Temperature and pH effect on methane production from buffalo manure anaerobic Digestion

Abstract

Anaerobic digestion is an established technology to treat different kinds of wastes and to simultaneously produce biogas, a mixture of methane and carbon dioxide, which is a useful and renewable energy source. In this work, the anaerobic digestion of buffalo manure is studied. The latter is a low cost substrate rich in carbohydrates, especially suitable to produce biogas in anaerobic digesters. The process is performed both under mesophilic (37 °C) and thermophilic (55 °C) conditions with pH spanning from 6.0 to 8.7. Many different samples, deriving both from lactating and non-lactating buffaloes, are used. Under mesophilic conditions, our results are essentially in line with literature, and the highest methane concentration in the biogas (even above 65 %) is obtained with pH = 7.0. Conversely, under thermophilic conditions, we observed that also with pH > 8.0, the anaerobic process runs efficiently. In particular, methane concentration in the biogas reaches values around 70 %, with production rates almost twice those obtained at 37 °C. This experimental observation is particularly interesting for those wastes showing a natural basic pH, as the buffalo manure at hand; in these cases, in fact, the digestion process can start without any manipulation of the pH.

Elevated biogas production from the anaerobic co-digestion of farmhouse waste: Insight into the process performance and kinetics

“…However, the range of 5.5–6.5 is more favourable for the activity of hydrolytic and acidogenic bacteria. The pH of the bioreactor is a critical factor for the decomposition of the anaerobic digester as it may cause perturbations on the microbiome dynamics and the subsequent metabolomic pathways (Carotenuto et al, 2016). Microbial activity is inhibited when the microbiome is exposed to low pH values, which impedes the digester operation.…”

Study of temperature control system of a solar-heated anaerobic digester in Cotonou, Benin Republic, using hardware in the Loop simulation

“…In the control system, the temperature range as set is [36°C -38°C]. The optimal temperature of anaerobic digestion in the mesophilic domain is around 37°C (Gavala et al, 2003;Carotenuto et al, 2016). Thus, as soon as heating starts, the temperature of the substrate at which it must be cut is 38°C, and…”

Combustion of Hydrogen Enriched Methane and Biogases Containing Hydrogen in a Controlled Auto-Ignition Engine

“…Equation 3predicts a CH 4 /CO 2 ratio ranging from 1, for simple carbohydrates like starch (C 6 H 10 O 5 ) n , or proteins (C 5 H 7 NO 2 ) to 2.35, for the conversion of lipids, e.g., C 57 H 104 O 6 . It is experimentally found that for the fermentation of water buffalo manure the CH 4 /CO 2 ratio is about 2 [39,40]. Being 2 is an intermediate value among the possible ones, we keep the CH 4 /CO 2 ratio constant and equal to 2 in all the biogases investigated in our simulations.…”