Wastewater comes from:
- Flushing toilets, doing laundry, washing dishes, and anything else that sends “used” water into a drain.
- Commercial and industrial operations
- Rainwater run-off, in areas where rain isn’t handled with separate pipes
In urban areas, wastewater is collected via regional and municipal pipe systems that flow underground to treatment plants where it is then treated and safely released to local waterways.
Recovering resources from wastewater
Wastewater and sewage are no longer seen as only a waste product, but is increasingly viewed as something that can provide valuable resources. ‘Water Resource Recovery’ is a fairly new terminology brought forward by WEF (Water Environment Federation) to describe wastewater treatment facilities and their ongoing efforts to recover and reuse resources.
Many resources are present in wastewater, which can be recovered and used, improving our overall environment and ecosystems. Examples include water, energy and heat, and nutrients.
Water can be recycled or reclaimed. Treated wastewater that is ready to release can be treated further, allowing the reclaimed water to be used instead of potable water for many different purposes, such as toilet flushing, industrial purposes, fire systems, and irrigation of gardens, parks, and golf courses.
Reusing water, which is a common practice in many arid regions of the world, conserves potable water needed for other purposes.
Energy from wastewater
Renewable energy can be recovered from wastewater by treating it anaerobically (without oxygen) and creating biogas, which contains “green”, renewable natural gas, also called biomethane. Once contaminants are removed, the biomethane can be used as a transport fuel or can be used to create electricity and heat. Doing so reduces our reliance on fossil fuels and reduces greenhouse gas emissions that contribute to global warming.
Heat can also be directly recovered from wastewater, because wastewater is warm (due to showers, baths and laundry machines). Recovered heat can be used to heat nearby buildings, including the Annacis Research and Event Centre.
Wastewater contains phosphorus and nitrogen, which are key ingredients in fertilizer. These can be recovered and beneficially used for landscaping and agriculture. Phosphorus recovery is particularly important, because worldwide phosphorus supplies are limited.