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In this study, we evaluated the photosynthetic performance of Zanthoxylum armatum seedlings to test the tolerance to reoxygenation after waterlogging. The experiment included a control group without waterlogging (NW) and three reoxygenation groups with reoxygenation after 1 day (WR1), 2 days (WR2) and 3 days (WR3). Seedlings were pretreated with concentrations of 0, 200 and 400 μmol L−1 of ethylene. The results showed that reoxygenation after waterlogging for 1–3 days decreased photosynthetic pigments content, enzymes activity, stomatal conductance (G s), net photosynthetic rate (P n), transpiration rate (T r) and water-use efficiency (WUE). However, pretreatment with ethylene increased photosynthetic pigments content, enzymes activity and gas exchange parameters under both NW and WR3 treatments. The chlorophyll fluorescence results showed that the maximum quantum yield of PSII (F v/ F m) and actual photochemical efficiency of PSII (Φ PSII) remained no significant changes under the NW and WR1 treatments, while they were significantly reduced with an increase in waterlogging days followed by reoxygenation under WR2 and WR3 treatments. Exogenous ethylene inhibited F v/ F m and the non-photochemical quenching coefficient (NPQ), while enhanced Φ PSII and electron transfer efficiency (ETR) under WR2 treatments. Moreover, the accumulation of exogenous ethylene reduced photosynthetic ability. These findings provide insights into the role of ethylene in enhancing the tolerance of Z. armatum to reoxygenation stress, which could help mitigate the impact of continued climate change. This study evaluated the effects of ethylene pretreatment on the photosynthetic performance and tolerance of Zanthoxylum armatum seedlings to post-waterlogging reoxygenation stress. The results showed that reoxygenation stress decreased photosynthetic pigments content and enzymes activity, gas exchange parameters and chlorophyll fluorescence. However, ethylene pretreatment increased above indicators to enhance the tolerance to reoxygenation stress. These findings suggest that ethylene could be used to mitigate the impact of continued climate change on plant growth and development. [ABSTRACT FROM AUTHOR]

Anaerobic and aerobic treatment of high-strength pharmaceutical wastewater was evaluated in this study. A batch test was performed to study the biodegradability of the wastewater, and the result indicated that a combination anaerobic-aerobic treatment system was effective in removing organic matter from the high-strength pharmaceutical wastewater. Based on the batch test, a pilot-scale system composed of an anaerobic baffled reactor followed by a biofilm airlift suspension reactor was designed. At a stable operational period, effluent chemical oxygen demand (COD) from the anaerobic baffled reactor ranged from 1,432 to 2,397 mg/L at a hydraulic retention time (HRT) of 1.25 day, and 979 to 1,749 mg/L at an HRT of 2.5 day, respectively, when influent COD ranged from 9,736 to 19,862 mg/L. As a result, effluent COD of the biofilm airlift suspension reactor varied between 256 and 355 mg/L at HRTs of from 5.0 to 12.5 h. The antibiotics ampicillin and aureomycin, with influent concentrations of 3.2 and 1.0 mg/L, respectively, could be partially degraded in the anaerobic baffled reactor: ampicillin and aureomycin removal efficiencies were 16.4 and 25.9% with an HRT of 1.25 day, and 42.1 and 31.3% with HRT of 2.5 day, respectively. Although effective in COD removal, the biofilm airlift suspension reactor did not display significant antibiotic removal, and the removal efficiencies of the two antibiotics were less than 10%. CE Database subject headings: Industrial Wastes; Wastewater management; Biofilm; Biodegradation; Biological treatment; Aerobic treatment.