Most frequently asked questions and troubleshooting solutions.


Yes! Information about the training we can offer is available on our Customer Training page

To our customers we offer exclusive access to our user manuals and instrument handbooks. Find out more information on our Customer Training page or contact your sales representative to gain access. 

In addition to exclusive content, on our webpage you will find information about instrument applications and our online webinar series dedicated to anaerobic digestion 

Our customer support team is readily available to assist you with technical issues or questions. To seek support, please visit our Support page and fill out a form. Alternatively, contact your sales representative. We aim to get back to all our customers quickly!

Instruments & Set-Up

In order to investigate the biomethane potential or biodegradability of substrates with a large particle size, you may need to homogenise your sample using a grinding machine.

 The simplest solution is to use a regular household/kitchen blender. There are also mill homogenisers for laboratory and industrial applications. According to the literature, samples such as corn silage can be ground through a Wiley mill followed by grinding with a Udy mill. 

To eliminate the necessity for periodically examining the water level in the thermostatic water bath and to minimise water loss due to evaporation, some laboratories use silicone oil (e.g. LABOTHERMOL S from NeoLab) to replace water. While this is an option, water is more cost effective, cleaner and easier to work with and does not attach to objects it comes in contact with. 

We also offer an alternative incubation unit, the BPC Air, which utilises air as an incubation medium and does not require refilling or maintenance. Read more about BPC Air on our products page.

A comprehensive guide to flushing, with pictures, can be found in the instrument handbooks for anaerobic set-ups.

For flushing the reactor headspace prior to an anaerobic batch tests, each bioreactor bottle has to be flushed with a flush gas separately. There is no practical way to flush all of the reactors at the same time. The flush gas should contain an oxygen free gas (e.g. N
2 or a mixed gas based on 60% CH4 and 40% CO2 or 60% N2 and 40% CO2). In most cases, the flush gas is stored in a gas pressurised bottle equipped with a double stage pressure regulator.

Before flushing a reactor, the gas tubes from the CO2-absorption unit must be disconnected.

The gas source has to be connected to the gas tube with either the push-in valve or the tubing clamp by using a plastic tube connector / reduction adapter. The tubing clamp or push-in valve from the reactor should then be opened and the reactor can be flushed gently with a low gas flow for 30 to 60 seconds.

In order to visualise the gas flow rate from the gas source, the gas tube which was disconnected from the CO2-absorption unit can be immersed into a beaker filled with water in order to use the bubble formation as a guide.

At the end of the flushing step, stop the flush gas, close the tubing tube clamp, take the gas tube from the water and connect it to the CO2-absorption unit. Disconnect the flush gas source and repeat the procedure for the remaining reactors.

Some of our thermostatic water baths are fitted with a conductivity sensor to monitor water level. As this sensor does not recognise distilled/deionised water, it may be necessary to add a small amount of tap water to the water bath. 

There may be various reasons for no gas registration. Some of them may relate to the experiment itself, others may concern instrument setup.

It is very important to isolate the issue before it is possible to find the right solution. Test if the flow cell is the problem by manually lifting the flow cell with your hand and seeing if the opening of the flow cell is registered by the software or not. If the software can register the opening of flow cell, the data acquisition of the instrument is intact.

Next, test the gas tightness of the test line from the bioreactor to the inlet of the gas detection unit. If there are no symptoms of gas leakage for the entire test line, you need to figure out if there are any biological issues (e.g. very low activity of inoculum, substrate inhibition, etc).

For instruments with an ex-situ carbon dioxide (CO2), the unit is connected to the bioreactor and subsequent detection unit using a piece of tubing. The tubing does not need to be submerged in the alkaline solution and we recommend to not include tubing within the absorption unit bottles.

All of our instruments with detection units have a built-in computer within the unit . An externally connected computer, tablet or smartphone is used for control and visualisation of the experimental data.

