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2 Journal of Ecological Engineering

2 2022

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Improving Wastewater Reclamation Using Constructed Wetlands by Artificial Plastic Biofilm Carriers

Zaboon Baneen Hussein, Al-Abbawy Dunya A. H., Yaseen Dina A.

Journal of Ecological Engineering

2022

Vol. 23, nr 11

241--253

Increasing the demand for potable water, followed by the high quantity of discharged effluents linked with the water scarcity problems has necessitated giving more attention to improving wastewater treatment processes and operations. The constructed wetland has proven to be an excellent green sustainable technique for purification. This study aimed to examine the performance of four experimental free water surface constructed wetlands (FWSCWs) for the depuration of sewage effluents as a secondary treatment stage during winter season conditions. The objectives were to assess the raw and treated wastewater concentrations, evaluate the removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD), nutrients, and total suspended solids (TSS) of each treatment line, and compare the impact of plastic rings (biofilm carriers) and Lemna minor L. with the presence of gravel bed on the treatment efficiency and bacterial growth, as well as assess the plant’s adaption and growth. The results showed that all treatment systems improved the water characteristics, and adding biofilm carriers enhanced the efficiency of water purification, especially BOD reduction. The combination of the plants, biofilm carriers, and gravel in the wetland filter significantly enhanced (ρ < 0.05) the treatment efficiency in terms of TSS, COD, BOD, Ammonia (NH3), Nitrates (NO3), and Orthophosphate (PO4) compared to the control treatment system (gravel bed). Plant growth was restricted in the presence of carriers in the system. Further study for examining the system performance under summer conditions, which may improve the nutrient reduction rates by biofilm carriers, is underway.

Effect of Different Plant Monocultures on Nitrogen Removal Performance in Wetland Microcosms

Wang Rujun, Quan Ying, Zheng ShaoKui, Zhang Xueyu

Journal of Ecological Engineering

2022

Vol. 23, nr 9

241--249

This study investigated the nitrogen removal performance in wetland microcosms individually planted with different plant monocultures, including emergent, free-floating and submerged plants during ammonia removals, or large- and small-leaf free-floating plants during nitrate removal. For ammonia-dominated wastewater, both emergent (common reed) and free-floating (water hyacinth) plants in wetland microcosms achieved higher total nitrogen removals than a submerged plant (eelgrass) that significantly improved the microbial nitrifying performance. For nitrate-dominated wastewater, efficient nitrate removals in wetland microcosms planted with free-floating plant were achieved by both a full cover of water surface and the concentration of organic oxygen-consuming substances, which resulted in low dissolved oxygen levels and boosted microbial denitrification in wetland microcosms. FWS-CW developers and managers should thus pay close attention to the selection of wetland plant types and optimize their design to achieve optimum nitrogen removal performance.