Desempeño de floculadores tubulares usando policloruro de aluminio como coagulante en la potabilización del agua

Abstract

The chemical processes of coagulation and flocculation are the most important processes in water treatment since, thanks to the addition of coagulants and flocculants, they cause certain colloidal substances present in raw water to agglutinate, facilitating subsequent processes for purification. It is for this reason that this study aimed to evaluate the performance of a horizontal flow tubular flocculator (FTFH) and a vertical flow tubular flocculator (FTFV) using Poly Aluminum Chloride (PAC) as a coagulant and cationic polyelectrolyte as flocculant, to remove turbidity and color and then compare the results with those of a conventional plant. For whic, experimental tests were carried out in two pilot flocculators made of PVC tubes with diameters of 75 mm and 110 mm for the FTFH and diameters of 63 mm and 110 mm for the FTFV, using different turbidities of raw water (15 , 50 , 100 and 1000 NTU), flow rates of 0.5, 1 and 2 L/s, as well as pipe lengths of 90, 97.6 and 187.6 m for the FTFH, and 90, 80 and 170 m for the FTFV. To determine the efficiency of turbidity and color removal, raw water, settled water and filtered water samples were taken, both from the pilot system and from the conventional system of the Bayas Potable Water Treatment Plant (PTAP-B). In turn, the efficiency of the PAC coagulant and aluminum sulfate was compared, in the latter the results of two previous studies were taken. Additionally, hydraulic parameters such as velocity gradients and retention time were determined using tracers. Finally, the results of this study showed that the efficiency at the filter outlet of the pilot system, with prior use of the FTFH, was 95.8 % for turbidity and 97.2 % for color; with the FTFV it was 98.48% and 99.4% for turbidity and color, respectively; while the PTAP - B was 98.78 % for turbidity and 99 % for color. Demonstrating in this way that both systems were efficient and complied with INEN 1108 regulations. It was also shown that there was a better performance of the process when substituting the aluminum sulfate coagulant for PAC.