Effect of wetting cycles on nitrogen removal in wetlands
Sahu, Pradip Kumar
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Nitrogen removal efficiency is one of the major focuses in the application of animal wastewater to wetland systems. Nitrification and denitrification are the two major nitrogen transformation processes that require aerobic and anaerobic conditions respectively, for maximum transformation rates. Providing aerobic and anaerobic conditions alternatively would help maximize the nitrogen transformation and hence removal from wetlands. The frequency of keeping the wetland system dry (primarily aerobic) and wet (primarily anaerobic) becomes a critical aspect in maximizing nitrogen removal. Using a commercial nitrogen source resulted in 50% TN removal for 1:1 (weeks) hydroperiod (wet:dry) that was significantly different (p<0.05) from the 25% removal when continuously loaded. The ammonia-nitrogen percentage removal in the same case was 50% for a 1:1 hydroperiod as compared to 32% when continuously loaded. The average TKN accumulated in the cattails biomass was 50%) more in hydroperiod ratio of 1:1 compared to when continuously wetted. Therefore, if maximum nitrogen removal is designed from a wetland system treating wastewater, installing a unit that is two times larger and operated with a wetting and drying cycle of 1:1 week would be more beneficial as compared to a continuously wet system. Another advantage is that the wetland plants could easily be harvested and used for beneficial purposes, such as an animal feed.