Methane production and hydrolysis kinetics in the anaerobic degradation of wastewater screenings

Abstract

Anaerobic biodegradability and hydrolysis rates of wastewater screenings were determined using the biochemical methane potential test at 37 °C. The extent and rate of screenings conversion to methane of this complex and particulate substrate were investigated and since two stages of hydrolysis were identified, corresponding to the different types of materials in screenings, a linear and non-linear model was used. No accumulation of intermediary products was observed and so it was possible to use the methane production rate and a linear model to estimate the hydrolysis rate in the first phase of hydrolysis. The measured values of 0.061-0.127 d(-1) are in the range reported for other comparable organic wastes. It was also observed that the inoculum-to-substrate ratio has a large impact on methane production rate of screenings. The difference in biodegradation rates from the materials in screenings and the overall hydrolysis could be represented by the modified Gompertz non-linear model which was able to describe the methane production rate of screenings with a high confidence. Screenings were found to have 52% biodegradability on average and this shows the potential for volatile solids destruction. A two-stage process with an improved hydrolysis rate is proposed to ensure that the full potential of the material is exploited.

Reviewing the Anaerobic Digestion of Food Waste: From Waste Generation and Anaerobic Process to Its Perspectives

“…Other transformation processes should also be reported (enzymatic or not) to transform the particulate matter into accessible polymeric compounds and expose the maximum contact surface for enzymes to act upon. Therefore, hydrolysis can be disaggregated into two different processes, (a.1) "disintegration" of POM into lipids, proteins, and carbohydrates, and (a.2) the proper enzymatic hydrolysis of LPCH [101]. As these two stages take place simultaneously and they are impossible to decouple, they are commonly included within a unique kinetics reaction.…”

Biomethane from fish waste as a source of renewable energy for artisanal fishing communities

“…Diauxic growth behaviour has been observed in the methane production from pacific saury fish waste, mackerel fish waste and cuttlefish waste, however, these fermentations had a longer duration than the process reported in this article with artisanal fish wastes [19]. Similar to FW, the AD of other heterogeneous substrates had evidenced diauxic growth, for example, the digestion of wastewater screenings [31]. In the future, to improve the production of biogas from artisanal FW is necessary to evaluate economic methods to achieve rapid solubilisation and hydrolysis of fats.…”

Effect of nutrients, inoculum and co-substrates on methane potential of cattle manure

“…In the same way, it could be noticed that the inoculum also had a positive influence on methane production. In this case, an inoculum with an important amount of well-adapted microorganisms increased the amount of active methanogens stimulating the methanogenic activity and, therefore, the methane production, as was described by [30] and [31] who mentioned that the quality and quantity of inoculum is a key factor for the implementation of the AD process. These authors concluded that an adequate amount of inoculum improves hydrolysis, accelerates biogas production, reduces time operation and helps prevent acidification.…”