Different Configurations of a Bioretention System Focused on Stormwater Harvesting in Brazil

Low impact development (LID) practices contribute to the reduction of flooding and improvement of water quality. Water crises may be a result of water scarcity and flooding due to climatic changes and the increase of impervious areas, and thus, stormwater harvesting becomes a sustainable alternative solution for relative water problems. The performance of a bioretention system with the submerged zone (SZ) and unsaturated zone (USZ) was evaluated as an alternative for stormwater harvesting. The study was carried out on a laboratory scale, using a bioretention box to simulate the processes that occur in a real system and in the field. The system was efficient in removing TP (68.5% and 76.5%), COD (71.6% and 56.9%), and NO2 (28% and 16.6%) in USZ and SZ events, respectively. NH3 removal (31%) occurred only at SZ events. NO3 was exported at all events tested but at values below the Brazilian CONAMA Resolution 357/2005 on the quality of water bodies for supply. The bioretention effluent showed relatively high values of turbidity; however, the pH parameter presented good values in all experiments (>6.5 and <7.5), and E. coli only in some cases presented satisfactory values to meet the Brazilian Standard for Rainwater Usage for nonpotable purposes (<200 MPN/100 mL). In general, both configurations provide different improvements for stormwater to support sustainable water resources management. This study presents a comparison between bioretention systems with and without SZ as an initial proposal for the improvement in bioretention systems in Brazil; however, more experiments must be monitored, and new improvements should be tested for reaching restrictive water reuse purposes.