Hydroponic systems, which utilize plants which are grown in a nutrient solution without soil, are expanding and raising great interest in the commercial and scientific community. They are engineered systems designed and constructed to utilize the natural processes involving macrophytes, media, and the associated microbial assemblages to assist in treating wastewaters. This is a relatively new approach in wastewater treatment by which a variety of emergent macrophytes are grown hydroponically on top of floating platforms with their roots developing freely into the flowing wastewater. The roots provide a support medium for attached microbial growth which participates in the treatment process.