Saturday, August 24, 2013

E is for Energy

In my past few blogs I discussed nutrients as the "N" in the context of the "N-E-W" paradigm for wastewater treatment (rebranded as "water resource recovery facilities" but it's taking me time to adjust so bear with me, please!). In this blog we turn our attention to Energy (that's a capital "E"!)

Energy is currently the hottest topic in our triumvirate of resources that we can recover at water resource recovery facilities (there, I said it) aka poop plants (sorry, couldn't resist!). I think this is due to the fact that we pay our electricity and gas bills and so we're conscious of the cost of energy. Of all resources, we relate to energy the most because we can link it back to the dollars and cents used to pay for it. Another way of saying the same thing is that ecologically minded people can think of energy recovery in terms of reducing carbon footprint and at the same time the more financially motived people can see the possibility for cost savings. In sustainability terms, this is a real "win-win" ( or "win-win-win" if we can rope in social benefits somehow in the triple bottom line) which overcomes the need to consider trade-offs between reducing environmental impacts and the financial cost. I think this is OK, and certainly makes it easier to make the decision to implement an energy project at a facility, but we need to be careful not to expect the "win-win" for all sustainability projects and we need to set expectations that not all energy and sustainability projects will have a short-term financial pay back. If it does, great, but that's not the only reason to do the project.

In thinking about energy neutrality, which is a goal for WERF and others, we need to think about it from both energy use (the "demand" side) and energy as a resource (the "supply side"). It makes no sense to produce lots of electricity on site and at the same time be running inefficient pumps and blowers. We really do need to think about energy as a whole. That's the focus for a WERF research project I'm helping on right now called "Energy Balance and Reduction Opportunities, Case Studies of Energy-Neutral Wastewater Facilities and Triple Bottom Line (TBL) Research Planning Support" (a bit of a mouthful but descriptive).

I encourage everyone to take a look at what WERF is doing in Energy recovery as well as other organizations. Feel free to post a reply to this blog if you know of other noteworthy activities in energy recovery for wastewater treatment plants... I mean water resource recovery facilities!


Friday, August 2, 2013

Nutrients Part 2


My original plan was to step from Nutrients to Energy to Water week by week in thinking through resource recovery from wastewater treatment plants, but I want to dwell a little longer on Nutrients as this past week I attended the WEF/IWA Nutrient Removal and Recovery 2013: Trends in Resource Recovery and UseIt was a very good conference. Just the fact that this annual conference that started out looking at nutrient removal now includes significant space for recovery of said nutrients is an excellent step forward. Last Blog I listed what I thought were 3 significant hurdles to nutrient recovery, namely Money, Focus and Knowledge. This past week certainly brought Focus to the topic and considerable Knowledge too... to be honest there was so much knowledge shared I need to go back through the proceedings to see what I missed! This is excellent news in our move toward a sustainable future.

So that's the good news, but still there is the significant hurdle of Money. I want to offer the suggestion that we need to broaden our perspectives when it comes to looking at the finances of nutrient recovery projects. One very obvious example is the benefit that comes from removing phosphorus from a treatment facility that is suffering from pipe blockages and equipment failure due to struvite. I have heard of a couple of utilities that have decided to do phosphorus recovery in order to remove phosphate from their sludge liquors where struvite was a major problem. There is also evidence that sludges rich in phosphorus (due to enhanced biological phosphorus removal) are more difficult to dewater. Finally, the content of P in most biosolids produced in a treatment facility is much higher than it needs to be for agronomic use. Connect all of these factors together, estimate the cost benefits of them and then add this to the economic analysis for P-recovery and it will significantly shift the balance.

And all this is can be acheived without considering the true value of phosphorus as a non-renewable resource. Throw in this factor, and the fact that it's doing the right thing, then I think the case for nutrient recovery is much stronger than many may realize. I'm excitied to be working on a P-recovery project at Stickney in Chicago over the next several months. I strongly encourage others to consider doing it - the financial aspects are much better than you'd expect if you take an holistic view, and it's just the right thing to do, so do it!