How to reuse water without compromising human health and the environment: Lessons of an ancient mariner – Peter Reeve

With the high honour of writing the first post for the Environmental Health at Flinders blog, I was pondering what to write. One thing came to mind: ‘water, water everywhere, but not a drop to drink’. I did a bit of research into this quote and found it is a common misquotation of a line from Samuel Taylor Coleridge’s longest work, The Rime of the Ancient Mariner, first published 1798. This poem peaked my interest as I saw strong linkages between its message and – a subject close to my heart – water resource management in Adelaide, South Australia! Resultantly, I thought I’d write this blog post around it!

And so the rime begins: A mariner stops a man in the street who is on his way to a wedding and begins to regale him with his tales from the sea. Despite being initially perturbed by this nuisance hold-up, the wedding-goer quickly becomes enthralled by the tale. Out at sea, the mariner and his crew found their ship drawn south into chilly Antarctic waters where they quickly became stuck in ice. Their fortunes changed, however, when an albatross appeared and guided them to safety from the ice jam. Once clear of the ice, to the great displeasure of his crewmates and, as it transpires, the ocean spirits, the mariner shot the albatross dead. Soon, the mariner and his crew find themselves stuck in windless doldrums:

“Day after day, day after day,
We stuck, nor breath nor motion;
As idle as a painted ship
Upon a painted ocean.

Water, water, every where,
And all the boards did shrink;
Water, water, every where,
Nor any drop to drink.”

Figure 2: Oh no! The mariner shot the albatross – would not recommend!
Source: http://www.victorianweb.org/art/illustration/wehnert/32.jpg

The situation worsens as all the crew slowly drop dead, leaving only the mariner. Eventually, the mariner has a revelation, seeing the true beauty in all creatures of the sea. From this point, the ocean spirits step in and help the mariner guide the ship back to port. Driven by guilt, the mariner wanders Earth repeating his story to whoever he meets, passing on lessons learnt. The man stopped at the beginning of the rime never made it to the wedding, choosing instead to go home for a good sleep, waking the next day a wiser man!

Now, I highly doubt that water management was at the fore of Coldridge’s mind as he wrote this poem (though the true meaning is still quite open for debate, so you never know), but I think the message of his rime is applicable to the situation in Adelaide.

In Adelaide, each year, 190 GL of stormwater and treated wastewater is discharged into the sea. Using values from SA Water for average residential consumption per household, this is enough water to supply over 1 million households. Given South Australia only has about 700,000 households, this is not a trivial amount of water. For those like myself who grew up in Adelaide during the millennium drought, or for those paying attention to the current droughts effecting farmers in Queensland and New South Wales, the thought of all of this water going to waste is rather abhorrent. The problem is, there’s not enough space to capture and store this water above the ground when it is plentiful, so it can be used later when it is needed: ‘water, water, every where, nor any a drop to drink’!

Figure 3: Major discharge of stormwater from River Torrens into Adelaide’s coastal waters on 25 October 2005. Dark region is increased turbidity. Photo: S. Bryars.

Deep below Adelaide, aquifers provide the gift of natural storage to reserve this water, and may well be our proverbial albatross, ready to guide us out of our water-wasting woes. An aquifer is a sponge like layer made of gravel and sediments that can store and transmit water. Via a system called Managed Aquifer Recharge (MAR), stormwater and wastewater can be intercepted, often in an urban wetland, such as that found at Oaklands Park in Marion, and injected down into an aquifer, where it can be stored and then later pumped out again when it is needed.

Figure 4: The process of Managed Aquifer Recharge described in this blog post is often referred to as Aquifer Storage and Recovery, illustrated here. Source https://www.mecrus.com.au/images/img_what-is-asr.jpg https://www.mecrus.com.au/images/img_what-is-asr.jpg

It is at this point that we need to heed the rime of the ancient mariner to make sure we don’t shoot our albatross through mismanagement. This is where my PhD research comes in.

Local councils, who often operate MAR schemes in South Australia, are becoming increasingly aware of potential health risks that water from MAR schemes could pose to public health, for example when used for irrigation or firefighting. Such risks may be chemical, in the form of organic pesticides, herbicides and surfactants, and microbiological, in the form of bacterial, viral and protozoan pathogens.

Figure 5: Collecting water samples from the outlet of Oaklands Wetland prior to injection underground.

The objective of this research is to determine the ability of aquifer substrates to remove selected organic chemicals of concern from stormwater injected into aquifers as part of MAR. The results of this work will be used to inform current and future management strategies for the collection, treatment and reuse of stormwater. A range of organic chemicals is often present in storm water and wastewater. If these chemicals are not adequately removed before the water is reused, they can pose a risk to human health and the environment. The problem is that it’s not well understood how these chemicals behave when stored underground, making risk management tricky. Do they stick to the surfaces of the rock (adsorb), get eaten up by microorganisms (biodegrade) or do they simply sit there in the water until it is extracted out again?

I am particularly interested in studying the role that biofilms play in the removal process. Biofilm comprises groups of microorganisms that stick together and often to a surface – think of that slimy layer you might feel on the inside of a hose pipe, that’s biofilm! Biofilm can also stick to the surfaces of the gravel and sediment in an aquifer, modifying that material’s surface, potentially enhancing adsorption and biodegradation.

By taking samples of the aquifer back into our laboratory, it is possible to perform experiments to find out how these chemicals behave while stored underground so that, unlike the sailor in 1789, we can embrace our albatross by sustainably reusing water without compromising the protection of human health and the environment.

Figure 6: These columns are filled with aquifer materials. By passing water containing the chemicals I am investigating through the column, it is possible to see how the chemicals interact with the aquifer material by measuring what goes in and what comes out.

For further information, please contact me via peter.reeve@flinders.edu.au – I promise I won’t stop you from going to a wedding!

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