MEDEIROS, M. R.; http://lattes.cnpq.br/5921612583032386; MEDEIROS, Mariana Rodrigues de.
Abstract:
Inactivation of pathogenic bacteria is a fundamental requirement in the treatment of
drinking water. Advances in water treatment research have been directed toward the
application of technologies that use fewer chemical reagents, thereby reducing the
formation of toxic byproducts and reducing the time of operation. The objective of this
study was to design and evaluate the efficiency of an electrolytic bench reactor
composed of the electrode pair: nickel sponge (anode) and carbon fiber (cathode),
continuously operating in the disinfection of the indicator bacterium Escherichia coli (E.
coli). Initially, the tests were carried out with LABDES / UFCG public contaminated
water in a laboratory with a constant concentration, evaluating the effects of applying
the potential differences (ddp) of 3.0 V, 5.0 V, 7.0 V and 9,0 V in the respective average
residence times (tm): 46.8 s, 65.4 s, 82.2 s and 121.8 s, estimated experimentally by
the method of injection of a tracer solution (NaCl) at the flow rates of 0.5, 1.0, 1.5 and
2.0 L.min-1, respectively, in the physico-chemical parameters and in the disinfection of
E. coli from this water. Subsequently, it was proposed to study the performance of the
reactor in relation to the same parameters (electrical conductivity, pH, turbidity and
color), adding the analysis of chloride concentration (Cl-). In this step, we considered
greater ranges of ddp and a mean constant residence time (121.8s), and evaluating
different types of water (deionized, NaCl solution, public supply water of Campina
Grande) without and with E. contamination. coli. The results obtained, in terms of
percentages of disinfection of E. coli in LABDES water, showed that under the ddp of
5.0 and 7.0 V, these percentages were 99.84 and 99.40%, respectively, for the highest
time of residence (121.8 s). In the experiments performed with the other waters, 100%
disinfection of E. coli was achieved in NaCl solution contaminated with 103 CFU.mL
-1, at current densities of 9.4 and 11.89 mA.cm-2, respectively, and in the public supply
water of Campina Grande in the same order of concentration of bacteria, disinfection
was 100% efficient at current densities of 9.92, 11.1 and 11.7 mA.cm-2. The results show that the proposal of the work to remove much or 100% of E. coli from waters, mainly waters of human consumption, was reached.