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WaterOperator.org Blog

Articles in support of small community water and wastewater operators.

Peracetic Acid (PAA) in Wastewater Disinfection

Peracetic Acid (PAA) in Wastewater Disinfection

Peracetic acid (PAA) has grown in popularity over the last several years for its use in the disinfection of wastewater and stormwater. Utilities use disinfectants as the primary mechanism to inactivate and destroy pathogenic organisms that spread waterborne disease. An appropriate disinfectant will sufficiently treat any disease-causing microbes including bacteria, spores, helminthes, and protozoa. While PAA technology has been employed in Canada and Europe for the last 30 to 40 years, this disinfectant has only become noticed in U.S. municipal wastewater treatment within the last 10 years. Competing with chlorine, an already well-established disinfectant, its use is still slow growing, however systems are discovering that PAA offers several benefits to wastewater treatment that chlorination does not.

What is peracetic acid? The alternative disinfectant is a clear, organic peroxide compound that readily hydrolyzes to acetic acid and hydrogen peroxide in water. It’s characterized as a strong oxidant and fast reacting disinfectant. Commercially available peracetic (CH3CO3H) is purchased in an equilibrium mixture of acetic acid (H3CO2H), hydrogen peroxide (H2O2), and water (H2O). Manufacturers typically add a stabilizer as well. The following formula represents the equilibrium equation: CH3CO2H + H2O2 ←→ CH3CO3H + H2O.

PAA can generally be purchased in concentrations of 5% to 22%. When PAA decomposes in water, free hydrogen peroxyl (HO2) and hydroxyl (OH) radicals are formed. These radicals have significant oxidizing capacity that play an active role in microbial disinfection. According to the EPA, bacteria are destroyed through cell wall lysis and leakage of any cellular constituents.

Wastewater systems consider moving to peracetic acid for several reasons. Unlike chlorine, PPA decomposes into biodegradable residuals of vinegar (acetic acid) and hydrogen peroxide that can pass fish toxicity tests without removal. These residuals are not toxic, mutagenic, or carcinogenic. Bioaccumulation in aquatic organisms is also highly unlikely. Neither chlorinated compounds nor harmful disinfection by-products (DBPs) are produced with its use. As such, PAA has been considered the potential answer to tough DBP regulations. Peracetic acid can also disinfect over a wide range of pH and is unaffected by nitrate and ammonia concentrations.

Chemical handling of PPA is toted for being easier and safer than chlorination. The disinfectant can be stored for long periods of time exhibiting less than 1% decrease in activity per year when properly stored. Its use does not require any special risk management plans (RMPs) required by the EPA when handling certain toxic chemicals. For systems that operate under cooler conditions to prevent contamination or elevated temperatures, PAA has a low freezing point. Switching to PAA requires minimal retrofitting with the chemical itself being offered at prices competitive to other disinfectants.

There can be some disadvantages to peracetic acid. Depending on the formula purchased, PAA introduces varying amounts of acetic acid into the wastewater effluent. This can contribute to biological oxygen demand (BOD) and may not be appropriate for systems that are struggling to meet these limits. The biggest challenge wastewater systems face is regulatory approval. While PAA has been approved by the EPA as a primary disinfectant, each state regulatory agency must also approve its use. A WaterOnline guest column includes an infographic of states that have approved PPA as of 2017. The guest column discusses how systems can approach local regulatory agencies to seek approval on a case-by-case basis.

The overall effectivity of PPA will depend on wastewater characteristics, the PAA concentration, contact time, and the reactor configuration. Dosage will depend on the target organisms, wastewater quality, and level of inactivation required. When monitoring PAA residuals, operators can use the same analyzer and method as for chlorine residuals. A standard EPA sampling method does not yet exist. The lack of established methods and protocols for PAA makes approval difficult for local regulatory agencies. To help investigate the use and implications of PAA in wastewater, the Water Research Foundation (WRF) completed a study to evaluate effluent toxicity as well as dosage and contact times required to meet compliance. Metro Vancouver’s Northwest Langley WWTP in Canada has also published findings from a multi-year pilot program that used PAA as a disinfectant. More studies will have to expand on existing research until peracetic acid can become easily and widely adopted.

