Lactic acid production from cassava mill effluent (CME) using Rhizopus oryzae immobilised in PVA-alginate sulphate beads

Cassava mill effluent (cme) is an effluent originated from tapioca tuber. it is produced by peeling off the skin,cutting and starch extraction. cme contains high concentration of starch,hence when it is disposed directly into the river,it will contribute to water pollution due to its high content of chemical oxygen demand (cod),biological oxygen demand (bod),and total solids (ts). in this study,cme was used as a fermentation medium to produce lactic acid. to improve the yield,spores of rhizopus oryzae were immobilised in pva-alginate-sulphate beads and fermentation was carried out for 6 days. 2-level factorial design was used in the screening of lactic acid production for different parameters; temperature (30°c - 40°c),agitation speed (120-200 rpm),ph (4-7) and beads percentage (5-10% (w/v)). analysis of variance (anova) showed significant influence of the tested factors and their interactions on the production of lactic acid (p<0.0001),except for ph with (p=0.0670). the regression model for lactic acid production fitted the data adequately and explained the variation of more than 99% in the response. the result showed that the maximum production of lactic acid (8.54 g/l) could be achieved at the initial fermentation medium of ph 7.0,temperature of 40°c,percentage of beads of 10% (w/v) and agitation speed of 200 rpm. this study intends to exploit the potential use of cme for the production of lactic acid with the hope of contributing to malaysia’s bioeconomy. © 2015 penerbit utm press. all rights reserved.