Analysis of the buffer system of the C.R.O.P.® -process

Abstract

The C.R.O.P.® -process (Combined Regenerative Organic food Production) was developed at the German Aerospace Center (DLR) as a subsystem for biological regenerative life support systems (BRLSS) and can also be applied on Earth in the sustainable production of fertiliser. The filter is a simply constructed fixed-bed biological filter and is used to recycle nutrients from wastewater such as urine. The microbial process of nitrification provides the basis for the reutilisation of nutrients by plants. The aim of this thesis was the optimization of the operating procedure of the C.R.O.P.® -process. Nitrification is related to the lime-carbon dioxide equilibrium and due to the acidic pH of the C.R.O.P.® -process, the lime-carbon dioxide equilibrium is shifted to the side of carbon dioxide. The insufficiency leads to an incomplete buffering of the process. Despite the incomplete buffering, the process achieves a production of about 80 % nitrate-N. Even without a buffer system, the production of nitrate-N only dropped by 6.84 % during the observed time.