32.5 PDH
In-Person Digester Operator School

August 14 – 18, 2023
University of Wisconsin – Oshkosh

Each ABC Operator School event we offer is unique and distinct from the next. What makes this one special is that you’re in-person and in the field with real operators. UW-Oshkosh not only has excellent teachers that specialize in anaerobic digestion with top-notch teaching facilities, they own two digesters that they operate, they run a commercial lab that digester owners, operators and designers from all over the country use, and they helped build this program.

The ABC has been holding Operator School here longer than anyone else. Former students love it for its hands-on style, authenticity, and summer camp vibe. We’ve also included the following with your registration: breakfast, lunch, and dinners at the main campus dining hall, and dorm style lodging. Past classes have been known to bond quickly, host informal happy hours and ping pong tournaments to wind down, and even request evening pizza parties to get more time with the instructors.

The digester tours are also special because while they are commercial operations, they’re owned and operated by the school which means that the operators giving you the tours are especially open and transparent about what works well and what doesn’t. They’re a teaching institution after all! As a bonus, when you visit the digesters, often the operators have delayed some recent maintenance so you can see first hand how they fix things and even get involved if you like. One year the class got to observe and assist the removal and overhaul of a manure pump. Another unique element is that you’ll get to visit both a dry urban digester handling food and landscaping waste and a wet dairy digester that’s co-digesting industrial food waste. You can read more about the systems you’ll visit plus the ERIC lab below.


Full Program
32.5 PDHs

Included with registration: breakfast, lunch, and dinners at the main campus dining hall, dorm style lodging, two in-person site digester site tours, ERIC digester laboratory tour, PDH certificate by request.

Members: $2,000
Non-Members: $2,400

* American Biogas Members will apply discount and checkout

Site Tours

This course offers in-person digester tours and a laboratory tour! On two afternoons, we’ll board a bus to go to the two digesters briefly described below. On a third, you’ll visit the biogas laboratory at the UW-Oshkosh Environmental Research and Innovation Center (ERIC). This is a fully functioning lab that digester designers and operators use to do everything from BMP tests of different feedstocks to testing and certifying digestate to the ABC’s Digestate Standard Testing and Certification Program. Learn not only how the tests are done, but perhaps more importantly for operators, when you should pay for testing and how to interpret the results to make sure your system stays operational at peak performance.

UW-Oshkosh Urban Dry Digester


In 2011, The UW-Oshkosh Foundation-Witzel, LLC built the first commercial-scale dry fermentation anaerobic biodigester in the Americas. It’s not only still a well functioning digester, it’s an urban system processing food and yard waste operating in a shopping plaza next to a bank and department store. The digester produces approximately 8% of the University’s electrical needs by recycling 10,000 tons/year of yard and food waste into 3300 MWh of electricity per year and an organic compost from the digestate.

Allen Farms Dairy Digester


The Allen Farms digester in Wisconsin is a mixed plug flow mesophilic digester processing approximately 7,000 tons/year of scraped dairy manure, bedpack/manure, and industrial food waste. The biogas is used in a 64 kW CHP system and the digestate is used on the farm.


Module 1 - Fundamentals of Anaerobic Digestion

This is the foundation for everything operators and anyone in the biogas industry needs to know. As such, almost every course will include and start with this module. We’ll cover the 4 steps of AD including the actual chemistry and biology so you know what to test for; vocabulary and concepts like BOD and VFA/Alk ratios; how to monitor AD performance; and how the primary characteristics of different digesters require a different approach to their operations.

Module 2 - Applying the Fundamentals to Operations

In this module, you’ll learn how to both optimize the performance of a digester and perhaps more importantly, how to avoid digester failures

Module 3 - Math for Digesters

This module consistently ranks as the most valuable by our past students. For those of you who haven’t had math in a while, we’ll start slowly talking about how to keep track of units when doing your calculations, imperial/metric conversions, how to monitor overloads, converting biogas into energy values, and business considerations like determining the value of heat and electricity compared to renewable natural gas. Finally, we’ll walk you through how to determine whether you should accept a truckload of material that shows up at your door.  Will the material make money or will it cost you more to deal with the water because there’s so little biogas potential in its contents?

