Application of hydrocyclone in chemical precipitation

This study demonstrates the use of hydrocyclone as a thickener to precipitate sulfate ions from wastewater. Simulated wastewater containing different concentrations of sodium sulfate (100–400 mg L−1) dissolved in distilled water was prepared. Lime was added as the precipitating agent. Different flow rates of the feed (3–11 L min−1) were used for two split ratios (0.1, 0.9). The results showed that increasing inlet flow rate, initial concentration, and split ratio enhanced the separation by concentrating sulfate ions in the underflow. Design Of Experiments was performed to determine the most effective factor on the response (underflow concentration) and to assign the optimum operating conditions. The effect was in the order: inlet flow rate, initial concentration, and split ratio. The quadratics of the factors also affected the separation in the order (inlet flow rate)2, (inlet flow rate) × (split ratio), (inlet flow rate) × (initial concentration). The optimum (maximum) value of the underflow concentration of sulfate ions was 856.538 mg L−1 at the optimum operating conditions (11 L min−1 inlet flow rate, 400 mg L−1 initial concentration, and 0.9 split ratio). The experimental value at the optimum operating conditions was 932 mg L−1 including 8% error. The process was applied on a real wastewater taken from a tile factory. The results confirmed the experimental results in that the pollutant was concentrated in the underflow. It was concluded that using hydrocyclone as a thickener was feasible to separate sulfate ions from wastewater. Also, the separation using hydrocyclone could be integrated with another technique such as electrocoagulation or ion exchange to recover sulfur as an attempt toward sustainable development requisites.