One of the most direct public impacts of algal blooms was seen in August 2014, when a harmful algal bloom in Toledo caused a “Do Not Drink” order to be issued for more than two days, an impact felt by residents and businesses alike. With direct guidance from state agencies at the front lines of algal drinking water crises like this one, HABRI researchers are developing new treatment methods that will give public health and water treatment professionals the tools they need to make informed decisions when water supplies are threatened by algal blooms.
Projects
Keeping Ohio’s Drinking Water Safe from Harmful Algal Bloom Toxins
Principal Investigator
Soryong Chae, University of Cincinnati
Project Summary
In recent decades, the amount of cyanobacterial harmful algal blooms occurring in Ohio’s freshwater bodies has increased, posing risks to public health and aquatic ecosystems. To remove contaminants, drinking water treatment plants often use a series of steps called coagulation, flocculation, and sedimentation (CFS), in which added chemicals force particles suspended in water to join together, forming large masses or “chunks” that can be settled down with gravity. With cyanobacteria, however, the treatment process can potentially disrupt cells and cause more toxins to be released, raising significant concerns for treatment plant operators.
Researchers aimed to uncover how site-specific environmental factors and water chemistry affect cyanobacteria and their removal from drinking water sources through CFS steps. They collected samples of water from Lake Erie and Grand Lake St. Marys on a bi-monthly basis, and then worked to characterize cyanobacteria species and cyanotoxins. Samples were used to conduct water quality tests before and after CFS treatments. Ultimately, researchers observed potential decreases in cyanobacteria (measured by their genes) and toxins following various CFS treatments.
With this data, the team created guidelines to share with water treatment plant operators to help optimize the removal of harmful cyanotoxins based on different environmental conditions. The information will be open source and made publicly available on a website soon. By following these guidelines, treatment plants can remove cyanobacteria at the beginning of the treatment process without releasing toxins into the water, thereby improving water quality and safeguarding public health.
The Bottom Line
New research provided guidelines for water treatment plants to maximize their efficiency in removing cyanobacteria and toxins based on different environmental conditions. Findings will help guarantee the safety of drinking water for the general public.
Eco-Friendly Methods to Remove Cyanobacteria from Drinking Water Sources
Principal Investigator
Soryong Chae, University of Cincinnati
Project Summary
Most algal toxins are contained within cells of cyanobacteria and can be released into the water if the cells die and their membranes rupture in a process called lysis. To prevent the release of harmful toxins, drinking water treatment processes should aim to eliminate cyanobacteria without “lysing” the cells. However, the additional steps required to address this challenge can be burdensome for water treatment facilities. Prolonged bloom seasons can exacerbate these challenges, as traditional processes typically treat water entering facilities, leaving the cyanobacteria remaining in reservoirs unaffected.
To mitigate this, researchers explored on-site treatment approaches to target HABs before affected water reaches the treatment plant. Many plants employ treatment steps called coagulation and flocculation to treat cyanobacteria, which can remove live cells without causing lysis and the release of toxins. The team aimed to devise eco-friendly steps to eradicate cyanobacteria in drinking water reservoirs and prevent their entry into treatment plants without using conventional chemicals that could harm aquatic ecosystems.
Researchers ran coagulation experiments employing chitosan, a natural biopolymer that can be extracted from shellfish shells, along with two types of clays native to Ohio to help separate cyanobacteria. They used a jar test apparatus and baffled flasks to replicate mixing conditions in water treatment processes and in lakes affected by blooms. The team also collected water samples from Grand Lake St. Marys and Lake Erie and measured water quality parameters before, during, and after treatment.
The study found that the chitosan treatments showed notable reductions in turbidity and cyanobacteria cell counts after coagulation. Adding clay into the system resulted in accelerated settling and the formation of larger chunks or “flocs.” Notably, water-soluble chitosan and clay induced buoyant flocs after a period of settling, which would allow cyanobacteria-containing scum to be removed from the water surface instead of settling at the bottom.
These outcomes pave the way for the development of in-lake or in-reservoir treatments for cyanobacteria removal, consequently reducing the risks posed by HABs. Insights from the project can potentially enhance water treatment practices, foster the adoption of more environmentally friendly coagulation chemicals, and promote a holistic approach to addressing HABs across entire water systems.
The Bottom Line
Drinking water treatment facilities have to take burdensome steps to ensure harmful algal cells don’t release toxins into the water. To help remedy this, researchers found success using eco-friendly materials to separate out cyanobacteria in reservoirs and lakes before treatment.
