Effectiveness of locally available plant materials in the dry zone of Sri Lanka as natural coagulants in treating turbid water

Abstract

Purpose: Polyaluminium chloride (PAC) is used to treat the turbid water at water treatment plants. As an alternative, natural coagulants are being tested as those are biodegradable and safe for human health. The study focused to test the locally available five different plant species as natural coagulants. Research method: Turbid water samples were treated separately by 50ppm to 100ppm of PAC as a control, and powdered Moringa (Moringa oleifera), Arjun (Terminalia arjuna), Jack fruit (Artocarpus heterophyllus), Clearing nut (Strychnos potatorum L.) seeds and Aloe (Aloe vera) as treatments. Turbidity, pH, and EC were measured before and after the treatments. The experiments were conducted as a full nested design to test the effect of coagulant variety and concentration on the turbidity removal with a mean comparison using Turkey’s Studentized Range Test at 0.05 significant level. Finding: Moringa showed the highest turbidity removal efficiency of 84.8 (± 8.9) %. Arjun and Aloe demonstrated turbidity removal efficiency of 42.6 (± 6.71) %, and 34.9 (± 6.03) % respectively and it was significantly (P<0.05) higher than those of Jack fruit 18.2 (± 9.3) % and Clearing nut 30.4 (± 23.7) %. This study concludes that among natural coagulants tested, Moringa has the highest capability of removing the turbidity of water. Research limitation: Clearing nut seed powder was taken from a shop which may be of inferior quality compared to the fresh seed powder. Originality/ Value: There is a higher potential to use Moringa seed collected from the dry zone as a natural coagulant.