Rudzanova, et al., reported in 2019 that steel production processes generate the coke wastewaters contaminated predominantly by highly toxic phenol. Numbers of physical, chemical and physicochemical methods have been developed for the removal of phenol from coke wastewaters. Biological methods are eco-friendly and present appropriate alternative of conventional processes. Various microorganisms are able to degrade phenolic compounds including sulphate-reducing bacteria (SRB). In this work, we study the adaptation of SRB isolated from natural source to phenol and consequently the application of the adapted bacterial cultures for the biodegradation of phenol from model solutions.
Two types of bacterial culture were used (monoculture containing SRB genera Desulfovibrio and mixed bacterial consortium containing SRB genera Desulfovibrio). In experiments the modified Postgate’s medium C was used - sodium lactate as the original energy and carbon source was replaced by phenol with concentration 10 mg/dm3 for adaptation and 50 mg/dm3 for biodegradation. The mixed bacterial consortium has been shown as more capable to be adapted and grow on phenol and it has the better potential for phenol biodegradation as the bacterial monoculture of SRB genera Desulfovibrio.
The authors concluded that in the present study, the possible adaptation of SRB and biodegradation of phenol under sulphate-reducing conditions was studied in some detail. Bacterial culture, used in the authors' experiments, was isolated from natural source without any organic contamination, and it is necessary to adapt SRB to new organic substrate. The utilization of phenol as the substrate can be accomplished when the microbial biomass can be acclimatized to it for a sufficient time. If bacteria are supposed to be able to degrade phenol with higher concentration, adaptation mechanisms responsible for degradation of phenol have to be created.
Biodegradation of phenol between pure and mixed bacterial culture was compared. The experimental results confirm that higher biodegradation of phenol was observed in biotic sample containing adapted mixed bacterial culture (ABC2). During Cycle I, in the case of adapted mixed bacterial culture (A-BC2), the strong reduction in phenol concentration was remarked after 80 days. After 97 days the phenol concentration decreased to 0.143 ± 0.09 mg/dm3. During Cycle II, the expressive utilization of phenol was observed after 54 days only at application of the adapted bacterial consortium (A-BC2). After 54 days of biodegradation experiments phenol concentration decreased from initial concentration 50 ± 0.48 mg/dm3 to 0.29 ± 0.02 mg/dm3.
Biodegradation of phenol in samples with adapted pure culture (A-BC1) was not observed. The results are consistent with scientific literature suggesting that mixed bacterial culture is more effective in comparison with pure bacterial culture. For this reason, it is better to use mixed microbial consortium with wide spectrum of metabolic activity. Results obtained provide bases for further biodegradation study working with higher phenol concentration and then with real wastewater samples.
Managed & Built by I2M Consulting, LLC | © 2010-