Can ‘Capturing’ Phosphorus Reduce Blooms?
Principal Investigator
Teresa Cutright, The University of Akron
Project Summary
Each summer, potential risks to human health arise when harmful algal bloom toxins are produced within Ohio reservoirs that are being used as a drinking water source. Water resource managers can control reservoir bloom impacts by using chemical additions such as algaecides on this source water. While traditional algaecides can kill off non-target organisms and leave residual elements behind, newer, hydrogen peroxide-based algaecides have proven to be more selective toward cyanobacteria. Recently, a manufacturer claimed that using a phosphorus-binding product, Phoslock®, in tandem with the hydrogen peroxidebased algaecide, PAK-27, could hold onto phosphorus released by cyanobacteria indefinitely.
Researchers aimed to test this claim and see whether the combined approach could be practical for reservoir managers. The team applied PAK-27 at different doses in water and cyanobacteria samples collected from multiple different Ohio reservoirs, and then, 24 hours later, applied the Phoslock® at a ratio of 200 pounds per every one pound of phosphorus. The levels of cyanobacteria, non-target organisms, and phosphorus were tracked over two weeks. Additionally, researchers conducted experiments using jars to see how much phosphorus would be adsorbed (held) or desorbed (released) over time.
Ultimately, the team found that PAK-27 was effective at controlling a bloom, even at a quarter dose, depending on the watershed and what organisms were present. They also found that the Phoslock® could do its intended job, binding the phosphorus released by cyanobacteria for some of the samples. However, under certain conditions, applying PAK-27 alone resulted in same phosphorus level after two weeks. Separate desorption experiments showed that the Phoslock® would release phosphorus over time. In addition, when sediment was present, the amount of phosphorus in the water would increase over time, depending on if system was aerobic or anaerobic.
Researchers concluded that the success of the combined application, which also happens to be expensive, will depend on the reservoir’s water chemistry and microbial community. After the project was completed, the team shared information with each of the water utilities that participated in the study.
The Bottom Line
To help water utilities be proactive in reducing blooms, researchers explored new potential methods to “capture” phosphorus released from cyanobacteria without harming other microorganisms and the ecosystem at large. Results showed that the applications were promising for some water resource managers, with limitations over time and depending on conditions of the water.
Improving Methods to Identify Harmful Algal Toxins
Principal Investigator
Dragan Isailovic, The University of Toledo
Project Summary
An excess of nutrients, or eutrophication, in lakes and rivers has led to an increased appearance of cyanobacterial harmful algal blooms in Ohio and around the world. Cyanobacteria — also known as blue-green algae — produce cyanotoxins that can impact human health and ecosystems. Notably, the structures and toxicities for most cyanotoxin forms or congeners produced by cyanobacteria in Lake Erie and the Maumee River remain unknown. Such insights would help negate potential threats to Ohio residents who use waterbodies affected by HABs for recreation or as their source of drinking water.
With this study, researchers aimed to enable quick and accurate identification of microcystins and other cyanotoxins found during HABs in northwest Ohio. Previous research indicated that using a combination of two analytical techniques — high-resolution mass spectrometry (HRMS) and liquid chromatography (LC) — showed promise for identifying cyanotoxins. The team aimed to refine their methods to identify more toxins and enable efficient purification and toxicology studies of novel cyanotoxins.
Because cyanotoxins appear alongside other molecules, researchers collected HAB water samples, extracted the toxic molecules, separated them using liquid chromatography, and determined their structures with high-resolution mass spectrometry. Python-based software was also used to analyze the data collected. Researchers employed toxicological assays, or laboratory tests, to study the toxicities of some of the more abundant microcystin forms.
Using a modern LC-HRMS instrument and software developed for data analysis, the team identified novel varieties of microcystins as well as anabaenopeptins and cyanopeptolins — cyanopeptides that accompany microcystins during HABs in Lake Erie and the Maumee River. Collaborative research is underway to isolate cyanotoxin varieties and determine their toxicities. The researchers aim to establish a database on cyanotoxin identities, distribution, and toxicity to guide decisionmaking related to water usage and treatment during harmful algal blooms in Ohio.
The Bottom Line
The structures and toxicities for most forms of algal toxins in Lake Erie and the Maumee River are unknown. Researchers developed new methods for quick and accurate identification of cyanotoxins found during harmful algal blooms.
Can Corncobs Remove Algal Bloom Toxins from Drinking Water?