What's on the Drinking Water Radar for the Year Ahead: 2019

What's on the Drinking Water Radar for the Year Ahead: 2019

Being a small-town water operator is not easy; it is up to you to ensure the quality of your community's water day-in and day-out, often with very limited resources. Let WaterOperator.org help you meet the challenge head-on with this list of tools and resources to put on your radar for the year ahead:

  • Have you gotten in the groove yet with the new RTCR requirements? Here are two new documents from the USEPA designed to help small public water systems: Revised Total Coliform Rule Placards and a Revised Total Coliform Rule Sample Siting Plan with Template Manual. Additional compliance help, including public notification templates, a RTCR rule guide, a corrective actions guidance and more can be found here.
  • While we know your hands are full just getting the job done, there are new and emerging issues you may have to deal with in the year ahead. For example, this past year many communities have been dealing with PFAS contamination issues. This ITRC website provides PFAS fact sheets that are regularly being updated on PFAS regulations, guidance, advisories and remediation methods. Especially of interest is this excel file that has begun to list the different state standards and guidance values for PFAS in drinking water as they are developed. Be sure to check back often for updates.
  • Your utility may also have to adjust to new compliance rules in the coming year. In Michigan, for example, a new Lead and Copper Rule arising from the water crisis in Flint has gone into effect, making it the strictest in the nation. Other states, such as Ohio, have also adopted tougher standards, or are now requiring schools to test for lead. Oregon has established temporary rules that will require drinking water systems in the state using certain surface water sources to routinely test for cyanotoxins and notify the public about the test results.
  • With a warming climate, these incidences of harmful algal blooms in surface water are on the increase, causing all sorts of challenges for water systems that now have to treat this contaminant. This cyanotoxin management template from the EPA can help assist you with a plan specific to your location.
  • Worker turnover and retirements will still be an issue in 2019. According to this article, the median age for water workers in general (42.8 years) and water treatment operators specifically (46.4 years) are both above the national average across all occupations (42.2 years). You can keep transitions as smooth as possible by using EPA's Knowledge Retention Tool Spreadsheet and/or this Electronic Preventive Maintenance Log.
  • New Tech Solutions: A UMass lab focusing on affordable water treatment technologies for small systems will be rolling out its Mobile Water Innovation Laboratory in 2019 for on-site testing. In addition, the facility is testing approaches to help communities address water-quality issues in affordable ways. "Early next year, in the maiden voyage of the mobile water treatment lab, UMass engineer David Reckhow plans to test ferrate, an ion of iron, as a replacement for several water treatments steps in the small town of Gloucester, MA.

But even without all these challenges and new ideas for the future, simply achieving compliance on a day-to-day basis can be tricky - if this sounds familiar, you may want to check out our recent video on how operators can approach the most common drinking water compliance issues.

It’s a bird, it’s a plane, it’s a DRONE!

It’s a bird, it’s a plane, it’s a DRONE!

So you are thinking it is about time to inspect the outside of your water tanks and above ground assets. According to the Illinois EPA, a water storage tank should be inspected at least every 5 years, so it just may be that time again.

You are probably familiar with the traditional tools for condition inspections such as ladders, scaffolding, harnesses, cherry pickers, helicopters, ROVs, divers and cameras. But these days, you can add another tool to your toolbox: unmanned aerial vehicles (UAVs), or more simply, drones. Drones can offer a safer and possibly more cost-effective method of visualizing the condition of a utility’s facilities. Certainly, these “eyes in the sky” can take a visual inspection to an entirely new level – literally.   

There are clear benefits to using drone technology. According to this Wall Street Journal article, researchers believe the use of drones could cut utility costs and improve worker safety, both for routine inspections and for surveying damage after disasters. Plus, set up and operating costs can be less expensive – initial drone systems can be had for as little as $6,000. Drones can also be used to supplement your GIS program for asset management and to map assets in remote and rural locations.

Yet there are some drawbacks as well. Depending on state and local ordinances and laws, there may be height and line of sight regulations as well as special training/licensing requirements for operators.

Interested in finding out more?

There will be a technical session on using drones at the 2017 APWA Public Works Institute in California in September. And the NCAWWA is offering a session at their 2017 Institute, also in September. Can’t wait until September? The Operator Training Committee of Ohio is offering a training in a few short weeks.

