{"id":9664,"date":"2023-02-10T15:15:34","date_gmt":"2023-02-10T20:15:34","guid":{"rendered":"https:\/\/blogs.dickinson.edu\/farm\/?page_id=9664"},"modified":"2024-03-25T09:15:59","modified_gmt":"2024-03-25T13:15:59","slug":"biogasproject","status":"publish","type":"page","link":"https:\/\/blogs.dickinson.edu\/farm\/biogasproject\/","title":{"rendered":"Biogas"},"content":{"rendered":"

Welcome to Dickinson College Farm Biogas!<\/h1>\n
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The current biogas digester, under construction (2015)<\/em><\/p><\/div>\n

\u00a0<\/h3>\n

What is Biogas?<\/h3>\n

Biogas digestion converts organic wastes into burnable methane gas, a versatile energy source for cooking, heating, and electricity generation.\u00a0 Since 2008, the College Farm has been experimenting with demonstration-scale biogas systems and laboratory research projects. Altogether this work includes numerous student projects,\u00a0 lab exercises, youth education programs, video and conference presentations resulting in international recognition for sustainability at Dickinson.\u00a0 Gas generated by the biogas digesters is used on the farm to fuel cooking appliances. In the near future, we will complete a farm-scale digester that will convert biogas to electricity and wipe out the farms power bill. \u00a0Use of biogas on the farm replaces propane and other fossil fuels thereby contributing to the farm and College\u2019s goal of net reduction of carbon emissions.<\/p>\n

Table of Contents:<\/h3>\n\n\n\n\n
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Current Initiatives<\/a><\/h2>\n<\/td>\n

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Videos<\/a><\/h2>\n<\/td>\n<\/tr>\n

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Papers and Articles<\/a><\/h2>\n<\/td>\n

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Commercial Digester Updates<\/a><\/h2>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Commercial Digester Development<\/h3>\n
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An example of a biogas digester facility.<\/em><\/p><\/div>\n

After over ten years of R&D with small scale biogas systems, the Dickinson College Farm is going big and building a farm-scale digester that will convert our waste into electricity!\u00a0 This initiative began in 2018 with a feasibility study<\/span><\/a>.\u00a0 Our project gained support of the USDA Natural Resource Conservation Service with a generous cost-share grant in 2020.\u00a0 From there things really picked up steam with project development and fundraising to pull it all together.\u00a0 Our expected completion time is autumn of 2023.\u00a0 Watch this space for periodic updates on the progress of this exciting, innovative project!<\/span>\u00a0<\/span><\/p>\n

Background:\u00a0 <\/span><\/b>We\u2019ve been making burnable biogas from cattle manure and food waste in our pilot scale (1000 gallon) digester since 2015.\u00a0 This system consumes only 150 lbs of food waste per week at full capacity, yet it already can produce more gas than we need for cooking and canning on the farm.\u00a0 Given that the College dining hall produces about 750 lbs of food waste per day, we knew we would need to convert the biogas into a more transferrable form of energy if we upsize to a full-scale project.\u00a0 By coupling a biodigester with a combined heat and power (CHP) generator, we can convert our biogas into electricity and heat.\u00a0 This electricity can be used on the farm or sold back to the utility (like a grid-tied solar project).\u00a0\u00a0 However, while 750 lbs per day is a lot of food waste, it is not quite enough material to power the smallest commercially available grid -tied CHP system.\u00a0 So we started looking around for more waste in the neighborhood.<\/span>\u00a0<\/span><\/p>\n

Through our feasibility study, we identified Triple L Farm dairy as a perfect partner for a shared digester.\u00a0 The Hoover and Charles families have rented the property directly adjacent to the College farm from Dickinson for over 20 years.\u00a0 Triple L Farm keeps about 150 dairy cattle on the property and expressed an interest in working with us to turn their waste into energy and fertilizer.\u00a0 Engineers from the USDA NRCS identified some manure management concerns at the dairy farm that made the project eligible for federal conservation funding, in the interest of improving water quality in the Yellow Breeches Creek nearby.\u00a0\u00a0 The dairy farmers are excited to have a modernized barn to house their cattle, an improved manure system, and free bedding from extracted manure solids which will lead to substantial cost savings over conventional bedding.<\/span>\u00a0<\/span><\/p>\n

