Changes in the process performance and microbial community by addition of the metabolic uncoupler 3,3′,4′,5-tetrachlorosalicylanilide in sequencing batch reactors

Abstract

A complete study about the effects of 3,3',4',5-tetrachlorosalicylanilide (TCS) on organic matter elimination performance, sludge production and on the microbial community of a biological wastewater treatment process has been performed. For this purpose two sequencing batch reactors (SBR) worked in parallel for 43 days with 0.8 mg•L -1 of TCS (SBR-1) and without this metabolic uncoupler (SBR-2). Results indicated that 63.3% of sludge reduction was achieved in SBR-1. However, COD removal efficiency was maintained in similar values in both reactors (89.1% and 92.1% in SBR-1 and SBR-2, respectively). The exhaustive mixed liquor characterization led to know deeply the action mechanism of TCS.In this way, a 69% of adenosine triphosphate (ATP) reduction was observed in SBR-1 in comparison with values measured in SBR-2. On the contrary, an increase in soluble microbial products (SMP) and DNA concentrations occurred as a consequence of TCS addition. Thus, 2 it could be concluded that sludge reduction due to TCS addition was due to both uncoupling effect and cellular lysis. Also, increase in all microbial hydrolytic enzymatic activities measured was observed, which explained the stable performance achieved in SBR-1 despite to the results explained above. It should be highlighted that this uncoupler should not be used in biological treatments that require nitrogen elimination because nitrifying bacteria were affected by its addition (Nitrosomonas and Nitrospira). Finally, the 16S rRNA gene amplicon sequencing informed that an important reduction of bacterial diversity resulted in SBR-1 due to TCS addition.

Effect of the Oxidative Phosphorylation Uncoupler Para-Nitrophenol on the Activated Sludge Community Structure and Performance of a Submerged Membrane Bioreactor

“…However, a significant increase (p < 0.05, in Duncan's tests) in the relative abundance of Bacteroidetes, Gammaproteobacteria and Firmicutes over Actinobacteria and Alphaproteobacteria occurred immediately after the pNP addition (Figure 6a). Similar to our study, Ferrer-Polonio et al [37] reported the dominance of Proteobacteria (all classes) in an SBR after the addition of the metabolic uncoupler TCS. These authors also reported an increase in the relative abundance of Gammaproteobacteria, although the opposite trend compared to this study was reported regarding Alphaproteobacteria.…”

Sequencing batch reactor technology for landfill leachate treatment: A state-of-the-art review

“…The phenomenon of uncoupled metabolism may be carried out under abnormal conditions such as the presence of inhibitory compounds or some heavy metals. The use of uncouplers are to reduce sludge production, control microbial contamination and increase substrate removal efficiency (Ferrer-Polonio et al, 2019).…”

Toxic Effects of Xenobiotic Compounds on the Microbial Community of Activated Sludge

“…Proteobacteria, Firmicutes, Fusobacteria , and Tenericutes made up 72.4 % of the overall bacterial population. As a result, sludge reduction owing to TCS addition could be attributed to both the uncoupling effect and cellular lysis 181. In a related study, metabolic uncoupling and energy distribution were found to be important factors in TCS‐induced sludge reduction.…”

“…where the chemical formulas of the cell and electron donor are The uncoupled metabolism phenomenon is promising because it can be quickly fed into a WWTP's aeration tank, eliminating the need for modification [180]. This can be done in unusual circumstances such as (i) presence of toxic compounds, (ii) when temperatures are not ideal, (iii) at limited nutrients, (iv) presence of oxic-anoxic cycling conditions, and (v) presence of chemical uncouplers [181].…”