Module 4 - Mechanical Systems

Although emphasis is often and rightly placed on the biological aspects of digester operation, it is important to remember that an AD system is primarily a MECHANICAL SYSTEM. Understanding how to make sure the mechanical systems are operating optimally is critical.  We’ll cover receiving material, conveyance, storage and pre-treatment; then mixing, heating and gas handling; finally, we’ll take you through digestate separation, and handling the separated liquids and solids.

Module 6 - Lab Testing. What does it all mean?

We’re fortunate that our friends at UW-Oshkosh have one of the best labs in the biogas industry and that they are a dedicated teaching institution. As such, you’ll learn directly from the experts who run the lab to understand how to use lab work to help digester performance and to trouble shoot issues.  Plus, we’ll help you learn how to apply the results from the lab tests your order and what it all actually means.

Module 7 - Odor Management/Prevention

Odor management and prevention starts and ends with good digester operations. We’ll show you which operations in particular most relate to odor issues so you know what to focus on first. This module is often interlaced with story time—anecdotes of what went wrong at some digesters and how those issues could have been prevented or management more effectively. If you’d like to dive into this issue more, the ABC has a day long course called “Odor Management at Anaerobic Digestion Facilities” which is available on-demand, anytime online (https://americanbiogascouncil.org/odor-management-at-anaerobic-digestion-facilities/)

Module 8 - Safety

The safety module usually lasts a full day. We’ve offered to past students to try to reduce the time we spend on this important topic, but universally, we’re told, all this time is needed.  We’ll cover H2S dangers, lockout/tagout, operating in confined spaces, rescue procedures, hot work, flammable and explosive properties, hazard communications, process safety and security, MSDSes and more.

Module 14 - Process flow overview/block diagram for site visits

This module is both an application of the content that you’ve learned in the previous modules and preparation for the tour this afternoon.  It’s often loud on site, so we’ll cover some of the technical details when it’s easier to hear to enhance the value of your experience on site.


Bernard Sheff

Montrose Enviornmental Group & ABC Board Chairman

Brian Langolf

University of Wisconsin – Oshkosh & ABC Director

Craig Frear

Regenis & ABC Director

Jessica LeRoy

Tetra Tech

Craig Ruberti

Montrose Environmental Group


Can I see a schedule for this event?

Yes! You can view the schedule here.

What is included in the ticket price in terms of lodging/meals?

Meals from Monday (8/8) dinner through Thursday (8/11) lunch, served at the Black Hawk dining hall on campus, are included. Lodging for Monday through Wednesday night is also included. Additional lodging can be added for Thursday night if needed, for $45/room. Additional meals can also be added for a small fee. Please email events@americanbiogascouncil.org if you need additional accommodations. 

What is the dress code?

This is not a formal event, please dress comfortably. For site visits, please plan to wear pants and closed toe shoes for your safety. All other necessary safety gear will be provided by the site. Denim, t-shirts, and polo shirts are all typical attire for attendees.

Is there onsite parking? What about Uber/Lyft?

Uber and Lyft are operational in the area, but we cannot guarantee their reliability. Parking is available at $5/day, with plenty of onsite parking. Email events@americanbiogascouncil.org to secure your parking pass.

What is the best airport to fly into?

Appleton International (ATW) is the closest, about 30 min away. The Dane County Airport in Madison (MSN) is also a good option, it’s 2 hours away but it’s a nice drive.

Approximately what time will the session end on the 11th?

We will likely be back on campus from the site visit by 6:30 pm. If you’re trying to plan a flight for that evening, in most cases you’re welcome to drive to the site visit to leave directly from the site to the airport.

Operator Certification

The American Biogas Council’s Operator Certification is the only digester certification offered in the US. Certified operators have higher performing biogas systems and more often avoid costly and sometimes smelly mistakes. For certification, operators must do three things: complete all 9 required modules in ABC Operator School, have 2,000 hours of operations experience, and pass ABC’s operator exam.

Upcoming Courses

View all of our upcoming Digester Operator School courses.