CataCOD

Background, objectives, contents

Stricter limit values and dynamic wastewater flows require robust online analytics. Laboratory methods for COD/BOD are complex, discontinuous and maintenance-intensive. The aim is to develop CataCOD: a compact, photocatalytic-electrochemical probe for the summarising and fractionating detection of organic water constituents - virtually maintenance-free and automated.

The measuring cell combines a photoanode/cathode, UV-A LEDs and potentiostat electronics (resolution ±20 nA). Thin catalyst layers and oxide semiconductors with a variable band gap (TiO₂, WO₃, CdS, ZnO) are used to specifically excite photocurrents; voltametric methods allow the separation of fractions. Conductivity measurement is integrated so that no electrolyte dosing is necessary. Galvanic self-cleaning minimises drift and maintenance; the aim is stable operation for ≥6 months.

Contents: (i) production and screening of stable photoanodes (hydrothermal/screen-printing), (ii) development of electronics/signal processing, (iii) modelling and calibration against laboratory COD/DOC with <5 % deviation in real matrices, (iv) investigation of interferences and voltametric fractionation, (v) construction of a demonstrator and validation in the field (municipal/industrial). The result is a practice-ready online probe for real-time monitoring and digital process control