Controlling methane emissions from Integrated Vertical-Flow Constructed Wetlands by using potassium peroxymonosulfate as oxidant.

It is very important to control methane emissions to reduce global warming. In this study, a new attempt of one oxidant (potassium peroxymonosulfate (PMS)) was made to adjust the oxidation-reduction potential (Eh) by adding different mass of (0 g, 31.25 g, 62.5 g, 125 g, 250 g and 500 g) for the reduction of methane emissions from integrated vertical-flow constructed wetland (IVCW), where the IVCW system has been divided into the root-water system and the stem-leaf system of methane emissions. Results show that the reduced CH4 emission from IVCW was the highest with decreased by 43.5% compared to blank group (PMS = 0), when adding 125 g PMS. Importantly, the reduced CH4 from the root-water system of IVCW was higher than that of the stem-leaf system of IVCW, when adding PMS. It's found that Eh not only has a significant correlation with CH4 flux, but also has a significant relationship between PMS quality, DO, water temperature and sampling time (yEh = -0.44XPMS + 6.82XDO + 0.38t - 264.1, R2 = 0.99). It concludes that PMS, as an oxidant, is a very feasible method for controlling methane emissions from IVCW. It's concluded from this study that it is a feasible engineering method by using PMS as an oxidant for reducing methane emissions from IVCWs when treating artificial domestic sewage. Further research may combine other methods together such as microbiology, physical control and hydrology control for mitigating the CH4 emissions from constructed wetlands for more types of wastewater.

Intermittent micro-aeration control of methane emissions from an integrated vertical-flow constructed wetland during agricultural domestic wastewater treatment.

It is very important to control methane emissions to mitigate global warming. An intermittent micro-aeration control system was used to control methane emissions from an integrated vertical-flow constructed wetland (IVCW) to treat agricultural domestic wastewater pollution in this study. The optimized intermittent micro-aeration conditions were a 20-min aeration time and 340-min non-aeration time, 3.9 m3 h-1 aeration intensity, evenly distributed micro-aeration diffusers at the tank bottom, and an aeration period of every 6 h. Methane flux emission by intermittent micro-aeration was decreased by 60.7% under the optimized conditions. The average oxygen transfer efficiency was 26.73%. The control of CH4 emission from IVCWs was most strongly influenced by the intermittent micro-aeration diffuser distribution, followed by aeration intensity, aeration time, and water depth. Scaling up of IVCWs is feasible in rural areas by using intermittent micro-aeration control as a mitigation measure for methane gas emissions for climate change.