City Approves WWTP Hauling Contract, Discusses Foul Odors

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 01/16/2017 - 14:57
Water Production and Wastewater Treatment Superintendent Bob Scull answers questions about the WWTP at last week's city council meeting.

“While it is a wastewater treatment plant, and some odors are unavoidable, the frequency and severity of these odors is simply unacceptable,” said Mayor Brain Marl in his state of the city address.

Issues related to the Saline Wastewater Treatment Plant (WWTP) dominated the discussion in City Council after the inauguration of newly elected council members and the mayor’s address. Both the handling of biosolids and the odor issue were considered.

The processing of sewage does not turn everything into clean water. A smelly undegradable slurry remains called biosolids. The city pays contractors to haul these biosolids off-site for surface application or, if necessary, deep well injection.

Participating farmers agree to have the biosolids applied to their fields to enhance fertility. Before they apply the material, the contractors analyze the material for metals, nutrients and coliform bacteria. When it is deemed too toxic it is not used on fields.

The business of collecting, analyzing and applying biosolids in the area has been dominated by two companies, Synagro Midwest and BioTech Agronomics. The City of Saline has worked with both contractors in the past, but most recently had a contract with Synagro.

The contract with Synagro expired on December 31, 2016 and, in the meantime, the company decided to cease business operations in Michigan. Saline needed a new contractor.

Rather than simply go with the dominant player remaining in the area, Wastewater Treatment Superintendent Bob Scull made a broader search and found two additional companies who were willing to submit a bid, NutriGro Environmental Solutions, Inc. of Charlotte and Burch Hydro, Inc. of Fredericktown, Ohio.

Based on Scull’s analysis, he selected NutriGro, who submitted a bid for a three-year contract costing $200,220. NutriGro would be contracted to do the hauling, quarterly analysis (required by law), land application and tank cleaning.

Since the City has had past dealings with BioTech, some council members were curious as to why they were not chosen. Scull replied that the city was also familiar with NutriGro since they had been backup for Synagro.

In addition, Scull pointed out that BioTech serves so many local municipalities that he feared they might not be able to handle the rush during the narrow window of time when surface application is possible.

During the citizen’s comments Mary Hess asked that the cost of $200,220 be attached to the motion. She also expressed her concerns about the city’s practice of accepting septage from private septic tanks in the area.

Hess pointed out the costs involved in building and operating a septage receiving facility and suggested that the plant may not be able to handle septage due to its greater concentration. She said that septage from outside is more than 1000-fold stronger than ordinary Saline sewage.

Scull addressed these concerns. He said that the city had raised the rate charged to septage haulers from $0.065 to $0.08 per gallon of material to help pay for the cost of biosolids hauling.

Furthermore, Scull said that the solids concentration is no more than 10-fold greater in septage compared to normal sewer effluent. And it is not a problem for the equipment, in part because it makes up only about 10 percent of the total processed waste.

In the past year, he said, septage has contributed nothing to the quantity of waste handled by the plant, nor has it contributed to the odors that have generated so much concern, because the WWTP has not been accepting septage since early in 2016.

After discussion, Council member Dean Girbach moved to accept the contract with NutriGro, adding the cost to the motion, as recommended by Hess. The motion, seconded by council member Janet Dillon, was approved unanimously.

Naturally the other WWTP issue that was discussed was the smell. Girbach noted that he had smelled it that very night on the way to the meeting. He also expressed concern that important issues like this were getting lost amidst an overly busy agenda.

“Personally, with the wastewater treatment plant, I am disappointed that I cannot look at my fellow citizens and say we can fix this right away,” Girbach said.

Scull gave an update on the odor issue. He said that Webster Environmental, whom the city contracted for nearly $100,000 to analyze the problem and make recommendations has completed their first round of testing, but they are still processing the data.

Scull also contacted another firm, Process Results, to provide advice on the problem. Next week he said he would be meeting with USP Technologies to talk about a stopgap chemical solution to the odor situation.

“I just want to make sure that everybody knows we are doing everything we can,” Scull said. “We are looking at the problem from every angle and a couple of new angles.”

The chemical solution would involve using an oxidant, hydrogen peroxide, to treat the odiferous gasses emitted by the plant. Much of the unpleasant odor comes from sulfides and these are oxidized by peroxide to less smelly and less volatile compounds.

Fun fact: Skunk spray also contains sulfides. The best way to treat a dog sprayed by a skunk is to wash with water to which hydrogen peroxide and baking soda have been added. It’s much better than ketchup, but with some dogs it could lighten their hair color.

Girbach wanted to know if the odor problems at the WWTP were caused by flaw in the design of the plant upgrade and were therefore the fault of TetraTech. Scull said he did not think so and that it was more likely “a matter of luck.”

Marl commented that the city has dealt diligently with this problem in the past, but “we weren’t always taking action based on data and analysis.” The hope is that with better science the problem can be cured once and for all.









Bob Conradi's picture
Bob Conradi Is a retired pharmaceutical scientist who has redefined himself as a photographer and journalist. He has lived in Michigan for 36 years and in the Saline area for 10. He enjoys researching and learning about new ideas. Reach him at [email protected] Follow him on Twitter at @RobertConradi.