Tapping into the ballast potential of sparingly soluble salts for enhanced floc physiognomies in algae biomass harvesting

Enhanced floc settling rates and reduced biomass volume were achieved when sparingly soluble salts of magnesium were used as ballast agent in the pH induced algae biomass harvesting operation. The floc characteristics of biomass harvested from non-ballasted pH induced system were compared with that of pH induced ballasted system that contained soluble (MgCl2) and sparingly soluble salts (i.e., Mg(OH)2 and Mg(OH)2 nanoparticles (NMg(OH)2)). The pH value for onset of coagulation was lower in soluble salt system (pH = 10.2) than in the sparingly soluble salt (pH = 11.4). The floc generated from the ballasted NMg(OH)2 system had the highest sedimentation rate (K (L/mol/s) = 1.0454), while that of the non-ballasted pH induced system had the lowest rate (K (L/mol/s) = 0.2155). The ballast agent enhanced the sludge volume index of the biomass by 66.04% and had no negative impact on the filterability. The values of the the specific cake resistance (α (m/kg)) and the resistance of the filter medium (Rm (1/m)) were within the same range. Both the growing and harvested biomass exhibited good strength and recovery factor (>90%). The evaluation of the effects of the ballast agents on the biomass viability showed that the ballast agent was not toxic to the harvested biomass

Intercalation of Gastropod Shell Derived Calcium Oxide in Clay and Application in Phosphate Removal from Aqua Medium

The phosphate sorption potential of the layered framework of naturally occurring clay, which acts as a host in the sorption process, was boosted via intercalation of CaO derived from a Gastropod shell (GS). GS was used as precursor for the synthesis of the CaO in the perspective of waste recycling and cost minimization in environmental remediation. The phosphate sorption potential, PZC, and the surface area of raw clay sample were substantially enhanced by the intercalation process. The value of the Langmuir monolayer sorption capacity (<i>q</i>_m mg/g) increased from 49.02 to 71.43, PZC values increased from 4.70 to 7.20, and the surface area (m²/g) value increased from 23 to 103 after the intercalation process. The modification caused no change in the clay surficial microstructure but increased the lattice spacing of the clay framework. Increase in phosphate solution pH triggered monotonical reduction in the magnitude of phosphate sorbed while increase in phosphate solution ionic strength and concentration of anionic interferences caused an increase in the amount of phosphate sorbed per gram of sorbent. Phosphate sorption caused no change in the surficial microstructure of either sorbents but the crystallinity of the sorbent was considerably impacted, especially in the raw sampl

Adsorption of methylene blue dye from aqueous solution by novel biomass Eucalyptus sheathiana bark: equilibrium, kinetics, thermodynamics and mechanism

This study was undertaken to evaluate the adsorption potential of a naturally available, cost-effective, raw eucalyptus bark (EB) (Eucalyptus sheathiana) biomass, to remove organic methylene blue (MB) dye from its aqueous solutions. Effects of various process parameters such as initial dye concentration, adsorbent loading, solution pH, temperature, presence of salts, mixture of dyes and surfactant onto MB dye adsorption by bark material were studied. Significant effect on adsorption was witnessed on varying the pH of the MB solutions. Results showed that the optimum pH lies between 7.4 and 10.0. The extent (%) of MB adsorption from aqueous solution decreased with the increase in the initial MB dye concentration, but increased with rise in temperature. The extent of MB dye adsorption was found to be enhanced due to increase of salts concentration. This is because of salting-out-effect, which comprises the changes of various short range forces.The overall kinetic studies showed that the MB dye adsorption by EB biomass followed pseudo-second-order kinetics. The mechanism of MB dye adsorption was analysed by intra-particle diffusion model and desorption study. Free energy change of adsorption (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were calculated to predict the nature of adsorption. The Langmuir adsorption isotherm model yields a better correlation coefficient than the Freundlich model and the dimensionless separation factor “RL” indicated favourable adsorption process. The maximum Langmuir monolayer adsorption capacity of raw EB for MB dye was found to be 204.08 mg/g at 30°C. A single-stage batch adsorber design for MB dye adsorption onto EB biomass has been presented based on the Langmuir isotherm model equation. The results obtained in this study suggest a promising future for inexpensive raw EB biomass as a novel adsorbent and a better alternative to activated carbon adsorbent used for the removal of MB dye from dye bearing effluents