Flocculation Effects Of Moringa Oleifera Extracts On Particulates In Water And Its Application

Lots of inorganic and organic contaminants introduced by nature calamities and anthropogenic activities enter into waters, giving rise to deterioration of water quality. High water turbidity is a basic issue to most river channel. Clays such as kaolin, coloured organic colliods such as humic salts and algaes are the main matters that can induce high turbidity. The main advantages of Moringa oleifera coagulant derived from plants as water treatment material are apparent:non-toxic, biodegradablity and little influence on environment and human. In this study, Moringa oleifera seeds were the main material to produce Moringa oleifera coagulant. We compared the ability of saline solution of different variety and concentration to extract active components and explored their properties; then we selected the appropriate agitation speeds. The Moringa oleifera coagulant was used to study the removal efficiency of kaolin suspensions, humic salts solution and Microcystis aeruginosa solution under different pH condition and coagulant concentration; At last, a set of flocculation device was used to research the efficency of Moringa oleifera coagulant to reduce riverwater turbidity and color, as well as its impact on water quality. The results are as follows:(1) Comparing the ability of saline solution of different variety and concentration to extract active components, the results revealed that 1 mol/L NaCl had better extraction efficiency. The part with molecular weight greater than 10 kD included cationic proteins, and could change the zeta potential of kaolin pariticles but not make them unstable and aggregate. The FTIR results showed that cationic proteins can play coagulation with the help of polysaccharide.(2) We chose following parameters as appropriate agitation conditions:fast agitation speed 200 rpm with 3 minutes; slow agitation speed 50 rpm with 20 minutes.(3) Moringa oleifera coagulant had high efficiency to remove turbidity for pH 7～9. For kaolin suspension with different initial turbidity, Moringa oleifera coagulant can decrease the turbidity from 20.6～99.1 NTUto 4～9 NTU.(4) Moringa oleifera coagulant had high efficiency to remove color of humic salt solution for pH 6-9. Dosage of Moringa oleifera coagulant increases by the concentration of solution. Colority removal rate reached 66.7～91.8%.(5) Moringa oleifera coagulant had high efficiency to remove algaes. The remove efficiency can reach up to 98% for various cell densities. After 25 days’ cultivation, the algaes didn’t resuspend. Moringa oleifera coagulant can reduce algals chlorophyll content and intracellular esterase activity, and destruct algals cell membrane.(6) Simulation tests showed that Moringa oleifera coagulant could decrease water turbidity and color comparing with control. In short time, Moringa oleifera coagulant had little effect on organic matter, nitrogen and phosphorus of water, but it would increase organic matter, nitrogen and phosphorus of sediment.