By Tom Warmuth, Katherine Oppold, Matthew Cerami, Tyler Arnold
“We observed a 60% increase in non-target organism survival and a more balanced aquatic ecosystem. This resulted in improved source water quality and operational cost savings.”
–Matthew Cerami, Tyler Arnold, Veolia
Executive Summary
In June 2024, early signs of a harmful algal bloom (HAB) were detected in a large-scale drinking water reservoir in the Northeastern U.S. In the past, copper algaecide has been utilized in reservoirs with minimal longevity and impact, requiring repeated and continued treatments for algae control. This continual application of copper algaecides has been shown to have a detrimental impact on beneficial green algae and phytoplankton. Rather than waiting for toxin levels or taste and odor issues to escalate, Veolia collaborated with BioSafe Systems to implement a proactive treatment strategy. Using GreenClean Liquid 5.0, powered by peroxyacetic acid (PAA) chemistry, the team responded promptly to initial bloom activity and successfully suppressed cyanotoxins and geosmin before they reached critical thresholds. Preserving non-target
beneficial phytoplankton is critical to water quality and healthy aquatic ecosystems.
This early intervention approach rapidly suppressed cyanobacterial activity and significantly reduced concentrations of cyanotoxins and geosmin. By mitigating bloom development at an early stage, the program minimized organic loading and reduced the strain on treatment operations. This strategy led to improved water quality outcomes, enhanced process efficiency, and measurable reductions in operational and labor costs. This document outlines the timeline of events, treatment methodology, resulting water quality improvements, and the broader benefits of using proactive oxidation to break down cyanobacterial cells and their associated organic matter, thereby safeguarding drinking water systems.
Understanding Cyanoblooms in Drinking Water Systems
Cyanobacteria
Also known as blue-green algae, Cyanobacteria are naturally occurring microorganisms found in freshwater ecosystems. Under warm, nutrient-rich conditions, they can multiply rapidly, forming dense surface accumulations known as blooms. These blooms are not only aesthetically unappealing, but also pose multiple challenges to drinking water providers and operational strain and increased costs associated with the filtration and removal of the compounds that cause issues in drinking water for human consumption.
Taste & Odor (T&O) Compounds
Cyanobacteria can produce volatile organic compounds (VOC); most commonly geosmin and 2-methylisoborneol (2-MIB). Though not toxic, these compounds impart strong earthy/musty odors and are difficult to remove with conventional treatment methods. These odors result in consumer complaints at minimal levels (as low as 5–10 ng/L).
Cyanotoxins
Some cyanobacterial species produce harmful toxins, including microcystins, anatoxins, and cylindrospermopsin, which pose risks to human and animal health. These toxins are now subject to regulatory scrutiny and guidance by the U.S. EPA and state agencies.
Operational Strain
As blooms die, the resulting organic matter leads to increased filter clogging, biofilm growth, shorter run times, and increased coagulant demand. This results in more frequent maintenance, higher chemical costs, and potential disruptions to water delivery.
The Case for Proactive Treatment
Most conventional algaecide applications are reactive, triggered only when toxin levels or cell counts surpass a critical threshold. However, this delay allows the bloom to mature, increasing the amount of organic biomass and VOCs in the water and compounding treatment challenges.
A proactive strategy, applied at the first signs of bloom development, controls cyanobacteria before toxin release or operational strain occur. By responding early—before reaching critical thresholds—the treatment reduced infrastructure burden and maintained system stability, avoiding the higher costs of reactive interventions.
The BioSafe Systems and Veolia Partnership
Veolia’s water operations team, in partnership with Tom Warmuth of BioSafe Systems, implemented an early-season control strategy in June 2024, utilizing GreenClean Liquid 5.0, a fast-acting liquid algaecide and oxidizer powered by peroxyacetic acid (PAA).
The treatment was strategically applied across 166 acres of the reservoir at a rate of 7 gallons per acrefoot, targeting the bloom early in its development. By applying GreenClean Liquid 5.0 during the initial bloom signal, rather than waiting for a full outbreak, the team successfully disrupted cyanobacterial activity and prevented the escalation of geosmin and cyanotoxin levels.
Why GreenClean Liquid 5.0?
Unlike most traditional chemical treatments, GreenClean Liquid 5.0 offers several advantages for drinking water applications such as a quick control response and selective cyanobacteria control.
Selective Control
GreenClean Liquid 5.0 works by delivering fast control of cyanobacterial cell membranes, breaking down cell membranes to cause immediate cell death. This rapid action limits the release of organic material into the water column, reducing oxygen demand, and minimizing strain on downstream treatment systems.
Operational and Financial Advantages
Proactive monitoring and planned treatment of the target cyanobacteria before it peaked provided measurable benefits to Veolia’s drinking water operations, both in water quality outcomes and system-wide efficiency:
Minimized Labor and Maintenance
Early monitoring and detection with proactive treatment significantly reduced organic loading, leading to fewer filter backwashes and less frequent cleaning of intake structures and screens.