Ready to give it a try?

NJ Water Association offers a drone service for asset management purposes, emergency response planning, tank inspections and more. Their drone and operator are both registered with FAA to maintain compliance with FAA Part 107 requirements.

Cellular Metering for Small Systems

Cellular Metering for Small Systems

Guest post from Brenda Koenig, Illinois State Water Survey.

Cellular-enabled water meters – also called smart meters – can make all the benefits of smart grid technology attainable for even for small systems on a budget. In this post, we’ll review the pros and cons of cellular vs. traditional metering systems.

Cellular meters offer service benefits

Due to their independence from physical infrastructure, a cellular system is better equipped to continue working through emergencies, such as floods, that might damage a large physical network. Cellular networks also make it easier to service dispersed or geographically diverse areas.

One of their greatest benefits is the speed of data. Cellular meters allow utility managers and customers to monitor their activity in real-time on the web. This improves leak detection and provides more opportunities for water conservation.

Weighing the costs

Cellular meters have potential to save utilities money on some fronts. Their use of cloud-based advanced metering analytic (AMA) software eliminates the need for expensive software installations at the plant. They also eliminate the need for a physical network of antennas, repeaters, wiring installations, and data collection units. Without the need for physical site visits to read traditional meters, utilities may also save staff time.

However, start-up costs for cellular metering can be significant, even without the expense of physical infrastructure. Buying and installing cellular meters can cost two to three times more than traditional meters. Staff and infrastructure costs will depend on what system you currently have in place. Cellular monitoring is compatible with most DEP and AWWA approved, AMR-compatible meters, but incompatible meters would need to be replaced. Staff may need to be retrained to install, maintain, and operate the new systems, as well as manage data, train customers, and set rates.

A growing trend

By 2020, it is estimated that 600,000 cellular water meters will be distributed annually, with companies such as Badger Meter, Arad Group, Neptune Technology Group, and Master Meter introducing cellular metering technologies.

So how does a small system decide if and when they too should adopt these new, game-changing cellular-based tools that are becoming more widely available and affordable? Much depends on each unique system’s needs and priorities, as well as the funding and political context in which they operate. Systems that are leak-prone or that need to step up their water conservation efforts may benefit from the daily feedback offered by cellular meters. Pilot programs or a comprehensive cost-benefit analysis can help utilities decide whether the tradeoffs in staff time, technology, and infrastructure expenses make sense. Finally, one of the best things to do is to talk to other systems about their experiences. Utilities with similar budgets, sizes, and goals can provide a lot of advice and references.

Resources:

Novato water district rolls out ‘smart’ meter pilot project news article, Marin Independent Journal 3/21/17

Big Data Flows: Water, Outsourcing, and the Flood of Data news article, EarthZine 6/30/15

Moving Towards Sustainable and Resilient Smart Water Grids journal article, Challenges 3/21/14

City looking to tap new water meters news article, Kingsville Record 3/1/15

RCAP - Water Metering Technologies presentation, RCAP Prezi 4/29/15

Advanced Metering Infrastructure, memo, City of Novi 4/24/15 

Featured Video: Water Utility Response On-The-Go

As winter gives way to spring, many of us look forward to the traditional activities associated with warmer weather: cookouts, swimming, gardening, camping. Of course, for some of us, spring and summer will bring less welcome events: storms, flooding, droughts, and extreme heat. As we approach the turning of the season, it doesn't hurt to refresh our memories on the resources available when the weather turns not-so-pleasant.

Water Utility Response On-The-Go is a site specifically formatted to be comfortably viewed on smart phones and other mobile devices. The homepage displays a menu of links for tracking severe weather, contacting response partners, responding to incidents, taking notes and recording damage, informing incident command, and accessing additional planning info. The weather tracking and response partners links use location data to help you access forecasts and contacts specific to your area. The Respond to Incidents section includes action checklists for drought, earthquake, extreme cold and winter storms, extreme heat, flooding, hurricanes, tornado, tsunami, volcano, and wildfire. The option labeled Take Notes and Record Damage leads to a section that includes a generic damage assessment form, while Inform Incident Command includes ICS forms 213 and 214 (the General Message and Activity Log, respectively), as well as additional information on Incident Command. The section on additional planning info includes links to EPA webpages on emergencies/incidents, planning, response, and recovery, as well as to WARN and mutual aid info.

