Recirculating Vertical Flow Constructed Wetland for On-Site Sewage Treatment: An Approach for a Sustainable Ecosystem

Abstract

Sewage can be considered one of the richest and most productive waters for crops since it contains nitrogen (5 - 7%) and phosphorus (3 - 5%) and in constructed wetlands it could be used as fertilizer. The feasibility of growing corn on a recirculating vertical flow constructed wetland (RVFCW) treating sewage on-site was examined. Corn was planted at 107,000 seeds/ha. Effluents from a septic tank and a RVFCW were analyzed for water quality variables. Treatment efficiencies (removal) were high for fecal coliform bacteria (99.9%), biochemical oxygen demand (98.4%), total suspended solids (95.6%), ammonium-nitrogen (95.3%), total Kjeldhal nitrogen (94.7%), total nitrogen (79.5%), and total phosphorus (75.5%), while relatively low for potassium (48.8%). Corn yield (only kernel) was 10,026 kg/ha. These results show that a RVFCW could be a sustainable alternative technology to grow corn providing a mechanism to remove pollutants from wastewater, reduce sanitation problems, and improve economic and social benefits.