Continuing advances in wastewater-to-energy technology
September 24, 2020
September 24, 2020
How thermal hydrolysis accelerates digestion to efficiently process wastewater while recovering valuable resources
The consequences of climate change include deadly droughts, forest fires, high intensity storms, floods, and more frequent extreme weather events. But one of the most significant ramifications of climate change isn’t always in the news: The global water crisis.
Not only do millions of people lack access to clean water, but most of the water being used is returned to clean water sources as is. In fact, the UN estimates that approximately 1.8 billion people use a source of drinking water that has been contaminated with under-treated (or untreated) wastewater.
One of the ways we are combatting this challenge is through One Water—a concept that integrates all forms of water as a shared resource. A key aspect of One Water is, of course, wastewater. How can we safely process wastewater? How can we get the most value out of it? Over the years, engineers have made good progress on recovering resources, but there is opportunity for more.
As improvements and (perhaps more importantly) attitudes change, industry professionals are progressing towards a near paradigm shift—treating wastewater as an opportunity and less like a requirement. Indeed, in addition to valuable water in wastewater, there are significant organic resources we can reuse in many ways. But how do we extract those resources? How can we use them? This blog will explore how thermal hydrolysis is able to effectively treat those recovered organic resources.
The way in which we manage our wastewater has gone through a remarkable transformation since the ancient Babylonians first developed the cesspit around 4,000 BCE. That was quite commonplace until about 100 BCE when the Romans invented latrines to safeguard sanitation. Now, in more developed communities, wastewater is transferred from residential, commercial, and industrial enterprises to the wastewater treatment plant (WWTP). Once there, through a series of biological, chemical, and physical processes, the suspended and soluble matter is separated from the liquid wastewater.
Next, the organic solids are transferred to an anaerobic digestion system and converted to biogas. The remaining residuals, known as biosolids, are used as a soil amendment. Anaerobic digestion is where thermal hydrolysis processing (THP) can make a big impact.
THP uses heat and pressure to convert the anaerobic digestion feedstocks more efficiently into biogas. Although there are several process variations on the market, the process typically injects steam into a reactor with highly concentrated organics to hydrolyze and solubilize the long-chained carbon molecules. THP offers:
To better understand THP, lets break the wastewater treatment process down into five key reactions:
Provided by Science Direct, the following chart visualizes the entire the treatment process and highlights the benefits we can leverage out of it.
Stantec has been providing THP and wastewater engineering services for more than a decade in Australia and the UK (where no other consultant has done more!). With increased interest in the process now in the North America, we’re implementing this technology with strong support from our veteran specialists in the UK. To highlight how our expertise in THP and wastewater engineering is rising to global demand, I present two examples below—one in Canada and one in the United States.
The world’s water crisis is already upon us. The earth’s temperature is getting hotter and the global population is on the rise. This means we must find ways to combat our environmental challenges—and fast.
We know that effectively treating our wastewater is a key barrier to our success in defeating water-related challenges. By applying THP to our wastewater engineering practices, we can salvage more reusable water and procure more organic resources in a more efficient fashion. And not only does THP help to remedy our water woes, but it also reduces the amount of greenhouse gases released into the atmosphere.
We all must work towards a more sustainable future and innovating our wastewater treatment practices is only one of the many tasks we have ahead of us. If we can do it right, we’re one step closer towards a greener—or bluer—future.