Anaerobic Digest

BioCycle November 2013, Vol. 54, No. 11, p. 14


Eaton, Colorado: Composter Teams With Ad Project

A1 Organics, a composting company based in Eaton, has entered into an exclusive substrate procurement agreement with Heartland Biogas, LLC, for its anaerobic digester project in Weld County, Colorado. A1 Organics, the Rocky Mountain region’s largest commercial composter, will deliver food waste, fats, oils and grease, and other substrates to the digester facility, and work with Heartland to develop high value organic amendments and fertilizer grade products from the digested solids and liquid residuals. The complete mix anaerobic digester is being constructed at a dairy, and will digest manure in addition to the off-farm substrates. It is sized to produce 4,700 MMBtu of biogas daily, which — after being conditioned to pipeline grade — will be supplied to a municipal power authority through a long-term gas purchase agreement as renewable natural gas. A1 is actively negotiating with and seeking new generators of digestible organic substrates. “Weld County has been the Wilson family home since the late 1800s,” notes Chuck Wilson, president and CEO of A1 Organics. “Now, after 40 years of providing composting options for Colorado’s organic waste streams, we are proud to be an integral part of this exciting and innovative project that is not only focused on providing the next level of sustainable and beneficial options for recycling of organic wastes, but also creation of renewable energy and beneficial by-products.”

Heartland Biogas, LLC is a wholly owned subsidiary of EDF Renewable Energy, a utility company based in France. HDR, Inc. was awarded a contract by Heartland Biogas for design, construction and startup of the digester facility, which was developed by AgEnergy USA. EDF Renewable Energy participated in late stage development activities. Construction started in August 2013, with full-scale operations anticipated in 2015. In the interim, biogas captured from a covered lagoon at the dairy will be conditioned and injected into the pipeline in the first quarter of 2014.


Bristol, Connecticut: Integrated Organics Recycling Facility

Turning Earth, LLC, an organics recycling facility developer based in King of Prussia, Pennsylvania, joined forces with Covanta Energy Corp., a waste-to-energy (WTE) company, to develop an anaerobic digestion and composting project in Bristol. The 10-year agreement calls for Turning Earth to build, own and operate an integrated organics recycling facility in central Connecticut to which Covanta will divert organic waste for beneficial reuse in partnership with municipalities and commercial customers. Turning Earth will utilize Aikan Technology’s high solids anaerobic digestion (HSAD) and in-vessel composting system. Covanta operates waste-to-energy plants in Connecticut, and plans to divert “post-recycled” waste to a WTE plant. “This arrangement enables Covanta to provide our area municipal and commercial customers the ability to include organics recycling within their sustainable waste management programs,” said Stephen Diaz, Covanta Energy Vice President. Feedstocks will be comprised of yard trimmings, food waste and other organics. Facility construction is anticipated to begin in the latter half of 2014 following site selection, receipt of permits and procurement of organic waste.

Akron, Ohio: Phase II AD System On-Line

Akron Renewable Energy Facility

Akron Renewable Energy Facility

What was once the City of Akron Composting Plant is now the Akron Renewable Energy Facility. In late October, city officials and KB BioEnergy, Inc. held a ribbon-cutting ceremony to mark the $32 million transformation of the plant where 100 percent of the sewage sludge from the city’s wastewater treatment plant (about 15,000 dry tons/year) will be anaerobically digested to generate electricity. The Akron Renewable Energy Facility is owned by the City of Akron and operated by KB BioEnergy, Inc., formerly known as KB Compost Services, Inc. It was funded in part with a $9.6 million federal renewable energy tax credit. Akron provides the sludge and gets the electricity produced, according to Brian Gresser of the city of Akron. KB BioEnergy, Inc. uses BioFERM/Schmack Biogas AG technology. The former composting plant, which was operated by KB Compost Services, is being decommissioned.

