Performance enhacement by using additives, especially the trace element supplementation
Beyond the use of machinery, the use of additives is the alternative – or complementary - way of optimizing an anaerobic digestion process.The use of additives has become an important topic due to their capacity to increase reactors performance in terms of process stability, biogas production and treatment capacity. Research experiences also showed that additives could lead to inhibitory phenomena.
Regarding inorganic additives, Co, Fe and Ni are the most investigated nutrients. Other reported inorganic additives comprise substances able to mitigate ammonia nitrogen inhibition and/or to immobilize anaerobic biomass.
Regarding biological additives, results clearly indicate that bioaugmentation might be a useful tool to improve digester performance: especially when the digester is subjected to stress conditions (e.g. start-up, inhibitory concentrations). However, its application in full-scale plants is still scarce due to its economic uncertainties and risks.”
The demand for optimisation is directly proportional to the number of existing biogas plants. A market overview of additives, made in Germany in 2012 found in this country alone over 250 additives, which demonstrates the demand for optimisation of biogas plants.
The effects of these additives are hardly investigated and can only be evaluated by costly, time-consuming tests (e.g. continuous anaerobic digestion experiments). Now, the offer is very fragmented – normally, one product for each parameter of optimisation –, with a low efficiency – from 5 to 15% higher biogas yield –, and moreover needed of tailored made solutions – often prepared individually for each plant –.
Additives can be classified by their main ingredients and function: Inorganic nutrient and trace element mixtures are often prepared individually for each plant to increase stability and performance by supplying the ideal concentration of trace elements for anaerobic digestion. pH stabilizers are used to avoid or to reduce fluctuations of the pH which is crucial for a stable process. Additives reducing the concentration of ammonia or hydrogen sulphide are also widely in use. Both substances pose a challenge for biogas purification and can lead to corrosion in the CHP. They also can inhibit anaerobic digestion at high concentrations. Anti-foaming and anti-floating-layer agents are another large group of additives that do not affect the bacteria directly but increase the performance of the digester. Few additives based on enzymes, algae and special microorganisms are on the market.
The nanotechnology solutiont hrough BioGAS+
In this context, the effect of nanoadditives on the anaerobic digestion process and consequently on the biogas yield is an active area of research and the most promising
The pioneering available solution from nanotechnology is BioGAS+ by Applied Nanoparticles.
There was a clear need for a unified, standard and efficient solution for the optimisation of anaerobic digestion. Applied Nanoparticles offers the trace element supplementation BioGAS+, a nanotechnology- based innovation that obtains the highest ever-reported improvement of biogas production. BioGAS+ can triple the biogas yield and offers all this other benefits for process optimisation:
1. Improving biomass to biomethane conversion efficiency.
2. Increase in both biogas and biomethane production.
3. Better biogas composition (higher methane share).
4. Reduction of the digestate fraction.
5. Higher waste degradation.
6. Increase digestion process stability (more reproducible).
7. Acceleration of the digestion process. Reduction in retention/residential time.
8. Proven to reduce H2S levels (precipitated in the form of pyrite).
9. Reduction on the amount of foam produced.
10. Enrichment of the residual material (digestate) with iron ions to obtain by-products with increased economic value such as high quality fertilizers.
11. Solution to inhibitory substances. Rescue digesters with problems.
12. Additive (it does not require any change in the biogas plant industrial process).
13. It does not require pre-treatment of the substrate/feedstock or maintenance to preserve the microorganisms.
14. Enlargement of biomass feedstock (oil, fat, meat) as it has been proved suitable for “difficult to digest” (recalcitrant) feedstock.
15. Enlargement of biomass feedstock (oil, fat, meat) due to the increased biogas/methane production.
16. Can be used with any kind of anaerobic digester.
17. Reduce AD plant energy consumption.
18. Minimize undesirable side effects in biogas plants such as the odours associated to HS and NH3, thus reducing the cost of associated conditioning measures.
19. Precipitation (recovery) of phosphorus (in the form of ferric and ferrous phosphate). 20. Disinfection of pathogens and multi-resistant bacteria.
BioGAS+ contributes directly to the metabolism of microbes, with the dosis of bioavailable iron that needs the microbe at each moment. This is a paradigm shift in the prevalent solutions for optimisation, from tailored product for each plant to tailored dosis for each microbe!