The use of constructed wetlands in the treatment of dairy processing wastewater

Abstract: Abstract The interest in the use of constructed wetlands for the treatment food processing wastewaters including dairy wastewater is growing. The reason is the intention to create clean technologies that can substitute the currently used “environmentally unfriendly” conventional facilities. This paper suggests options for adopting a constructed wetland system to treat wastewaters from diaries. The potential use of two stage wetland systems is investigated. Examples of multi-stage wetland use are reviewed. The calculations based on the k-c ' model (Kadlec and Knight 1996) showed that a reasonable option is to use a subsurface wetland 160 m2 area followed by a free water surface wetland 2000 m2 area. However, these calculations are influenced by the use of older data. The most significant effect is the use of the rate coefficient values for both FWS and HSSF wetlands. A comparison is made to show the effects the new data might have on the calculations. Other measures that can increase the efficiency of the suggested wetland systems like filtration media, deep zones and engineering solutions are suggested. Finally, an overall investigation of the costs involved suggests that the wetland option can be cost effective if all the factors that affect the wetland´s construction and functioning are properly dealt with.