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Basic overview of digesters planned location.<\/em><\/p><\/div>\n

Our feasibility study and discussions with our dairy neighbors, USDA engineers and experts in the digestion industry has resulted in the following plan:\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

We\u2019re building a new structure that will serve as combined dairy cow housing and waste collection & processing system.\u00a0 The dairy farmers will push their manure into a collection pit each day, then College Farm staff will take over waste management from there.\u00a0 Food waste will be delivered to the site daily, chopped and mixed in a separate pit before blending with the dairy manure.\u00a0 The combined manure and food waste slurry will be pumped to the digester for processing into biogas and digestate (liquid fertilizer).\u00a0 Liquid effluent from the digester will flow back to the cattle & waste building, where it will be passed through a screw press to remove manure fibers which will be used as cow bedding.\u00a0 The liquid fraction of the effluent will flow to a final storage tank to await spreading on the fields or addition to compost piles.\u00a0 Biogas from the digester will be fed to a 50kW CHP engine which will produce electricity and heat. The heat will keep the digester warm through winter months (they operate best at cow body temperature, about 100F) or be used to heat greenhouses and dry grain and vegetables.\u00a0 Electricity will be used to power all machines on the project site, with excess sold back to the Met Ed utility.\u00a0 We anticipate energy output of 200-300,000 kWh per year of clean renewable electricity.\u00a0 To optimize productivity of the system we are seeking additional food waste from the Carlisle community and have thus far secured an additional 2000-3000 lbs per week of external waste from the local food bank, a commercial bakery, a restaurant and a craft brewery.\u00a0<\/span>\u00a0<\/span><\/p>\n

Overall beneficial attributes of this project include reduced manure odors, reduced water pollution through modernized manure management, reduced loading of landfills with food waste, and reduced greenhouse gas emissions.\u00a0 All the while we will generate renewable, carbon negative electricity, revenue for the farm, and strengthen the farm economy in the Cumberland Valley.\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

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A flow chart detailing the process of the digester.<\/em><\/p><\/div>\n

 <\/p>\n

What makes our project especially exciting and unique is its modest scale.\u00a0 While 150 cows and 4000 lbs. per day of food waste seems like a lot to us, this is actually a small system as commercial biodigesters go.\u00a0 In the US most digesters are on farms with 500 or more cows due to economies of scale.\u00a0 However, in Europe, smaller \u201cpocket digesters\u201d have been proven effective on farms with herds as small as 50 cattle.\u00a0 So we are working with experienced Pennsylvania based manure management partners to build a smaller custom digester using domestic and European components. When complete, ours will be the smallest commercial digester in Pennsylvania.\u00a0 We will use this showcase system to teach and inspire farmers from around the mid-Atlantic to consider adding a small digester to their operations.\u00a0 There are about 5000 dairy farms in PA, with an average size of 85 cows.\u00a0 So the success of our project should pave the way for a lot more waste to energy digestion in our area.\u00a0\u00a0\u00a0 <\/span>\u00a0<\/span><\/p>\n

Because we are building a lot of new infrastructure (cattle barn, waste pits, digester, final manure storage tank, new electrical service, new service road), our project will be costly with an expected total price tag of $1,600,000.\u00a0 Thankfully projects like this are eligible for lots of state and federal agricultural conservation incentive programs.\u00a0 To date we have secured over $1,300,000 in grants, donations and internal College funds to support development of the project.\u00a0 We are actively fundraising to complete the project \u2013 interested donors should contact <\/span>collegeadvancement@dickinson.edu<\/span><\/a> or the farm at <\/span>farm@dickinson.edu<\/span><\/a>.\u00a0\u00a0 The expected completion date of the digester project is autumn of 2023.<\/span>\u00a0<\/span><\/p>\n

