Abstract: The aim of the investigations was the development and test of an equipment to measure total N and total P and subsequently in the outfall of a sewage treatment plant. A method was developed for disintegration of both total N and total P using UV radiation for subsequent flow injection determination as nitrate and orthophosphate in 1 step. In testing of the complex monitor in the outfall of a pilot sewage treatment plant over a period of 3 mo the results matched well with lab. experiments 76% Of all measured values from the monitor for total N deviated <20% from the lab. results in a range of 4.0-49.0 mg/L Ntot. With the determination of total P in the range 0.5-10.0 mg/L, 77% of all results had a deviation <20%.