At ALPS Ecoscience, we specialise in addressing one of the most critical challenges in anaerobic digestion: ammonia inhibition. Whether you’re using chicken litter, which offers a cost-effective alternative to maize silage, or another high-nitrogen feedstock, the risk of ammonia toxicity is a significant factor that can impact the efficiency and stability of your biogas plant. Our expertise in biological process optimisation and ammonia removal technologies ensures that you can maximise biogas output while managing the risks associated with high ammonia levels.

Our approach to managing ammonia inhibition starts with optimising the biological processes within your digester. By carefully controlling factors such as dilution, pH levels, temperature, and feedstock composition, we can help you maintain a balanced microbial environment that minimises the risk of ammonia toxicity.

Dilution: Reducing the concentration of ammonia through careful feedstock management and dilution strategies can lower the risk of inhibition.

pH Control: Maintaining an optimal pH level is crucial in preventing the formation of toxic free ammonia.

Temperature Optimisation: Adjusting the digester’s temperature can influence the equilibrium between ammonia and ammonium, helping to keep toxic levels in check.

Process Monitoring: Continuous monitoring allows for real-time adjustments to prevent ammonia levels from reaching inhibitory concentrations.

However, there are limits to what biological engineering can achieve. In situations where the desired feed rate of chicken litter or other high-nitrogen feedstocks pushes ammonia levels beyond the tolerance of the microbial community, more direct intervention is required.

When biological optimisation alone is insufficient, ALPS Ecoscience offers advanced chemical treatments to physically remove ammonia from the digester. One of the most effective methods we use is Ammonia Stripping. This process involves the removal of ammonia by converting it into a gas and stripping it out of the digestate through a combination of high pH and elevated temperatures.

Ammonia stripping is particularly valuable when the ammonia concentration exceeds the biological system’s capacity to manage it. By integrating this technique into your operation, we can help you maintain optimal biogas production even when using challenging feedstocks like chicken litter.

While chicken litter presents a cost advantage over maize silage as a feedstock, the risk of ammonia inhibition is a critical consideration. The tipping point, where the cost savings are outweighed by reduced biogas output due to inhibition, must be carefully managed. In the sensitive environment of an anaerobic digester, there are no absolutes, and the risk of ammonia toxicity remains a commercial concern.

By implementing appropriate process optimisation strategies, such as dilution, pH control, and temperature management, the negative impacts of ammonia can be mitigated. However, when feedstock levels push beyond the point where biological measures are effective, ammonia stripping becomes essential to maintain the health of the microbial community and the efficiency of biogas production whilst maximising the gate fee saving opportunity.

Contact us today to learn how we can help you optimise your biogas plant’s performance and manage the risks associated with high-ammonia feedstocks.

Read more detail about ammonia inhibition here.

In our typical configuration sulphuric acid is reacted with the ammonia in the digestate, resulting in a 40% ammonium sulphate solution. This byproduct is a sustainable green chemical.  ALPS has developed a supply chain for this product and can support the off-take of this solution and manage its certification and onward distribution.