1% and the highest was 2.0%, with an interval of 0.5%. The measurement of flocculating activity was in the same manner as described flocculation assay Section 2.2.2.6. Data AnalysisTreatments used for each experiment were done in minimum of three to four replicates with mean especially and standard deviation values determined. Significant differences were analyzed through analysis of variance (ANOVA), where differences were considered significant at 0.05 confidence level. Prior to the ANOVA test, all data were checked for normally distribution and verified for homogeneity of variances using Levene’s test as the basic assumptions for ANOVA. Multiple comparison post-hoc tests, namely, the least significant difference test (LSD) and Games-Howell test were used as the basis for determination of the highest flocculating activity achieved in each assay; for cases of equality of variances assumed or not assumed, respectively.
3. Results and Discussion3.1. Cation Dependency of the Bioflocculant Produced by UPMB13Effect of different sources of cation on flocculating activity of bioflocculant produced by UPMB13 was evaluated and is depicted in Figure 1. Flocculating activity of UPMB13 bioflocculant on kaolin suspension was significantly affected with the addition of cations. Synergistic effects were observed with the addition of Na+, Ca2+, and Mg2+ while the addition of Al3+ and Fe2+ leads to a decrease in flocculating activity both in terms of optical density percentage and observation of flocs formation. Figure 1The effect of monovalent, divalent, and trivalent cations on the flocculating activity of bioflocculant produced by Bacillus spp.
UPMB13. (+) Biofloc treatment act as control for comparison with the other cation treatments.The principle of cation addition in bioflocculation is basically for the purpose of charge destabilization of negative repulsion charges of the suspended particles and the residual charge of functional groups of the bioflocculant [14]. This is true according to the study by Salehizadeh and Shojaosadati [19], whereby the cations used decrease the negative electrical charge of kaolin particles and the biopolymer flocculant. Cation acts as a coagulant which neutralizes the zeta potential in the kaolin suspension allowing the suspended kaolin particles to be attracted and bind together before the bridging mechanism of the bioflocculant occurs.
Addition of monovalent cation, namely, Na+ has a slight synergistic effect of about 8% on flocculating activity. Monovalent cations produce bonds that are loose in structure Carfilzomib and, therefore, result in a decrease in floc density, size, and floc resistency to shear compared to divalent cations [9].Al3+ acts as a trivalent cation source. From the result, the flocculating activity based on optical density for the treatment with the addition of Al3+ is 62.5% indicating that the upper phase of the kaolin suspension is quite clear.