Natural processes have always cleansed water as it flowed through rivers, lakes, streams, and wetlands. In the last several decades, systems have been constructed to use some of these processes for water quality improvement. Constructed wetlands are now used to improve the quality of point and nonpoint sources of water pollution, including stormwater runoff, domestic wastewater, agricultural wastewater, and coal mine drainage. Constructed wetlands are also being used to treat petroleum refinery wastes, compost and landfill leachates, fish pond discharges, and pretreated industrial wastewaters, such as those from pulp and paper mills, textile mills, and seafood processing. For some wastewaters, constructed wetlands are the sole treatment; for others, they are one component in a sequence of treatment processes. One of the most common applications of constructed wetlands has been the treatment of primary or secondary domestic sewage effluent. Constructed wetland systems modelled after those for domestic wastewater are being used to This Handbook has been prepared as a general guide to the design, construction, operation, and maintenance of constructed wetlands for the treatment of domestic wastewater, agricultural wastewater, coal mine drainage, and stormwater runoff in the mid-Atlantic region, The Handbook is not a design manual. The use of constructed wetlands to improve water quality is a developing technology. Much is not yet understood, and questions remain regarding the optimal design of wetland systems and their longevity. As our experience with these systems increases, the information offered here will be replaced by more refined information. The Handbook should be used with this clearly in mind. The Handbook is divided into five volumes. This, the first, provides information common to all types of constructed wetlands for wastewater and runoff. It is to be used in conjunction with an accompanying volume that provides information specific to a particular type
of wastewater or runoff.