Characterization of Cypermethrin-degradation by a Novel Molybdenum-reducing Morganella sp. Isolated from Active Agricultural Land in Northwestern Nigeria

The increasing use of cypermethrin in agricultural fields, household and industrial applications for effective pest control had increased the global burden of the pollutant over the years. Consequently, there is an urgent need to devise techniques to eliminate this pollutant from the environment. A bacterium capable of degrading cypermethrin has been successfully screened and characterized. The bacterium was grown in a mineral salt medium (MSM) supplemented with cypermethrin as its sole carbon and energy source at an optimum pH 7.5, temperature 40 ºC, a carbon source concentration of 4 g/L, optimum incubation time of 24 h and an inoculum size of 400 µL. The potential of Morganella sp. to degrade cypermethrin makes it an important instrument for the degradation of cypermethrin. This knowledge may be useful for the optimization of environmental conditions for cypermethrin bioremediation and important for detoxification of cypermethrin polluted sites.

OPTIMIZACIÓN DE LA PRODUCCIÓN DE BIOMASAS DE Kluyveromyces marxianus EN LACTOSUERO

Whey is a by-product of cheese making and represents a danger of environmental contamination when discarded without prior treatment. However, due to its high content of lactose, vitamins and proteins, whey should not be considered a waste, but rather a raw material for obtaining value-added products. Among the alternatives for its use, biomass production stands out through fermentation with Kluyveromyces marxianus. Therefore, this work determines the best operating conditions for biomass production, minimizing residual lactose. To this end, a Doehlert Experimental Matrix Design was used to optimize the effects of aeration and nitrogen source concentration on the growth of K. marxianus by a minimum number of experiments. The results obtained allow maximizing the biomass production, the consumption of lactose and protein by K. marxianus, thus achieving a more effective treatment of whey prior to its discard.

Analysis of Factors for Compacted Clay Liner Performance Considering Isothermal Adsorption

The concentration profiles and breakthrough curves of the 2 m thick compacted clay liner (CCL) given in the specification were compared, considering three different adsorption isotherms (upper convex, linear, and lower concave). In addition, the effects of transport parameters, sorption isotherms, and source concentrations on pollutant migration were analyzed. The results showed that the dimensionless breakthrough curves of different source concentrations considering the linear adsorption isotherm coincided with each other, as the partition coefficient of the linear adsorption isotherm was constant. For the lower concave isotherm, the migration of a large source concentration was slowest, because the partition coefficient of the lower concave isotherm increased with an increase in concentration. For the upper convex isotherm, the migration of a large source concentration was fastest, because the partition coefficient decreased with an increase in concentration. The effects of the nonlinear isotherms on the shape of the outflow curve were similar to the effects of a change in the hydrodynamic dispersion (Dh): the concentration front of the upper convex isotherm was narrower, which was similar to the effect of a reduction in Dh (i.e., PL), and the concentration front of the lower concave isotherm was wider and similar to the effect of an increase Dh (i.e., PL). Therefore, the diffusion and adsorption parameters were fitted separately in the study, in case the nonlinear adsorption behavior was mistakenly defined as linear adsorption.

Optimisation of Lactic Acid Fermentation from Cassava Peel by Lactobacillus casei (ATCC334)

The demand for lactic acid is steadily increasing due to the desire of its bioproduction over chemical synthesis. The associated cost, however, is a significant hurdle. This study reports lactic acid fermentation by Lactobacillus casei ATCC334 from cassava peel. It investigates the effect of unhydrolysed cassava peels, acidic, alkali hydrolysates; fermenting pH; substrate concentration; nitrogen source concentration; duration; and inoculum size. An attempt at a cheaper purification and recovery protocol relative to those currently in use was similarly performed. Acidic hydrolysate yielded 10.53%, unhydrolysed substrate gave 4.80% with alkali hydrolysate yielding 4.75%. The highest LA yield was obtained at pH 6.0, 2.0% v/v inoculum size, 25% w/v substrate concentration, 5% nitrogen source concentration. A post-optimisation combination yielded 18.3% LA suggesting that one-factor-at-a-time may be unsuitable for optimisation studies involving cassava peel and L. casei ATCC334. FTIR spectra of product suggests effective partial purification. Hence, an improvement in the optimization strategy for production is recommended for subsequent study.

HEAT SOURCE FOR TIG WELDING MODELLING

A new model of heat source applicable to TIG welding is proposed. The model uses three calibration parameters - efficiency, effective heating spot radius and heat source concentration factor. Based on the experimental results, the model was calibrated and the results obtained for the form of penetration were compared with the experimental ones.

Enhancing the compost maturation of swine manure and rice straw by applying bioaugmentation

Microorganisms capable of decomposing cellulose, xylan, starch and protein were individually isolated from swine manure compost and soil in this study. The correlations with pH, carbon source concentration, C/N ratio and enzyme activity among these isolated microorganisms were also investigated. Furthermore, the effect of additional inoculation in the compost was studied by measuring variations in the C/N ratio, enzyme activity and compost maturation rate. The inoculated microorganisms used in this study included four bacterial isolates and one commercial microorganism Phanerochaete chrysosporium. The results indicated that the isolated Kitasatospora phosalacinea strain C1, which is a cellulose-degraded microorganism, presented the highest enzyme activity at 31 ℃ and pH 5.5, while the C/N ratio was 0.8%. The isolated xylan-degraded microorganism Paenibacillus glycanilyticus X1 had the highest enzyme activity at 45 ℃ and pH 7.5, while the C/N ratio was 0.5%. The starch-degraded microorganism was identified as Bacillus licheniformis S3, and its highest enzyme activities were estimated to be 31 ℃ and pH 7.5 while the C/N ratio was 0.8%. The highest enzyme activity of the protein-degraded microorganism Brevinacillus agri E4 was obtained at 45 ℃ and pH 8.5, while the C/N ratio was 1.0%. The rate of temperature increase in the compost inoculated with P. chrysosporium was only higher than that of the compost without inoculation, and its compost maturation level was also lower than that of other composts with additional inoculation. The optimal initial C/N ratio of the compost was 27.5 and the final C/N ratio was 18.9. The composting results also indicated that the secondary inoculation would benefit compost maturation, and the lowest final C/N ratio of 17.0 was obtained.