Algal-mediated nitrogen removal and sustainability of algal-derived dissolved organic matter supporting denitrification.

Algae-mediated nitrogen removal from low carbon vs. nitrogen (C/N) wastewater techniques has garnered significant attention due to its superior autotrophic assimilation properties. This study investigated the ammonium-N removal potential of four algae species from low C/N synthetic wastewater. Results showed that 95 % and 99 % of ammonium-N are eliminated at initial concentrations of 11.05 ±â€¯0.98 mg/L and 42.51 ±â€¯2.20 mg/L with little nitrate and nitrite accumulation. The compositions of secreted algal-derived dissolved organic matter varied as C/N decreased and showed better bioavailability for nitrate-N removal by Pseudomonas sp. SZF15 without pre-oxidation, achieving an efficiency of 99 %. High-throughput sequencing revealed that the aquatic microbial communities, dominated by Scenedesmus, Kalenjinia, and Micractinium, remain relatively stable across different C/N, aligning with the underlying metabolic pathways. These findings may provide valuable insights into the sustainable elimination of multiple nitrogen contaminants from low C/N wastewater.

Insights into the proton-enhanced mechanism of hexavalent chromium removal by amine polymers in strong acid wastewater: Reduction of hexavalent chromium and sequestration of trivalent chromium.

Adsorption is a green technology of treating heavy metal-contaminated strong acid wastewaters for the recycling of heavy metal and reuse of strong acid. Herein, three amine polymers (APs) with different alkalinities and electron donating abilities were prepared to investigate the adsorption-reduction processes of Cr(VI). It was found that the removal of Cr(VI) was controlled by the concentration of -NRH+ on the surface of APs at pH > 2, which relies on the alkalinity of APs. However, the high concentration of NRH+ significantly facilitated the adsorption of Cr(VI) on the surface of APs and accelerated the mass transfer between Cr(VI) and APs at strong acid environment (pH ≤ 2). More importantly, the reduction of Cr(VI) was enhanced at pH ≤ 2, due to the high reduction potential of Cr(VI) (E ≥ 0.437). The ratio of reduction to adsorption (α) of Cr(VI) was above 0.70, and the proportion of Cr(III) bonding on Ph-AP excessed 67.6 %. Finally, a proton-enhanced mechanism of Cr(VI) removal was verified by analyzing FTIR and XPS spectra as well as constructing DFT model. This study provides a theoretical basis for the removal of Cr(VI) in the strong acid wastewater.

Phosphorus biorecovery from wastewater contaminated with multiple nitrogen species by a bacterial consortium.

Recovering finite and non-substitutable phosphorus from liquid waste streams through bio-mediated techniques has attracted increasing interest, but current approaches are incredibly dependent on ammonium. Herein, a process to recover phosphorus from wastewater under multiple nitrogen species conditions was developed. This study compared the effects of nitrogen species on the recovery of phosphorus resources by a bacterial consortium. It found that the consortium could not only efficiently utilize ammonium to enable phosphorus recovery but also utilize nitrate via dissimilatory nitrate reduction to ammonium (DNRA) to recover phosphorus. The characteristics of the generated phosphorus-bearing minerals, including magnesium phosphate and struvite, were evaluated. Furthermore, nitrogen loading positively influenced the stability of the bacterial community structure. The genus Acinetobacter was dominant under nitrate and ammonium conditions, with a relatively stable abundance of 89.01% and 88.54%, respectively. The finding may provide new insights into nutrient biorecovery from phosphorus-containing wastewater contaminated with multiple nitrogen species.

Characterization and biocompatibility of injectable microspheres-loaded hydrogel for methotrexate delivery.

Injectable thermosensitive hydrogels have widely been studied as drug delivery systems for their minimally invasive administration and localized drug release. However, burst drug release limits clinical applications of such hydrogels. A double-component injectable formulation (microspheres-loaded hydrogel, CMs-CS-HG) was thus fabricated to eliminate the limitation. Gelation temperature, gelation time, complex viscosity and syringeability tests for CMs-CS-HG demonstrated excellent injectability. After injection, the drug-loaded chitosan-based microspheres (CMs) were localized within the hydrogel, leading to localized drug release. Moreover, CMs-CS-HG had good hemocompatibility and histocompatibility, and had non-genotoxicity and non-cytotoxicity to Kunming mice. In addition, both in vitro and in vivo methotrexate (MTX) releasing efficiencies were evaluated, demonstrating long-term sustained MTX release from MTX-loaded CMs-CS-HG. These results showed the double-component CMs-CS-HG not only maintained good injectability and biocompatibility but also prolonged drug-releasing time in comparison with the single-component CS-HG or CMs, suggesting that CMs-CS-HG may be a promising drug delivery system.