Can Your Plant Remove Nutrients Cost-Effectively? EPA Study Aims to Show You How

U.S. EPA collects data on cost-effective and efficient approaches to reduce nitrogen and phosphorus for permit compliance or simply good watershed stewardship.

Can Your Plant Remove Nutrients Cost-Effectively? EPA Study Aims to Show You How

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Stricter effluent nutrient limits pose a dilemma for clean-water plant teams: How to comply with the new permit, and at what cost?

Major plant upgrades to drive down nitrogen and (especially) phosphorus can cost millions of dollars and may be out of reach for facilities serving small communities, especially those with lower-income populations that can’t easily absorb a big rate increase.

The U.S. EPA has compiled a study on efficient and cost-effective approaches for nutrient removal, looking to help communities find ways to meet stricter limits, or simply contribute to better watershed quality, without undue financial burden.

Through its National Study of Nutrient Removal and Secondary Technologies, the EPA seeks to learn about and promote alternate ways in which clean-water plants can reduce nutrient discharges by optimizing operation and maintenance practices, while avoiding major facility upgrades and their large capital expenses.

The study has three main goals: Collect nationwide data on nutrient removal, encourage improved facility performance with less expense, and provide a forum for plant teams to share best practices. Paul Shriner, project manager and senior engineer with the EPA Office of Water, Engineering and Analysis Division, talked about the study in an interview with Treatment Plant Operator.

: What is the background on this study?

Shriner: The study consists of three phases. The first phase began in 2016 and culminates with the current screener survey. The aim is to collect basic information to identify existing secondary treatment facilities. The second phase will include a detailed survey sent to a subset of secondary facilities to collect more detailed treatment and operational information. The third phase will involve sampling of influent, effluent and intermediate points in the treatment system at a further subset of facilities to determine nutrient-removal performance.

: Why is it necessary to conduct a survey of this kind?

Shriner: This study will help fill nationwide information gaps that are critical to promoting successful nutrient management. At present, there is a lack of information on improvements to plant performance that can be made with minor changes to processes, and on nutrient removals that can be achieved by optimizing operation and maintenance of existing equipment.

: How did you publicize this survey to the treatment facilities?

Shriner: We collected mailing addresses and emails by working with trade associations like the Association of Clean Water Administrators, NACWA, WEF and National Rural Water. Those folks were the most likely to know where the plants are and how to get in touch with them. We sent letters and emails, and we advertised the study through the trade association magazines and newsletters.

: How many facilities would you estimate you have contacted?

Shriner: We estimate 15,000 to 16,000. We’ve received about 1,700 completed surveys so far.

: What do the responses look like?

Shriner: It is a really great mix. We don’t delve into their methods so much. Subsequent surveys in the study will do that. At this stage it’s more about what technology they have in place and whether they have experimented with it. Results to date demonstrate that all types of treatment plants can improve nutrient removal. They show that more than 1,000 facilities with different biological treatment methods, conventional and advanced, can achieve effluent total nitrogen of 8 mg/L and total phosphorus of 1 mg/L.

: How easy is this survey for operators to complete?

Shriner: The survey is very low burden. It uses a lot of check boxes and a lot of ranges. There is no requirement to collect information they don’t already have on hand. It asks for design flow; their basic treatment technology; the character of influent, such as whether they have industrial input; the size of the population served; whether they monitor for nutrients; and things of that general nature. It takes most operators about an hour to complete.

: What will be done with the results of this study?

Shriner: The completed survey will be used to establish a statistically representative, nationwide baseline for nutrient removal at these facilities. It will also enable EPA to develop a basic characterization of each type of treatment facility. We will share the results as an online, searchable tool on technologies and operational strategies for nutrient removal that may cost less to implement.

: How will this study help treatment plants and their operators?

Shriner: The results should benefit plants and state agencies in multiple ways. A number of plants have made significant nutrient reductions through process optimization, and a statistically representative study can help operators evaluate whether these site-specific cases can be applied to their facilities. In addition, many states are developing nutrient reduction strategies and total maximum daily loads. Our study will provide the national information needed to identify nutrient load allocations. This in turn will foster understanding of tradeoffs between point and nonpoint source controls on water bodies impaired by nutrients. 

: As a practical matter, how might operators use the information?

Shriner: Optimization approaches are not going to work for every plant, because every plant is different. But we want to give operators the tools to say, “Don’t bother trying this, because other plants like ours already did, and it didn’t work.” Or, “Give this a whirl, because most of the plants like ours have been successful with it, and here’s what they did to get there.” And if they want to talk to some other operators who have been successful, here’s a list of contacts.

: Ultimately, what specific resources do you expect to offer to operators?

Shriner: We’re working on two tools that would be available on the internet. The first one is meant for the operators. Basically, it’s about how many plants like mine have done something like this? Who has done this particular technique? The second tool gets a lot more into the actual survey data and lets agencies do data analysis. That’s down the road. The immediate goal is a tool for operators. We’ll be talking to operators and the trade associations on what the search functionality should look like in order to be the most useful.

: How would you characterize the potential for optimization procedures to be effective, as opposed to big-ticket plant upgrades?

Shriner: It’s fair to say that almost any plant can do something, and there will be some level of improvement. How far will that take them? That’s hard to say, because every plant is unique.

: Is this all about meeting ever-stricter effluent permit requirements?

Shriner: Not entirely. Many locations don’t have effluent nutrient requirements. They may be coming and they’re not there yet. Or maybe in a given watershed they’re not going to be enacted. Regardless whether they have a nutrient requirement, operators are stewards of the watershed. They care. They are there to protect the water. So even if they don’t have a limit, I believe a lot of them would be interested in removing nutrients, although they’re not required to, if it’s a low-cost, low-risk thing to do. We don’t tie it to regulation, and the study is not for regulatory purposes. It’s about what plants can do with what they’ve got.   



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