Characterization of pulp and paper waste water samples using a prototype sensor (Langis Oy) : Study on the corelation of COD with UV-abs and IR-abs.

Usually online effluent water quality measurement systems are not incorporated in pulp and paper mills. Laboratory analyses are used to measure the parameters like suspended solids, Chemical Oxygen Demand, Biological Oxygen Demand (BOD5), turbidity, pH and conductivity. The quality of the effluent can fluctuate between the timespan of sampling and getting the results. Hence, the real time monitoring and control of the effluent requires using online water quality sensors. In this study, an online water quality sensor (prototype) was used to characterize the effluent from a Finnish pulp and paper mill. The sensor was manufactured by Langis Oy. The prototype was able to measure electrical conductivity, turbidity, total suspended solids, color and total dissolved solids from the given sample. Measurement of theses parameters was based on optical phenomenon except for the electrical conductivity. Results showed that the waste water samples could not be characterized solely using the prototype. Laboratory experiments were performed in order to complete, compare and verify the prototype measurements. Infra-Red absorbance and conductivity measurement of the prototype was out of range; hence, recalibration and tuning was suggested to the manufacturer. Laboratory results shows conductivity, suspended solids and turbidity show good correlation among each other and help in estimating the level of chemical oxygen demand. Thus, the control system of the mill should be based on the online measurement of these parameters