Nutrient Removal: Sustainable Solutions

By Charles Bott, Conference Chair, WEF Nutrient Removal 2009 Conference

Last week WEF convened their second Nutrient Removal Conference: Sustainable Treatment Solutions. As chair, I had the challenging task of following up on a very successful 2007 event, but I had the assistance of great conference steering and planning committees as well as WEF staff to help with the program development.

While this year’s conference in Washington, D.C. was again located in the Chesapeake Bay watershed, which has some of the most stringent nitrogen and phosphorus discharge limits in the world, it is clear that more widespread removal of nutrients from point sources is gaining momentum. Eutrophication and the growth of hypoxic zones such as in the Gulf of Mexico will be driving more broad-based nutrient removal.

From the beginning of the conference planning process, it was clear that the focus of nutrient removal from wastewater treatment plants had transformed drastically in less than two short years. In 2007, the focus was on removing nutrients to extremely low levels using new technologies and approaches. Looking back, there was surprisingly little discussion about carbon footprints, net environmental benefits, or water quality benefits achieved.

However, the direction of our sector has shifted and the makeup of our program reflected that change. Discussions about environmental and societal costs in addition to the usual financial costs framed our nutrient removal debates in the context of a triple bottom line approach. In a resource-constrained world, energy efficiency and resource recovery both play a role in a more sustainable approach to nutrient removal from wastewater.

In the Opening General Session, I asked the audience to focus on three efforts:

1. Reduce the cost and environmental footprint associated with removing nutrients. This will come from a focus on energy efficiency, greenhouse gas emissions, lower chemical usage, resource recovery, and reliability of operations. Clearly, a continued focus on new and more cost-effective nutrient removal technologies is an important part of this challenge, but it must be balanced with environmental and societal cost concerns.


2. Move forward on the “new paradigm” of wastewater treatment and integrate these concepts into current planning and upgrades. This means thinking about wastewater as a resource for water reuse and reclamation and incorporating approaches such as decentralization and even source separation.


3. Engage the broader water quality community and the public. We will continue to make significant investments in our infrastructure. The understanding of the high quality effluent we produce can only increase the political will to further our nutrient removal efforts associated with more diffuse sources like urban stormwater, air deposition, and agriculture.

So what will be the focus of Nutrient Removal 2011? What issues or trends will shape our thoughts on the program and information needs for WEF’s members and beyond? Check back to the conference website and WEF’s Nutrient Removal Knowledge Center and let us know what you think.

Nutrient Removal: Everywhere, All the Time?

By Jeanette Brown, 2008-2009 Vice-President of the Water Environment Federation

As water quality experts know, many treatment plants throughout the United States are required to remove nitrogen, phosphorus or both. And if you manage or work at a utility like mine, in a region where nutrient removal is required, you know there are significant related costs, both capital and operating, as well as increased process monitoring requirements. As stewards of the environment, we take great pride not only meeting permit requirements but also in trying to achieve much greater removal of pollutants. Now we must all address a fundamental question as to whether or not every water body would benefit from nutrient removal. It’s complicated, because while we strive for the cleanest water possible, we understand this objective must be balanced against most effective use of environmental resources and diverse considerations that impact water quality at the regional and local levels.

The Natural Resources Defense Council (NRDC) has petitioned EPA to issue generally applicable nitrogen and phosphorus removal requirements for wastewater treatment plants. They contend that total phosphorous limits of 1.0 mg/L and total nitrogen limits of 8.0 mg/L are consistently attainable on an annual average basis using current secondary treatment technology. They also contend that many treatment plants are currently doing this with either a slight increase in cost or in some cases reduction of costs.

Many of us who currently operating nutrient removal plants have some concerns about this proposal because we understand how cold temperatures, wet weather and changing influent characteristics can impact nutrient removal efficiencies. In order to evaluate this petition, which will certainly be a hot topic at the upcoming Nutrient 2009 meeting, members of WEF and the National Association of Clean Water Agencies (NACWA) developed a questionnaire which has now been completed by many plants throughout the country. The results give us an understanding of the processes used at plants, whether or not they are doing nutrient removal, effluent quality, and costs. The goal is to provide EPA with expert advice as they continue to address nutrient criteria and issues.

Additionally WEF has convened a nutrient issues workgroup. This workgroup is assessing base line performance of conventional secondary treatment plants that evaluate how much nitrogen and phosphorus can be removed by the process. They are also evaluating state-of-the-art processes for nutrient removal, including cost and performance.

It is vitally important that we continue to thoroughly address this question of universal benefits of nutrient removal before any final decision is made to mandate generally applicable nutrient removal requirements. As stewards of clean water, we all have a stake in the answer, and I’d appreciate your thoughts.

P.S. You may want to check out the Nutrient Removal Knowledge Center on WEF's website for more information.