On the removal of natural organic matter from superficial water by using UF and MF membranes

摘要

Excessive chlorine usage in surface water disinfection may constitute a problem, since residual chlorine reacts with natural organic matter (NOM), already present in surface water, giving birth to disinfection by-products (DBPs). Aim of the work was to experimentally test the feasibility of a disinfection process by combining chlorination and ultrafiltration (UF), thus minimizing chlorine dosage. At the scope, in this paper, the removal of humic acid (aldrich humic acid, AHA), representative of NOM, has been studied by using tubular UF and microfiltration (MF) membranes (50nm, 20nm, 0.2m). Results show that, regarding AHA rejection and turbidity, investigated membranes are not influenced by transmembrane pressure and AHA concentration, while UF membranes seem to be more effective in salt separation. Anyway, both UF and MF show a removal efficiency up to 90%. Moreover, a process scheme aimed at water use/reuse is proposed, in which the chlorination step is substituted by a double filtration step (UF followed by reverse osmosis), in order to obtain high quality water, usable also for industrial purposes in which a high purity water is needed.