Unplugging the ethernet cable or shutting down / restarting a computer that is connected to the instrument has no effect on the data being registered and there is no risk that it will interrupt ongoing experiments.

Answer: Condensation of water between the bioreactor and ex-situ carbon dioxide absorption unit is regularly seen during our anaerobic tests utilising ex-situ CO2-absorption units (AMPTS II & III, Gas Endeavour, BPC Blue Premium). This additional liquid does not affect the efficiency of the CO2-absorption step and gives no negative impact on the accuracy and precision.

Explanation: The biogas produced during an AD process contains water vapour and the fractional volume of water vapour is a function of the AD process temperature.

The biogas produced in each bioreactor passes through individual CO2-absorption units containing an alkaline solution before reaching the detection unit. Due to temperature drops in the water saturated biogas exiting the bioreactor, condensation water can be formed in the gas tubes which connect to the CO2-absorption bottles.

This phenomenon cannot be avoided in our standard set-ups since biogas which is produced at a high temperature (e.g. 37 or 50 oC) is coming into contact with a gas tube kept at a lower temperature (i.e., room temperature). Part of the water accumulated in the gas tube is transferred by the gas produced in the bioreactor into the CO2-absorption bottles. The level of liquid in the bottles can increase around 25% during one batch test. 

Where the ex-situ absorption units are kept at a similar temperature to the bioreactors (eg. using BPC Air), less condensation is expected.

BMP Tests & Biogas

The VS parameter provides an estimation of the organic material content in a sample. It is expressed either i) relative to the total amount of wet sample VS% (w/w) or ii) relative to the total solids VS% (VS/TS).

The VS parameter should be defined when a BMP test is performed with the help of the AMPTS III or other instruments. This means that the entered data for the inoculum and substrate concentration should be based on the organic material content relative to the initial weight of wet sample.

The user has to enter the VS values (VS%, w/w) for the inoculum and substrate together with inoculum to substrate ratio (ISR), as well as the total amount of mixture in the Experiment page of our instrument software. The software will automatically calculate and present the values for the weight of the substrate and inoculum which needs to be added to each test flask.

Control experiments are usually performed for testing the quality and activity of inoculum using a standard substrate (e.g. cellulose, starch or gelatin). Cellulose is most commonly used as a reference substrate for energy crops or waste from agriculture, starch for food residue, whereas gelatin is used for household waste rich in meat products.

The average methane yields for cellulose, starch and gelatin are reported in the literature as 350±29, 350±33, and 380±2 NmL CH4/g VSadded at an ISR of 2 (Raposo et al 2011). However, according to more recent publications, the methane yield for cellulose and starch should be within 85-90% of the theoretical value (i.e., 415 Nml/gVS), which means above 350 NmL/gVS (Holliger et al 2016).

When cycles of high gas production followed by plateau levels are periodically observed, it is recommended to check the water level in the thermostatic water bath. When the amount of water falls below the recommended level, there is a risk of temperature drop in the incubated reactors. This can lead to less or no gas production and therefore appears as multiple steady-states. The user needs to check the water level of the thermostatic water bath regularly, e.g. twice per week. In cases of an experiment running under thermophilic conditions, more frequent checks are suggested. The level of water should reach the plastic glass lid of the thermostatic water bath.

For high precision and accurate test data, the experiment should be set-up correctly: high amount of inoculum-substrate mixture (e.g. 400 g in 500 ml bottles), low bioreactor headspace volume, sufficient substrate quantity and suitable inoculum to substrate ratio (in the range of 2 to 4). This will lead to a high volume of gas production at a high flow rate and will allow for a high signal to background noise ratio.

AMPTS III can be utilised to measure accumulated biomethane (CH4), with the ex-situ carbon dioxide (CO2) absorption unit in place. By removing the CO2 absorption unit, total biogas can be measured.

For enquiries about specific applications, older instrument versions or use cases, please contact us and speak to one of our expert team.