Renewable energy desalination pilot plant: energy, mass and volume balances

Abstract

Facing the current scenario looking for water scarcity solutions, water desalination is an alternative for this problem, because it can treat water with a high concentration of total dissolved solids (TDS) and making it potable. The present work had as objectives to detail the energy consumption and elaborate the balances of energy, mass and volume of a pilot plant of brackish water desalination with production capacity of 1 m³.h-1. The pilot plant was composed by an ultrafiltration system (UF) and softening as a pre-treatment of the reverse osmosis (RO), and fed with brackish water due to the mixture of sea and river waters. The energy supply by means of integration between the conventional grid, and solar converted in electricity using photovoltaic panels. The system was installed in the dependencies of the water treatment plant of Sanepar, in Praia de Leste, located in the county of Pontal do Parana, Parana State. There were realized 20 operations: the first 10 treated brackish water with initial concentration of TDS of 3,500 ± 100 g.m-3 and the last 10 with TDS initial concentration of the brackish water of 7,000 ± 100 g.m-3. The total consumption of energy during the 20 operations was 388.61 kWh, the production of solar energy during the study period was 111 kWh and the quantity of energy provided by the conventional grid was 277.61 kWh. The effective consumption of energy for the permeate production was approximately 4.30 kWh.m-3. The total consumption of energy composed by the consumption of preparing the brackish water and the UF and RO systems during the first 10 operations was 5.84 kWh.m-3 to produce 28.06 m³ of permeate with TDS concentration of 28 g.m-3. In the last 10 operations the total consumption of energy was 5.34 kWh.m-3 and produced 26,85 m³ of permeate with TDS concentration of 67 g.m-3. At the monitoring it was observed that the removal of color and turbidity in water occurred in the UF system and the removal of TDS happened in the RO system.