Co-digestion of cow manure, food waste and intermittent input of fat

Abstract

Pulses of oil were added to completely mixed reactors fed with dairy cow manure and food waste, after achieving a stable performance at an organic loading rate of 4.6 ± 0.1 gCOD/(l reactor day), an oily waste effluent from a canned fish processing industry was fed in the form of pulses. The oil concentration rose up to 9, 12, 15 and 18 gCOD oil/l reactor, after the pulse feeding in the reactor. The highest fat concentration of 18 gCOD oil/l reactor promoted a persistent inhibition in the process of the continuous reactor, although in batch assays, the reactor content evidenced a capacity to degrade more oil and to degrade the accumulated organic matter. All the other pulses had a positive effect in the methane production. From a practical point of view, this work demonstrates that controlled intermittent inputs of oil can enhance the methane production in a co-digestion of cow manure and food waste.