Uncouplers and activated sludge—the impact on synthesis and respiration

Halogenated organics are among the most commonly‐encountered anthropogenic compounds accumulating in the environment. These compounds have many behavioral characteristics in common. Many are carcinogenic; many are toxic; almost all resist biodegradation; all undergo bioconcentration and concentration in sediments. One group of halogenated materials, the halogenated phenols, interact with microbial cell tissue and higher‐life forms in a way not seen with the other compounds in this broad category. That is, they will uncouple oxidative phosphorylation, the energy transfer process which permits the accumulation of the energy of substrate oxidation as adenosine triphosphate which is subsequently used in synthesis. The present study reports on laboratory work which serves to quantify the various results of energy uncoupling. These are an increase in oxygen use, a decrease in synthesis and a decrease in the rate of normal substrate uptake. The work is carried out utilizing four common types of organics as growth substrates. The consequence of the phenomenon of uncoupling in full‐scale treatment plants, based on experiences at one of the Phoenix wastewater treatment plants, is discussed.