Friday, April 4, 2014

WWTmod2014 - The Process Design and Optimization Seminar

I'm sitting in Brussels airport the day after the last day of the latest in a series of seminars focused on process modeling under the moniker "wwtmod" for "waste-water treatment modeling." The previous 3 biannual wwtmod's were held at Mont-Sainte-Anne, just outside Quebec City in Canada, but the latest in the series - WWTmod2014 - was held in the lovely European town of Spa, Belgium. In this blog I'd like to summarise a few of the many highlights of WWTmod2014, but first I'd like to digress a little to ponder the name and the focus of this seminar series.

WWTmod2008 was first concieved to be a follow-up to a series of modeling-focused seminars called "Kolle-kolle" which I'm told were an excellent set of seminars in the 1990's to discuss wastewater treatment models, from which the IWA's "ASM" activated sludge models were developed. Process models have come a long way since the 1990's, shifting from the realm of academia to mainstream design and operations also. Any consultancy worth it's salt will use process models to develop or refine their designs. In fact, it's all but impossible to design a good nutrient removal facility doing nitrogen and phosphorus removal without the use of models. A few stalwart old-scholers might argue differently but they're a fading voice. This has meant that the WWTmod seminars, from the very start, have pulled together academia and practitioners to discuss process models and these models are now at the heart of process design. Despite the name including "mod" in the title, the seminars very quickly shifted into discussions about the mechanisms and processes that go into the models and so I'd argue that it is now the premiere seminar for process designers and those wanting optimize their waste water plant operations (maybe using models to help!) I can't think of another conference that draws together the top researchers from universities with experts from practice, the way that it's done at WWTmod. If you're a university researcher wanting to understand the challenges of practice, come to a WWTmod seminar. If you're a practitioner wanting to discover the latest tools and techniques to overcome your challenges, come to a WWTmod seminar!

So, what were the highlights of the latest, WWTmod2014? The program covered a broad range of topics in wastewater treatment, from screenings and grit to model extensions for trace organics; the latest in nitrogen reaction pathways and current thinking on phosphorus removal; primary settler and secondary settler performance; integrated modeling and LCA. At the closing session, the chairman of the scientific committee, Ingmar Nopens, had a slide with a few "Useful Quotes and Concepts", so maybe I'll focus on those:

"Wipers versus Washers" - there's nothing like the topic of bum wiping to get a partly humorous and partly serious discussion going on wastewater treatment. It's not pleasant to discuss the fate of toilet paper but there are serious considerations when it comes to understanding the biodegradability of the material when it gets to the treatment plant. If it's not biodegradable, it uses up treatment capacity and increases the mass of residuals that have to be handled. If it is biodegradable, it's a valuable source of material for biogas generation. Ultimately there wasn't a consensus on its biodegradability, but on the whole it was thought that it wasn't too degradable within the wastewater treatment plant (despite what it says on roll!)

The "Drinker-Barman Concept" - trying to be a little radical, I suggested that the Monod equation, near and dear to the hearts of all who model biological processes, may be past its sell-by date and that consideration of diffusion may be key to shifting to simpler kinetics where the "intrinsic" half-saturation coefficient can be ignored. I'm already getting too much into the details here but needless to say I had to use a nice analogy involving beer to make my point and hopefully make it more palitable!

"Communism/socialism versus capitalism in biological processes" - Dr Zhiguo Yuan discussed how the models we use assume that substrate is shared evenly amongst the different organisms that use it (like socialism shares out everything) but in fact there is competition for the substrate that is akin to biological capitalism.

"Being within the law is not always the good thing" - Dr George Ekama has produced many of the most memorable quotes at these seminars. A few years back he said (I'll get it wrong, but hopefully close enough): "The main problem is to keep the main problem the main problem" and he's also the source of the wipers quote above. His latest quote may sound revolutionary but it's really meant to highlight that some of regulations that govern treatment standards don't always result in the best overall environmental solution. In particular we discussed the focus on carbon emissions at wastewater treatment facilities and legislation pushing them to reduce energy use and carbon footprint when in fact the carbon emissions per person served by a treatment plant is peanuts - maybe less than 1% of their overall emissions - and they'd be better driving less or using less hot water.

Beyond these highlights another fun part of the conference was the use of twitter to post comments. I confess I was a twittering fool but it was fun! Check out the hashtag #wwtmod2014 to see!