A full-scale anaerobic baffled reactor and hybrid constructed wetland for university dormitory wastewater treatment and reuse in an arid and warm climate

Abstract

In low-income regions and small/medium communities, the use of conventional/mechanical methods for wastewater treatment is not always financially and technically feasible. Thus, nature-based solutions such as constructed wetlands (CW) appear as a more appropriate option. Additionally, there is limited application and reporting on the use and efficiency of this sustainable technology in arid and warm climates such as in the Middle East. In order to get a better insight into the feasibility of CWs under such climate and socio-economic context, a full-scale demonstration hybrid CW facility was built and monitored for the first time at a university campus in Iran for one year. The facility consists of an anaerobic baffled reactor, a vertical flow CW and a polishing horizontal subsurface flow CW and has a total area demand of 2.5 m2/pe. The goal was to evaluate the system's efficiency and investigate the need for one or two CW stages to reach the national effluent reuse standard. The CW were planted with local species (Arundo donax, Cortaderia selloana, Phragmites australis) and received 20 m3/day from a university dormitory at a hydraulic loading rate of 5 cm/day. The facility proved to be effective and removed 88.9%, 86.0%, 92.2%, 63.5%, 66.5%, and 65.7% of BOD5, COD, TSS, PO4-P, NH4-N, and NO3-N, respectively, while the effluent complied with the reuse standard. This study showed that hybrid CW can be effectively used under dry and warm climates using native plant species providing a technically feasible, cost-effective, and sustainable wastewater treatment solution.