FAIRMONT - Lake chemistry is a complicated thing.
For the past few weeks, Sam Chin has been experimenting with different chemicals and doses at a pilot plant set up inside Fairmont's water treatment facility. His goal is to remove algae from water pumped in from Budd Lake, the source of Fairmont's drinking water.
Chin, a pilot plant engineer with Degremont, is using a system called AquaDAF. AquaDAF - "DAF" stands for Dissolved Air Flotation - is a "high-rate clarifier for low turbidity surface and algae laden waters," according to Degremont Technologies' website.
When the new water plant is built in Fairmont, AquaDAF could be the first step in treating the city's water after it's pumped from Budd Lake.
"It's been very effective," Chin said. "Right now we're analyzing cost. ... We can scour the water down to practically drinkable on the first step."
But finding the right mix of chemicals hasn't been easy. The lake chemistry is changing from week to week, making it difficult to compare how effective different chemicals are in treating the water.
"The lake chemistry is going all over the place," said water plant supervisor Butch Hybbert, noting the pH changed from 8 to 7 in a single day. "... It's presenting quite a challenge."
A series of large metal tanks, the AquaDAF system starts by mixing chemicals - this week it's ferric chloride - with water pumped in from the lake. These chemicals bind with particulates in the water, like algae and silt. Air is then added, which forms tiny little bubbles, on which the particulates and chemicals float.
"All the nasty stuff they're trying to get rid of is mixed with the chemicals to form the sludge on top," Chin said.
Pointing to the brownish-red sludge, Hybbert explained, "Mostly what you're looking at is iron, which contributes to the color."
The blanket of scum is easily removed from the top of the final AquaDAF tank and potentially reused. Composed mainly of water, the moisture is pressed out of the substance, and then can be dried into cakes to burn for energy or used on farm land for fertilizer, according to Chin.
"We try to be as effective as we can with all the processes we do at the plant," he said.
Hybbert wants to see the product go to farms: "If that doesn't work, this will have to go through the sanitary sewer, but we'd like to recycle it."
Fairmont's existing water plant operates without anything like the AquaDAF.
"Right now we're removing algae and geosmin with filters," Hybbert said.
But the taste and smell of the city's drinking water during algae blooms clearly indicates the system could stand improvement.
A carbon filter planned for the new treatment plant will improve taste and odor problems, but removing some of the algae when it first comes into the facility should help even more, as well as cutting down wear and tear on the carbon filter.
AquaDAF also could assist with removing total organic carbon - "TOC." TOC reacts with disinfection byproducts to create stuff you don't want in your drinking water, according to Hybbert.
While the AquaDAF unit works well - "really well," Hybbert said - the cost of the chemicals is high when the system is working to remove as many particulates as possible from the water. That's why the pilot study is scaling back to focus on just algae removal.
"We don't want to increase operation costs on top of debt payments," said Andy Noll, chairman of Fairmont Public Utilities Commission.
