Evaluation of modified basalt fiber as biological carrier media for wastewater treatment with the extended DLVO theory model.

In this study, environment-friendly inorganic basalt fiber (BF) was used as bio-carrier for wastewater treatment. To enhance the bio-affinity, raw BF was modified by grafting the diethylamino functional groups to make the surface more hydrophilic and electro-positive. Contact angle and zeta potential of modified basalt fiber (MBF) were characterized. The capacity of MBF bio-carriers was evaluated by microorganism immobilization tests. To explain the mechanism of capacity enhancement by modification, the profiles of total interaction energy barrier between raw BF (or MBF) and bacteria (Escherichia coli, E. coli) were discussed based on the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The results showed the contact angle of fiber decreased from 89.71° to 63.08° after modification, and zeta potential increased from - 18.53 to +10.58 mV. The microorganism immobilization tests showed that the surface modification accelerated the initial bacterial adhesion on fiber. The total interaction energy barrier between MBF and E. coli disappeared as a result of electrostatic and hydrophilic attractive forces, and enhanced the irreversible adhesion. MBF bio-carrier medium provides a promising alternative to conventional bio-carrier materials for wastewater treatment. Graphical abstract.