Potencial de um sistema de eletrocoagulação-flotação para o pré-tratamento e reciclo da água de lavagem de filtros em uma estação de tratamento de água

Abstract

The production of potable water in the complete conventional cycle water treatment plants (WTP) generates wastewater from filters washing, which is difficult to handle and dispose, requiring the implementation of treatment systems for its best use. In this scenario, the objective of this proposal was to evaluate the pre-treatment of filter washing water (ALF) of a complete cycle WTP for its reuse through the application of an electrocoagulation-flotation (ECF) system. The system used in the study consisted of an electrocoagulation reactor associated with a helical tubular flocculator (FTH) (according to patent filing nº BR 10 2021 008218-6) and operated with a flowrate of 0.8 L/min. The electrocoagulation reactor consisted of an acrylic tube, 3.6 cm in diameter and 35.5 cm in height, with 8 aluminum electrodes (29 cm in height, 8 cm in width and 0.05 cm in thickness) with a distance of 0.3 cm between them and connected to a direct current power supply. The diameter of the ring units used in the FTH was 60 mm and the diameter of the FTH tube was 9 mm. For the evaluation of the best treatment conditions, an experimental design of the rotational central composite type (DCCR)2² was carried out with the independent variables initial pH and aluminum concentration. The results showed that with the dosage of 10 mg/L and initial pH 6 it was possible to obtain a turbidity removal above 90%, which fitted in the USE-PA (2002) standards for filter wash water reuse. So, it was possible to conclude that the ECF system is a promising technique for the treatment of filter washing water.