A. Kahru et al., The toxicity and biodegradability of eight main phenolic compounds characteristic to the oil-shale industry wastewaters: A test battery approach, ENVIRON TOX, 15(5), 2000, pp. 431-442
The toxicity of eight phenolic compounds characteristic to the oil-shale in
dustry wastewaters was analyzed using a battery of seven microbiotests with
species representing different trophic levels (photobacteria, protozoa, cr
ustaceans, microalgae). Altogether five monobasic phenolic compounds (pheno
l, p-cresol, 2,4-dimethylphenol, 2,3-dimethylphenol, 3,4-dimethylphenol) an
d three dibasic phenolic compounds (resorcinol, 5-methylresorcinol, and 2,5
-dimethylresorcinol) were studied. Phenol, 2,4-dimethylphenol, 2,3-dimethyl
phenol, and 5-methylresorcinol were classified as "toxic" (lowest 50% letha
l (effective) concentration L(E)C-50 of the battery 1-10 mg/L). P-cresol, 3
,4-dimethylphenol, resorcinol, and 2,5-dimethylresorcinol were classified a
s "very toxic" (lowest L(E)C-50 of the battery less than or equal to1 mg/L)
. The most sensitive test organisms were crustaceans and/or photobacteria.
The toxicity of three different equitoxic mixtures (mixture of all eight ph
enols, mixture of five monobasic phenols, and mixture of three dibasic phen
ols) was studied using Vibrio fisheri, Daphnia magna, and Thamnocephalus pl
atyurus. For all three test organisms the toxicities of individual phenols
were proved additive. The efficiency of biotreatment on the toxicity reduct
ion of the individual phenolic compounds (2.5 mM) as well as the equimolar
mixtures of all eight phenols (1/8*2.5 mM each), five monobasic phenols (1/
5*2.5 mM each), and three dibasic phenols (1/3*2.5 mM each) was studied usi
ng acclimated and nonacclimated activated sludges, in the case of both acti
vated sludges phenol, p-cresol, resorcinol, and 5-methylresorcinol were mos
t rapidly detoxified. Dimethylphenols and the mixtures had moderate detoxif
ication times, while the slowest was the detoxification of 2,5-dimethylreso
rcinol and the mixture of resorcinols. Thus, out of eight phenolic compound
s studied 2,5-dimethylresorcinol was considered most environmentally hazard
ous as very toxic (LC50 for crustaceans 1-5 mg/L) and slowly biodegradababl
e. (C) 2000 by John Wiley & Sons, Inc.