The most successful wetland operation has been at the end of conventional treatment processes such as Activated Sludge, or Lagoons. In this manner the wetland operates as a polishing process. The filtering action provided by the media and plant growth has been shown to be a viable option for the filtering of TSS and insoluble BOD in treated wastewater effluents. The problem with this is the filtering will also lead to clogging of the wetlands. Treatment for removal of nitrogen has not been as successful. Most data reported on wetlands has been sporadic and inconsistent. Long term testing of wetland effluents, by Michael Richard, Ph. D. on systems in Colorado, shows periodic purging of nitrogen and phosphorus by the wetland systems.
While there is very little an operator can do to control or improve the operation of wetlands, there is maintenance required.
Much of the maintenance is similar to the maintenance of lagoon systems. The dikes need to be maintained. A low growing grass should be planted to prevent erosion. The grass should be cut regularly and the clippings disposed of. Burrowing animals will be attracted to the lush vegetation and need to be discouraged from burrowing into the ground around the wetlands.
Housekeeping is essential to keeping odors, insects and rodents under control. Screenings and grit removed in the pretreatment of the wastewater need to be removed daily and disposed of properly. Trash must not be allowed to accumulate on the grounds and an overall neat and clean appearance should be maintained.
The vegetation growing in the wetland will need to be removed at the end of the growing season. While burning these plants is an option, care needs to be taken to protect the lining of the wetlands as well as any exposed plastic pipe (sampling ports, distribution pipes) in the area. The exposed pipe can be covered with wet burlap and then enclosed by a 5 gallon bucket prior to setting the wetlands on fire. Permits for burning the wetlands also need to be obtained from the proper authorities. Insure that a good supply of water and manpower is available to prevent the fire from escaping the wetland area. The plants can also be cut and the cuttings will need to be removed and properly disposed of.
The wetland system needs to be tested. Testing should include pH, temperature, DO, and nitrate. Effluent DO, pH, and temperature testing should be done at least twice a week. Based on this testing, changes to the flow pattern should be made to maintain a minimum effluent DO of 0.5 mg/l. Nitrogen sampling should include both influent and effluent for total nitrogen as well as testing the effluent for nitrate nitrogen. Weekly or at least monthly testing for nitrogen should be considered. In order for this data to be of use, good flow measurements along with a totalized flow will be necessary. The flow measurements need to be taken at the influent and effluent of the facility.
Records need to be kept. The records of flow and process control testing are necessary for the proper operation and maintenance of the system. In addition the operator needs a copy of the as-built drawings and all permit testing done on the facility. Daily records of the temperature and weather conditions will also be helpful in troubleshooting the system.