Abstract
We observed both an increasing number of experimental studies and full-scale applications of vertical flow reed bed filters. Studies also concern the biological treatment mechanisms of wetland systems and their degradation activities on substances dangerous to the environment such as hazardous organic compounds and/or endocrine disruptors, Nutrients removal, and in particular that of phosphorus, also aroused an interest as shown by several communications dedicated to specific media which can play a positive role in sorption/precipitation of phosphorus compounds. The use of Constructed Wetland systems continues to spread in terms of the number of full-scale systems [several thousand now in the EU] and its application to treating more and more different pollutants. Though waste stabilization ponds have been used for 40 years, the technique has to evolve in order to cope with new challenges: growing population, enhanced treatment requirements in terms of reliability and effluent quality, treatment of agro-industrial effluents, footprint reduction, limitation of environmental impact, sludge (including latrine septage) management. These new challenges have driven both technological and scientific developments: - A diversification of the technology which offers the possibility to combine different types of ponds (deep, shallow, aerated, high-rate algal ponds ~ and wetlands) and a revival of the interest in facilities and devices such as baffles, recirculation systems and gravel filters. - The growing complexity of waste stabilisation pond technology and the demand for higher performance predictability require more in-depth knowledge of the mechanisms involved in the treatment process, taking into account that most of these mechanisms are highly dependent on the meteorology. Significant advances in the knowledge of physical and biological mechanisms involved in the removal of nutrients and micro-organisms have been presented.