Biodegradation of p‐cresol and sulfide removal by a marine‐denitrifying consortium

Abstract

The simultaneous removal of sulfide and p-cresol was carried out by using a marine-denitrifying consortium collected in the coastal zone of Sonora, Mexico. Different experimental conditions were used to evaluate the capacity of the consortium to simultaneously eliminate nitrate, sulfide, and p-cresol. For instance, the first set of assays was conducted at different sulfide concentrations (20, 50, and 100 mg S(2À) L(À1) ), with a fixed concentration of p-cresol (45 mg C L(À1) ). The second set of assays was developed at different concentrations of p-cresol (45, 75, and 100 mg C L(-1) ), in the presence of 20 mg S(2À) L(À1) . In all cases, the concentration of nitrate was stoichiometrically added for the complete oxidization of the substrates. The results showed removal efficiencies up to 92% for p-cresol and nitrate at 20 and 50 mg S(2À) L(À1) ; whereas at 100 mg S(2À) L(À1) removal efficiencies were 77% and 59% for p-cresol and nitrate, respectively. On the other hand, sulfide (20 mg L(À1) ) was completely removed under different concentrations of p-cresol tested, with a partial accumulation of nitrite according to the increment of p-cresol concentration. The results obtained indicate that the marine consortium was able to simultaneously remove the pollutants studied.

Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR)

“…The detected SRB genera were also of lower abundance ( Desulfobulus -like species (<0.01%) and Desulfomicrobium -like species (<0.01%)) than the previous study ( Desulfobulus -like species (10.6%) and Desulfomicrobium -like species (10.5%)) 6 . Instead, the denitrifying bacteria genera, such as Thiobacillus genera (4.7%) 26 27 , Thioclava genera (1.1%) 28 , Paracoccus genera (3.2%) and Thauera genera (24.3%) 29 , and Unclassified genera (26.1%) were identified to be the predominant groups in the sludge sample which was not considered and investigated in previous studies.…”