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Internships Anaerobic Digestion

Enschede, Overijssel, NetherlandsInternships

Job description

For the R&D Biogas engineering department we are looking for interns! The following internships / graduation assignments are available. Apply using the apply button and select the (graduation) internship you are interested in.

Atex documentation / set up preventive maintenance system / structuring

Only BSc

The biogas exploitation department manages and operates several biogas locations throughout the Netherlands. Biomethane is produced at these locations and injected directly into the Dutch gas network. For this period we are looking for an intern who can help draw up our ATEX documentation. In addition, there will be some additional tasks that we will tackle together along the way, such as preventive maintenance system and structuring digital project folders. During this internship you will visit the production locations to inventory what is installed and analyze whether this is correct based on legislation and calculations. An improvement plan and maintenance plan will have to be drawn up on the basis of this documentation. During your internship you will be supervised by the biogas exploitation manager and the exploitation project engineer.

Your tasks:

  • Draw up our ATEX documentation;
  • Setup preventive maintenance system;
  • Structuring digital project folders.

Commissioning nitrogen stripper Marrum

Anaerobic digestion is a biological process which efficiency is highly dependent on the conditions inside the reactor (in this case a big, concrete tank). One component that could result in inhibition of the process is dissolved nitrogen. If this concentration gets too high, certain reaction steps in the digester start slowing down, and less biogas will be produced. At the installation that HoSt exploits in Marrum (Friesland) the nitrogen concentration is (too) high. A nitrogen stripper will be installed to reduce this nitrogen concentration. This is a new piece of equipment, and as such starting up (commissioning) this stripper has to be done with care. This is where you come in! When the stripper is running we of course also want to check whether it would be possible to run the stripper more efficiently be changing around some parameters.

Your tasks:

  • Help out with the commissioning of the nitrogen stripper;
  • Perform tests and analyse the results to run the stripper most efficiently.

Design of H2S removal system from biogas

Anaerobic digestion is a biological process in which organic feedstock is converted into biogas. The biogas mainly consists of CH4 and CO2, but also small concentrations of other gasses can be present. This internship focusses on H2S specifically. Only a very small concentration of H2S in the biomethane when delivered to the grid. The ‘gatekeeper’ for H2S is activated carbon, this material adsorbs the H2S. This is however a quite costly intervention. A cheaper ‘first line of defense’ is a net inside the digester. On this net micro-organisms grow, which can use oxygen to convert H2S into elementary sulfur, which drops to the bottom of the tank. Currently HoSt installs a single net inside the tank, but wants to research if and how this system could be improved. Are there alternatives or improved versions of the net inside the tank? Could we use a small, dedicated reactor (vessel) for biological desulphurization? Are there alternatives for using a net and oxygen?

Your tasks:

  • Literature study on biological desulphurization (using oxygen), or alternatives;
  • Design of dedicated biological desulphurization reaction vessel;
  • Building and commissioning of test setup;
  • Performing tests on test setup.

Design of mega-microferm

HoSt builds a.o. anaerobic digesters and biogas upgrading installations. Because of efficiency a large part of those installations is standardized. On farm scale HoSt has developed an installation that combines a digester and an upgrading system that can produce and process up to 80 NM3 of biogas per hour from manure. In the market larger systems are desired. As such HoSt wants to develop a similar standard solution that can produce and process up to 150 NM3 biogas/hour. You have to figure out what equipment would be required and combine them in efficient standard building blocks. End goal: standard solution named mega-microferm.

Your tasks:

  • Understanding current microferm solution. Are there any points that we could improve upon?
  • Determining what can be reused from microferm, what has to altered;
  • Design new standard building blocks. (iterative process with other HoSt employees);
  • Design standard layout for complete mega-microferm.

Heat recovery from digestate optimalisation

A large part of the operational costs of a digestion installation is due to keeping the digesters at the desired operating temperature. With increasing energy prices, this cost is becoming more and more and important. HoSt wants to use as little as possible external energy, but wants to re-use heat within the installation. For one, the digestate leaving the digesters still contains a lot of energy. The challenge is to recover this heat as cheaply as possible to heat up the digesters. HoSt has developed multiple systems to efficiently heat up the digesters. Those systems have been implemented but have not yet been compared to one another.

Your tasks:

  • Gathering data of multiple heat (recovery) systems;
  •  Analyzing data to determine what heat (recovery) system to use in what situation;
  • Investigate alternatives and ways to improve the current systems;
  • Find the cheapest solution.

Predictive viscosity determination

Viscosity might not sound as the most exciting topic ever, but is a very important engineering parameter in an anaerobic digestion installation. The installation can be fed with about any organic feedstock, which results in digestate (the liquid in side the digester) that can have very varying consistency. This digestate has to be pumped through heat exchangers and towards further processing units. Depending on the viscosity of the material the mixer configuration inside the digester, size of pumps, heat exchangers and other equipment might have to be changed. Those changes have a tremendous effect on the investment of the installation, while underestimating the viscosity can result in an installation that simply does not meet the design criteria (and thus unhappy client).

Unfortunately it is difficult to determine this digestate viscosity from a list of feedstocks for an installation. We ask you to come up with a system to be able to get a better feeling for the to be expected viscosity.

Your tasks:

  • Literature study on viscosity in digestate from anaerobic digestion;
  • Discussion with experienced HoSt employees to put their viscosity knowledge on paper;
  • Design (simple) tests to estimate viscosity;
  • Data analysis on existing installations to find common denominators for high viscosity.

Job requirements

Who are you?

  • BSc / MSc in Chemical Engineering / Mechanical Engineering / Sustainable Energy;
  • Interested in sustainable energy technology;
  • Plan-minded and independent worker.

What do we offer?

  • Working at the technology forefront of the energy transition;
  • Groundbreaking tech company in the field of biofuels, carbon capture and thermal conversion;
  • Minimum wage based on 40 hours per week for interns with an EU working license / Monthly fixed fee of € 400 based on 40 hours per week for students without an EU working license. Please note: it depends on your type of internship at HoSt which fee you receive;
  • Lots of responsibility and room for own initiatives;
  • Professional support, guidance and insights;
  • Interesting international environment only a 5-minute walk from the ‘Kennispark’ train station in Enschede;
  • Nice and sustainable welcome gift;
  • A dynamic, energetic, passionate young team;
  • Flexibility in working from home / office.


Go to to apply for this internship. General questions can be addressed to Mariëtte Huis in `t Veld, internship coordinator at For questions and more details about the internship please contact Sjors de Groot (Hiring Manager) on +31 (0) 53 - 460 90 80.

Enschede, Overijssel, Netherlands


About HoSt Group

Advancing the energy transition is our mission at HoSt Group, awarded 'Best Company of Twente 2023'. Our team of over 500 across 7 countries and with offices in the US and Europe innovates in renewable energy technologies, aiming for global sustainability.

Originating from a 1991 joint-venture between Holec Projects and Stork, HoSt Group is a large family company and an industry leader in transforming waste into bioenergy and valuable products, dedicated to achieving sustainability ambitions.

We engineer, build, and maintain bioenergy systems producing sustainable energy and valuable end-products from residual streams, striving to a zero-waste society.