Effect of Lactate on the Microbial Community and Process Performance of an EBPR System

Abstract

Candidatus Accumulibacter phosphatis is in general presented as the dominant organism responsible for the biological removal of phosphorus in activated sludge wastewater treatment plants. Lab-scale enhanced biological phosphorus removal (EBPR) studies, usually use acetate as carbon source. However, the complexity of the carbon sources present in wastewater could allow other potential poly-phosphate accumulating organism (PAOs), such as putative fermentative PAOs (e.g., Tetrasphaera ), to proliferate in coexistence or competition with Ca . Accumulibacter. This research assessed the effects of lactate on microbial selection and process performance of an EBPR lab-scale study. The addition of lactate resulted in the coexistence of Ca . Accumulibacter and Tetrasphaera in a single EBPR reactor. An increase in anaerobic glycogen consumption from 1.17 to 2.96 C-mol/L and anaerobic PHV formation from 0.44 to 0.87 PHV/PHA C-mol/C-mol corresponded to the increase in the influent lactate concentration. The dominant metabolism shifted from a polyphosphate-accumulating metabolism (PAM) to a glycogen accumulating metabolism (GAM) without EBPR activity. However, despite the GAM, traditional glycogen accumulating organisms (GAOs; Candidatus Competibacter phosphatis and Defluvicoccus ) were not detected. Instead, the 16s RNA amplicon analysis showed that the genera Tetrasphaera was the dominant organism, while a quantification based on FISH-biovolume indicated that Ca . Accumulibacter remained the dominant organism, indicating certain discrepancies between these microbial analytical methods. Despite the discrepancies between these microbial analytical methods, neither Ca . Accumulibacter nor Tetrasphaera performed biological phosphorus removal by utilizing lactate as carbon source.

Survey of full‐scale sidestream enhanced biological phosphorus removal (S2EBPR) systems and comparison with conventional EBPRs in North America: Process stability, kinetics, and microbial populations

“…It should be also noted that the relative abundances obtained from 16S rRNA gene sequences do not necessarily correspond to the actual population abundance due to PCR biases, variation in the number of 16S rRNA gene copies across different organisms, the presence of legacy DNA from EPS, nonactive organisms, etc. Therefore, the relative abundance of organisms revealed by 16S rRNA gene sequencing cannot be directly compared with FISH results that detect active populations and use biomass volume as a metric (Rubio‐Rincón et al, ).…”

Putative metabolism of Ca. Accumulibacter via the utilization of glucose

“…However, the presence of fermentative PAOs such as Tetrasphaera could also prove to be detrimental to the EBPR process since an additional source of energy (as ATP) such as the one provided via fermentation could cease the poly-P hydrolysis. This theory is supported by Marques et al (2017) and Rubio-Rincón et al (2019). The latter suggested that neither Tetrasphaera nor Ca.…”

“…The reactor's working capacity was 2.5 L, with an internal diameter of 12.5 cm and a water depth of 20.5 cm. The overall experimental setup is comparable to the one used by Rubio-Rincón et al (2019).…”

The impact of mixtures of xylose and glucose on the microbial diversity and fermentative metabolism of sequencing-batch or continuous enrichment cultures

“…This amount of biomass is assessed by FISH where a quantification is made based on cell-surface area. Recently in other studies a similar discrepancy between biovolume and cell numbers due to differences in cell size have been reported (Saccà 2016;Domaizon et al 2017;Rubio-Rincón et al 2019) A "full cycle rRNA analysis" of a microbial community structure, as proposed by Amann, Ludwig and Schleifer (1995) is needed to get a quantitative view of a microbial community structure.…”