Advanced treatment of WWTP effluent; no use or reuse?

Abstract

From 2006 until 2008 a research project is executed at wastewater treatment plant (WWTP) Leiden Zuid-West (The Rijnland District Water Control Board). The research focus is on the removal of nitrogen, phosphorous, heavy metals and priority hazardous substances from WWTP effluent with different treatment techniques to reach the effluent quality which is required by the Water Framework Directive 2000/60/EC. The semi-practical installation at WWTP Leiden Zuid-West consists of small full scale installations and has a maximum capacity of 150 m3/h. The installation is divided into two parallel streets. The first street consists of flocculation tanks and a continuous sand filter. The second street consists of a continuous sand filter, flocculation tanks and a dual media filter. The continuous sand filters are denitrifying filters. The results of this research up to now show that continuous sand filtration has the ability of removing total nitrogen and total phosphorous to MPR values (maximum permissible risk) at high filtration rates. This means that continuous sand filtration is suitable as pre-treatment for ultrafiltration and reverse osmosis to produce ultra pure water. The advanced treatment of WWTP effluent is not only good to reach a better water quality but makes also the possibility of reuse easier.