Food Waste Diversion<\/h3>\n

While most farms digesters run livestock manure, “co-digestion” has proven to be more effective and provide more burnable gas. Co-digestion is when multiple types of organic matter such as manure, food waste, or plant matter are digested in the same biodigester together. With this in mind, the digester can be used as a mean to divert food waste from landfills. Currently the farm collects 700 pounds of cafeteria waste every day as well as X pounds of food waste weekly from various establishments in the Carlisle, PA area with the goal of collecting X pounds for the commercial digester.\u00a0<\/p>\n

The goal of food waste collection is to divert organic matter from landfills, where they will release methane into the atmosphere and where their nutrients will be lost and become unviable for future usage in biogas but also in agricultural systems. Biogas is made up of carbon, hydrogen and oxygen, while the important plant nutrients needed for composting (nitrogen, phosphorus, potassium and trace elements) are passed through the system and come out in a more bioavailable form for future usage in agriculture.<\/p>\n

Education and Outreach<\/h3>\n
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Local girl scout troop visits the farm\u2019s small biodigester to learn about food waste diversion and renewable energy.<\/em><\/p><\/div>\n

A critical function of the farm’s biogas program is our education and outreach initiative.\u00a0 Since 2008 we have worked to inspire students of all ages through demonstration of sustainable organic waste recycling into energy and fertilizer.\u00a0 Beginning with plastic jugs of sheep manure in the farmhouse basement, we have progressed through several iterations of lab and homestead scale anaerobic digestion systems, all built by farm students and staff.\u00a0 At present we maintain a 1000-gal pilot-scale reactor for cooking fuel production, numerous lab-scale research units, and are in process of constructing a commercial-scale waste to electricity farm digester.\u00a0 \u00a0These are used to educate Dickinson students and the public through lab exercises, hands-on internships, field trips and day camps for K-12 youth and clubs, farmer field days, and presentations at regional conferences.\u00a0 Our team is also available for direct support to teachers and school programs looking to add biogas and composting units to their curriculum.\u00a0 \u00a0To support the in-person experiences, we also produce educational biogas videos<\/span><\/a> targeted at audiences of all ages.<\/em>\u00a0 Public education is fundamental to our objective of helping to increase deployment of biogas technology on farms, in schools and at homesteads across our region.\u00a0<\/p>\n

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Teachers at St. Patrick\u2019s School in Carlisle PA with a biogas experiment station designed by the Dickinson Farm project.<\/em><\/p><\/div>\n

If you are a farmer, teacher, club leader, or student interested in learning more about biogas systems through tours, field trips, internships, presentations or virtual lessons, please contact project leader Matt Steiman for more information.\u00a0 The microbes and biogas await your inquiry!<\/p>\n

Matt Steiman:\u00a0 E-mail steimanm@dickinson.edu<\/a><\/p>\n

College Farm Education & Outreach coordinator:\u00a0 farmcoordinator@dickinson.edu<\/a><\/p>\n

Research<\/h3>\n

Our ongoing research efforts have three components:<\/span>\u00a0<\/span><\/p>\n

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  1. Replicated lab-scale digestion for alternative feedstock analysis.<\/span><\/b>\u00a0 In addition to cow manure and food waste, virtually all organic waste materials can be digested into biogas and fertilizer, so long as they are free of toxins and other contaminants.\u00a0 Combining multiple waste resources in one digester, known as co-digestion, can result in synergistic benefits such as diversification of the nutrients available to microbes and pH balancing, often resulting in higher levels of energy output compared to mono-substrate digestion. Taking advantage of locally available feedstocks enables a farm digester owner to increase revenue from additional energy generation as well as tipping fees for some externally produced wastes.\u00a0\u00a0 Common questions facing digester operators are \u201cwhat is the energy and nutrient value of a new feedstock\u201d, and \u201cwhat other operational impacts will occur if I add this feedstock to my manure digester?\u201d.\u00a0 Establishing methane gas and nutrient production values for various feedstocks on a per kg basis is vital to successful extrapolation for planning and design purposes.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span>\u00a0<\/span><\/li>\n<\/ol>\n
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    Figure 1: Analisa Groble ’22 (left) and Prerana Patil \u201824 (right) with the research digester set.<\/em><\/p><\/div>

