Abstract: Textile industries cater to varied customer preferences and contribute substantially to the economy. However, these textile industries also produce a considerable amount of effluents. Prominent among these are the azo dyes which impart considerable color and toxicity even at low concentrations. Azo dyes are also used as coloring agents in food and pharmaceutical industry. Despite their applications, azo dyes are also notorious pollutants and carcinogens. Popular techniques like photo-degradation, biodegradation and the use of oxidizing agents are not applicable for all kinds of dyes, as most of them are stable to these techniques. Chemical coagulation produces a large amount of toxic sludge which is undesirable and is also ineffective towards a number of dyes. Most of the azo dyes are stable to UV-visible light irradiation and may even resist aerobic degradation. Adsorption has been the most preferred technique owing to its less cost, high capacity and process efficiency and the possibility of regenerating and recycling the adsorbent. Adsorption is also most preferred because it may produce high quality of the treated effluent and it is able to remove different kinds of dyes. However, the adsorption process is influenced by many variables whose inter-dependence makes it difficult to identify optimum conditions. The variables include stirring speed, temperature, initial concentration and adsorbent dosage. Further, the internal diffusional resistance inside the adsorbent particle leads to slow uptake of the solute within the adsorbent. Hence, it is necessary to identify optimum conditions that lead to high capacity and uptake rate of these pollutants. In this work, commercially available activated carbon was chosen as the adsorbent owing to its high surface area. A typical azo dye found in textile effluent waters, viz. the monoazo Acid Orange 10 dye (CAS: 1936-15-8) has been chosen as the representative pollutant. Adsorption studies were mainly focused at obtaining equilibrium and kinetic data for the batch adsorption process at different process conditions. Studies were conducted at different stirring speed, temperature, adsorbent dosage and initial dye concentration settings. The Full Factorial Design was the chosen statistical design framework for carrying out the experiments and identifying the important factors and their interactions. The optimum conditions identified from the experimental model were validated with actual experiments at the recommended settings. The equilibrium and kinetic data obtained were fitted to different models and the model parameters were estimated. This gives more details about the nature of adsorption taking place. Critical data required to design batch adsorption systems for removal of Acid Orange 10 dye and identification of factors that critically influence the separation efficiency are the key outcomes from this research.
Abstract: The aim of the present work was to statistically design
an autotrophic medium for maximum biomass production by
Chlorella pyrenoidosa using response surface methodology. After
evaluating one factor at a time approach, K2HPO4, KNO3,
MgSO4.7H2O and NaHCO3 were preferred over the other
components of the fog’s medium as most critical autotrophic medium
components. The study showed that the maximum biomass yield was
achieved while the concentrations of MgSO4.7H2O, K2HPO4, KNO3
and NaHCO3 were 0.409 g/L, 0.24 g/L, 1.033 g/L, and 3.265 g/L,
respectively. The study reported that the biomass productivity of C.
pyrenoidosa improved from 0.14 g/L in defined fog’s medium to 1.40
g/L in modified fog’s medium resulting 10 fold increase. The
biochemical composition biosynthesis of C. pyrenoidosa was altered
using nitrogen limiting stress bringing about 5.23 fold increase in
lipid content than control (cell without stress), as analyzed by FTIR
integration method.
Abstract: In this study, statistical optimization design was used to study the optimum disinfection parameters using defatted crude Moringa oleifera seed extracts against Escherichia coli (E. coli) bacterial cells. The classical one-factor-at-a-time (OFAT) and response surface methodology (RSM) was used. The possible optimum range of dosage, contact time and mixing rate from the OFAT study were 25mg/l to 200mg/l, 30minutes to 240 minutes and 100rpm to 160rpm respectively. Analysis of variance (ANOVA) of the statistical optimization using faced centered central composite design showed that dosage, contact time and mixing rate were highly significant. The optimum disinfection range was 125mg/l, at contact time of 30 minutes with mixing rate of 120 rpm.
