Rainwater treatment using an acrylic blanket as a filtering media

Abstract

Rainwater harvest is a desirable alternative clean technology where water is scarce, but the economic viability of its implementation is reduced by the need to install pumps and pipes. The type of filter bed and the frequency of filter changes can increase costs, compromise the quality of the water obtained by this treatment and increase the environmental impacts. This study focuses on a system for collecting and treating rainwater that is compact, innovative, dispenses with the use of pumps, and can be adapted for use in homes and industries, contributing to clean production. An acrylic blanket (Acrylon) was used as a filtering medium because it is a low-cost alternative and is easy to obtain and handle. The experiment was carried out in a company located in the industrial city of Itaboraí (Rio de Janeiro). Water characterization was monitored before and after contact with the roof, and after passing through the treatment equipment (11 rain events). Samples were collected in triplicate; the first sample was collected within 10 min of the onset of rain (first flush), the second after 15–30 min of rain, and the third after 30 min of rain. The second and third samples were used to generate a “continuous” sample. The evaluated parameters were turbidity, apparent color, hydrogenionic potential, temperature, free residual chlorine, and the presence of coliforms (total and tolerant). The apparent color removal efficiency was 81.70% for first flush and 49.54% for continuous samples, and the turbidity removal efficiency was 74.28% and 52.19%, respectively. These removal efficiency results are similar to those achieved by traditional rainwater treatment systems that do not discard the first flush. It was found that the treatment met the requirements of the Brazilian standard for the use of rainwater based on turbidity (less restrictive standard), residual chlorine, and absence of coliforms, but did not meet the requirements for hydrogen potential and color removal.