Biosorption of nitrophenols on anaerobic granular sludge

4-nitrophenol removal from aqueous solutions by emulsion liquid membranes using type I facilitation

Nitrophenols are common organic pollutants that enter the environment during the manufacture and processing of a variety of industrial products. The removal of 4-nitrophenol (4NP) from aqueous solutions by emulsion liquid membranes using the type I facilitated transport mechanism is investigated in this paper. The liquid membrane consisted of kerosene as the organic diluent, sorbitan monooleate as the emulsifying agent and sodium hydroxide as the stripping agent. The most important operational variables governing the emulsion stability and the 4NP removal process--such as the stripper agent and surfactant concentrations, the volume ratios of membrane phase/internal phase and emulsion phase/feed phase and stirring speed - were studied and the optimal conditions of the removal process were experimentally determined. Apparent initial permeabilities of the transport process in the different operational conditions were also obtained. Ninety-eight per cent of4NP was removed in 10 minutes and an apparent initial permeability of 1.2986 min(-1) was obtained in those optimal conditions.

Kinetics of p-nitrophenol degradation by Pseudomonas pseudomallei wild and mutant strains

Pseudomonas pseudomallei EBN-10 strain, previously isolated from a local pharmaceutical industry's wastewater, was spontaneously adapted to higher p-nitrophenol (PNP) levels, which then was subjected to gamma ray-induced mutagenesis; the efficient isolates hence obtained were designated as EBN-11 and EBN-12, respectively. EBN-12 mutant strain could completely mineralize PNP (100 mg/L) on the minimal media in 24 h while, the parent strain utilized only 6% of it. Addition of glucose as co-substrate further increased the PNP degradation rate; however, phenol inclusion inhibited the degradation process. Ammonium sulphate was experienced as the best of the nitrogen sources used by EBN-12 mutant strain, while degrading PNP.

Continuous biotransformation and removal of nitrophenols under denitrifying conditions

The effect of COD/NO(3)(-)-N ratio on the biotransformation and removal of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP) was studied in bench scale upflow anaerobic sludge blanket (UASB) reactors. Sodium acetate and sodium nitrate were used as electron donor (substrate) and electron acceptor, respectively. Nitrate nitrogen loading was increased from 0.098 to 0.6 kg/m(3)d in order to keep COD/NO(3)(-)-N ratio as 20.8, 14.3, 9.8, 5.0, 4.0 and 3.33. Throughout the study, input nitrophenolic concentration and hydraulic retention time (HRT) were kept constant as 30 mg/l and 24h, respectively. 2-Aminophenol (2-AP), 4-aminophenol (4-AP) and 2-amino,4-nitrophenol (2-A,4-NP) were found as the major intermediate metabolite of 2-NP, 4-NP and 2,4-DNP, respectively. Removal of all the three nitrophenols increased with lowering of COD/NO(3)(-)-N ratio. However, nitrophenols removal got adversely affected when COD/NO(3)(-)-N ratio was reduced below 5. Maximum removal achieved were 91.63%, 90.17% and 86.10% for 2-NP, 4-NP and 2,4-DNP, respectively at a COD/NO(3)(-)-N ratio of 5. Simultaneous denitrification and methanogenesis was observed in all the reactors throughout the study.