Water, Vol. 17, Pages 1766: Stability Enhancement of Microalgae–Fungal Pellets

Water doi: 10.3390/w17121766

Authors:
Guang Zhang
Kai Cheng
Hong Mei

Microalgae–fungal pellets (MFPs) effectively degrade pollutants in high-density aquaculture wastewater; however, their structural instability limits their long-term applicability. This study evaluated the effects of three crosslinking agents, sodium alginate (SA), chitosan (CTS), and polyvinyl alcohol (PVA), on enhancing the stability of MFPs. The results demonstrated that the initial 20 g/L SA-crosslinked MFP sample (SMFP0) exhibited significantly improved structural stability, maintaining superior mechanical hardness (57.05 g) after 9 days. Further analysis revealed that SMFP0 exhibited a more negative absolute Zeta potential (−13.05 mV), increased fluorescence intensity (0.020) in its tightly bound extracellular polymeric substances (TB-EPSs), and significantly higher protein (PN, 64.22 mg/L) and polysaccharide (PS, 56.99 mg/L) concentrations compared with the control (p < 0.05). These findings suggest that SMFP0 possesses physicochemical properties that are conducive to microalgae–fungal aggregation. A scanning electron microscopy (SEM) analysis confirmed that the SA gel network enhanced the system’s stability by strengthening the microalgae–fungal interfacial adhesion and maintaining a porous, light-permeable structure. In practical wastewater treatment, SMFP0 achieved superior removal rates for COD (84.19%), ammonia nitrogen (95.29%), total nitrogen (89.50%), and total phosphorus (93.46%) compared with non-crosslinked MFPs (p < 0.05). After 9 days of continuous operation (SMFP9), the pollutant removal efficiencies remained comparable to those observed in the initial stage of the non-crosslinked system, indicating improved structural durability for extended practical application.

Source link

Guang Zhang www.mdpi.com