Effects of wastewater discharge on microbial populations and enzyme activities in mangrove soils

Estimating the toxicities of organic chemicals to bioluminescent bacteria and activated sludge

The effect of toxicants on the BOD degradation rate constant was used to quantitatively establish the toxicity of triclosan, phenol, and copper (II) against activated sludge microorganisms. Toxicities were tested over the following ranges of concentrations: 0-450 mg/L for phenol, 0-2 mg/L for triclosan, and 0-35 mg/L for copper sulfate (pentahydrate). According to the EC(50) values, triclosan was the most toxic compound tested (EC(50) = 1.82 +/- 0.1 mg/L), copper (II) had intermediate toxicity (EC(50) = 18.3 +/- 0.37 mg/L), and phenol was the least toxic (EC(50) = 270 +/- 0.26 mg/L). The presence of 0.2% DMSO had no toxic effect on the activated sludge. The toxicity evaluation method used was simple, reproducible, and directly relevant to activated sludge wastewater treatment processes.

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Toxicities of triclosan, phenol, and copper sulfate in activated sludge.

Mixed nitrifying bacteria culture under different temperature dropping strategies: Nitrification performance, activity, and community

A simple system to rapidly monitor activated sludge health and performance.

ATP measured by the luciferin-luciferase bioluminescence assay was used to examine the effect of toxic substances on whole microbial communities in activated sludge mixed liquor samples. The response of the microorganisms to toxicants is rapid using ATP reduction as the criterion. The sensitivity of the mixed populations to various toxicant types (e.g., organic material and heavy metals) is lower than when using single species toxicity tests such as the Microtox bioassay. The differences in sensitivity is considered a function of acclimatization, modification of the toxicant by the waste physicochemical environment, and the predominance of less sensitive organisms than those used in the Microtox bioassay (Photobacterium phosphoreum). ATP bioluminescence is, however, considered an important rapid test utilizing natural waste treatment microorganisms in determining the toxicity of wastes discharged to sewer. It can detect whether wastewater will have an effect on the biodegradation capability of the resident population of microrganisms. © 1997 by John Wiley & Sons, Inc. Environ Toxicol Water Qual 12: 23–29, 1997

J. M. Heap

Papers

The effect of toxic discharges on ATP content in activated sludge