Sustainable modulation of anaerobic malodorous black water: The interactive effect of oxygen-loaded porous material and submerged macrophyte

Depleted oxygen (O2) in the sediment and overlying water of malodorous black water poses a potential threat to aquatic ecosystems. This study presents a method for sustainable regulation of the dissolved oxygen (DO) levels towards the malodorous black water. Oxygen-loaded natural porous materials were prepared by vacuum degassing to remove air from the pores and fill them with pure O2. Capping anaerobic sediment with the prepared 6 oxygen-loaded porous materials was effective in prompting the DO concentration of the malodorous black water. Although granules activated carbon (GAC) displayed the highest oxygen-loading capability, oxygen-loaded volcanic stone additive was more efficient for long-lasting combating of the anaerobic condition because the DO level at sediment-water interface (SWI) and the DO penetration depth showed approximately 5.38- and 3.75-fold increase, respectively, compared with the untreated systems. The improvement in DO was substantially enhanced in the presence of submerged macrophyte (Vallisneria natans), during which the release of O2 from oxygen-loaded volcanic stone facilitated the plant growth. With the joint efforts of the O2 released from volcanic stone and photosynthesis by the macrophytes, the DO levels were maintained at approximately 6.80 mg/L after a 41-day incubation, which exceeded (P