The influence of yellow water to methane production with the anaerobic digestion

The critical aim of this study is to observe the influence of yellow water for methane production with anaerobic digestion system and to compare the bacterial activity under different temperature conditions. This research is one part of the project which called “Aquanova project” was planed to install the digester in the mountain hut on the Alps Mountain. To realise the maximum concentration for the yellow water composition of mixed substance for avoiding the ammonia inhibition is one of the most important research to install this system in the mountain. The anaerobic digestion with mixed sewage cannot make good performance from ammonia inhibition by excess amount of yellow water. In these experiments, the adding possibility and limits of yellow water is tested with different mixed rates. The augmentation of anaerobic bacteria is necessary in order to take in ammonium ions, but a high concentration of ammonium causes high concentrations of free ammonia, which is a toxic issue for methanogenic bacteria. And this parameter has strong dependence from the pH and temperature in the digestion reactor. Both tests with thermophilic and mesophilic conditions show almost the same limit of concentration of free ammonia as 150 mg/l. The inoculum which is adapted under normal condition as domestic waste treatment plant can treat until this concentration of free ammonia addition without any special adaptation.