Degradation of aniline: sodium alginate/modified pomelo cellulose double cross-linking system as a bacterial immobilization carrier

Pectin cellulose grafted with glycidyltrimethylammoniochloride (GTMAC) was successfully obtained following the processes of depectinfibrillation and cellulose cationization using ordinary Shatian pomelo peel produced in Yongzhou, Hunan, as the raw material. This is the first report on a new type of functionalized sodium alginate-immobilized material prepared from the fibers of pomelo peel. The material was prepared by combining modified pomelo peel cellulose and sodium alginate following the processes of physical and chemical double cross-linking. The prepared material was used to embed the target bacteria to achieve the biodegradation of p-aniline. The concentration of CaCl₂ was adjusted when the alginate gelled, and the alginate to yuzu peel cellulose ratio was tuned. The immobilized material-embedded bacteria help achieve the best degradation effect. Bacteria are embedded during the process of the degradation of aniline wastewater, and the functionalization of the cellulose/sodium alginate-immobilized material results in unique surface structure performance. The performance of the prepared system is better than that of the single sodium alginate-based material characterized by a large surface area and good mechanical properties. The degradation efficiency of the system is improved significantly for the cellulose materials, and the prepared materials can potentially find applications in the field of bacteria-fixed technology.

Influence of organic ammonium derivatives on the equilibria between NH4+, NO2- and NO3- ions in the Nistru River water

The toxic effects of ammonium derivatives in the river water depend dramatically on their natural or synthetic origins and on their chemical structures. It has been proved that 1-naphtylamine (1-NA) and diphenylamine (DPA) breaking impact on the ammonium oxidation and especially on nitrite ions oxidation processes in natural waters is associated with its toxicity. The NH₄⁺ oxidation process slows down for about five days and ten days in river water samples with 0.5 mg/L DPA and corresponding 0.5 mg/L 1-NA. The NO₂⁻ oxidation delay in model samples of river water with 0.025 and 0.05 mg/L 1-NA, is four days and 35 days in the one with 0.5 mg/L 1-NA. For the sample with 0.05 mg/L DPA the delay of the NO₂⁻ oxidation is approximately of six days and 25 days for sample with 0.5 mg/L, DPA. The laboratory simulations have revealed: (1) absorption–desorption, the micro biotic reaction to the instantaneous increase of the concentration of ammonium ion in the river water (so-called shock/stress effect) and (2) the NH₄⁺ increase stimulated by a certain (0.05 mg/L) concentration of 1-NA.The diethylamine (DEA) decomposition leads to increasing with approximately 3.8 mg/L NH₄⁺ in river water samples of 20.0 mg/L DEA.

Community Structure Analysis and Biodegradation Potential of Aniline-Degrading Bacteria in Biofilters

Aniline has aroused general concern owing to its strong toxicity and widespread distribution in water and soil. In the present study, the bacterial community composition before and after aniline acclimation was investigated. High-throughput Illumina MiSeq sequencing analysis illustrated a large shift in the structure of the bacterial community during the aniline acclimation period. Bacillus, Lactococcus, and Enterococcus were the dominant bacteria in biologically activated carbon before acclimation. However, the proportions of Pseudomonas, Thermomonas, and Acinetobacter increased significantly and several new bacterial taxa appeared after aniline acclimation, indicating that aniline acclimation had a strong impact on the bacterial community structure of biological activated carbon samples. Strain AN-1 accounted for the highest number of colonies on incubation plates and was identified as Acinetobacter sp. according to phylogenetic analysis of the 16S ribosomal ribonucleic acid gene sequence. Strain AN-1 was able to grow on aniline at pH value 4.0-10.0 and showed high aniline-degrading ability at neutral pH.

Analysis of biodegradation by-products of nitrobenzene and aniline mixture by a cold-tolerant microbial consortium

A cold-tolerant microbial consortium, which can use nitrobenzene (NB) and aniline (AN) as sole carbon, nitrogen and energy sources, was isolated from an NB and AN contaminated site. Pilot 454 pyrosequencing analysis of the consortium showed that it was mainly made up of Pseudomonas spp. (98%). At 10 °C, the consortium degraded the mixture of 50mg/L NB and 50mg/L AN at a similar rate as those achieved at 20 °C and 30 °C. The biodegradation by-products with different initial NB and AN concentrations at 10 °C were analyzed. Azobenzene, azoxybenzene and acetanilide were observed in NB and AN mixtures degradation. These by-products are generated by the reaction between different intermediates resulting from the NB and AN degradation as well as the parent compounds. To the best of our knowledge, this is the first report confirming the by-products of NB and AN mixture biodegradation by a cold-tolerant microbial consortium.

Biodegradation of aniline in an alkaline environment by a novel strain of the halophilic bacterium, Dietzia natronolimnaea JQ-AN

Dietzia natronolimnaea JQ-AN was isolated from industrial wastewater containing aniline. Under aerobic conditions, the JQ-AN strain degraded 87% of the aniline in a 300 mg L(-1) aniline solution after 120 h of shake flask incubation in a medium containing sodium acetate. This strain had an unusually high salinity tolerance in minimal medium (0-6% NaCl, w/v). The optimal pH for microbial growth and aniline biodegradation was pH 8.0. Two liters of simulated aniline wastewater was created in a reactor at pH 8.0 and 3% NaCl (w/v), and biodegradation of aniline was tested over 7 days at 30 °C. For the initial concentrations of 100, 300, and 500 mg L(-1), 100%, 80.5% and 72% of the aniline was degraded, respectively. Strain JQ-AN may use an ortho-cleavage pathway for dissimilation of the catechol intermediate.

Defluoridation of water via electrically controlled anion exchange by polyaniline modified electrode reactor

A polyaniline (PANI) modified electrode reactor was designed for fluoride removal from aqueous solutions. The innovative concept behind the reactor design is that the uptake and elute of fluoride could be well controlled by modulating the potential of the PANI film. The maximum fluoride removal capacity of PANI is more than 20 mg/g at a positive voltage based on the electrically controlled anion-exchange mechanism. The results of batch tests showed that terminal potential values had a major impact on fluoride removal by this PANI, with optimal removal occurring at 1.5 V. The fluoride removal capacity (q(e)) increased rapidly within 5 min and reached equilibrium within 10 min, which indicated a rapid removal velocity of fluoride by PANI under this condition. The applicability of defluoridation using the PANI reactor to treat fluoride-contaminated tap water was also tested through flow cell breakthrough studies. At initial fluoride concentrations of 5 mg/L and 10 mg/L, the breakthrough capacities were 20.08 mg/g and 19.24 mg/g, respectively. Moreover, during the first half of the period before the breakthrough point, the fluoride concentration of the treated solution was below the WHO's recommended levels (1.5 mg/L). The results of the five consecutive treatment-regeneration studies also showed that the PANI films could be reused. Taken together, these results implied that the electrically controlled anion exchange by the PANI-modified electrode reactor may be an effective technique for the removal of fluoride from water.