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    Figure 2: Average daily and cumulative gas production from 7.5 L continuous flow manure digesters (CM) and manure plus brewer’s grain (BSG) \u2013 n=3. Addition of brewer\u2019s grain to digesters started on day 11. Note that the slope of the cumulative BSG line increases shortly after BSG addition began.<\/em><\/p><\/div>

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    Figure 3: Daily gas collection from manure and manure with BSG digesters. Extended meter sticks are connected to 4\u201d diameter tubular gas floats in the water-filled 6\u201dcylinders seen in the rack \u2013 daily gas accumulation is read by noting the height of the meter stick above the rim of the base cylinder. The three highest sticks correspond to the BSG plus manure treatment replicates. This result has been typical since soon after the start of BSG addition to the daily feed mix.<\/em><\/p><\/div>\n

    We are now completing our third season of focused lab-scale anaerobic digestion research mostly focused on the value of brewers spent grain as an alternate feedstock.\u00a0 During this period we developed and refined an effective yet inexpensive apparatus for lab digesters that simulate larger-scale conditions.\u00a0 At the core of our apparatus are 2.5 gallon Fort-Pak type square plastic containers that we modify into semi-continuously fed mini digesters.\u00a0 We like this particular container because it can produce a functional AD system at a cost of only $20-25 per unit.\u00a0 The large volume (by lab digester standards) and 1\u201d diameter fluid piping readily accommodate high solids blends of cow manure and food waste without significant clogging.\u00a0 Each digester is connected to a floating cylinder gas collector equipped with a meter stick for recording accurate gas volume data on a daily basis.\u00a0 Daily service of the digesters includes feeding, releasing digestate, and recording biogas production.\u00a0 Collected biogas is analyzed at least once per week to assess methane content.\u00a0 The experiments are run for about 100 days to generate data that reflect the long-term performance of novel feedstocks in a farm digester. For a more detailed view of the lab digester system, please visit our DIY Research Digester video on Youtube.<\/a>\u00a0<\/span><\/p>\n

    Students\u2019 roles in this experiment were fabrication and troubleshooting of equipment, feeding and data collection, and physical and chemical analysis of feedstock and effluent under in the Chemistry lab.\u00a0 Physical analyses of materials included loss on drying and loss on ignition tests to establish % total and volatile solids, respectively.\u00a0 Chemical analyses included titration for alkalinity and testing for total nitrogen, total phosphorus, and chemical oxygen demand.\u00a0 The newly developed digester set is user-friendly, accurate, spill resistant and productive.\u00a0 In 2022 we built a second set of six digesters to test blends of brewers grain, cow manure and campus food waste.<\/span>\u00a0<\/span><\/p>\n

    Click here<\/span><\/b> for a brief fact sheet on the brewers grain digestion project.\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

    2. Digestate value as fertilizer:\u00a0 <\/span><\/b>Liquid effluent (digestate) from the biodigesters conveys plant nutrients from the starting feedstocks broken down into a more bioavailable form through the action of microbial decomposition.\u00a0 While carbon, hydrogen and oxygen leave the system as biogas, nutrients important to crop growth (e.g. nitrogen, phosphorus and potassium) pass through the system and reside in the digestate.\u00a0 It is common practice for farmers to use digestate as liquid crop fertilizer.\u00a0 Our objective with this portion of the study is to assess the value of digestate as fertilizer for field and greenhouse crops using bioassays and crop nutrient analysis in the chem lab.\u00a0 This objective builds on a study conducted by Max Lee \u201819 in 2018.<\/span>\u00a0<\/span><\/p>\n

