AN ANAEROBIC BIOLOGICAL WASTE TREATMENT SYSTEM IS THE BEST AVENUE FOR A SUSTAINABLE HOG OPERATIONS

DES MOINES, Iowa (June 6, 2008) – As environmental restrictions continue to tighten in the swine industry, many producers are going to be faced with compliance levels that will seriously challenge the capabilities of their existing manure and wastewater treatment facilities, said Bill Campion of Pro-Act Microbial, Warren, Rhode Island.
         Mr. Campion spoke at the Environmental Information Center sponsored by Engineered Storage Products Company held Friday June 6 at the 2008 World Pork Expo in Des Moines, Iowa.
         “There are regulatory, environmental, health and aesthetic reasons to treat animal waste,” said Campion. “As hog operations have become bigger, and communities grow into their backyard, there are greater concerns about odor, water quality and pathogens that become more difficult to address as these operations expand and produce more waste.”
         Campion’s presentation outlined an “ideal” biotreatment system that deals with all these issues. Physical removal of solids through a solids separator is an important first step, but not enough – biological waste treatment is “Mother Nature’s way of cheaply dealing with biodegradable organics that produce odor,” he said. “Our goal is to remove solids, treat biodegradable organics, eliminate pathogens and remove nutrients for later use, ending up with good quality irrigation water so no nitrogen or phosphorus enters our streams.”
         There are two major types of biological waste treatment – aerobic (bacteria needs oxygen to grow), and anaerobic (bacteria will not grow in the presence of oxygen). Aerobic treatment is sufficient for municipal wastewater treatment, but anaerobic is necessary to handle the significantly higher levels of organic matters found in hog manure.
         “Hog waste is a challenge due to its higher nitrogen content. The higher nitrogen levels help give hog manure its distinctive odor. Ideally, you need to balance the carbon to nitrogen ratio,” Campion says.
         The ideal hog waste treatment system relies on anaerobic digestion using microbes in a multi-step process, Campion said.
         “This is not a pit additive,” adds Campion. “Anaerobic microbes work best in pull plug or flush systems in combination with processing tanks and larger storage like a Slurrystore or lagoon.”

The NextStep™ System

Manure is first transferred to a processing tank for removal of solids containing nitrogen and phosphorus. This is best accomplished using a combination of a separator and natural settling. Nutrient rich sludge stays at the bottom of the tank for easy removal.
The tank is covered to collect the methane by-product and to prevent this potent greenhouse gas from escaping into the atmosphere. The captured biogas is used to power a boiler that heats the contents of the tank to benefit the microbes.
Top water from this tank is pumped to a larger tank or lagoon. This tank is not covered. A floating diffuser provides oxygen to the top layer to grow an aerobic odor cap that prevents odor from escaping; while anaerobic microbes digest manure wastes in the bottom layer. Augmented microbial mix is added to the lagoon -- the microbes will circulate around the manure system through flushing to stabilize all of the anaerobic process throughout the system, and to help the performance of the solids separator.

The system meets producers’ requirements of being economical and easy to use and maintain, according to Campion, or it wouldn’t be adopted and used. An advantage of this system is that it is possible to proceed in stages. For instance, a hog operation can use microbes and a diffuser to tackle odor, solids, and nutrients first. Processing tanks can be added at a later time.
“Many larger hog operations already have a separator and lagoon system,” Campion added. “We are suggesting adding one, possibly two above-ground tanks such as Slurrystores to complete the system and get the desired results.”
Anaerobic biotreatment requires less energy and feeder nutrients and produces methane for energy but much less biological sludge. However, starting an anaerobic biotreatment facility requires patience.
“It can take months to get started,” Campion warned. “Many producers take starter material from an anaerobic digester that is already working to reduce startup time to a few weeks.”
The system he recommends addresses the potential for odor and formation of corrosive gases, either physically by covering the tank, or by forming the biological odor cap, or both. By stabilizing the anaerobic treatment system, less hydrogen sulfide is produced. Using a solids separator to take out recalcitrant material prior to anaerobic digestion, allows only the relatively easier digested materials into the processing tank to circumvent the hydrolysis bottleneck and reduce the digestion time needed.
Anaerobic systems are also temperature sensitive and slow down greatly in cold weather. In the system, methane-fueled boilers keep the tank warm enough so the microbes continue to thrive, even in northern climes.
It’s not possible for anaerobic digestion to remove nitrogen and phosphorus biologically, thus the need for physical removal in the separator first to capture these nutrients as solids before anaerobic treatment begins, Campion added.
Finally, anaerobic biotreatment can be fussy, Campion said. Anaerobic systems are prone to “upsets” and need a great amount of attention as compared to aerobic systems, so dairy producers unnecessarily abandon them.
“That is the role of the augmented microbes, to keep the anaerobic system active and stable,” Campion explained. “If we address traditional, well-known challenges of anaerobic biotreatment, we can maintain a wonderful waste treatment system that captures nutrients for fertilization while keeping regulators satisfied, streams clear, odor contained and communities more accepting of our growing hog operations.”

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