Phase I of the AD facility was a pilot project launched in 2007 to determine the feasibility of using the Schmack Biogas AG high solids AD process as a means to manage the solids. The pilot facility was designed to process one-third of the annual solids; the biogas fueled a 335kW combined heat and power (CHP) engine (see “Processing Biosolids Via A High Solids Digester,” September 2010). Phase II incorporates the Schmack Biogas technology used in Phase I, but on a larger scale. The plant has two tanks — each measuring 68 feet in diameter and 26 feet high and capable of holding 704,000 gallons of sludge pumped in from the sewage plant on the east side of the Cuyahoga River. The sludge is heated to 95°F and remains inside the domed tanks equipped with a double membrane layer for 28 to 29 days. Biogas will fuel three 600 kW CHP units. Like Phase I, the expected parasitic load will be around 10 percent of the power generated. The remaining power will be used to reduce operational costs at the wastewater treatment facility. The digestate will be dewatered and processed through an indirect dryer, resulting in material that will be 95 percent or higher dry solids. These “pellets” will meet the Class A “Exceptional Quality” biosolids standard. Approximately 15,000 cubic yards will be produced annually.

Galt, California: Dairy Digester Up And Running

An open house at the New Hope Dairy’s anaerobic digester was held in early November. The $3.5 million digester, developed by California Bioenergy (CalBio) and using technology supplied by MT Energie, is processing manure from about 1,200 dairy cows. Operations got underway in June. The 450 kW of electricity generated is supplied to the Sacramento Municipal Utility District (SMUD). The Sacramento utility received $5.5 million in grants from the federal Department of Energy and the California Energy Commission to help bankroll the building of New Hope’s digester and another one at the nearby Van Warmerdam dairy in Galt. The power from the New Hope digester “is a hedge against costly peak-hour power,” said SMUD board President Bill Slaton in an article in the Sacramento Bee. “The generator produces energy that SMUD would use during the peak hours of 4 to 7 p.m.” About 27 percent of SMUD’s energy supply comes from renewable sources, he added. New Hope Dairy leases the land that houses the digester and generator to CalBio.

Vitoria, Spain: Converting Digestate To Fertilizer Product

A consortium of private companies, working with the European Commission’s Eco-Innovation program, has developed a process to convert digestate from biogas plants into dry granular fertilizers. The project, High Added Value Ecofertilizers from Anaerobic Digestion Effluent Wastes (WAVALUE), mixes digestate with mineral fertilizers; the mixture is granulated in a Spouted Bed dryer. WAVALUE is building a pilot plant near Vitoria, Spain (Basque Country) that will utilize about 1,000 tons of digestate to produce different commercial organomineral fertilizers that will be tested agronomically and commercially. Different viability studies and business models will be conducted, in order to combine the agrobiogas production with the production of those fertilizers, creating as many synergies as possible and a sustainable fertilizer production model. The plant will be the first of its kind in Europe, according to the consortium. It has received about $1.2 million in funding from the European Union. After the pilot phase, two full-sized plants will treat over 60,000 tons/year of digestate. “Management of digestate is an important issue for every agrobiogas project, but rarely creates economic value for the biogas plant manager, and sometimes is a serious limiting factor,” explains Aritz Lekuona of EKONEK, the company serving as WAVALUE’s project coordinator. “The volume and nitrogen content of digestate produced in the biogas extraction process are very similar to the original waste treated. Digestate granulation plants can deliver a reasonable return on investment, based on the sales of the final fertilizer product.” www.wavalueproject.eu


Milwaukee, Wisconsin: Tribal Community Opens Food Waste Digester

The Forest County Potawatomi Community (FCPC) opened a $20 million renewable energy facility in late October near its Potawatomi Bingo Casino in Milwaukee’s Menomonee Valley. According to an article in Milwaukee’s BizTimes.com, the facility has two 1.3 million gallon tanks along with smaller feed tanks used to accept individual waste streams. It is designed to receive 100,000 to 130,000 gallons/day of source separated food waste from area food and beverage manufacturers, grocery stores and other generators. Retention time in the mesophilic digester is about 30 days. A 2 MW GE Waukesha gas engine was installed. Power will be sold to Wisconsin Energy Corp. under a special tariff to offset the Potawatomi Community’s energy costs throughout the state. A $2.6 million Department of Energy grant awarded to the FCPC in 2011 is contributing to the project. FCPC Renewable Generation LLC, the entity created by FCPC for the digester project, retained Advanced Waste to transport the waste and slurry from producers to the plant. Milwaukee-based Titus Energy has been developing the digester for three years. Symbiont, Inc. did the engineering and Rockwell Automation manufactured the motor controls.

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