Pounsamy Maharaja

This present study investigated the removal of COD and ammoniacal nitrogen (NH₄⁺–N) from tannery deliming wastewater (TDLWW) through microbes immobilized carbon consisted a bioreactor (MICCR) and reactive struvite crystallization process. Initially, 90% of the organic content of TDLWW was removed using a MICCR reactor at 24 h retention time. Nanoporous carbon (NPC) was used as the carrier matrix for the MICCR reactor. SEM and AFM images of NPC used in the MICCR reactor identify different microorganisms on its surface. The microbial profile of NPC used in the MICCR was analyzed, and the relative abundance is phyla Firmicutes, 25.64%; Proteobacteria, 43.68%; Bacteroidetes, 6.58%; Cyanobacteria, 2.22%; Actinobacteria, 2.34% reason for organic removal. The removal of organics follows the pseudo-second-order rate kinetics with the rate constant of 1.75 × 10⁻³ L COD⁻¹ h⁻¹. For the reactive struvite crystallization, MgO and Na₂HPO₄.2H₂O were taken as the precipitating agents. The optimum molar ratio for the maximum conversion of NH₄⁺–N into struvite was obtained as 1:1.4:1.4 (NH₄⁺–N:MgO:Na₂HPO₄.2H₂O). The volume of struvite precipitate was 48.5 mL/L of TDLWW, and the dry weight was 8.89 g/L. More than 93% of NH₄⁺–N was converted as the struvite fertilizer. The conversion of NH₄⁺–N into struvite follows the pseudo-first-order rate kinetics with the rate constant of 1.67 × 10⁻² min⁻¹. Despite the conversion of NH₄⁺–N into struvite, COD removal was observed, which confirms the conversion of organic nitrogen into struvite. The struvite was evaluated using SEM, XRD, TGA, DSC, and FT-IR spectroscopic analysis. Hence, the integrated MICCR and the reactive struvite crystallization process can be applied to manage tannery deliming wastewater.

The present investigation was carried out for the degradation of fatty components in high TDS containing wastewater (soak liquor) discharged from leather industry, and the degradation was achieved by saline-tolerant lipase-immobilized functionalized nanoporous-activated carbon (STLNPAC). The lipase was extracted from the halophilic organism, Bacillus cereus. The optimum conditions for lipase production such as time, 60 h; temperature, 50 °C; pH, 10; and substrate concentration, 2.5% (w/v) were determined through response surface methodology (RSM). The functionalization of NPAC was done by ethylenediamine/glutaraldehyde covalent interaction technique followed by the immobilization of saline-tolerant lipase onto FNPAC. The functional properties of STLNPAC were analyzed through instrumentation techniques such as TGA-DSC, FT-IR, XRD, and SEM images. The lipid content of soak liquor was removed by > 99% at HRT of 60 min using STLNPAC-packed bed reactor. The efficiency was evaluated by using UV-visible and FT-IR spectroscopic analyses. The degradation of lipids was best obeyed by pseudo first-order rate kinetics, and the rate constant was found to be 1.6 × 10⁻³ min⁻¹. The biodegradability index of soak liquor was increased from 0.322 to 0.426, highly favorable for the complete removal of organic components in subsequent operations.

Prodigiosin (PG) is a bioactive compound produced by several bacterial species. Currently, many technologies are being developed for the production of PG by fermentation processes. However, new challenges are being faced with regard to the production of PG in terms of the recovery and purification steps, owing to the labile nature of PG molecules and the cost of the purification steps. Conventional methods have limitations due to high cost, low reusability, and health hazards. Hence, the present investigation was focused on the development of surface-functionalized magnetic iron oxide ([Fe₃O₄]_F) for solvent-free extraction of bioactive PG from the bacterial fermented medium. Fe₃O₄ was functionalized with diethanolamine and characterized by FT-IR, diffuse reflectance spectroscopy, thermogravimetric analysis, scanning electron microscopy, and confocal microscopy. The various process parameters, such as contact time, temperature, pH, and mass of Fe₃O₄, were optimized for the extraction of PG using functionalized Fe₃O₄. Instrumental analyses confirmed that the PG molecules were cross-linked with functional groups on [Fe₃O₄]_F through van der Waals forces of attraction. PG extracted through Fe₃O₄ or [Fe₃O₄]_F was separated from the fermentation medium by applying an external electromagnetic field and regenerated for successive reuse cycles. The purity of the extracted PG was characterized by high-performance liquid chromatography, FT-IR, and UV–visible spectroscopy. The iron oxide–diethanolamine–PG cross-linked ([Fe₃O₄]_F–PG) composite matrix effectively deactivates harmful fouling by cyanobacterial growth in water-treatment plants. The present investigation provides the possibility of solvent-free extraction of bacterial bioactive PG from a fermented medium using functionalized magnetic iron oxide.