Optimization of ethanol production from spent tea waste by Saccharomyces cerevisiae using statistical experimental designs

Abstract

The aim of this study was to investigate the prospect for the use of spent tea waste (STW), an important municipal waste, as a potential substrate to generate hydrolysates for fuel ethanol production. Acid pretreated STW was used as substrate for ethanol production. The critical variables that affected ethanol fermentation from STW were identified by Plackett-Burman designs and further optimized by using a five-level-three-factor central composite design of response surface methodology. The optimum conditions for ethanol fermentation were determined to be NH 4 Cl concentration of 2.7 g/L, yeast concentration of 11.7 g/L, and temperature of 42.8°C. Maximum concentration of reducing sugar and ethanol under the optimum conditions were 28.90 g reducing sugar/L and 12.72 g EtOH/L, respectively. Predicted ethanol concentration was obtained using quadratic polynomial equation. The predicted ethanol concentration was 13.38 g EtOH/L in the optimal conditions. Validity of the predicted model was confirmed using verification experiment (12.72 g EtOH/L).

Optimization and Modelling of Process Conditions Using Response Surface Methodology (RSM) for Enzymatic Saccharification of Spent Tea Waste (STW)

“…Total hydrolysate was centrifuged at 5000 rpm for 10 min and then the concentration of reducing sugar was determined by Miller's method [17]. We have optimized the ethanol production from spent tea waste in our previous study [16]. The fermentation conditions (NH 4 Cl concentration, yeast concentration and fermentation temperature) were changed between 0.3 and 3.7 g/L for NH 4 Cl concentration, between 3.3 and 11.7 g/L for yeast concentration, between 27 and 43°C for fermentation temperature.…”

“…Also were determined the optimum conditions for ethanol fermentation to be NH 4 Cl concentration of 2.7 g/L, yeast concentration of 11.7 g/L, and temperature of 42.8°C. Therefore we selected the fermentation conditions according to results of our previous study [16]. Fermentation experiments for ethanol production were conducted in 250 mL flasks with a working volume of 100 mL.…”

“…The fermentation medium contained yeast, NH 4 Cl, KH 2 PO 4 , 1 g/L; and MgSO 4 Á7H 2 O, 0.3 g/L. To determine ethanol concentration, aqueous phase samples were centrifuged at 5000 rpm for 10 min and then analyzed by gas chromatography [16].…”

“…Response surface methodology (RSM) is a statistical approach to design experiments, to build models, to evaluate the effects of many factors and to find the optimal conditions for desirable responses and to reduce the number of required experiments [10][11][12][13][14][15]. Also, we have successfully used RSM to optimize of ethanol production conditions in our previous study [16]. Literature survey reveals that there is no report on optimization of enzymatic saccharification of spent tea waste by chemometric approach.…”

Bioethanol Production from the Raw Corn Starch and Food Waste Employing Simultaneous Saccharification and Fermentation Approach

“…Around 60 % of the total ethanol is produced by fermentation [5]. Research and development efforts aimed at commercial production of ethanol by fermentation from renewable resources such as crop residues and biomass waste [6][7][8][9][10][11], municipal solid wastes (MSW) [12][13][14][15][16], municipal sludge [17], and dairy/cattle manures [18] have increased.…”