Hybrid wetland system for a pet-care center wastewater treatment

Abstract

A hybrid wetland (HW) consisting of a free-water surface flow wetland (FWSW) followed by a horizontal subsurface flow wetland (HSSFW) was constructed for the final treatment of wastewater from a pet-care center. Typha domingensis was planted in both wetlands. During the first year of operation, wastewater was separated from solid pet waste (first period). Then, that solid waste and liquid wastewater were treated together, causing a significant increase in the concentration of the pollutants (N, P, and organic matter) in the effluent treated in the HW (second period). The objectives of this work were to evaluate the performance of the system and compare its efficiency between periods. The HW was efficient in both periods, except for nitrate removal. Total mean removals were: 66.9 and 82.8% for COD, 74.9 and 88.3% for BOD, 61.9 and 83.0% for ammonium, 67.7 and 83.8% for TKN, 5.65 and 20.37% for nitrate, and 56.9 and 62.1% for TP in the first and second period, respectively. In the second period, mean removal efficiency percentages increased and the contaminant concentrations in the outlet were not significantly different from those of the first period. In the second period, the highest pollutant removal occurred in the FWSW mainly for COD, BOD and TKN. TP and TKN concentrations in plant tissues of the inlet area of FWSW were significantly higher than those in plants from the HSSFW. The study showed that this HW is a low cost, efficient and sustainable solution for the pet-care center wastewater treatment.