Intermittent aeration incubation of drinking water treatment residuals for recycling in aquatic environment remediation

Abstract

Abstract Recycling of drinking water treatment residuals (DWTRs) in aquatic environment remediation can provide numerous benefits. The hazardous effect of DWTR metals on the environment is shown to be limited; however, DWTR may release excessive nitrogen and organic matter, hindering recycling in the aquatic environment. To eliminate any potential unfavorable effect, self-purification via intermittent aeration incubation for DWTRs was developed. Results indicated that after approximately 5–6 months of incubation, the easily released nitrogen and organic matter in the DWTRs were mostly removed. The removed nitrogen was found to mainly consist of ammonium nitrogen from inorganic and organic nitrogen groups in the DWTRs. The removed organic matter consisted mainly of humic-like substances associated with the carboxyl group, distributed on the surface of the DWTRs. Biological mechanisms for effective nitrogen and organic matter removal were further explored based on the analysis of bacterial community structure, which indicated that the dominant bacteria genera (e.g., Geothrix, Methylotenera, and Geobacter) in the DWTRs after incubation were closely related to nitrogen and carbon cycles. In addition, the phosphorus adsorption of the DWTRs after incubation was maintained, and the specific surface area, total pore volume, microporosity, and mesoporosity of the DWTRs after incubation tended to increase because of organic matter removal. Accordingly, intermittent aeration not only addressed the concerns caused by potential excessive release of nutrients from DWTRs but also enhanced the favorable effect of DWTRs on biogeochemical cycles. Self-purification can potentially promote the beneficial recycling of DWTRs in the aquatic environment.