Automation algorithm and installation for sequential processes for the treatment of toxic wastewater with high organic content

Abstract

Biological treatment of wastewater, including industrial, is often applied, due to economic and also technical performance. However, the pollution of the industrial wastewater is determined in many cases by complex mixtures of organic and inorganic species and their removal could necessitate multi-stadia phases, i.e. aerobic and anaerobic conditions, but also employment of such measures that mitigate the toxic character of pollutants over biomass. The sequencing batch reactors (SBR) separate the process phases in time (one phase starts after the previous one is finished), using a single reaction tank and are basically unsteady, unlike the activated sludge with continuous flow, when separate tanks are used for different phases with steady conditions. This paper presents some achievements for exploiting the SBR flexibility by adjusting the feeding algorithm and the duration of different phases. Such algorithms were tested for high concentrated phenolic solutions, up to near 3 g/l and ammonium rich (250 mg/l) phenolic solutions, with the aim of complete phenol removal and also complete denitrification. Testing lab installation was controlled by PLC (with user free adjustment of parameters for feeding strategies and duration of sub-phases) and the algorithms were successful in mitigation of toxic effect of the phenol. Next stage is a transition to a data acquisition and control system (computer based) which will allow automatic phase switching by identification of critical points by first and second order derivative processing of monitoring data, i.e. for pH, ORP, DO.