Sistema de membrana reciclada assistido por energia solar fotovoltacia para recuperação ambiental da água de lagos ornamentais eutrofizados

Abstract

Eutrophication is a pressing environmental challenge worldwide, which associates the increase in primary productivity and the excessive development of algae and/or aquatic macrophytes, which implies adverse effects on aquatic ecosystems, such as the development of anoxic conditions and of species diversity. In addition, eutrophication affects ecological goods and services derived from lakes and reservoirs, such as water supply. At the same time, the negative impact of potable water shortages has stimulated interest in decentralized water treatment systems using membrane separation processes (PSM) aided by renewable energies. The use of photovoltaic solar energy (PV) to drive these installations occurs in a satisfactory way to form a PVmembrane system with low specific energy consumption, mainly indicated for regions disconnected from the grid. Recent studies have developed the recycling of reverse osmosis membranes, at the end of their useful life, as an alternative to their disposal. Low-cost, recycled membranes are used in less restrictive separation processes. The present study evaluated the performance of a recycled membrane system aided by PV solar energy for the treatment of eutrophic waters from ornamental lakes. On a bench scale, the treatment of eutrophic water samples, collected from two ornamental lakes, using a recycled membrane, similar to commercial ultrafiltration (UF) membranes, was investigated. On a pilot scale, a recycled UF membrane module in spiral configuration was evaluated in a PV solar powered system. The treatment was evaluated for removal of apparent color, turbidity, chemical oxygen demand (COD), total phosphorus (TP), nitrate, ammonia, total organic carbon (TOC), total nitrogen (TN) and chlorophyll a. The results showed that the recycled UF membranes provided a permeate with average values of 0,1 UNT for turbidity; 2.2 uH for apparent color; 26.3 mg.L-1 of COD; 1.6 mg.L-1 of TP, 7.4 mg.L-1 of TOC; 0.2 µg.L-1 of chlorophyll a and 0.4 mg.L-1 of NT. The highlights were removals higher than 90% for TP, TOC and COD; higher than 96% for chlorophyll a and apparent color; higher than 98% for turbidity and higher than 40% for TN removal. The PV-recycled UF membrane system demonstrated satisfactory operation capacity, with no risk of drastic reduction in operating pressure or shutdowns, for the purpose of algae removal and recovery of the environmental quality of eutrophicated ornamental lakes.