Structure of Microbial Communities When Complementary Effluents Are Anaerobically Digested

Abstract

Olive oil and pig productions are important industries in Portugal that generate large volumes of wastewater with high organic load and toxicity, raising environmental concerns. The principal objective of this study is to energetically valorize these organic effluents—piggery effluent and olive mill wastewater—through the anaerobic digestion to the biogas/methane production, by means of the effluent complementarity concept. Several mixtures of piggery effluent were tested, with an increasing percentage of olive mill wastewater. The best performance was obtained for samples of piggery effluent alone and in admixture with 30% of OMW, which provided the same volume of biogas (0.8 L, 70% CH4), 63/75% COD removal, and 434/489 L CH4/kg SVin, respectively. The validation of the process was assessed by molecular evaluation through Next Generation Sequencing (NGS) of the 16S rRNA gene. The structure of the microbial communities for both samples, throughout the anaerobic process, was characterized by the predominance of bacterial populations belonging to the phylum Firmicutes, mainly Clostridiales, with Bacteroidetes being the subdominant populations. Archaea populations belonging to the genus Methanosarcina became predominant throughout anaerobic digestion, confirming the formation of methane mainly from acetate, in line with the greatest removal of volatile fatty acids (VFAs) in these samples.

Performance of AnMBRs treating low strength wastewater with different carbon sources at decreasing HRTs and its linkage to Methanosaeta with high specific affinity

“…3,10 Therefore, in AnMBRs treating low-strength wastewater, a substrate may enhance the selection of specific species where microbial competition exists, and intermediate products from hydrolysis and acidogenesis could further affect the competition between different groups downstream (i.e., acetogenic bacteria and methanogens). Although the effects of various substrates on microbial communities of anaerobic wastewater treatment process have been studied, [11][12][13] whether there is any interspecies mass transfer limitation of different substrates and intermediate products and how would that affect anaerobic treatment performance at decreasing HRTs remain to be determined. 14,15 As the main components of municipal wastewater, carbohydrates vary from 25% to 50%.…”

“…, acetogenic bacteria and methanogens). Although the effects of various substrates on microbial communities of anaerobic wastewater treatment process have been studied, 11–13 whether there is any interspecies mass transfer limitation of different substrates and intermediate products and how would that affect anaerobic treatment performance at decreasing HRTs remain to be determined. 14,15…”

Complementary Substrates-Brewery Wastewater and Piggery Effluent—Assessment and Microbial Community Profiling in a Hybrid Anaerobic Reactor

“…Operational techniques based on the complementary effluents concept can alternatively contribute to solve the disadvantageous initial composition of an "anti-substrate". Effectively, the combination of effluents that complement each other has been successfully applied in anaerobic digestion of unbalanced, toxic and/or concentrated substrates to promote organic matter conversion, avoiding substrate chemical adjustments and/or pre-treatments [14][15][16][17][18][19][20]. In addition, the reduction in plant operational expenses can be expected.…”

“…In a previous study, the authors used the Next-Generation Sequencing (NGS) technique to find that changes in the organic composition of the substrate had a clear relationship with changes in the structure of microbial communities during the anaerobic digestion of olive mill wastewater (OMW) and piggery (PE) effluent, by exploiting the complementary effluents concept [20]. The reduction in the initial population diversity occurred towards an acclimation of the operational conditions in the anaerobic process, and the predominant microbial sequences allowed the finding of the best substrate proportion, 30% OMW plus 70% PE (v/v).…”