Protected Infrastructure
By preventing the decay of algal biomass, the treatment reduced the buildup of organic material that contribute to corrosion, biological fouling, and scaling. This helped extend the service life of pumps, sensors, and downstream equipment.
Improved Regulatory Confidence
The proactive strategy kept cyanotoxin concentrations below actionable thresholds, avoiding the need for public notification, emergency response, or corrective compliance measures.
Maintained Public Trust
Taste and odor (T&O) complaints are among the most common public concerns for water utilities. Early suppression of Geosmin prevented these issues from reaching consumers, supporting continued confidence in water quality.
Validated Through Chemical Usage Reductions
Activated Carbon (-78.7%): Typically used to remove T&O compounds like geosmin and 2-MIB, this major drop indicates that early PAA application reduced the need for secondary treatment of organoleptic compounds.
LOX (-16.4%): Utilized within the treatment plant as a pre-oxidation step, serving as an alternative to pre-chlorination. The reduction in LOX usage indicates a decreased organic load entering the plant, likely due to the early intervention with GreenClean Liquid 5.0. This reduction in organic matter lessened the demand for pre-oxidation, enhancing overall treatment efficiency.
Polymer Coagulant (-34.0%): Reduced turbidity and total suspended solids (TSS) from suppressed bloom activity meant fewer particulates entering the plant, resulting in decreased coagulant use.
Conclusion
This case sets a new benchmark for harmful algal bloom (HAB) control in drinking water systems, demonstrating how a proactive, chemistry-driven approach can deliver superior outcomes compared to traditional reactive strategies. By intervening early with GreenClean Liquid 5.0, Veolia and BioSafe Systems achieved rapid toxin elimination, improved overall water quality, and realized measurable reductions in operational costs. The treatment further safeguarded infrastructure and provided a DBPfree solution that integrated seamlessly with existing disinfection protocols.
As cyanobacterial blooms become increasingly common across the country, this example offers a compelling and scalable model for municipalities seeking a scientifically sound, operationally efficient, and environmentally responsible strategy for protecting their drinking water supplies.
Additional Data:
Profiler Heat Maps:
These heat maps visualize water column dynamics at the treatment site over the week of June 10–16, 2024. Each graph captures a different parameter—temperature, dissolved oxygen (DO), and oxidation-reduction potential (ORP)—measured at various depths (0.5 to 3.5 meters). The white vertical dashed line marks the application of GreenClean Liquid 5.0 (GCL) on June 11.
Fig. 1: Temperature
Stable thermal layers support ecosystem balance and help predict bloom risk zones
Following the June 11 application of GreenClean Liquid 5.0, temperature stratification remained consistent throughout the water column. This stability indicates that the treatment did not disrupt natural thermal layers, preserving ecosystem balance while targeting algal activity.
Blues/Greens = Cooler water
Yellows/Reds = Warmer water
Fig. 2: Dissolved Oxygen
Shows oxygen availability for aquatic life and system health
Following the June 11 application of GreenClean Liquid 5.0, dissolved oxygen levels decreased in the upper water column, shifting from high levels (red/orange) to lower levels (blue/green). This drop is a common short-term effect of algaecide treatments as algal biomass breaks down, temporarily consuming oxygen during decomposition. Monitoring post-treatment oxygen levels is important to ensure system recovery and to guide aeration needs if necessary.
Yellows/Reds =
higher oxygen concentrations
Greens/Blues =
low oxygen (hypoxic conditions)
Fig. 3: Oxidation-Reduction Potential
Reflects the oxidative or reductive state of the water column
Following the June 11 application of GreenClean Liquid 5.0, ORP readings showed a shift toward more oxidative and stable conditions, particularly in deeper zones. This change reflects a reduction in organic loading and improved redox balance throughout the water column.
Oranges/Reds =
More Oxidative Environment
(favorable for organic break down)
Greens/Blues =
More reductive environment (often linked to organic build-up or decay, reflects microbial and chemical activity in water column)
Fig. 4: Blue Green Algae- Phycocyanin Fluoresence
Direct indicator of harmful algal bloom (HAB) risk
Following the June 11 application of GreenClean Liquid 5.0, cyanobacterial concentrations dropped significantly, as shown by the decline in BGA-PC fluorescence. This reduction was especially apparent in surface waters where blooms typically form, indicating a rapid and effective treatment response
Yellows/Oranges/Reds = High Phycocyanin concentrations (indicates elevated cyano bacterial biomass or bloom presence)
Greens/Blues = Lower Phycocyanin concentrations
(reduced or minimal cyanobacterial presence)
Fig. 5: Fluorescent Dissolved Organic Matter
Influences treatment cost and DBP formation
Organic material, measured through fluorescent DOM, showed signs of stabilization after treatment. While some transient peaks likely reflected the breakdown of algae, the overall signal trended toward lower variability, suggesting reduced organic inputs and system recovery.
Yellow/Orange/Red:
High concentrations of dissolved organic material, often from decaying algae or watershed runoff.
Green/Blue:
Lower levels of organic matter, indicating clearer and less impacted water