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    Figure 4: Field application of digestate via the pump wagon. This experiment did not yield measurable differences in grass growth.<\/em><\/p><\/div>\n

    We set up two pilot studies in 2021. The first involved field application of digestate from the farm\u2019s 1000 gal pilot unit to pasture grasses using a pump wagon pulled by a tractor.\u00a0 To calibrate the field application we used a large rectangular tub of known area to catch and weigh a sample of digestate as the pump wagon was pulled through the pasture.\u00a0 These data allowed us to estimate the quantity of digestate applied per acre to the larger pasture.\u00a0 However after several weeks of grass growth, it was determined that no significant difference in grass growth was observed in comparison to an adjacent area <\/span>where digestate was not applied.<\/span>\u00a0<\/span><\/p>\n

    In the second pilot trial, we planted kale seedlings in 1-gallon pots in the Stafford research greenhouse and applied the following treatments:<\/span>\u00a0<\/span><\/p>\n\n\n\n\n
    \n

    Treatment ID<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    C-Control<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    DE-Digestate<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    DF-Digestate<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    DG-Digestate<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    P-Fish<\/span>\u00a0<\/span><\/p>\n<\/td>\n<\/tr>\n

    \n

    Fertilizer<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    Water only<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    1 digestate:2 water<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    1 digestate: 3 water<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    1 digestate: 6 water<\/span>\u00a0<\/span><\/p>\n<\/td>\n

    		\n

    Commercial fish fertilizer<\/span>\u00a0<\/span><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \u00a0<\/span><\/p>\n

    Five replicate pots of each treatment were grown.\u00a0 Kale pots were checked daily and uniformly watered as needed.\u00a0 Once weekly all pots were fertilized with an equal volume (200 ml) of their designated treatment.\u00a0 This experiment was run for five weeks before we destructively harvested all kale plants.\u00a0 Plants were measured and photographed before placing them in freezer storage for further analysis for antioxidant content in the chemistry lab (this assessment will be carried out this fall).\u00a0 As seen in figure 4 below, the biomass production did not differ substantially between treatments.\u00a0 We suspect this was due to the quality of the potting mix used as a growth medium \u2013 note that the control plants which were not fertilized at all did not appear to suffer substantially due to lack of nutrients.\u00a0 We intend to repeat this experiment in the fall and spring semesters using a more nutrient-poor growth medium.\u00a0\u00a0 A difference in concentration of antioxidants in the kale tissue may be discovered upon further testing in the chem lab later this fall.<\/span>\u00a0<\/span><\/p>\n

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    Figure 5: Greenhouse grown kale plants fertilized with no fertilizer (control), liquid fish fertilizer (P) and three dilutions of digestate. Biomass growth and crop health did not differ substantially between treatments.<\/em><\/p><\/div>\n

     <\/p>\n

    The digestate as fertilizer trial was repeated in 2022 using red russian kale and beets as test crops.\u00a0 In this experiment we used a more nutrient-poor growth medium and only dosed the potting mix with digestate once prior to planting. From that point forward all pots were moistened only with tap water.\u00a0 Kale plants grew successfully under this system.\u00a0 Currently the harvested biomass is in frozen storage for analysis in the chemistry lab to assess differences in plant nutrient content across the treatments.\u00a0<\/p>\n

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    Uyen Nguyen tends pots of beets grown in diluted digestate from the biogas system in 2022.<\/em><\/p><\/div>\n

