Possible causes of excess sludge reduction adding metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS), in...

Area of Science:

• Environmental microbiology
• Wastewater treatment technologies

Background:

• Sludge reduction is crucial for efficient wastewater treatment.
• Uncouplers are chemicals that can disrupt microbial metabolism.
• Understanding uncoupler mechanisms is key to optimizing treatment processes.

Purpose of the Study:

• To investigate the mechanisms behind sludge reduction caused by uncouplers.
• To differentiate between metabolic uncoupling, energy consumption for resistance, and lysis-cryptic growth.

Main Methods:

• Operation of two parallel sequence batch reactors (SBRs), one with and one without TCS (Trichlorosuccinate).
• Measurement of electronic transport system (ETS) activity and specific cellular ATP (SATP).
• Analysis of extracellular polymeric substances (EPS) using chemical methods and EEM fluorescence spectra.
• Quantification of DNA concentrations in reactor effluents.

Main Results:

• TCS addition significantly reduced ETS activity and SATP, confirming metabolic uncoupling.
• Increased EPS production in the TCS reactor suggests higher energy consumption for microbial resistance.
• No significant difference in effluent DNA concentration indicates TCS did not intensify sludge lysis.

Conclusions:

• Uncouplers primarily cause sludge reduction through metabolic uncoupling.
• Microorganisms expend more energy to produce substances that resist uncouplers.
• Sludge lysis is not a significant factor in uncoupler-induced sludge reduction.