Abstract: Assessment evaluation of the reliability level of methane gas production dependence on organic loading rate and hydraulic retention time during biodegradation of fruit wastes was carried out. A two-factorial linear model was derived and validated for the predictive analysis and evaluation. The validity of the model; ζ = - 0.3127 (ln ϑ - ln ɤ) - 0.2014 was rooted on the core model expression ζ + 0.2014 = - 0.3127(ln ϑ - ln ɤ) where both sides of the expression are correspondingly approximately equal. Regression model was used to generate results of methane gas yield, and its trend of distribution was compared with that from derived model as a means of verifying its validity relative to experimental results. The results of this verification show very close dimensions of aligned areas designating methane gas yield, which precisely translated into significantly similar trend of data point’s distribution for experimental (ExD), derived model (MoD) and regression model-predicted (ReG) results. Evaluations from generated results indicated that methane gas yield per unit hydraulic retention time and organic load mass as obtained from experiment, derived model & regression model were 0.0242, 0.0239 & 0.0209 m³ kg ^-1 VS d^-1 and 0.0064, 0.0063 & 0.0055 (m³ kg ^-1)² respectively. Standard errors incurred in predicting the methane gas yield for each value of the hydraulic retention time and organic loading rate considered as obtained from experiment, derived model & regression model were 0.1032, 0.1042, & 0.0011 % and 0.1237, 0.1220 & 2.5x10^-5 % respectively. Deviational analysis indicates that the maximum deviation of model-predicted methane gas yield from the experimental results is less than 22%. This translates into over 78% operational confidence and reliability level for the derived model as well as over 0.78 reliability coefficient for the methane gas production dependence on organic loading rate and hydraulic retention time.

Abstract: Dyewaste effluent samples were collected from textile dyeing unit as well as CETP located in Tirupur. Strains having decolorizing ability of various textile reactive dyes were obtained from primary and secondary screening methods. Stenotrophomonas maltophilia RSV-2 strain could degrade the mixed dyes up to 2100 ppm with in 67 hrs and 58 % decolorization was obtained through acclimatization study. The strain was identified based on biochemical and 16S ribosomal RNA gene sequence study. Optimization of yeast extract composition, pH, temperature, salinity and biomass composition was determined. Decolorization performance of individual dyes using two different substrates was also studied.

Abstract: The present study aimed at assessing the ability of Pseudomonas spp. to decolorize and degrade Methyl Orange dye. Pseudomonas spp. ETL-M could tolerate Methyl Orange dye upto 500 mg^-1. A bacterium identified as Pseudomonas spp. ETL-M was isolated from dye contaminated soil. This strain rapidly decolorized a methyl orange azo dye solution. Features of the decolorizing process related to biodegradation and biosorption were also studied. The dye was efficiently decolorized in static compared to shaked cultures. The bacterium exhibited a remarkable color removal capability over a wide range of dye concentration (50-200 mg/l), pH (6-10) and temperatures (30-40^oC). The Pseudomonas spp. ETL-M decolorized the repeated addition of methyl orange dye up to four cycles with variable decolorization rate (10-94%).

Abstract: In this study, the semiconductor photocatalytic disinfection of secondary treated municipal wastewater was investigated. Natural water from a spring in Ethiopia prefecture, which is used for the water supplies for the city of Ethiopia, Crete, and samples from the effluents of the secondary settling tank of the municipal wastewater treatment plant of Ethiopia were collected. The samples were exposed to UV-A irradiation in the presence of TiO₂. The parameters examined in this study were the length of TiO₂ / UV-A treatment for effective disinfection, the microorganism type (total coliforms, enterococci), the relative bactericidal activity of three different types of TiO₂, the amount of the catalyst needed, and the pH of the samples. The results presented here show that commercial TiO₂ powder Degussa P25 is the most effective catalyst of the three used. Enterococci showed a stronger resistance to photocatalytic disinfection, whereas small pH changes do not seem to have a significant effect on it.

Abstract: In the present study, an attempt was made to examine the potential of isolated bacterium for decolorization of Remazol Black B dye in batch reactors. A potential bacterial strain was isolated and selected from the textile effluent on the basis of rapid azo dye Remazol Black B (250mgl^–1) decolorization and later identified as belonging to genus Bacillus based on phenotypic characterization. The effect of pH, temperature, carbon & nitrogen source was studied with an aim to determine the optimal conditions required for maximum decolorization and degradation. Decolorization was effective at pH 8, 35°C with starch and peptone as carbon and nitrogen sources and in static conditions. This decolorization potential increased the applicability of this microorganism for the dye removal. The results show that the isolated bacterium has a dynamic potential in removal of Remazol Black B dye from wastewater under aerobic conditions.

Abstract: Azo reductase are often associated with decolorization of non-degradation of non-degradable azo dyes via cleavage azo bonds. In this study, Pseudomonas stutzeri ETL-79 bacterium was used for the decolorization of Reactive Black dye. The highest activity of azoreductase was obtained during the end of log phase. Azoreductase produced intracellularly had the highest specific activity of 0.0334 U/mg compared to the culture supernatant (Extracellular), resting cell and cell debris with low enzyme activity of 0.034 U/mg, 0.010 U/mg and 0.200 U/mg respectively. The optimum assay condition for the maximum azoreductase activity were at 37°C, pH 7, Reactive Black dye concentration of 100 mg/L and NADH concentration of 0.2 Mm by using phosphate buffer as a medium for the enzyme reaction. Alternatively the azoreductase assay was also carried out using ionic liquid that may function to enhance the activity and stability of azoreductase. Results using phosphate buffer (pH-7) showed higher enzyme activity twice that of the ionic liquid besides enhancing the stability of enzyme. Under the optimum assay condition upto 93% of decolorization was achieved after 8h of incubation. In addition, growth of bacteria was also concurrently observed during decolorization of Reactive Black.