Propionic acid metabolism

DFG Projekt (53326257)
Laufzeit: 2007-2018

Propionic acid metabolism during anaerobic biowaste treatment – Comparison of different digestor regimes

Propionate accumulates during start-up, restart and process imbalances in anaerobic biowaste digesters and rapidly decreases when obtaining steady-state conditions. In this project, propionate formation and degradation in biowaste (Karlsruhe) or market wastes (Bandung/Indonesia) in different anaerobic digesters or digestion regimes will be investigated. The influence of composition, pH, buffers and of (bioavailable) trace metals on propionate formation and degradation, shock-loading or restart of digesters will be investigated in Karlsruhe.

Propionate degradation via the methylmalonyl-CoA or non-randomizing C6-dismutation pathway in different reactor systems and with different substrates will be investigated with pulse addition of specifically 14C-labeled propionate. Results should allow conclusions on the type of predominant propionate degraders. At LIPI, Bandung/Indonesia, the digestion of market waste suspensions in one stage or two-stage (acetogenic and methanogenic stage separated) CSTR reactor systems will be optimized and at ITB, Bandung/Indonesia, waste will first be separated into a liquid and solid phase and both fractions will then be digested either in a fixed-bed reactor (liquid) or in a dry fermentation system (solids). Such process alternatives are state of the art for wastewater treatment, but even in Europe experience with biowaste or biowaste fractions is scarce.