The main feature of dung is its high protein content. During the decomposition of protein in biogas plants ammonium is released. It inhibits the process of methane formation. Ammonium itself is needed to build bacteria cells. Inhibition occurs when the ratio of carbon to nitrogen less 30:1
Addition of sewage water leads to decrease in ammonium concentration. On the other hand, this leads to an increase in reactor volumes.
The second disadvantage of this method is the presence of effluent that need to be discharged onto filtration fields or in sewage treatment plants.
Adding carbon-rich organics has an effect: the addition of carbon changes the ratio of nitrogen to carbon in the mixture to non-inhibition levels
In fact, this method is very similar to the sewage adding method described above. An additional module for wastewater treatment is added to a conventional biogas plant. The effluent is cleaned, and water is recycled. Such an additional module adds a half to the cost to a biogas plant.
However, the plant provides additional benefits in the form of a mineral fertilizer - ammonium sulfate. The ANA-strip reactor is a standard product and produced in large quantities.