Advanced degradation of refractory organic compounds in electroplating wastewater by an in-situ electro-catalytic biological coupling reactor: Removal performance, microbial community and possible mechanism

Regulation of desiccation-immersion cycle on the rate and fate of dissolved organic carbon release by Ulva pertusa

Macroalgae widely distribute in intertidal zones, one of blue carbon organisms. However, the regulatory mechanisms of tide on the carbon sequestration of macroalgae are still unclear. This study explored the effects of desiccation-rewetting cycles induced by tide on dissolved organic carbon (DOC) release from Ulva pertusa, which is prevalent from high to low tidal zones. Results showed that during desiccation stage, the DOC release of U. pertusa varied with desiccation levels, releasing 0.082, 0.22, and 0.35 mg g-1 FW at 0%, 40%, and 80% water loss, respectively, DOC accumulated on the surface of U. pertusa at a rate of about 0.52 mg g-1 FW h-1. Following 4 h of rewetting, DOC released surges to 0.99, 2.51, and 2.10 mg g-1 FW h-1. Using a stable isotope (13C) tracer method, we found that most DOC released by U. pertusa come from early fixed carbon. At 40% water loss, partial DOC stemmed from newly fixed carbon. DOC composition varied with desiccation level, affecting its bioavailability. After 16 days of degradation, DOC concentrations from U. pertusa at 0%, 40%, and 80% desiccation were 1.99, 3.22, and 2.54 mg g-1 FW, respectively. The 80% water loss showed the highest degradation rate, while the non-water-loss treatment group had the most potential to form refractory DOC. This study underlines the complex relationship between tide and the dynamics of DOC release in U. pertusa, highlighting their role in coastal carbon cycling.

Deciphering behaviors of 6:2 chlorinated polyfluorinated ether sulfonate (alternative-PFOS) on anammox processes: Nitrogen removal efficiency and microbial adaptability

This study investigates the behaviors and effects of F-53B, an alternative to perfluorooctane sulfonate on anaerobic ammonium oxidation (anammox) processes. Results showed that the nitrogen removal efficiency (NRE) reached 83.8 % at a F-53B concentration of 0.5 mg·L-1, while NRE decreased to 66.9 % with 5 mg·L-1 of F-53B. The defluorination rates of 17.8 % (0.5 mg·L-1) and 9.3 % (5 mg·L-1) were observed, respectively, suggesting the occurrence of F-53B degradation. The relative abundance of Ca. Kuenenia decreased from 26.1 % to 16.2 % with the F-53B concentration increasing from 0.5 mg·L-1 to 5 mg·L-1. Meanwhile, Denitratisoma was selectively enriched with a relative abundance of 40.7 % at an F-53B concentration of 0.5 mg·L-1. Ca. Kuenenia could reduce reactive oxygen species induced by F-53B to maintain the balance of oxidative stress. This study gains insight into the behaviors and metabolic mechanisms of F-53B in anammox consortia, suggesting the feasibility of anammox processes for industrial wastewater.