Journal of Ecological Engineering (Aug 2020)
The Removal of Salinity in a Reed Bed System Using Mangroves and Bacteria in a Continuous Flow Series Reactor
Abstract
The supply of clean water is a major environmental problem in some areas, which is possibly handled through the biodesalination technologies, a concept that involves separating the salt content, and reducing salinity, using bacteria and plants. This research therefore applied Avicennia marina (AM) and Rhizophora mucronata (RM) mangroves, in addition to Vibrio alginolyticus, in 12 reactor reed bed systems arranged in series (AM-RM) to attain a continuous flow. The evaluated salinity level was 20‰ and 25‰, obtained using artificial saline water. Meanwhile, the reed bed system, measuring 0.14 m3 (0.7x0.5x0.4 m), comprises a filter layer component, which consists of sand and gravel, with a diameter of 1 cm and 2 cm. This investigation was performed for 18 days, and samples were collected every 2 days, and the main parameters of salinity, Na, Cl and the potassium ion concentration, electric conductivity and Colony Forming Unit (CFU), as well as the supporting parameters, including pH and temperature, were evaluated. The results showed a water discharge rate of 18 mL/min, and the addition of Vibrio alginolyticus, produced the best salinity level (90%) on day 6 of operation. The outcome of the initial 25‰ sample value, measured as 20.09‰ at the inlet, was reduced to 1.99‰ at the outlet, after treating with Rhizophora mucronata. This was within the range for brackish water, and the calculations using the final salinity values showed a Cl-content of 1129.47 mg/L, while the best conductivity value was 3,485 mS/cm. In addition, the highest selective media CFU was Log 5.6, observed in the Avicennia marina 25‰ reactor, to which Vibrio alginolyticus was added. The supporting parameters of temperature and pH measured 30oC and a range of 6-8, respectively. Therefore, the removal of salt from brackish water using the mangrove operation is assumed to continuously produce low salinity levels.
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