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|What we’re working on: Manure digesters|
|Dairy basics - Manure|
|Written by PD Editor Karen Lee|
|Monday, 28 March 2011 05:31|
Progressive Dairyman selected a few companies that specialize in manure digesters to comment on industry trends and how they are working to meet the needs of today’s dairy producers. Here are their responses:Avatar Energy, LLC
Avatar Energy, LLC, is a renewable energy company that designs, installs and operates anaerobic digester systems for small- to medium-sized dairy farms in the U.S. and Canada. It has offices in Vermont, California and Nevada. Avatar Energy uniquely addresses three hot-button issues in the industry:
Avatar Energy has two systems in final stages of startup: Bakerview EcoDairy in Abbotsford, British Columbia, and the Keewaydin dairy in Stowe, Vermont. Both feature the AnD 1B22 digester, equipped to handle 22, 472 gallons of waste. Bakerview is the company’s first international installation and it’s generating many levels of interest in digester technology for dairymen throughout Canada. The farm hosts numerous visitors to learn about this unique system and its onsite applications. The Keewaydin dairy farm project will be operational in April 2011, when the Avatar team will invite guests for informational green energy tours.
Avatar Energy has three systems scheduled to break ground this summer in Nevada. In Yerington, Avatar will install a 3B87 series digester, which can handle 87,030 gallons of waste, for the Frade Ranch; and a 4B145 (145,050 gallons of waste) at the Desert Hills Dairy. The third project is at the Hillside Dairy farm in Fallon, where we will install a 6B213 (213,288 gallon) digester system.
Bio-Terre Systems Inc.
The Bio-Terre technology was developed in Canada. It was invented and patented by Agriculture and Agri-Food Canada (AAFC) and the University of Ottawa. The technology was later taken to commercial scale and field validated by Bio-Terre Systems Inc., a company formed by three Canadian engineering firms from Quebec and Manitoba.
The idea was to develop a technology for the average size dairy farm (1,000 head) and to address the fact that the high-liquid portion of manure doesn’t provide anything but volume to a digester system.
The Bio-Terre anaerobic digestion process uses a sequential approach at a low temperature of 68-77°F (Psychrophilic). At this temperature the microorganisms at work are very hardy and thrive in large numbers across a broad range of genotypes. This sequential batch process creates a longer solid retention time without increasing the hydraulic retention time.
Since the Bio-Terre system requires less heat to operate compared to other systems, 15 to 50 percent more methane is available for alternative uses rather than being committed to process heating.
Bio-Terre’s process provides maximum flexibility in the choice of infrastructure and equipment. This translates into important economic savings, both for the initial construction costs as well as the ongoing costs to operate and maintain the system. Over the years engineers associated with Bio-Terre have optimized the system to operate over a regime of extreme weather conditions and broad situations and difficult field circumstances with minimal expenses.
Not including exports, GHD has more than 75 digesters constructed at 56 sites, with 21 more under construction. We’ve started to develop projects in California and have been investing heavily in R&D.
Performance is king, especially when times are lean. This means GHD (while fortunate to be the market leader for on-farm digesters) is continually focused on making our digesters ever-more “farm-sensible” – by increasing efficiency and reliability while making them even simpler to operate and maintain. Today’s digesters need to be more flexible, too. Some must operate efficiently on low-energy waste streams with no additional substrates, and others need to handle complex inputs from multiple agricultural or industrial feedstocks.
Say goodbye, E-coli. Successful waste management doesn't stop after the digester. Recently, increasing regulatory pressure has spawned our development of a proprietary Nutrient Recovery (NR) system, which (for the first time) practically and economically captures Nitrogen in the form of ammonia from digestate. Phosphorus removal is enhanced, too. The significantly reduced nutrient content per gallon will allow a farmer to apply more digestate on less land. Other benefits of NR include a “Class A” bioliquid with pathogen levels that are typically “undetectable.”
Those aren’t ‘laurels’ you’re sitting on. The high quality of GHD’s digested biosolids employed as dairy cattle bedding has long been recognized by our customers (even those who formerly bedded on sand). But other uses and markets for GHD biosolids are being developed in concert with the U.S. Forest Products Laboratory. For one, digested solids can be employed as low-cost building blocks for, well, building blocks! Odor-free fiberboard and particleboard panels made with GHD solids panels require no resins and are both stronger and more water-resistant than wood-based panels. For demonstration purposes the Forest Products Lab has even built a bench you can sit upon, from dairy solids. PD