Editor's Note: This article is part of an operator profile on Mike Welke of Warren, Ohio. Watch for a special feature in the October 2015 issue of Treatment Plant Operator. Not a subscriber? Take care of that right here and now. Click here to have TPO delivered monthly to your mailbox.

Buying the least expensive product is not always the wisest choice. Mike Welke, biosolids manager and maintenance supervisor, saw this firsthand during one of the first emulsion polymer bids the City of Warren, Ohio, accepted for its plate-and-frame filter presses.

“We’d mix a batch with the polymer and, if it went bad, the whole sump was bad,” he says.

In 1999, Larry Stadwick, retired biosolids manager, and other in-house staff developed a polymer trial to ensure that the city contracted for the best product, and not necessarily the lowest priced. Welke helped adjust some parameters. As word of the trial spread through the biosolids community, Welke gave presentations on the procedure. His most recent was at the 2008 Northeast Section Ohio Water Environment Association conference.

Annually, the city invites interested vendors to determine which product to bid via jar tests.

“We recommend they provide polymer for six hours, because they have two hours to adjust dosing before the trial begins,” says Welke. “Those who submit bids then have four hours to prove their product will work.”

Welke grades the trials using a spreadsheet with various parameters, including product appearance.

“Even though the polymer might dewater well, if it doesn’t break down with heat in the EnVessel Pasteurization system (RDP Technologies), it won’t produce a visually pleasing, marketable granular product,” he says. Nature’s Blend Processing Facility produces Class A exceptional quality biosolids.

Even current supplier SNF Polydyne must bid and take part in the trial to renew its contract. In 2014, three vendors bid, but one withdrew. “The other polymer had some good numbers, but the granular product wasn’t pleasing enough,” says Welke. “Polydyne’s polymer gave the winning performance.”

On another occasion, the trial was a disaster for a vendor. During the first adjustment hour, the polymer wouldn’t break the floc properly. “I offered him the full two hours to get it right, but he admitted to low-balling his bid,” says Welke. “He was honest about choosing the wrong product and that it wasn’t going to work. I had the highest respect for him.”