Water Recovery of brine water treatment from a small-scale desalination system in Nakhon Ratchasima

Abstract

This study aims to recover water from treating brine water of a small-scale desalination using a solar still. The design focuses on keeping temperatures inside at conditions suitable for water evaporation from the brine water basin. Water vapor rises and condenses into water droplets on the transparent glass cover, moving down the slope into a channel and collecting outside. The solar still is 1.0 m x 1.0 m x 0.5 m (width x depth x height) with a 25-degree slope for a transparent glass cover on top. This slope allows the water droplet to move down without reentering into the brine water basin below. The brine water was placed on top of the carbonized rice hull. The black residues can absorb heat energy by being a dark color, locally available, environmentally friendly, and stable. The test results during rainy and early winter months showed that the prototype solar still produced the average recovery water of 150 mL/day/set, with the hourly temperatures inside the chamber ranging from 30 to 70.1 Celsius. The highest inside temperature occurred at 2 PM, with an average of 70.1 Celsius. A correlation was observed between temperature and the amount of distilled water. Water recovery from the prototype ranged from 1,090 to 1,256 mL/day. Low recovery occurred in the rainy months. Estimation of water recovery rates in Nakhon Ratchasima ranged from 45 to 55 mL/m²/day. The solar still provides an alternative to recover water and mitigate the direct impact of brine water discharge from the small-scale desalination in Nakhon Ratchasima from possible effect of salinity water discharge. The method is economical, less burdensome to the caretaker, and low budget. The recovery water is freshwater; thus, it can be reused and has no long-term impact. The use of solar still is an auxiliary device that can be used with small-scale desalination in areas with saline water.