Toxicity and Anaerobic Biodegradability of Substituted Phenols Under Methanogenic Conditions

Abstract

Phenol, 2, 2, were evaluated for their anaerobic biodegradability and toxicity to methanogenesis using two anaerobic bioassays, the biochemical methane potential (BMP) and the anaerobic toxicity assay (ATA). The BMP and ATA were used to evaluate the stoichiometric conversion of added substrate carbon to COz and CH4. Each substrate was the only added carbon source (20-200 mg/L) prepared in prereduced defined medium using a 10% (v/v) inoculum of municipal digester sludge. All concentrations of phenol and low concentrations (20 mg/L) of 2-chlorophenol, %-nitrophenol, 4-nitrophenol and 2,4-dinitrophenol were completely mineralized. Higher concentrations of these same substrates (100 mg/L) and all concentrations of dimethylphenol, 3-methyl-4-chlorophenol and 2-methyl-4,6-dinitrophenol were observed to undergo no significant mineralization of added substrate and inhibited methanogenesis to varying degrees. Significant biotransformation of the monosubstituted nitrophenols occurred, resulting in the production of the corresponding aminophenols. Acclimation for most compounds took several days to weeks before methane could be detected in the substrate-amended cultures. Generally, the greater the substitution of the phenolic ring, the greater were the recalcitrance and toxicity of the substrate. The fate of these compounds can be significantly influenced by both their concentration and their residence time in anoxic environments.

Nickel nanoparticles decorated on electrospun polycaprolactone/chitosan nanofibers as flexible, highly active and reusable nanocatalyst in the reduction of nitrophenols under mild conditions

“…For these reasons, nitrophenols are considered as a priority pollutant by the Environmental Protection Agency (EPA) of USA, and its concentration in natural waters is restricted to less than 10 mg/L [5,6]. Up to date, various techniques such as membrane filtration [7,8], microbial degradation [9,10], photocatalytic degradation [11,12], electro-Fenton method [13,14], electrocoagulation [15,16], adsorption [17,18], electrochemical treatment http://dx.doi.org/10.1016/j.apcatb.2016. 10.020 0926-3373/© 2016 Elsevier B.V. All rights reserved.…”

Reduction of 4‐Nitrophenol as a Model Reaction for Nanocatalysis

“…Th e presence of a nitro-group in the aromatic ring enhances stability, making chemical and biological degradation diffi cult in the purifi cation of wastewater polluted with 4-NP. Th ese pollutants are unaff ected by aerobic biodegradation [33], and anaerobic degradation produces nitroso and hydroxylamine compounds which are known to be carcinogenic [34]. Due to their high toxicity, water solubility, and stability as well as their resistance to water purifi cation methods [34], attention has been given to researching the fate of these compounds in the environment, and to develop methods to remove these compounds from surface and groundwater.…”

“…Th ese pollutants are unaff ected by aerobic biodegradation [33], and anaerobic degradation produces nitroso and hydroxylamine compounds which are known to be carcinogenic [34]. Due to their high toxicity, water solubility, and stability as well as their resistance to water purifi cation methods [34], attention has been given to researching the fate of these compounds in the environment, and to develop methods to remove these compounds from surface and groundwater. Th ese methods include direct photolysis, microwave-assisted catalytic oxidation [35], microbial degradation [34], photocatalysis [26,27,[36][37][38], polymeric adsorption [39][40][41][42][43], the electro-Fenton method [44], electrocoagulation [45], and electrochemical treatment [46].…”

Effect of simulated solar light on the autocatalytic degradation of nitrobenzene using Fe3+ and hydrogen peroxide

“…Nitroaromatic compounds are extensively used as raw materials in many industrial processes such as in the preparation of pesticides, explosives, dyes, pulp and paper. The detoxification of wastewaters containing these compounds is very difficult since, due to their high stability, they are usually refractory to biological degradation [9]. Several studies have addressed the use of photo- systems frequently display autocatalytic concentration profiles with an initial slow phase followed by a catalytic phase [14,15].…”