Analysis of the effectiveness of combining inorganic coagulants with chitosan and bentonite in the treatment of raw water

Abstract

The production of drinking water often leads to the creation of a high residual concentration of aluminum when mineral salts are used. This concentration must be carefully monitored and controlled. A study was carried out at a drinking water production facility situated in Al Hoceima, Northern Morocco.Throughout this investigation, the treated water from the plant underwent comparative testing, evaluating the effectiveness of chitosan as a flocculant and bentonite as an adjuvant with inorganic coagulants (aluminum sulfate and ferric chloride). The objective was to reduce the residual aluminum concentration in the water after treatment while minimizing the use of inorganic coagulant. Coagulation-flocculation tests, employing a jar test, optimized coagulant dosage while enhancing turbidity and oxidability removal rates.The coagulation-flocculation tests showed that the combination of aluminum sulfate with 10 mg/L of chitosan and 140 mg/L of bentonite, proved to be significantly more effective. Compared to traditional treatment methods using aluminum sulfate alone, this combination reduced the residual aluminum concentration by 38.88%. The optimal parameters were as follows: aluminum sulfate dose of 10 mg/L, a pH of 7.83, an aluminum concentration of <0.07 mg/L, and a turbidity removal efficiency reaching 95.94% and oxidability removal of 42.70%.

Keywords

• Coagulation-flocculation
• Jar test
• Ferric chloride
• Alum
• Turbidity