MONITORING OF DISSOLVED REACTIVE PHOSPHORUS IN WASTEWATERS BY FLOW-INJECTION ANALYSIS .2. ONLINE MONITORING-SYSTEM

An automated-flow injection (FI) analyser for the determination of dis solved reactive phosphorus (DRP) in wastewaters is described. The anal ytical method is based on the formation of molybdenum blue. The limits of detection using a solid-state photometric detector (LED-photodiode ) were 0.05 mg P 1(-1) and the linear range was 0-20 mg P 1(-1). Detai ls of construction, field-testing (including sample filtration) and va lidation are given. The analyser proved very reliable during an unatte nded operational period of seven days. Operational costs were minimise d, with low reagent consumption and minimal operator intervention. Dat a retrieval and analyser status were remotely interrogated by means of a cellular telephone-based communications link. The real-time results from the analyser showed good correlation with those generated by a v alidated laboratory method. Copyright (C) 1996 Elsevier Science Ltd