Utility uses more than a year’s worth of PAC in two months to address high concentrations of MIB

Author: Devon Santistevan, Director of Sales Operations and Marketing at Arq.

For eight weeks in the summer of 2024, Louisville Water Company treated a massive algal superbloom that had the potential for an exceedingly bad taste and odor for nearly one million people. The size of the initial bloom alone would have been a water treatment challenge, but to compound the problem, a prolonged drought and lack of rainfall along the Ohio River – Louisville Water’s source – had made the river and its tributaries especially sluggish, which resulted in a sustained algal bloom that would linger for weeks. 

Louisville Water’s partnership with Arq helped avoid a water treatment challenge and public relations crisis. 

The Problem: A Large, Persistent Superbloom

Louisville Water Company provides clean drinking water to about one million people every day. The utility is a national standout in terms of its commitment to innovation and investments in water quality, infrastructure revitalization and environmental sustainability. In fact, it’s the only utility in the nation to have branded its tap water, known as Louisville Pure Tap®, and takes the quality of its water very seriously.

Part of Louisville Water’s commitment to water quality involves hundreds of daily tests of the water moving through its system, starting with its source water: the Ohio River. Every day, the utility tests its intake water, and when problems are detected, Louisville Water scientists work with the Ohio River Valley Water Sanitation Commission (ORSANCO) to get data from as far as 55 miles upriver to discern the source, nature, and size of the problem. This level of testing gives the utility advanced warning of unexpected or unusually high contamination. In late June, testing crews sounded the alarm: an algal superbloom was emerging.

Driven by higher air temperatures, the waters of the Ohio River had been on a warming trend, and that warmer water fueled the reproduction of blue-green algae (cyanobacteria). Testing on intake water alerted plant operators to the presence of 2-methylisoborneol (MIB), a normal byproduct of cyanobacteria metabolism and one of the primary causes of bad taste and smell (although not a public health danger). This would normally initiate the dosing of powdered activated carbon (PAC), a highly effective treatment for MIB that most utilities keep in supply. But subsequent upstream testing revealed that the problem would not be solved quickly or with the usual amount of PAC. The concentration of MIB in the utility’s source water was high and getting higher. Louisville Water needed more PAC immediately.

The Solution: More Than a Year’s Supply of Powdered Activated Carbon in Eight Weeks

Louisville Water often goes days without needing PAC for taste and odor issues, and its onsite storage tanks can hold about 160,000 pounds of PAC to use as needed. The quickly rising levels of MIB, however, meant their reserves would not last long. 

Fortunately for Louisville Water, one of their vendors was prepared to help them respond in time to treat the water before it affected customers. Louisville Water’s PAC supplier Arq quickly sprang into action, marshalling all their resources to help their customer. 

By July 17, the utility needed close to 60,000 pounds of PAC a day to mitigate the MIB, going from a typical delivery schedule of about one truckload of PAC per month to a truckload every one to five days. Not every supplier would have been able to deliver 30 times its contracted amount with just a few days’ notice, but Arq was ready for the challenge for several reasons. 

First, Arq is a vertically integrated manufacturer of activated carbon, meaning it has complete control of its entire supply chain, from feedstock to finished product. Having all supply chain entities aligned under one owner allows Arq to rapidly switch gears and pivot when a customer is in need, without having to manage multiple contracts and relationships.

Also, Arq’s activated carbon is 100% manufactured in the United States, so international shipping is not a factor in their logistics. All their activated carbon is sourced domestically and manufactured in Louisiana, and ramping up production is a much simpler affair than it is for companies with sources and plants scattered abroad.

On top of these foundational attributes, Arq’s sales forecasting team hit the mark for 2024, and the company had an ample supply of finished product initially ready for delivery. To maintain the increased supply, the company provided extra capacity by ramping up PAC production at both of its Louisiana manufacturing plants.

Arq also has strong relationships with their carriers, and for this event, they secured dedicated drivers assigned to transport PAC as often and for as long as it would take to get Louisville Water through the superbloom. They also pre-loaded trailers with 30,000 pounds of PAC, so that drivers could more quickly start the two-day return journey from Arq’s Louisiana plant to Louisville Water. To manage the complex and intense logistics, Arq’s customer service staff maintained frequent and organized communication to keep all involved parties consistently informed throughout the order-to-delivery process.

The heroic measures taken by Louisville Water’s staff were critical during this event, as they worked around the clock to stay on top of the MIB treatment campaign with shipment receipts and treatment activities happening at all hours of the day and night.

“The quality of our water is very important to all of us,” said Eric Gant, Plant Operations Manager for Louisville Water. “This was a high priority, and everyone pitched in.” 

The Results: Rapid Superbloom Intervention Contained a Superbad Smell and Taste

Most humans can detect MIB at around 10 ppt (parts per trillion), and Louisville Water initiates MIB treatment when sampling reveals 6 ppt. At the height of the bloom, plant intake water showed concentrations of MIB at 128 ppt, a level that had the potential to cause enormous public concern and the erosion of trust. MIB – even at very high concentrations – is not toxic to humans, but most people react strongly to bad taste and smell in water and believe it to be unsafe. Quick intervention at Louisville Water kept taste and odor complaints from customers at levels that barely notched above what the plant typically receives. 

From its earliest detection to its final exit, the superbloom lasted from late June to early September, ultimately driving the total delivery of 956,820 pounds of Arq’s CarbPure TRA between June 23 and September 5, 2024. 

Gant was pleased with Arq’s ability to dramatically ramp up production to meet the plant’s needs. “We aren’t the only water utility that pulls from the Ohio River, so everyone needed PAC last summer,” he said. “I don’t think we would have been as successful in treating the algal bloom without Arq’s help in meeting our surge in demand.” 

Looking Ahead to the Next Bloom

While Arq helped Louisville Water manage through the utility’s largest taste and odor event in decades, the utility is proactively planning for the next outbreak. Anticipated to be operational in 2027, a new treatment system will have three times the PAC storage capacity of its current system. Warmer river water, when combined with longer drought periods or upstream water demands, mean that algal blooms – and their byproducts – are likely to become more common in source water, and that utilities will need to be pre-equipped with more PAC. In keeping with its dedicated mission to uphold the taste and quality that customers expect from Louisville Pure Tap, Louisville Water will be ready.

Continued Partnership     

Committed to client success, Arq continues to support Louisville in times of need. When Louisville Water raised concerns about securing enough carbon from its primary supplier should water conditions change, Arq quickly stepped in agreeing to be a secondary supplier.

Arq’s vertically integrated, domestically focused model allows for control across every stage of the supply chain, ensuring consistent quality, cost efficiency and supply resilience. Delivering on its customer-centric approach, Arq fosters innovation, trusted partnerships and shared success while offering consistent high-performance solutions for customers like Louisville Water in a rapidly evolving marketplace.