Principal Investigator
Dragan Isailovic, The University of Toledo
Project Summary
In order to combat drinking water contaminated by cyanotoxins, treatment plants often rely on the physical process of adsorption to remove contaminants from the water. Activated carbon, also called activated charcoal, has proven to be the most efficient adsorbent available because of its large surface area with many pores. However, commercial activated carbon — often derived from wood or coal — isn’t environmentally sustainable, and it tends to be expensive. Corncobs, meanwhile, are a common byproduct of agriculture in the Great Lakes and Midwest regions, and previous studies showed they can remove contaminants from water when modified.
Recognizing this potential solution, researchers explored whether corncobs could be used to make materials that will adsorb potent cyanotoxins from drinking water. The team received corncobs from The Andersons of Maumee, Ohio, and chemically treated and heated the corncobs to increase their surface area and porosity, creating biochar and activated carbon. These sorbent materials were characterized to determine their important properties, such as pore sizes and surface area. Then, researchers put the materials to the test by conducting experiments with samples of water taken from western Lake Erie during harmful algal blooms from 2020 to 2022.
Researchers found that corncob-based activated carbon is especially efficient at removing microcystins from HABs as well as nodularin, a closely related cyanotoxin. The activated carbon produced has an estimated sorption capacity slightly lower than commercially available activated carbon used in water treatment plants. The team has published their results in the academic journal Separations. They are also currently developing a new generation of activated corncob that is expected to have higher sorption capacity and remove nonpolar forms of microcystin more efficiently.
The Bottom Line
Drinking water treatment plants use activated carbon to adsorb toxins from harmful algal blooms, yet commercially available materials have environmental and economic limits. Researchers found that carbonized corncobs may serve as an effective alternative.
Innovating Drinking Water Treatment to Address Algal Toxins
Principal Investigator
Youngwoo Seo, The University of Toledo
Project Summary
Many drinking water treatment plants in Ohio struggle to effectively remove cells of harmful algal blooms and their associated algal organic matter. This is largely due to a step in the treatment process called sedimentation, in which particles with a higher density than water are separated out using gravity. Cyanobacterial cells, which naturally float on water due to their low density, aren’t effectively removed through this process. The step also requires high doses of chemicals for cyanobacteria removal, generating large amounts of leftover chemical waste.
Recently, researchers have optimized the chemical treatment for dissolved air flotation (DAF) as a cost-effective alternative for treating water impacted by harmful algal blooms (HABs). Within this system, billions of microscopic air bubbles attach to contaminants and float them up to the water surface, where they can be skimmed off and separated.
Through the project, Seo’s team tested the performance of DAF using laboratory experiments and a full-scale study at a drinking water treatment plant in Celina, OH. In the lab, researchers worked to optimize chemical treatment for the system, considering the impacts of organic matter during HAB events. Then, at the plant, the team monitored the long-term performance of a DAF system by tracing the fate of cyanobacteria and toxins. Finally, researchers used their findings to develop guidelines for DAF operation and management, offering practical advice for water treatment plant operators.
The study yielded significant outcomes. From the lab tests, the team identified the best chemical types and doses to use in DAF systems. Meanwhile, the full-scale system installed at the Celina plant is the first of its kind in Ohio to treat water impacted by HABs. Researchers made recommendations to the plant and are monitoring its impacts, collecting and analyzing samples biweekly. The team compared drinking water treatment residuals from the Celina water plant with other plants in Ohio that employ conventional processes to treat raw water from Lake Erie.
The Bottom Line
Researchers tested a cost-effective alternative for treating drinking water impacted by harmful algal blooms with successful results.
Impacts of Low UV Wavelengths on Cyanobacteria and Cyanotoxins in Drinking and Natural Water Treatment
Principal Investigator
Natalie Hull, The Ohio State University
Project Summary
Exposing water to ultraviolet (UV) light is one technique used for the remediation of cyanobacterial harmful algal blooms. This technique focuses on exposure to wavelengths of UV that the bacteria and toxins are known to absorb. This research compares the exposure of various algal toxins to UV light with wavelengths of 254 and 222 nanometers, also called UV254 and UV222. One potent algal toxin, Microcystin- LR, has a 2.9 to 7.3 times greater degradation rate when exposed to UV222 compared to UV254. Other toxins tested did not show the same pattern of degradation as determined by the researchers’ analysis. Cellular tests are ongoing with UV222 exposures resulting in lower cellular permeability than UV254 exposures. So far, UV222 shows promise as a water treatment technique comparable to UV254 with the potential to be more effective.