Research on application of flowforms in combination with planted constructed wetland for improving water quality of urban polluted lakes

Abstract

With continuously increasing urbanization in Vietnam, urban lakes pollution by domestic wastewater has become a serious issue, which results in degradation of lake water quality and consequent deterioration of landscape as well as environment for urban residents. Finding low-cost, simple and sustainable solutions would help to overcome that issue in Vietnam’s context. This study aims at proposing a solution which includes low-cost, nature- and landscape-friendly processes such as wetlands and flowforms for improving polluted urban lakes. The study was carried-out on a pilot system consisting of a cascade of flowforms and a planted constructed wetland with flow recirculation. Water samples used in this study have been collected from an urban lake in Hanoi, which receives wastewater from a densely populated residential area. The research results have demonstrated that this solution could achieve high treatment efficiencies: Color - 92%, Chemical oxygen demand (COD) - 92%, Ammonia (NH₄⁺-N) - 98% and Total Phosphorus (TP) - 87%. The effluent quality could meet requirement by Vietnam’s National technical regulation on surface water quality QCVN 08-MT:2015/BTNMT, level B1 in terms of the above mentioned parameters.