The solid removal efficiency of plantago psyllium mucilage with sewage and tannery effluent is shown in Figure 1. It shows the plots of percent removal of SS vs. polysaccharide dose. It is apparent from the plots that with increase in polymer dose, percent removal of SS increases and the optimal dose (at which maximum removal is seen) is 1.2 mg/L in both cases. After a certain polymer dose, decreasing trend in solid removal is seen with further increase in polymer dose. This trend suggests that increase in polymer concentration beyond the optimal dose in suspension causes the aggregated particles to redisperse in the suspension and also disturbs the particle settling [13].
The solid removal efficiency of the mucilage is shown with varying contact time in Figure 2. Figure 2 shows percentage removal of the solid waste from sewage and tannery with contact time at different polymer doses. Maximum solid removal was 66.29% in case of sewage, whereas it was 57.89% in case of tannery effluent samples. The optimal time for the maximum removal was 1 and 5 h for sewage and tannery, respectively. Further increase in contact time also shows a reverse trend in solid removal. The most plausible reason for this trend may be the change in the surface chemistry of effluent with time and due to the destabilization of the aggregated particles after optimal contact duration [14].