Mathematical modelling of real-time control system for industrial wastewater management

摘要

The composition of wastewater produced in industrial processes can vary dynamically and often randomly. immediate intervention is necessary to preserve the water quality before any parameter of the wastewater exceeds the threshold limit; therefore, the parameters of the wastewater must he determined in real time. Direct laboratory methods have long lead times; indirect methods (refraction, pH, conductivity, turbidity, etc.) would be suitable as they measure indirect values, so correlations must be found between the measured values and the component(s) for analysis. These correlations are often stochastic in nature having a standard deviation of the same magnitude as the measured values. This paper deals with pharmaceutical wastewater with a high sucrose content, the online measurement of its organic material content characterised by chemical oxygen demand (CODcr), refraction and resistance. It finds a correlation between the CODcr and resistance-corrected refraction (r*). To reduce the standard deviation, the concept of cumulative CODcr is introduced. Concentration limit values could be determined to compare with the cumulative CODcr values calculated continuously during the fill up of the wastewater tank. This means that the treatment with the wastewater (into the drain, dilution and transfer) can be decided. The validity of the model is checked by trial calculations based on a high number of measurements.