Anaerobic Digest

BioCycle October 2016, Vol. 57, No. 9, p. 13

Portland, Maine: Teaming Up On Food Scraps Digestion

Ecomaine, a regional trash and recycling nonprofit based in Portland, processes about 175,000 tons of trash and 45,000 tons of recyclables annually for 57 member communities. On September 7, 2016, Ecomaine began a food scraps diversion program that is available to its 57 member communities. Commercial food scraps generators are being targeted first. Collected food scraps will be brought to Ecomaine’s solid waste facility, where they will be picked up by Agri-Cycle Energy and taken to the farm-based Exeter Agri-Energy digester in Exeter. Ecomaine awarded the 5-year collection and processing contract to the sister companies after an RFP process. Commercial generators and households are allowed to place their food scraps in clear plastic bags. They will be opened at Exeter Agri-Energy by a Scott Turbo Separator; the plastic bags will be taken back to be combusted in Ecomaine’s waste to energy plant. Food scraps are codigested with dairy manure.

Ecomaine is charging $55/ton for food scraps at its solid waste facility, compared to $70.50/ton for trash. The discount creates an incentive to member communities to encourage participation in a food scraps diversion program, as it covers the cost of collection and handling this material.

Fukuoka, Japan: Toyota Using Biogas To Power Fuel Cell Cars

Toyota Motor Corporation launched a hydrogen fuel cell car, the Mirai, in November 2014, but the lack of fueling stations has stymied sales. Toyota may have found a way out of that dilemma, according to At its manufacturing plant in Fukuoka, it has teamed with the City of Fukuoka wastewater treatment plant, which generates biogas from its biosolids digesters. Toyota takes the biogas, filters out the carbon dioxide (CO2) and adds water vapor, which creates hydrogen and more CO2. The CO2 is removed again, leaving hydrogen for fueling the Mirai. Currently, the Fukuoka plant makes about 300 kilograms of hydrogen daily (kg/day), which is enough to fuel 65 Mirai cars. This could increase to 600 kg/day if all the plant’s biogas were upgraded to hydrogen.

The 2016 model year Mirai has a total range of 502 km (312 mi) on a full tank, with a combined city/highway fuel economy rating of 66 miles/gallon (3.6 L/100 km) equivalent, making the Mirai the most fuel efficient hydrogen fuel cell vehicle rated by the EPA, and the one with the largest range.

Linköping, Sweden: Sustainable Biogas Supply Chain

The European Union (EU) managed a project called the Advanced Technologies for Biogas Efficiency Sustainability and Transport (ATBEST). The project’s outputs have focused on delivering improvements to the effectiveness and efficiency of each stage of the biogas supply chain. These include investigating alternative feedstocks and better digester configurations, novel monitoring techniques, new biogas upgrading solutions and improved biogas utilization techniques. The ATBEST project recently hosted its final international conference in Linköping, Sweden, where it outlined its toolbox of innovative solutions to support and promote the future growth and sustainability of the European biogas sector (

The ATBEST researchers’ findings are expected to influence the biogas industry across Europe as it faces challenges posed by reduced government subsidies and competition from other renewable energy technologies. “For example, we have developed new knowledge surrounding control of viscosity in digesters which will lead to lower mixing power requirements, novel absorbents which will reduce the size of, and energy used by, the equipment employed to upgrade biogas to biomethane, and explored alternate biogas utilization technologies to capture the energy currently lost when biogas is used in a CHP engine,” notes Dr. Simon Murray, ATBEST project manager, with Queen’s University in Belfast, UK.He added that this work has been underpinned by life cycle analysis and economic modelling that will allow the correct decisions to be made to ensure increased economic and environmental sustainability of the biogas industry.

Montpelier, Vermont: Energy Compliance Standards Draft Released

Renewable energy generation has become one of Vermont’s largest new land uses, resulting in more attention being focused on integrating energy planning with land use planning. Act 174 was created as a result of recommendations from both the governor’s Energy Generation Siting Policy Commission and the Solar Siting Task Force. The Act establishes a new set of municipal and regional energy planning standards, which, if met, allow those plans to carry weight in the siting process for energy generation.

The Vermont Department of Public Service, which administers the new program, recently released draft determination standards to be used by a municipality or region when submitting a plan for determination. They appear as a checklist-based application form divided into four parts: analysis, targets, pathways and mapping. Analysis and targets standards address how energy analyses are done within plans and whether targets are established for energy conservation, efficiency, fuel switching and use of renewable energy across sectors. Pathways standards identify actions to achieve the targets. Mapping standards address the identification of suitable and unsuitable areas for the development of renewable energy.

Along with the determination standards, the department is also publishing a set of recommendations from the 2016 Comprehensive Energy Plan (CEP) tailored to local and regional action. To receive a determination of energy compliance, a municipal or regional plan must be consistent with the recommendations for energy planning pertaining to efficient use of energy and siting of development of renewable energy resources contained in the state energy plans, which are contained in the 2016 CEP. Farm, nonfarm and landfill methane biogas are included, encouraging municipalities that are remodeling their waste treatment facilities to consider implementing anaerobic digestion to capture methane as part of their treatment system.

Akron, Ohio: Biosolids Ad Plant To Open Doors To Food Waste

In 2007, KB BioEnergy installed anaerobic digesters at the former composting facility at the City of Akron’s wastewater treatment plant. This initial 5,000 ton/year project was expanded in 2013 to handle all of the 15,000 tons/year of biosolids produced at the plant. KB BioEnergy installed three Schmack Biogas AG (now BIOFerm) Croccus® complete-mix, low solids digesters, three Euco® Titan plug flow digesters and three 600 kW MWM engine-generators. The digestate is dried and pelletized to 92 percent solids content.

The pending Phase III expansion will add 50,000 tons/year of liquid food wastes and 25,000 tons/year of high solids food wastes. The liquid food waste trucked in will be stored in newly constructed, heated holding tanks located in an indoor feedstock receiving area to control and treat odors. A storage and transfer area will be erected for the high solid food waste. These waste streams are expected to consist of minimally contaminated, preconsumer food waste such as fats, oils and greases (FOGs), grocery waste, and local food processing residuals, bakery scraps. The high solids portion of this mix will undergo grinding and maceration with new preprocessing equipment; if materials have higher than anticipated contamination levels, screening and sorting may also be required.

Istanbul, Turkey: Engineered Nanomaterials’ Impact On Ad Processes

Engineered nanomaterials (ENMs) are commonly used in commercial products, including sunscreens, cosmetics, sporting goods, stain-resistant clothing, tires, and electronics. They are also in medical diagnosis, imaging and drug delivery and in environmental remediation. As a result of increasing demand and consumption, a greater amount of nanoparticle (NP) containing products eventually reach wastewater treatment plants (WWTPs). The impacts of NPs, such as silver (Ag), zinc oxide (ZnO), titanium dioxide (TiO2), and copper oxide (CuO) within activated sludge (AS) wastewater treatment systems have recently been discussed in the scientific literature. Some studies also cover the effects of these NPs on anaerobic digestion of biosolids. While relatively little information exists about the impacts and behaviors of inorganic metal oxide NPs on anaerobic wastewater treatment systems during conversion of organic matter into biogas, it can generally be concluded that metal oxide NPs such as CuO, ZnO, CeO2 and in some cases Ag, adversely affect biogas generation rates due to inhibition and toxicity in AD systems, due to release of metal ions from NPs. This literature review appeared in the February 2016 issue of Process Biochemistry.

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