(July 26, 2013) Along with the usual number of satisfying things about an Ocean City vacation – such as the pristine beaches, calm sea breeze, or convenient public transportation – visitors can now add another feel-good to the list.
Your poo is going to a good cause, possibly in your own community.
As of this month, the city has successfully secured a contract with a private hauler to take its ‘class A’ biosolids to farms in southern Maryland and the lower Western Shore, instead of paying to dump them at the county landfill.
“They’re going to an agricultural use, which is a big deal to us,” said Jim Parsons, the city’s Deputy Director of Public Works. “We really don’t like to see these go to a landfill.”
Biosolids is an industry term for what is, in essence, sewage treatment by-products that have been pasteurized and alkalized to the point where they can be used as fertilizer without risk to soil or water quality, although some environmental groups like the Waterkeep Alliance have disputed this.
However, most health and sanitation issues related to the agricultural use of biosolids in past years have been the result of ‘class B’ biosolids, which are rated by the federal Environmental Protection Agency as being 95 percent pathogen-free. The biosolids produced by the city are EPA ‘class A,’ meaning that infectious agents have been reduced below detectable levels.
“It’s referred to by the Maryland Department of the Environment as PFRP – process for the further reduction of pathogens,” Parsons said. “As a ‘class A’ biosolid, they’re essentially pathogen-free.”
Since its inception in 2004, the city’s biosolids program has been pitched as a win-win project: It reduces the volumetric burden of the city’s outsized sewage treatment capacity, brought on by the sheer number of summer visitors and the corresponding volume of waste they produce.
“I kind of feel like it’s a poetic justice,” Parsons said. “We produce so much sewer sludge because we have so many visitors in the summer. So now we treat the sludge and take it back to farms on the other side of the bay – where most of the visitors come from.”
At the same time, the biosolids project saves money in the long term. Despite costing millions to set up a ‘class A’ processing system, the town sees incremental savings in having the waste taken away by a distributor, who charges less to haul it since he is able to sell it to farmers.
“We’re seeing about a $65,000- to $75,000-savings this year using this contractor, versus hauling it all to the landfill,” Parsons said.
Because of the extreme level of regulatory scrutiny that goes into the city’s production of certified ‘class A’ biosolids, the product can be used by farmers quite freely, as opposed to less well-treated sludge.
“They can be distributed to anyone to be used,” said Jay Apperson of the Maryland Department of the Environment. “With other classes of biosolids, or if you’re a farmer that’s receiving them from another source, you’d need to get permits and do on-site monitoring.”
The material processed to make Ocean City’s biosolids is a controlled mixture of both ‘primary’ and ‘secondary’ sewer sludge. Primary sludge consists of high-density material that settles, by gravity, at the bottom of wastewater clarification tanks.
The remaining liquid is then drained into a secondary tank, where microorganisms are introduced to literally eat the remaining contaminants in what is known as an ‘activated sludge process.’ This results in a secondary sludge, which consists of the waste generated by dead microorganisms.
“A lot of people think that this sludge is just the stuff they flush down the toilet,” Parsons said. “What this really is, is the bacteria that eat the stuff they flush down the toilet.”
Some of this material is re-introduced to start the next digestion process. The rest, mixed with some primary sludge, is first sent through presses to reduce its water content. Lyme is then added, using augers heated to 900 degrees Fahrenheit, and the mixture is pasteurized at a minimum of 158 degrees for a at least 30 minutes.
But despite their high level of treatment making them hassle-free, the use of Ocean City’s biosolids does have a few things working against it. First, the town’s peak capacity for production is reached in the summer, just as farmers are winding down their spring fertilization process.
The city produces nearly 4,000 tons of biosolids per year, Parsons said, of which roughly half is generated from Memorial Day to Labor Day. The town’s product is 35 to 40 percent solid, a much better ratio of moisture than most others.
“You don’t want to pay to be hauling water,” Parsons said.
Second, because of the lime used to stabilize the biosolids and prevent further decomposition, the city’s product is highly alkaline. When the program first started, Parsons said the city was able to give the biosolids away to local sod and turf farmers, but only for a certain time.
“By definition, biosolids have very high pH,” Parsons said. “You put this stuff on your lawn for a period, and it loves it. Especially because we have naturally acidic [low pH] soils here. But they can’t use it in perpetuity because it’ll eventually drive the level too high.”
For the past several years, the city has been taking most of its biosolids to the county landfill, although it has been able to put some to use with local crop farmers. But even that market has died down since a series of environmental lawsuits, such as the recently settled Hudson Farms case.
All biosolids, even if free of pathogens, contain a concentration of nutrients that can change water chemistry and affect the balance of marine environments if runoff is not controlled, environmental groups have said. Algae blooms are a particularly strong case.
“Being ‘class A’ meant more ten years ago than it does today,” Parsons said. “There’s so much concern now about nutrient runoff, and whether it’s ‘class A’ or not, it has a certain nutrient content. A lot of the regulations just got ratcheted down more and more to the point where we had a lot of participants who said ‘We’re going to wait and see how it shakes out before we take more biosolids.’”