The biogas plant of the Biorender AG in Münchwilen, Switzerland is processing animal by-products (ABP) as a mono substrate. The feedstock for the three fermenters is almost exclusively by-products from the meat processing industry. This particular raw material, mainly consisting of protein and fat has high demands on the equipment and process technology of a biogas plant and requires novel process combinations for an industrial scale plant. The system of Biorender AG clearly proves that a quasi mono- digestion of animal by-products (ABP) is possible at a high level. However, the operation of this complex system places high demands on the operators.
The plant does not reach the forecasted performance. The reasons for this have been identified in the strong formation of foam, which leads to a lowering of the liquid level in the fermenter and the throughput of the ultrafiltration which is too low.
The reasons for the foam formation are investigated and several suggestions for improvement are being established. The prevention of foam has priority, but also the elimination of the foam shall be discussed.
The ultrafiltration provides only 10% of the performance for which it was designed. There are probably three reasons for this: insufficient hydraulic inside the filter container, fine material in the fermentation sludge, which form a secondary membrane and formation of gas (CO2) in the filter container, which disturbs the hydraulic and causes blockage symptoms such as scaling or fouling. Measures to avoid these problems are discussed and discussed for the problems of the fine material and gas formation.
The formation of organic sulphur compounds within the system led to the rejection of upgraded bio- methane in spring 2013. This problem was investigated and initial solutions have been realised.
The high ammonia content in the fermentation has no influence on the degradation rate, but possibly on the formation of foam. A further increase of the ammonium concentration, without major reduction of the general plant performance, would defuse the problem of the low ultrafiltration throughput. This question shall be checked with further tests.
The main technical problems of the system and the goal of a higher plant performance are solvable.