Development of an Environmentally Friendly Energy Efficient Biofiltration System for Brackish Water Desalination

Abstract

Desalination has garnered significant interest as a means of addressing the demand for freshwater; nonetheless, traditional desalination methods can prove expensive and have adverse environmental effects. Hence, this study aimed to design and develop a 'brackish water desalination system, that integrates marine algae and a biofilter liner system composed of mature compost, clay-polyethylene-clay composites. To begin, marine algae samples were gathered from Negombo, “Thalpe” beach, and Baticoloa lagoon and cultivated in a controlled laboratory environment. A well-developed sample was then chosen for the treatment system. Next, a portable trapezoidal pit-shaped model was constructed, measuring 90 cm across the top square, 30 cm across the bottom square, and with a depth of 30 cm. This structure was encased with steel wire mesh, with the bottom layer of mesh serving to release the water. The biofilter system was constructed with a 20-cm clay polythene-clay composite liner along with a mature compost layer. Algae have shown great potential in desalination processes due to their unique biological properties. The incorporation of algae abundant Negombo Lagoon water in the final layer of the biofilter system serves a crucial role in desalinating the water. Characterization of brackish water of Negombo lagoon electrical conductivity, salinity %o, total dissolved solids and pH was 17,910mS/cm, 35%, and 8,957ppm, 7.76 respectively. Hydraulic conductivity of the liner was 2.64 × 10-7 cm/sec. Parameters were taken from both filtrate and inside the bioreactor regularly at 4.00pm. The collaborative efforts of mature compost, algae, and the microalgal community proved successful in achieving a 90% reduction in salinity.