    3.\u00a0<\/span> Impact of diversion of food waste to digesters on existing composting program.\u00a0 <\/span><\/b>The majority of campus food waste collected is currently processed through a farm-scale composting system with the resulting compost used as a soil improving amendment in vegetable fields.\u00a0 A third set of experiments seeks to assess the impact of routing the food waste through an anaerobic digestion system for energy extraction before the nutrients are added to leaf compost piles as digestate.\u00a0 The results of this study will help us predict future impacts on the farm while potentially guiding other commercial composters who may consider adding a digester to their food waste recycling program.\u00a0 This study also continues the work of Max Lee \u201919 from the 2018 summer research period.\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

    We set up two sets of compost experiments in 2021. In each experiment, three replicates of 1 m<\/span>3 <\/span>compost piles were built for each treatment \u2013 Food Waste (FW) piles containing leaves, compost seed material and campus food waste, and Digestate (D) piles containing leaves, seed material and digestate. Food waste was added to the FW piles on the day of pile construction, while digestate was added to D piles at regular intervals throughout the experiment. The gradual addition of digestate was necessary to prevent liquid saturation of the D piles.\u00a0 Each time digestate was added to D piles, an equivalent amount of water was added to FW piles to control for moisture addition.\u00a0 Temperature of all piles was recorded three times per week throughout the summer, and piles were turned manually at regular intervals.\u00a0 When compost piles were deemed near to maturity (no longer heating up after turning) their CO2 respiration and ammonia production were measured using SOLVITA colorimetric compost testing paddles (Woods End Laboratory, Mt. Vernon, ME).\u00a0 At the end of the experiment a seed germination bioassay was run on the finished composts to assess suitability for use as potting soil.\u00a0 <\/span>\u00a0<\/span><\/p>\n

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    Prerana Patil builds the digestate composting research piles in 2021.<\/em><\/p><\/div>\n

    The first round of this experiment yielded promising results that align with our expectations for compost behavior (the second round is still underway).\u00a0\u00a0 While the FW piles attained higher average temperature than D piles during the initial weeks of composting, this pattern flipped in the latter weeks of the trial.\u00a0 This is likely explained by <\/span>the timing of nitrogen addition.\u00a0 N is a limiting nutrient for microbial growth and is typically balanced with carbon at a ratio of 30C:1N in an ideal compost pile.\u00a0 <\/span>The leaf base of our composts is mostly carbon, while N is applied as either food waste or digestate. Since the FW piles received their N allotment in the initial construction, it makes sense that they would heat up early, while D piles had their N dosed at intervals throughout the trial and thus maintained moderately high temperature for a longer period while the FW piles cooled off after exhausting their supply of nitrogen.\u00a0 <\/span>No difference was seen between the finished piles using the SOLVITA testing <\/span>paddles (both treatments displayed characteristics of normal maturing composts).\u00a0 Likewise there were no substantial<\/span><\/p>\n

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    Figure 7: Prerana Patil adding digestate to D compost piles (left), recording compost temperatures (right).<\/em><\/p><\/div>\n

    differences in germination rate of three crops (corn, bean, radish) between the FW and D piles, but both treatments exhibited faster germination response than seeds grown in a commercial <\/span>potting soil control (fig <\/span>7<\/span>).\u00a0\u00a0<\/span><\/p>\n

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    Figure 6: Germination bioassay of composts. Note performance of digestate compost (left) and food waste compost (right) exceed the commercial potting soil (center) seeded on the same day.<\/em><\/p><\/div>\n

    While we had some experiments <\/span>in 2021<\/span> that did not yield the results we expected, all efforts did add<\/span> substantially<\/span> to the experience of our team.\u00a0 As we continue to gain proficiency with the materials, equipment and procedures used to assess the <\/span>performance of anaerobic digestion systems and associated components at the farm, we are confident in our ability to achieve results that are of interest to operators in this field and ideally publishable in environmental engineering and chemistry journals.\u00a0\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n

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    Figure 9: Prerana Patil prepares samples of brewers spent grain for total solid analysis in the chem lab.<\/em><\/p><\/div>\n

    Videos:<\/h2>\n

    For K-12 audiences – intro to biogas and compost:<\/h4>\n