Some of the external links from the site are not formatted for mobile viewing, and the .pdf forms may require an Adobe Reader app if you wish to fill them out on your mobile device. However, the site overall is well organized and easy to navigate, and can be a great tool for utilities dealing with weather emergencies and natural disasters. For a visual overview of how the site works, see the EPA’s video, below.
 

Interested in attending training or finding more information on emergency planning? Search our calendar and document database using the category “Water Security/Emergency Response.”

Developing and Implementing Tools for Small Systems to Evaluate and Select Appropriate Treatment Technologies

Water utilities can struggle to know which treatment technologies to consider and then which one to select and implement to solve their water quality and compliance challenges. This is particularly challenging for small water systems without resources to stay up-to-date on the range of appropriate technology options and their associated treatment and operational performance. The DeRISK Center is dedicated to addressing this challenge by developing and implementing tools for small systems to evaluate and select appropriate treatment technologies. These tools are designed to help utilities, states, consultants, and technology providers make technology selection decisions based on public health protection and sustainability beyond just regulatory compliance.

A conventional analysis of technology alternatives is typically performed when water systems need to upgrade or replace major treatment facilities. This analysis consists of identifying the feasible alternatives that will accomplish the treatment goals, comparing the alternatives based on some criteria, and selecting the “best” alternative. The criterion most used is cost—capital cost, operation and maintenance cost, or an engineering life-cycle cost analysis that includes the anticipated life-span of major equipment.
 
The DeRISK Center tools employ a decision support methodology that improves on this conventional approach. The major steps in the methodology are deciding what criteria are most important to stakeholders and providing and easy way to compare technology alternatives to each other with respect to each criterion. Our approach strives to go beyond just a comparison of costs. As shown in Figure 1, the decision support methodology expands on the conventional analysis of alternatives process by including:
  • Facilitated methodology that incorporates stakeholder input
  • Data on innovative treatment technologies
  • Relative health risk protection of treatment approaches
  • Sustainability measures of treatment approaches
  • Stakeholder preferences

Performance information such as treated water quality and performance data along with other characteristics, including source water quality constraints, are used to identify feasible technology alternatives. The characteristics for feasible alternatives are then fed into the analyses of health risk, sustainability, and stakeholder preferences in order to provide data to the decision support methodology.  
 
Microbial and chemical agents in drinking water can pose significant human health risks. Evaluating the combined impacts from multiple contaminants can provide new insights into how best to manage that risk and protect public health to meet regulatory compliance and achieve the greatest risk protection possible given feasible alternatives. The DeRISK Center tools utilize the Relative Health Indicator (RHI)—a semi-quantitative metric developed to harmonize the cancer and non-cancer impacts from a wide range of drinking water contaminants—to compare the relative health risks posed by multiple waterborne constituents.
 
The DeRISK Center is also focused on analyzing and improving the environmental and economic sustainability of small drinking water treatment systems. To achieve this, life cycle analysis (LCA) methodology is being used to quantify and characterize environmental impacts associated with various drinking water technologies. These impacts (using EPA’s TRACI assessment method) include ozone depletion (kg CFC-11 eq), global warming (kg CO2 eq), smog (kg O3 eq.), acidification (kg SO2 eq.), eutrophication (kg N eq.), carcinogenics (CTUh), non carcinogenics (CTUh), respiratory effects (kg PM 2.5 eq.), ecotoxicity (CTUe), and fossil fuel depletion (MJ surplus). A comprehensive LCA model framework was developed utilizing water treatment data, experience, and commercial information.
 
Last, the DeRISK Center is putting these tools to the test evaluating treatment technology decisions through cases studies with actual small water systems needing to address water quality and compliance challenges. The first case studies are assessing disinfection alternatives for small water systems in New Hampshire. 

If you are interested in testing these tools and collaborating with DeRISK Center researchers to assess treatment technology alternatives for your water system, please contact Chad Seidel at chad.seidel@colorado.edu