Performance of Combined Vertical and Horizontal Flow Sub-Surface Constructed WetlandsProgram in Viet Nam

Abstract

The present study demonstrates wetland projects to treat industrial wastewater for reuse implemented for different hydraulic & organic loadings. The combination of vertical and horizontal flow wetland treatment system with fill and draw controls provides a design for effective contact of wastewater with the root system to achieve higher treatment efficiencies by creating necessary environments for nitrification-denitrification removal of organic materials, and phosphorus adsorption reactions. Systems have been implemented for large scale applications in automobile, sand reclamation, municipal leachate and other industries for process and domestic wastewater treatment & reuse. The results show that there is a marked removal efficiency using Typha species & several other indigenous plants. The percentage reductions in various physicochemical parameters such as Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), Nitrate (N), Phosphate (P), and Fecal Coliforms (FC) are 85%, 90%, 70%, 60% and 95% respectively. The study further reveals the effect of variable hydraulic loading rates on treatment efficiencies. The system has been successfully adopted for the past 3 years reducing electrical, mechanical operations and maintenance requirements for wastewater treatment by almost 70% benefiting industries to a great extent and exploring opportunities for application in other industrial sectors for implementation of such technologies which were not in practice earlier.