BioStym Reduces the need for co-substrate in Anaerobic Digesters

In a pilot at a mesophilic anaerobic digester it was established that the use of BioStym led to a reduction in the need for co-substrates whilst maintaining the biogas yield.

BioStym is a product developed with the purpose to improve the biological process in (co-) digester installations. The effect of BioStym on the digestion process was researched at a location in The Netherlands. For this purpose the biogas production and the quantity of digestion products where monitored during an eight week period.

BioStym is a natural product which realizes an optimization of the ecosystem inside the digester. The microorganisms present in the digester, which are responsible for the conversion process of organic matter from which they derive their energy, are able to function optimal. This results in a higher biogas yield during the methanogenic phase of the digestion process.

BioStym is composed out of fermented plant and algae extracts and contains vitamins, enzymes and trace elements which are utilized by the microorganisms.

The main feed source in the pilot digester was liquid manure (50%). This was supplemented with co-substrates like; solid manure, grass silage, grain, corn silage, bio-grain, Ecofrit and glycerine. The biogas yield of each of these co-substrates was determined.

The digester volume was 1100 m3 with an average flow of 15-20 tonnes/day. The residence time inside the reactor was +/- 50 days and the temperature between 30 - 40°C.

The first 2 weeks where used as a reference period and the BioStym dosing of 150 ml/day started in week 3. During the 6 weeks of BioStym dosing the biogas yield increased with 13,5% at the end of the pilot. An extra electricity output of 713 kWh/day was established at the end of the pilot period.

The dosing of BioStym demonstrated an increase of biogas production. Per ton of feed more biogas was produced and therefore savings could be realized on the co-products that needed to be purchased. During the pilot 9.000 kg of co-products were added to the digester. Because of the increased biodegradability of the feed (13,5%) a saving of approximately 1.215 kg of co-products could be realized. Average co-product price in the area of the pilot was € 67,-/ton. This resulted in a saving of € 81,- per day.

Due to reduced inflow of co-product there was a reduction in digestate production of approximately 800 kg. (including volume reduction due to degradation of dry solids)

Assuming an average digestate discharge price of € 10,-/ton this resulted in a total savings due to BioStym application of € 89,- per day (not including the purchase price of BioStym).

For a copy of the report or more information on BioStym please contact us.

QM Environmental Services specialises in environmental biotechnology and offers integrated solutions for wastewater treatment, bioremediation, air pollution, odour-, algae control and anaerobic digestion. Visit us from 7 to 11 May at the iFAT-ENTSORGA in Munich, hall A2 stand 322.