Water: balancing quantity and quality

In a relatively short period, says Paul Hennessey – oil and gas business manager at atg UV Technology – water treatment has become a great deal more effective and discerning. The clue to this, ironically, is the prevalence of incidents that have highlighted things supposedly going wrong.

The focus of this is the single celled parasite Cryptosporidium – still the prime culprit for gastrointestinal infection in Britain and which thrives in contaminated, publicly accessible water.

“What has changed is the testing method which has come on in leaps and bounds. You may have noticed that in the last two years it seems there have been more cryptosporidium outbreaks.

“It’s not that there is more Cryptosporidium than there was, it’s just that the testing regime is better.”

There’s a parallel perhaps with the leaps in understanding that occurred in medicine at the turn of the previous century – first identifying the role of microbes in infection, then progressing to an understanding of how individual microbes were associated with specific types of infection.

Water and wastewater treatment has become a great deal more refined, explains Hennessey [pictured left]. Once UV (ultraviolet) treatment consisted of a large-scale approach consisting of ‘frying’ everything in a wastewater effluent plant: “It made it more expensive than it needed to be, because at one time you didn’t know exactly what was in the water – so you had to reckon to design for the worst case.”

Now, where industrial effluent is concerned, for example, the tests have become more standardised which has made them cheaper to implement and allowed a greater frequency.

“I know a lot of people are doing a lot more random sampling of their effluent and they’re finding inconsistencies and incompatibilities and they’re putting methods in to protect against that.”

It’s a familiar process theme – a move away from ‘one size fits all’ to something more bespoke and customer-focused.

In the water sector, UV’s progress has been variable – it’s been a feature in the wastewater industry for several decades since Anglian Water pioneered its use. Whereas it was only in 2010 that it was approved for use against cryptosporidium in drinking water.

That was too late to properly participate in the five-year AMP5 Asset Management Period that began that same year.

AMP6 afforded greater latitude, but the expectation is that it is AMP7, starting in 2020 with various tender processes already underway, that should see UV take advantage of a boost in takeup.

It’s not that there is more Cryptosporidium than there was, it’s just that the testing regime is better

Paul Hennessey – oil and gas business manager, atg UV Technology

Agile responsiveness will determine how far its practitioners can develop. That entails an appreciation of the biology with which UV specialists must contend – and adapting products and data capture accordingly, explains Hennessy.

Tracking enables a better comprehension of bacterial behaviour and its seasonal variations can be fed into systems in order to ensure that action taken – and costs involved – are commensurate with the activity at that time of year, he explains.

“In the bacteria ‘breathing period’ in spring, when they become more active, you can see an increase from 200,000 cfu (colony-forming units) to above 1 million cfu.

“If you simply design to always run for a million cfu, then you’re are going to have an oversized plant for most of the year. So you need to be looking for ways for one piece of equipment to do several jobs.” UV transmittance (UVT) monitoring ensures precise dosing of water that takes into account the actual conditions on the ‘ground’ and informs the system so it can respond accordingly.

Working with the likes of Phillips and Heraeus Group, atg UV has developed the use of responsive dimmer-style UV lamps capable of reducing when necessary to 30% power. It has also collaborated with digital pioneer Real Tech to ally real time sensors with data analytics.

We’re treating all [Cuadrilla’s] water with UV so they don’t have to use any chemicals. It’s a brand new market where UV is at the start of that product line

Paul Hennessey – oil and gas business manager, atg UV Technology

Says Hennessey: “[Previously], normally what you would do would be to get a year’s worth of data from the company and that’s what you would design the plant to. Now they are reading the system all the time and feeding into our system – so it’s actually matching the water quality.

“Before that you would just have had to go off the worst case and accept that everything else was over-treatment.”

That might not make a difference to the success of eliminating bacteria but it impacted more seriously on electricity bills and operating costs. Now this factor’s absence removes one disincentive to adoption.

Automation advances have assisted too, as PLCs have become smarter and the cost of writing software has reduced. Whereas companies might have invested previously in a couple of large UV units, the trend is moving towards more but smaller and operating on a different flow rate.

Again this permits a greater ability to react to events and seasonal variation, but it has other useful implications: maintenance is easier and less disruptive while lamplight use can be spread evenly.

Environmental analysts Frost & Sullivan predict that the market for water technology will experience vast growth but earmarks membrane technology and sewage sludge processing for a more spectacular increase than UV. An indication maybe that the latter is peaking?

Unlikely, insists Hennessey, because penetration has not been uniform across all sectors. While wastewater has been an early adopter, the drinking water market is probably at the start of what could be a 10-year curve.

And whereas UV technology has had a lengthy presence in the oil and gas industry, it is more recently making headway in the area of seawater reinjection, where unease in some quarters about the use of biocides has increased: “As the regulations are getting much more stringent they’re looking at new, chemicalfree technologies, so we’re involved in two very, very high level pilot studies in Norway and the USA looking at this.”

Fresh fields

Back home, it is onshore activity in the shape of shale exploration that has opened up new commercial streams, starting with oil and gas exploration and production company Cuadrilla.

“We’re treating all their water with UV so they don’t have to use any chemicals. It’s a brand new market where UV is at the start of that product line.”

UV’s ability to eradicate bacteria and their products might provide an environmental edge, asserts Hennessey.

Geosmin, one common algae and bacterial-produced chemical, is not known to have adverse side effects, but can be detected by humans in quantities as minute as 10 ppt (parts per trillion). Although chlorine and other treatments may be effective, their odours can be equally off-putting.

And while membrane technology has recorded impressive advances including the ‘holy grail’ of back flushable products, its approach to cryptosporidium is less lethal, says Hennessey.

“What it does is separate it out but the backflush goes back to the environment so what we may have been doing is to increase the concentration. Whereas UV obviously kills it.”