Growth condition and bacterial community for maximum hydrolysis of suspended organic materials in anaerobic digestion of food waste-recycling wastewater

Abstract

This paper reports the effects of changing pH (5-7) and temperature (T, 40-60 degrees C) on the efficiencies of bacterial hydrolysis of suspended organic matter (SOM) in wastewater from food waste recycling (FWR) and the changes in the bacterial community responsible for this hydrolysis. Maximum hydrolysis efficiency (i.e., 50.5% reduction of volatile suspended solids) was predicted to occur at pH 5.7 and T = 44.5 degrees C. Changes in short-chain volatile organic acid profiles and in acidogenic bacterial communities were investigated under these conditions. Propionic and butyric acids concentrations increased rapidly during the first 2 days of incubation. Several band sequences consistent with Clostridium spp. were detected using denaturing gel gradient electrophoresis. Clostridium thermopalmarium and Clostridium novyi seemed to contribute to butyric acid production during the first 1.5 days of acidification of FWR wastewater, and C. thermopalmarium was a major butyric acid producer afterward. C. novyi was an important propionic acid producer. These two species appear to be important contributors to hydrolysis of SOM in the wastewater. Other acidogenic anaerobes, Aeromonas sharmana, Bacillus coagulans, and Pseudomonas plecoglossicida, were also indentified.

Metabolic and microbial community dynamics during the hydrolytic and acidogenic fermentation in a leach-bed process

“…The clostridia are strict anaerobes and represent one of the most prevalent bacterial groups in biogas reactors. C. thermocellum and C. stercorarium were identified as the major players in the hydrolysis of plant biomass [41], whereas C. thermopalmarium was found to be the main butyric acid producer in a wastewater treatment system [42]. The clostridia represent the majority of the light-independent fermentative bacteria which have the ability to produce hydrogen [43].…”

Fate of Clostridium botulinum and incidence of pathogenic clostridia in biogas processes

“…Since the organism among others is considered to play an important role in butyric and propionic acid production in the anaerobic digestion (Kim et al 2010), its appearance in the studied agricultural biogas systems was not too surprising. Since the organism among others is considered to play an important role in butyric and propionic acid production in the anaerobic digestion (Kim et al 2010), its appearance in the studied agricultural biogas systems was not too surprising.…”

Characterization of food waste-recycling wastewater as biogas feedstock

“…4). The high food-to-microorganism (F/M) ratio of 48 g COD/g VS allowed monitoring of acidogenesis prior to methane detection by 18.5 d. This F/M ratio is higher than a typical ratio of a biomethanation assay (Cho et al, 1995;McKeown et al, 2009) but ranges within the initial F/M ratios of an acidogenesis bioreactor reported in the literature (12.5-400 g COD/g VS) (Dareioti et al, 2014;Jung et al, 2015;Kim et al, 2010). During the batch period, COD and lipid concentrations remained unchanged (±5%); only a small fraction of the COD (3% of the initial) was converted to methane (Speece, 1996).…”