APPLICATION OF CONSTRUCTED WETLANDS FOR WASTE-WATER TREATMENT IN HUNGARY

This paper presents a brief survey of the Hungarian constructed wetlan d types that have been established for wastewater treatment in the las t thirty years, and gives an analysis of the design and performance of those reed ponds that have been constructed for the polishing of petr ochemical wastewaters. Natural treatment processes are in great demand because they are protective of the environment and have low operation costs and satisfactory purification efficiency. Three major types of treatment wetlands are utilized in Hungary: free water surface system, subsurface flow system, and artificial floating meadow system. Since the 1970s, the petrochemical industry has utilized sewage treatment sy stems consisting of ponds of emergent and/or submerged macrophyte vege tation that operate as free water surface systems. In the wastewater t reatment system of Nyirbogdany, the average COD removal efficiency is around 60%, while the reed-submerged weeds pond has an efficiency of 2 5%. In the reed pond of the TIFO post-treatment pond system, the total phosphorus removal averaged 40% for several years, while the nitrogen removal efficiency has not exceeded 35%. For both constructed wetland s, the nutrient stabilising and heavy metal accumulating role of the a quatic plant-periphyton complex has been quantified, and the biologica l water quality has been found to be typical of any other natural wate r bodies. (C) 1997 IAWQ. Published by Elsevier Science Ltd.