A vortex of poo? Thinking differently about vortices

Attending the Global Engineering Congress last year led to a new train of thought about harnessing the power of vortices to extract energy from human waste.  Past Future Leader Louisa King, Project Engineer at Black & Veatch, explains.

How can energy from vortices best be used? Image credit: Levi Xu/Unsplash
How can energy from vortices best be used? Image credit: Levi Xu/Unsplash
  • Updated: 17 May, 2019
  • Author: Louisa King, Project Engineer, Black & Veatch
I've long been fascinated by vortices.  When undertaking my dissertation two years ago, I focused on whether energy could be harnessed when a turbine head was installed within a vortex separator. At the time, this was as far as my knowledge and understanding of engineering would allow. 

My focus then was to try to encourage the installation of vortex separators within surface water drainage systems throughout the UK, to enable better treatment and cleaning of water prior to reaching a water treatment plant, and thus reducing costs. 

The idea of power generation came from looking, quite simply, at gullies in our road networks.

Typically, these are positioned within close proximity to street lighting. My idea was, however naïve at the time, that streetlights could be powered through the energy generated from water passing through the vortex separator. 

As my dissertation got submitted, I became quite obsessed with the idea of continuing this research as a PhD.  Sadly, however, it soon became clear, this was my obsession, and no one else’s…
 

New thoughts on vortices

Roll forward two years and now I’m working as a project engineer on pipelines and flood risk projects, with the ability to further my development and learning. I have had a very fortunate past two years.  And then in October 2018, I attended the Global Engineering Congress (GEC) at ICE.

While there, I attended every workstream relating to water that I could find. One of these was being led by Roger Bailey in relation to the Thames Tideway scheme and I found my brain and obsession returning to vortex separators once more. 

As Roger carefully led us through the intricacies and innovation of the project, I couldn’t help but think that even within this project, there was the opportunity to look at cleaning the water, and potentially the feasibility of energy generation once more.
 

A new way to use vortex separators

The concept of a vortex separator is very simple: it comes in, the flow is slowed allowing the separation of floatables and sediment, before the cleaned water flows out again.

Think of it as how filter coffee ‘sediment’ stays around the plug hole when you try and rinse your cafetière out in the sink. 

This time however, with my increased knowledge, which was increasing by each session I was attending at the GEC, I had a new way of thinking about energy generation. Why was I limiting it to water? Why shouldn’t I expand this to utilise a resource we have in abundance and don’t value?

I am, of course, talking about poo. 
 

A vortex of poo?

So far, my idea hasn’t expanded much further - and I’m sure that someone with a much greater technical ability would be able to develop it further.  However the basic concept as I see it is as follows:

Using a vortex separator on CSO [combined sewer overflows] or foul drainage networks would allow the separation of waste.

This waste could then be removed from each separator and undergo compression, with water being collected and treated at a WWTW [waste water treatment works].

The waste could then be put within an anaerobic digestion machine, to produce a biogas, which can be used as a renewable energy source. 
 

Thinking differently to solve global challenges

While this idea may not be feasible, I strongly feel that we need to look at what's being done throughout the world. In many developing countries, they're relying heavily on container-based systems where waste is contained, collected, transported, treated and then either reused or disposed of. 

I would very much be interested to learn what streams of research are being done in regards to energy generation from vortex separators for excess water to be retained, treated etc. 

We could, if integrated correctly in areas of severe water and sanitation poverty, reduce open defecation and contamination of watercourses. We could, improve our water quality, green credentials and unlock hidden resources, by looking at the value of poo.  

And I’m very encouraged by my experience of attending the GEC and being stimulated to see things I was already interested in differently from before.  
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