Ekambaram Nakkeeran

Worldwide climate change, rising population, and industrialization have raised the global demand for freshwater. Desalinating brackish water has become a sustainable technology for drinking and agriculture to overcome global water scarcity. Thriving biodesalination technology has become more attractive and eco‐friendly than the present physicochemical desalination methods, which are expensive and energy‐intensive. Researchers are exploring the bioutilization of nature's potential for desalination using halophiles like haloarchaea, halobacteria, halophytic algae, and plants. Biomimetic desalination membranes have been developed, inspired by the desalination mechanism in animals. This comprehensive review explores recent advancements and potential applications of halophiles in biodesalination to exploit them effectively. It provides an overview of the opportunities and challenges associated with harnessing halophiles for the removal of salts from brackish and seawater sources. This review also focuses on insights into biomolecules produced by the halophilic microorganisms and halophytes in the desalination process. Understanding the mechanism of action of these biomolecules will edify the effective unexplored research areas in biomimicry and bioutilization to overcome the existing limitations in water treatment.

The interest in pullulan produced from industrial wastes has substantially increased due to its industrial applications. The major constraint in pullulan production is expensive and low yield. In this study, attempts were made on the evaluation of media components for maximum pullulan production from Aureobasidium pullulans MTCC 1991 using cassava waste in solid-state fermentation. A statistical approach was scrutinized to evaluate the effects of yeast extract, K₂HPO₄, (NH₄)₂SO₄, MgSO₄⋅7H₂O, and NaCl on pullulan production. The optimal conditions eliciting the maximum pullulan yield (6.45 g pullulan/L of culture broth) were found to be 0.6 g/L yeast extract, 3 g/L K₂HPO₄, 0.2 g/L (NH₄)₂SO₄, 0.3 g/L MgSO₄⋅7H₂O, and 1 g/L NaCl. The produced pullulan was extracted using the solvent precipitation method and characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy spectroscopic analysis that confirmed pullulan with linear α (1–6) linkage. The results revealed that cassava waste could be used as an effective carbon source for the production of pullulan.

Background: Forward osmosis is a sustainable membrane process employed for concentrating thermo-sensitive compounds to minimize storage and transportation costs with improved shelf life. Objective: In this study, the intervention of high molecular weight osmotic agents in the concentration of Opuntia betacyanin using forward osmosis was studied. Furthermore, the statistical model was used to estimate the probabilistic behavior of the forward osmosis process during concentration. Method: By using 2k-full factor analysis, the hydrodynamic variables, such as flow rate (50 and 150 mL/min) and temperature (20 and 50ºC) of the feed solution and osmotic agent solution (OAS) were selected. The study focused on inquiring and developing a statistically significant mathematical model using four independent variables on transmembrane flux, concentration factor and concentrate recovery. Results: Betacyanin feed flow rate of 50 mL/min at 28ºC, and OAS flow rate of 150 mL/min at 50ºC were determined as optimal conditions with a 2.5-fold increase in total soluble solids for a processing time of 4 h. Furthermore, forward osmosis enhanced the betacyanin concentration from 898 to 1004 mg/L and 98.7% recovery with 0.40 L/m2h transmembrane flux with comparable improvement in its physicochemical characteristics. The lower p-value of the main effects on the responses validated the significance of the process parameters on betacyanin concentration. Conclusion: The study suggested that a high molecular weight sucrose could be used as an osmotic agent for the concentration of Opuntia betacyanin during forward osmosis.

The idea of eliminating noxious metal ions from electronic waste contaminated water has led to the use of the metal adsorbing ability of biological matter. The principle of an ion exchanger of biological origin is the key in exhibiting this metal binding feature of microbial biomass. In this study, dead biomass of Aspergillus carbonarius was immobilized using sodium alginate and tested as a biosorbent for hexavalent chromium elimination from effluent. Size and functional groups were characterized for the immobilized bead containing biomass. Optimization of boundary variables like bead size, biosorbent dosage, contact time, pH, and temperature were performed. Maximum elimination of 92.43% hexavalent chromium was achieved at pH 2.0 for 12 h at 37°C, with 20 g/25 mL adsorbent dosage. On application of adsorption isotherms, the data were found to fit Freundlich isotherm and exhibited a high value of correlation coefficient proving the ability of A. carbonarius biomass to act as an effective quencher of hexavalent chromium from electronic waste contaminated water. Graphical Abstract