Abstract: A statistical optimization of the saccharification
process of EFB was studied. The statistical analysis was done by
applying faced centered central composite design (FCCCD) under
response surface methodology (RSM). In this investigation, EFB
dose, enzyme dose and saccharification period was examined, and the
maximum 53.45% (w/w) yield of reducing sugar was found with 4%
(w/v) of EFB, 10% (v/v) of enzyme after 120 hours of incubation. It
can be calculated that the conversion rate of cellulose content of the
substrate is more than 75% (w/w) which can be considered as a
remarkable achievement. All the variables, linear, quadratic and
interaction coefficient, were found to be highly significant, other than
two coefficients, one quadratic and another interaction coefficient.
The coefficient of determination (R2) is 0.9898 that confirms a
satisfactory data and indicated that approximately 98.98% of the
variability in the dependent variable, saccharification of EFB, could
be explained by this model.
Abstract: A statistical optimization was studied to design a media composition to produce optimum cellulolytic enzyme where palm oil mill effluent (POME) as a basal medium and filamentous fungus, Trichoderma reesei RUT-C30 were used in the liquid state bioconversion(LSB). 2% (w/v) total suspended solid, TSS, of the POME supplemented with 1% (w/v) cellulose, 0.5%(w/v) peptone and 0.02% (v/v) Tween 80 was estimated to produce the optimum CMCase activity of 18.53 U/ml through the statistical analysis followed by the faced centered central composite design(FCCCD). The probability values of cellulose (
Abstract: Enzymatic hydrolysis of starch from natural sources
finds potential application in commercial production of alcoholic
beverage and bioethanol. In this study the effect of starch
concentration, temperature, time and enzyme concentration were
studied and optimized for hydrolysis of Potato starch powder (of
mesh 80/120) into glucose syrup by immobilized (using Sodium
arginate) α-amylase using central composite design. The
experimental result on enzymatic hydrolysis of Potato starch was
subjected to multiple linear regression analysis using MINITAB 14
software. Positive linear effect of starch concentration, enzyme
concentration and time was observed on hydrolysis of Potato starch
by α-amylase. The statistical significance of the model was validated
by F-test for analysis of variance (p ≤ 0.01). The optimum value of
starch concentration, enzyme concentration, temperature, time and
were found to be 6% (w/v), 2% (w/v), 40°C and 80min respectively.
The maximum glucose yield at optimum condition was 2.34 mg/mL.
Abstract: Direct fermentation of 226 white rose tapioca stem to
ethanol by Fusarium oxysporum was studied in a batch reactor.
Fermentation of ethanol can be achieved by sequential pretreatment
using dilute acid and dilute alkali solutions using 100 mesh tapioca
stem particles. The quantitative effects of substrate concentration, pH
and temperature on ethanol concentration were optimized using a full
factorial central composite design experiment. The optimum process
conditions were then obtained using response surface methodology.
The quadratic model indicated that substrate concentration of 33g/l,
pH 5.52 and a temperature of 30.13oC were found to be optimum for
maximum ethanol concentration of 8.64g/l. The predicted optimum
process conditions obtained using response surface methodology was
verified through confirmatory experiments. Leudeking-piret model
was used to study the product formation kinetics for the production
of ethanol and the model parameters were evaluated using
experimental data.
Abstract: Plackett-Burman statistical screening of media
constituents and operational conditions for extracellular lipase
production from isolate Trichoderma viride has been carried out in
submerged fermentation. This statistical design is used in the early
stages of experimentation to screen out unimportant factors from a
large number of possible factors. This design involves screening of
up to 'n-1' variables in just 'n' number of experiments. Regression
coefficients and t-values were calculated by subjecting the
experimental data to statistical analysis using Minitab version 15.
The effects of nine process variables were studied in twelve
experimental trials. Maximum lipase activity of 7.83 μmol /ml /min
was obtained in the 6th trail. Pareto chart illustrates the order of
significance of the variables affecting the lipase production. The
present study concludes that the most significant variables affecting
lipase production were found to be palm oil, yeast extract, K2HPO4,
MgSO4 and CaCl2.