Water Quality Assurance with Constructed Wetlands in Latvia

Abstract

Constructed wetland is a well-known and widely used method over the countries to improve water quality. This chapter outlines the experience of Latvia in wastewater treatment and nutrient retention in constructed wetlands. In Latvia constructed wetlands as a domestic wastewater treatment systems were initially implemented in the year 2003. Wastewater from small villages with up to 1000 inhabitants was collected and purified in subsurface flow constructed wetlands with flow regime and dimensions adapted to site-specific requirements. Constructed wetlands can provide biochemical oxygen demand (BOD) reduction efficiency up to 98% without a frequent maintenance. Two pilot-scale constructed wetlands for nutrient retention were implemented in agricultural areas and monitored since the year 2014. The monitoring results obtained during the study period showed the reduction of the average concentrations of total nitrogen and total phosphorous by 53% and 89%, respectively. Basing on the initial results presented in this chapter, constructed wetlands could gain more trust to be implemented for water quality assurance as treatment systems for the wastewater from household and agricultural sectors in Latvia.