and cleaning required. Hydrogels are produced from waste products from other industries. The hydrogel in the system can be reused by precipitating the particulate matter, or alternatively used as fertilizer/plant growth medium in areas around London or in hydroponic systems, since many components of PM2.5 are beneficial to plant growth. The hydrogel is fully biodegradable.

 

Element: How compatible is this design with all surrounding living systems? Is it safe? How is it more sustainable than the alternatives? The design minimizes the pollution inhaled by users of the London Underground, which ultimately reduces health risks. Therefore, it adds to the life of the people that live in the city of London. This hydrogel is made from natural materials, which do not pose any threats to passengers. Moreover, the product is out of reach of travelers, as it is placed below the walking area. Finally, the product takes up very little space, thus taking into account the already cramped situation in the London Underground. Regarding sustainability, the hydrogel is part of a life cycle that makes use of waste streams and creates raw materials.

 

(Re)connect Element: Describe how this innovation helped the team connect with the natural world. (Re)connection is very much about going outside and (re)discovering the profound connections with the natural world. Nevertheless, this project and the idea gave the team the opportunities to investigate in detail the capabilities and intrinsic resourcefulness of the body, and in this case, the clearance of pollution. It was also interesting to look into organisms that possess structures and characteristics similar to humans. It stood out that similar structures are always adapted to the particular needs of that organism and the habitat it resides in.

 

How were Nature’s Unifying Patterns or Life’s Principles applied to this design? The most important component of this design is circularity. The hydrogels are made of waste products of another industry and the harmful pollutants can be captured and used as fertilizer or other purposes. Another important lesson is choosing optimization above maximization. The capturing of all pollutants would probably require a lot of energy and non-renewable resources, thus doing more harm than good. This design aims only to catch so many particles in a given time period, allowing for a new lower equilibrium closer to the levels above ground. By sticking to nature’s way of design, it is ensured that “waste” products will not be dangerous for living organisms, and can even be used by plants. Finally, the design is very much locally attuned. It was specifically designed for the conditions of the London Underground, but with a few small adjustments, it can be used in similar situations.