Abstract
In this study, the potential to fully exploit sewage sludge as a raw material for bio ethanol a
source of bio
fuel is investigated. Sewage sludge hydrolysate was first made by introducing Bacillus flexus in
order for saccharification to take place before fermenting to bio ethanol using yeast. The
hydrolysate was then prepared for fermentation by introducing 10 g/L of peptone, 2 g/L of KH2PO4
and 1 g/L of MgSO4. Af- terwards, fermentation was allowed to take place at varying pH (4.0e7.0),
temperature (15e45 o C), in-
cubation time (10e70 h) and yeast concentrations (2e10% (v/v). Bio ethanol concentrations were
characterized through spectrophotometry and its physicochemical properties analyzed by standard
methods. Pearson Correlations Coefficients in MATLAB 13.0 were used to determine the coefficients of
interaction between the various parameters in bio ethanol production at 95% confidence interval.
Highest bio ethanol yields of greater than 40 mL/L were achieved at an incubation period of 10
days, with an operating temperature of 30 o C and pH of 6.5 with yeast concentration of 6% wt. The
interactions between incubation temperature and pH had the best interaction coefficient of 0.9759
being achieved for optimal bio ethanol yield. The bio ethanol produced had a flash point of 19.2 o
C, pour point of 4.9 o C, cloud point of 20 o C and viscosity of 1.30 cP.