Research On The Methods Of The Water COD Online Detection

Eutrophication is the root reason for the outbreak of cyanobacterial bloom in Taihu Lake.Eutrophication is closely related with the indicators of chemical oxygen demand, which isalso the focus of the water quality monitoring. The most of current online automaticmonitoring devices for water COD follows the national standard methods, using the potassiumdichromate method or potassium permanganate index method, achieved under conditions of hightemperature and reflux, water sample digestion cycle is long time, high running cost, and theadditive chemical oxidation reagents may have secondary pollution. Therefore, research anddevelopment of a new water COD online detection device is particularly important. Thispaper respectively studies oxidation digestion, detecting method and the device structures andso on, and a new water COD online detection device was developed which is simplestructured, easy to operate, environmental protection, accomplished in the normal temperatureand pressure, fast and efficient. The main research results are given bellow:1、 Through methods of comparison and experimental research, this device designed andbuilt a set of oxidative digestion device based on ozone and ultraviolet which is fast andefficiency to deal with all kinds of refractory organic pollutants.2、 A COD online detection device has been developed, which has simple structure andprocess, the short reaction time, the high detecting accuracy. The device uses the newdesign of multi-sensor information fusion technology, the adjustable and quantitativeinjection pump, the level controller of O3, homemade cooling module and so on.3、 This device is using Programmable Logic Controller (PLC) as the control core, achievedboth automatic and manual mode. Realization of human-computer interaction throughLabVIEW, monitoring interface is clear and simple, enable automatic sampling, automaticdigestion, automatic storage and other functions.