RESUMEN

ABSTRACTThe problem of wastewater pollution in the production of monosodium glutamate (MSG) is becoming more and more serious. A novel type of chemically modified Salix psammophila powder charcoal (SPPCAM) was synthesized to address the chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) in MSG wastewater. SPPCAM was prepared by carbonization method, in which inorganic ammonium molybdate (AM) was used as modifier and Salix psammophila powder (SPP) was used as raw material. Under optimal treatment conditions, maximum removal rates (removal capacities) of 45.9% (3313.2 mg·L-1) for COD and 29.4% (23.2 mg·L-1) for NH3-N in MSG wastewater were achieved. The treatment results significantly outperforming the unmodified Salix psammophila powder charcoal (SPPC), which only achieved removal rates (removal capacities) of 10.6% (763.9 mg·L-1) for COD and 12.9% (10 mg·L-1) for NH3-N. SPPC and SPPCAM before and after preparation were analysed by FT-IR and XRD, and Mo ions in the form of Mo2C within SPPCAM were successfully loaded. SEM, EDS-Mapping, BET, and other methods were used to analyse SPPCAM before and after MSG wastewater treatment, demonstrating that SPPCAM effectively treated organic pollutants in monosodium glutamate wastewater. The NH3-N in the treated MSG wastewater has reached the standard of safe discharge.

RESUMEN

A group of Bacillus sp. was extracted from monosodium glutamate wastewater. Lignocellulose/montmorillonite composite was selected as the carrier. Lignocellulose/montmorillonite composite immobilized Bacillus sp./calcium alginate microspheres were prepared by immobilized microorganism techniques. The microspheres were used to treat monosodium glutamate wastewater with significantly reduced ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) concentrations. The optimum preparation conditions of microspheres in the treatment of NH3-N and COD of monosodium glutamate wastewater were studied. The concentration of sodium alginate was 2.0 wt%, lignocellulose/montmorillonite was 0.06 wt%, Bacillus sp. was 1.0 wt%, CaCl2 solution was 2.0 wt%, coagulation time was 12 h, and the removal capacities of NH3-N and COD were 44832 and 78345 mg/L, respectively. The surface structure, element content, functional group change, and crystal structure of the microspheres were characterized by SEM, EDS, and other methods. The results showed that the -COOH in lignocellulose/montmorillonite and the -OH in the Bacillus sp. form intermolecular hydrogen bonds. The Si-O and Al-O bonds in lignocellulose/montmorillonite reacted with sodium ions in sodium alginate. New crystal structures appear inside the material after crosslinking, and the microspheres was formed. Thus, the study has shown that the microspheres were successfully prepared and contributes to the treatment of NH3-N and COD in monosodium glutamate wastewater. This work can provide an interesting strategy for the removal of COD and NH3-N in industrial wastewater by reasonably combining bio-physicochemical processes.

Asunto(s)

Bacillus , Aguas Residuales , Glutamato de Sodio , Bentonita , Alginatos

RESUMEN

Salix psammophila wood flour /polyvinyl alcohol hydrogel composite membrane (SPPM) with high adsorption capacity and good cycle adsorption performance was prepared by wet spinning technology. The SPPM was characterised by the scanning electron microscope (SEM), specific surface area test (BET), energy dispersive spectrum (EDS) thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectroscopy (XPS). The results showed that the surface of SPPM is rough and porous, with good pore structure and thermal stability, and mercury ions (Hg(II)) have been successfully adsorbed on SPPM. At the same time, the effects of adsorption conditions (Hg(II) initial concentration, pH, adsorption time, and temperature) on the adsorption performance of SPPM were studied. Results from the adsorption experiment showed that the adsorption capacity of SPPM for Hg(II) can reach 426 mg/g. After four adsorption and desorption experiments, the adsorption capacity can reach 375 mg/g, which indicates that SPPM has good cycle adsorption performance. The adsorption kinetics was better described by the Pseudo-second-order kinetic, and their adsorption isotherms were fitted for the Langmuir model. The obtained results showed that SPPM is an available, economical adsorbent and was found suitable for removing Hg(II) from an aqueous solution.

Asunto(s)

Mercurio , Contaminantes Químicos del Agua , Espectroscopía Infrarroja por Transformada de Fourier , Adsorción , Biomasa , Mercurio/química , Temperatura , Cinética , Contaminantes Químicos del Agua/química , Concentración de Iones de Hidrógeno