How might we develop a low-tech water treatment solution to improve access to clean water?
Worldwide, nearly 1.8 billion people lack access to safe drinking water, making up practically a third of the global population.
Even more people also lack access to safe sanitation, with about 2.5 billion people — or 35% of the world’s population — unable to meet their basic water needs to maintain daily hygienic routines.
THE IMPACTS OF SEWAGE POLLUTION
Around the world, urban centers are growing exponentially as population levels rise and increasingly more rural populations relocate to urban areas for job opportunities. Urban infrastructures must be adapted to maintain how greater populations will process more resources without negatively affecting the local environment.
Sewer overflows are an increasing phenomenon in many cities around the world, where growing populations are processing an increasing amount of wastewater that local municipal infrastructures were not originally sized to handle. Sewer overflows can severely impact local aquatic ecosystems by polluting the environment, reducing the amount of oxygen in water, and increasing the mortality rates of aquatic wildlife.
THE DESIGN CONTEXT
Globally, less than 1% of the Earth’s freshwater supply is accessible and safe to drink; this proportion drops even further in most desert regions where clean water access is severely lacking.
It’s estimated that humans are only able to use about 0.3% of the water on Earth, which constrains our supply model even more drastically.
Yet though water could be classified as a nonrenewable resource, it’s also among our most circular of resources, as all water — even consumed, polluted water — returns to the atmosphere and global bodies of water for reutilization within a relatively short timespan. With a growing population demanding greater amounts of an increasingly scare resource, it’s time we started looking at ways of facilitating and augmenting our water lifecycle to meet each other’s daily needs.
PRIOR & EXISTING SOLUTIONS
Building or replacing water pipes is typically the most intensive but effective method of provisioning clean water to entire communities. Infrastructure upgrades are large-scale operations typically costing hundreds of thousands or even millions of dollars.
Providing water filters to households or individuals is a short-term solution to purifying water in regions where there’s limited safe water infrastructure. Many filters are produced relatively cheaply and can be portable for users.
Green infrastructure including rain gardens, bioswales, and constructed wetlands can be used for both households and communities to capture excess rainwater or wastewater during storm surges. Many green infrastructure solutions are low- cost and have a variety of benefits outside of reducing sewage pollution.
Drainage cisterns are typically constructed below-ground to capture and hold excess stormwater and wastewater during flood periods. Water is then slowly released back into municipal wastewater infrastructure after peak levels reside, where it can be processed at the municipal wastewater treatment plant. Drainage cisterns are expensive projects that can last several years before completion.
Greywater systems that recycle water within building structures can directly reduce the proportion of wastewater that becomes sewage pollution. However, their intensive installation processes make them feasible solutions only for new developments or complete retrofits.
AREAS FOR INNOVATION
Household technologies for water filtration and greywater recycling can be expensive, often making them inaccessible for low-income families who are at the greatest risk of receiving unsafe water. Greywater systems are even less financially feasible for many people, because their installation requires repiping the connections between the sinks, showers, toilets, and any outdoor space, which in turn requires gutting household walls and floors and reinstalling those as well. As an effect, greywater systems as the main wastewater recycling technology availble to date are often only realistic for new developments or complete retrofits.
One of our guiding points of innovation was designing a household water filter and greywater system that would be affordable to a low-income family. To do so, we prioritized passive design and a compact equipment size to reduce costs. We also examined where in the household could greywater equipment be retrofitted without removing walls or flooring to enhance the accessibility of the installation process.
Operating and maintaining both a water filter and a greywater system can be tricky, and in many cases requires at least some training and practice before homeowners feel confident caring for the technology on their own. Users can forget to change the cartridge of their water filter – in effect risking exposure to contaminants – or to replace membrane filters on wastewater systems, thereby risking equipment failure as an effect of brine build-up.
To optimize the usability of our technology, we applied the principles of intuitive and human-centered desgn to style an interface that could be operated intuitively without relying extensively on written instructions. We also limited the need for manual operations wherever possible by constructing passive and automated mechanisms.
Cycleau is a compact, low-cost technology designed to capture and treat greywater to drinking water within buildings.
Created after a growing movement of off-grid developments known as “Earthships,” Cycleau aims to advance how we minimize our water footprints while also augmenting our own access to a clean, reliable water resource.
Cycleau operates as both a stand-alone piece of equipment as well as one that integrates into a household’s preexisting water infrastructure, with connections available for supply lines and drain pipes that may already be in use.
Contaminated greywater can be treated in this compact, low-energy system as it passes through five comprehensive stages of water treatment which include coagulation, bed media filtration, membrane filtration, disinfection, and advanced oxidation.
Our technology keenly innovates on existing water treatment system design by adopting a modular construction that allows what were once exclusively massive-scale systems to be reconfigured into a compact equipment piece capable of fitting below the average sink or wash basin.
HOW IT WORKS
BED MEDIA FILTRATION
Larger particles are then filtered out through a sediment filter containing fine sand, activated carbon, and drainage gravel, all together known as “bed media.” This reduces the load of particles that will eventually pass through membrane filters, and also improves the appearance and taste of water.
Membrane filters with pore sizes ranging from 10 nanometers to 10 micrometers can filter out the smallest of particles which still contaminate water.
In Cycleau, a microfilter, ultrafilter, and nanofilter are used consecutively to comprehensively filter water three times. We have selected to use these three membrane filters in place of a single reverse osmosis filter as another point of innovation when compared to similar products. Using these three membranes reduces the sediment load which can threaten the durability of any single membrane, while also reducing the energy usage and amount of water which can be rejected as discharge by a reverse osmosis filter.
Even with all that filtration, some bacteria and pathogens can still be lurking in the water. Disinfection, either with the chemical chlorine or through UV irradiation, can inactivate bacteria to prevent consumers from being infected. In Cycleau, an ultraviolet bulb disinfects the water after filtration.