By Kayleen White
Principal, Wastewater Engineer
It’s widely acknowledged that water, an essential human need, is becoming an ever scarcer global resource. Most people prefer to think as little as possible about wastewater, which is any water that has been affected by human use.
But wastewater is an asset that engineers are learning to harness.
As with every business operating in today’s environment, rapid change continues to impact us and several emerging trends in the world of wastewater are particularly exciting.
Energy from wastewater treatment
Anaerobic treatment is likely to continue being developed as it is a proven and energy-efficient method for treating wastewater. It uses anaerobic bacteria to convert organic pollutants, measured as COD (chemical oxygen demand), into biogas in an oxygen-free environment. This biogas can be used as a renewable fuel source.
My team at SMEC recently recommended the use of a new anaerobic treatment plant for a small facility, and it is particularly pleasing to see the process being successfully adapted to benefit small scale operators. This century has seen tremendous progress in the industry’s ability to model anaerobic processes, and that is likely to lead to anaerobic treatment becoming more common at wastewater plants.
”We help prevent adverse outcomes, maximise the use of positives like nutrients, and help the world move towards a circular economy.
Experts in adaptation
The wastewater treatment industry has a history of enabling new processes to be adapted to different purposes.
As an example, the activated sludge process was developed in a laboratory in the early 1910s and made its way to townships in the 1920s and 1930s. In the 1970s and 1980s it was “miniaturised” to compact plants that could be fitted into a high-rise building’s basement and treat residents’ wastewater.
A notable example of this miniaturisation trend is the improvements in household-scale composting toilets. It is likely that these will be used more widely in the future, but they won’t be suitable for everyone, and safe use for the composted sludge must be agreed. A side benefit could be a reduction in suspended solids in wastewater, which can, in turn, offset the reduced use of water resulting from the Millennium Drought. And the current ultimate in miniaturisation, of course, is the potable wastewater reuse system on the International Space Station.
Moving towards a circular economy
Modern wastewater treatment has its origins in concerns over public health and, to some extent, public amenity. On one level, it was about avoiding odour and aesthetic problems. On a more immediate level, it was about continuing to meet public health needs.
But nowadays, we are acutely aware of the need to manage the environmental impact for the communities of the future. Our specialists advise clients on selecting levels of treatment, types of treatment processes, and best forms of reuse. We help prevent adverse outcomes, maximise the use of positives like nutrients, and help the world move towards a circular economy. A circular economy is an alternative to a traditional linear economy (make, use, dispose) in which we keep resources in use for as long as possible, extract the maximum value from them whilst in use, then recover and regenerate products and materials at the end of each service life.
As an example, two of our projects return bio-solids to agricultural areas, which is a nice close to the nutrient cycle. When the initial treatment is anaerobic, this approach can also be combined with power generation and the use of struvite precipitation processes, which allows for a far higher quality nutrient by-product.