Pradeep Sharma - Department of Environmental Science, Graphic Era (Deemed to be) University, Dehradun, Uttarakhand, India
Anju Rani - Department of Microbiology, Graphic Era (Deemed to be) University, Dehradun, Uttarakhand, India
Deepa Minakshi - Department of Environmental Science, Graphic Era (Deemed to be) University, Dehradun, Uttarakhand, India
Piyush Malaviya - Department of Environmental Science, University of Jammu, Jammu and Kashmir, India

Three vertical sub-surface flow (VSSF) constructed wetland (CW) systems (CW-۱, CW-۲ and CW-۳) filled with different filter media, each ۴ m۲ in area, planted with Arundo donax was operated for ۴ years for treating dairy farm wastewater. The vertical CW systems received high fluctuations in influent concentration and loads i.e. BOD (۲۶ to ۶۱۹ mg L-۱ and ۱.۵ to ۳۴ g m-۲ d-۱), TSS (۱۶۵ to ۶۴۳ mg L-۱ and ۹.۱ to ۲۴ g m-۲ d-۱), TP (۱۶ to ۴۹.۹ mg L-۱ and ۱.۲ to ۲.۷ g m-۲ d-۱) and NH۴-N (۲۴.۵ to ۷۶.۲ mg L-۱ and ۱.۳ to ۴.۲ g m-۲ d-۱) during the assessment period. Average annual removal rates showed fluctuations in removal of BOD (۷۰.۵ to ۹۲.۹%), TSS (۸۲.۵ to ۹۷.۵%), TP (۵۱.۱ to ۹۱.۹%) and NH۴-N (۳۴.۶ to ۶۹%). This shows that the removal of BOD is very sensitive to inlet load fluctuations in CWs. High inlet loads may confine good nitrification that affects ammonium-nitrogen removal while TP removal rate reduced when inlet TP loads reduced. The average concentration of the pollutants (BOD, TSS, TP and NH۴-N) in the treated effluent showed noticeable decrease: ۴۳.۴ to ۱۶.۱ mg L-۱ for BOD; ۴۳.۳ to ۱۱.۷ mg L-۱ for TSS; ۱۷.۹ to ۳.۱ mg L-۱ for TP and ۳۳.۲ to ۲۲.۷ mg L-۱ for NH۴-N. Thus from the outcomes of the current study, it can be concluded that the VSSF CW system may provide promising outcomes despite there is fluctuations in the influent loads.

Vertical sub-surface flow constructed wetland, influent loads, dairy farm wastewater, Organic matter, BOD