The design implications of the various wetland processes and components are discussed. Although constructed wetlands have been used to control nutrients in urban runoff and industrial effluents, the report focuses on their performance in relation to municipal sewage effluent. A summary of the performance of some full-scale systems is included in the report. Nutrient removal performance depends on a range of factors and since these vary from site to site, results to date have been quite variable. Process design and operating guidelines are consequently, not yet fully developed.
Present guidelines are sketchy and at times contradictory.
Treatment system sustainability is poorly documented since apart from some natural wetlands, no successful constructed system has been operational for more than 20 years. However a number of experimental and fully operational systems throughout the world are beginning to build up a database from which agreed criteria will emerge allowing process variables to be optimised. Nevertheless, there are some major constructed wetlands planned as part of water quality protection programs in the Sydney region.