Decolorization and azo dye degradation by anaerobic/aerobic sequential process. Enzyme Microb Biotechnol
ABSTRACT This study investigates the anaerobic treatability of Reactive Black 5 in an anaerobic/aerobic sequential process. Laboratory scale upflow anaerobic sludge blanket (UASB) reactor/completely stirred tank reactors (CSTR) were operated at different organic loadings and hydraulic retention times (HRT). The effects of shock organic loading on the chemical oxygen demand (COD), color removal, and methane gas production efficiencies were investigated in UASB reactor. The effects of both sludge retention time (SRT) and food to mass (F/M) ratio on the color and COD removal efficiencies were also investigated in aerobic reactor. The reactive dye used in this study contains the groups NN, SO3, SO and is in use in the some textile industries in Turkey. The studies were carried out in continuous mode and the effluent of the UASB reactor was used as feed for the CSTR reactor. COD removal efficiencies decreased from 56 to 27% with increases in COD loadings from 5 to 25 kg COD m−3 per day in the anaerobic UASB reactor. The color removals were 92 and 87%, respectively, for aforementioned organic loadings. The methane percentages were found to be 76 and 60% at organic loading rates of 2.49 and 14.8 kg COD m−3 per day, respectively, in UASB reactor. COD removal efficiencies of 28, 42, and 90% were obtained at SRTs of 1.7, 5.7 and 11 days in the aerobic CSTR reactor. Optimum sludge retention time was 11 days in aerobic reactor. A total of 67 and 28% COD removal efficiencies were obtained at F/M ratios varying between 0.05 and 0.17 and between 0.30 and 1.4 kg COD kg−1 MLSS per day. A 90–95% color and 40–60% COD removal efficiencies were obtained depending on the applied organic loadings in the UASB reactor. The remaining COD was removed with a treatment efficiency of 85–90% in the aerobic CSTR reactor.
- SourceAvailable from: V. Murali
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- "Sequential anaerobic–aerobic system facilitated the mineralization of azo dye (Sponza and Is ßik, 2002; Hosseini Koupaie et al., 2011). In certain study, the metabolites from anaerobic system may resist to undergo further degradation in aerobic system (Jonstrup et al., 2011). "
ABSTRACT: This study was to investigate the mineralization of wastewater containing methyl orange (MO) in integrated anaerobic-aerobic biofilm reactor with coconut fiber as bio-material. Different aeration periods (3h in phase 1 and 2; 3, 6 and 15h in phase 3; 24h in phase 4 and 5) in aerobic chamber were studied with different MO concentration 50, 100, 200, 200 and 300mg/L as influent from phase 1-5. The color removals estimated from the standard curve of dye versus optical density at its maximum absorption wavelength were 97%, 96%, 97%, 97%, and 96% and COD removals were 75%, 72%, 63%, 81%, and 73% in phase 1-5, respectively. The MO decolorization and COD degradation followed first-order kinetic model and second-order kinetic model, respectively. GC-MS analysis indicated the symmetrical cleavage of azo bond and the reduction in aromatic peak ensured the partial mineralization of MO.Bioresource Technology 06/2013; 143C:104-111. DOI:10.1016/j.biortech.2013.05.122 · 4.49 Impact Factor
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ABSTRACT: Abstract: In 2009, 201 samples of live bivalve mussels (Mytillus galloprovincialis) were analyzed for presence of Listeria monocytogenes. The samples were collected from three sampling points (BM1-south, BM1-north and BM1-west) in Butrinti lagoon located in the south of Albania. The examination confirmed incidence of this pathogen with average value 4.5%. Based on the results, high incidence was reported in winter with 6.7% of analyzed samples. The incidence of L. monocytogenes was also reported respectively in spring of 2009 with 4.35% and in autumn with 2.3% of controlled samples. There is no big difference in values of incidence of L. monocytogenes between summer and autumn. The northern part of the lagoon was more indicated by contamination of L. monocytogenes. Examination of 67 samples of M. galloprovincialis, collected in the northern part of this lagoon, showed five cases or about 7.5% of them to be confirmed as positive. Referring to the study results, periodic controls of the sea products, particularly of live bivalve mollusks, for presence of L. monocytogenes remains a necessary objective of food inspection in Albania. Key words: L. monocytogenes, incidence, mussel, Butrint, Albania.
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- "Sequencing batch reactors (SBR) and other reactor types such as fluidized bed and packed bed reactors have also been used in recent studies to achieve dye removal (Sponza and Isik 2002; Ong et al. 2005). These presently available systems for dye degradation consists of two biological conversion steps (aerobic and anaerobic degradation ), and require a large space for the aerobic and anaerobic units along with complicated operations. "
ABSTRACT: The degradation of C.I. Direct red 80, a polyazo dye, was investigated using Bacillus firmus immobilized by entrapment in tubular polymeric gel. This bacterial strain was able to completely decolorize 50 mg/L of C.I. Direct red 80 under anoxic conditions within 12 h and also degrade the reaction intermediates (aromatic amines) during the subsequent 12 h under aerobic conditions. The tubular gel harboring the immobilized cells consisted of anoxic and aerobic regions integrated in a single unit which was ideal for azo dye degradation studies. Results obtained show that effective dye decolorization (97.8%), chemical oxygen demand (COD) reduction (91.7%) and total aromatic amines removal were obtained in 15 h with the immobilized bacterial cell system whereas for the free cells, a hydraulic residence time of 24 h was required for an equivalent performance in a sequential anoxic and aerobic process. Repeated-batch experiments indicate the immobilized cells could decolorize C.I. Direct red 80 and reduce medium COD in five successive batch runs with enhanced activity obtained after each consecutive run, thus suggesting its stability and potential for repeated use in wastewater treatment. UV-visible spectrophotometry and HPLC analysis were used to confirm the partial mineralization of the dye. Data from this study could be used as a reference for the development of effective industrial scale biotechnological process for the removal of dyes and their metabolites in textile wastewater.03/2012; 2(1):67-78. DOI:10.1007/s13205-011-0035-3