Decolourisation of Textile Wastewater by Dye Degrading Microorganisms Isolated from Textile Effluent

Dyes mostly used in the textile industry end up in their wastewater. The treatment of textile effluent has become necessary because of its associated environmental and health problems. In this study, five bacterial isolates were obtained from textile effluent. The isolated bacteria were used to decolourise effluent samples in a time-dependent manner and the change in colour was observed using an Ultraviolet-visible spectrophotometer. After 24 hours, decolourisation efficiencies of the five isolates were calculated and the highest decolourisation efficiency (78.5%) was observed with one of the isolates (E12). Isolate E23 recorded 64.7% followed by isolate E9 (62.0%) and E21 (53.7%). Isolate E19 had the lowest decolourisation efficiency (2.6%). The isolated bacteria were identified with E9 as Aeromonas hydrophilia, E12 as Aeromonas hydrophilia, E19 as Pseudomonas aeruginosa, E21 as Aeromonas hydrophilia and E23 as Pseudomonas fluorescens. To achieve a decolourisation efficiency of 78.5%, 25 ml of textile wastewater should be inoculated with 1 ml of the isolate (E12) culture. Thus, Isolate E12 (Aeromonas hydrophilia) is considered a promising candidate for biological textile wastewater treatment followed by isolate E23 (Pseudomonas fluorescens).

Calcium Salts Enhance Activity and Azo Dye Decolourisation Capacity of Crude Peroxidase from <i>Armoracia rusticana</i>

Armoracia rusticana is the commercial source of the enzyme Horseradish Peroxidase (HRP). Calcium ions play an important role in the functional conformation of HRP. The present study assesses the effect of three calcium salts viz., calcium chloride (CaCl2), calcium nitrate [Ca(NO3)2] and calcium sulphate (CaSO4) on the guaiacol activity of crude peroxidase extracted from the shoots and roots of in vitro grown plantlets of A. rusticana and their growth medium. The highest activity was observed in the shoot extracts of 25 mM CaCl2 treated plantlets (1.92 U/mL) and the root extracts of 25 mM Ca(NO3)2 supplemented plantlets (2.84 U/mL). The crude peroxidase activity of the medium containing 25 mM CaCl2 supplement was highest (0.13 U/mL). The capacity of the shoot and root extracts to decolourise a 10 ppm solution of methyl orange over 48 hours, was also tested. The decolourisation capacity was highest in the shoot extracts from CaCl2 treated plantlets (49.32%) and root extracts from Ca(NO3)2 treated plantlets (29.72%) respectively. Hence, the addition of calcium salts to growth medium enhances both peroxidase activity and decolourisation capacity of crude extracts of A. rusticana plantlets. These findings are of significance in enzymatic treatment for decolourisation of effluents containing dyestuffs.

Optimisation of Decolourisation Conditions of Crude Shea (<i>Vitellaria paradoxa</i>Gaertner F) Butter: Yellow Type

In this study, response surface methodology applying Doehlert experimental design was used to optimise decolourisation parameters of crude yellow shea butter. The decolourisation process was significantly influenced by three independent parameters: contact time, decolourisation temperature and adsorbent dose. The responses of the process were oil loss, acid value, peroxide value and colour index. Contour plots of the decolourisation responses were superimposed and well defined the optimum zone. The optimum decolourisation conditions were found to be: contact time (30 min), decolourisation temperature (80℃ - 95℃) and adsorbent dosage (1 - 2 mass%). These conditions gave decolourised shea butter with the following responses;oil loss (6.2% ± 0.2%), peroxide value (1.7 ± 0.1 meq O2/kg), colour (0.21 ± 0.05 Lovibond yellow) and acid value (25.6 ± 0.7 mg KOH/g).

Optimisation of Decolourisation Conditions of Crude Shea (<i>Vitellaria paradoxa</i>Gaertner F) Butter: Black Type

In the present study, response surface methodology applying Doehlert experimental design was used to investigate decolourisation parameters of crude black shea butter. The decolourisation process was significantly influenced by three independent parameters: contact time, decolourisation temperature and adsorbent dose. The responses of the process were oil loss, acid value, peroxide value and colour index. Contour plots of the decolourisation responses were superimposed and well defined the optimum zone. The optimum decolourisation conditions were found to be: contact time (30 min), temperature (72℃ - 95℃) and adsorbent dosage (1.5 - 2.5 mass %).

Effect of Texture and Surface Chemistry of Palm Nut Hull Activated Carbon on the Adsorption of Pigments and Free Fatty Acids from Vegetable Oils

Activated carbons were produced from palm nut hull,which is a waste material of palm oil extraction industries.Activated carbons having various pore size distributions and surface composition were obtained by conventional carbonization method via the sulphuric acid solution pre-treatment method.The surface areas,mesopore volume and-OH groups of activated carbons increase with the increases of sulphuric acid solution concentration.The activated carbons obtained were tested for the adsorption of pigments and free fatty acids from palm oil and shea butter.It comes out from this study that the amount of adsorbate(i.e.pigments and free fatty acids)fixed increases with the increase of the adsorption temperature and with the increases of mesopore volume.Intraparticle diffusion,pseudo-first-order and pseudo-second-order kinetics models were used to analyze the kinetics data obtained at different temperatures(temperature range 60℃ to 90℃).Among the kinetics models used,the pseudo-second order was the best applicable model to describe the adsorption of oil pigments and free fatty acid onto activated carbons.The activation energies obtained by applying the Arrhenius equation for the adsorption of pigments were low(i.e.less than 40 kJ·mol^-1 for the both vegetables oils),indicating that the adsorption could be assigned to physisorption.