Performance of a Pilot Constructed Treatment Wetland For Membrane Concentrate Produced From Reclaimed Water

A pilot study was conducted for the City of Oxnard to assess treatment options for an advanced water purification facility using microfiltration and reverse osmosis to create high quality product water from reclaimed wastewater effluent to replenish groundwater. However, this process yields a concentrate with a high salt and ammonia content requiring disposal. The City is incorporating a constructed wetland into the facility to treat the concentrate as a demonstration project, with the long-term objective of using the treated concentrate for creating coastal wetland habitat. In a pilot study, a portable subsurface flow constructed wetland was used to evaluate the acceptability of this treatment method. Bulrush, a common wetland plant, was found to tolerate the high levels of total dissolved solids and provided significant mass removal of nitrogen, selenium, biochemical oxygen demand, phosphorus and other constituents in the concentrate. No evident objectionable color or odors were observed during the pilot study.