Study On The Natural Macromolecular Flocculant Of Cactus

More attention have been paid on natural polymer used in the water treatment because of its advantages, such as non-toxic, easily biodegradable, no secondary pollution, many raw materials and low prices in recent years. This dissertation analyzes and sums up the existing natural polymer flocculants preparation and flocculation in order to develop a new type of green flocculating agent from the o Milpa Alta cactus which is resourceful as well as low-priced.Gel, powder, and polysaccharide flocculants were prepared using Cactus, and they are employed to degrade kaolin suspension, and the turbidity removal rate has reached more than 98%. Gel was chosen from the series of flocculation experiments in terms of lower cost and well flocculating effect. The results indicate that the cactus gel has good flocculating in kaolin suspension system, adding 1mg/L～6mg/L of cactus gel, the turbidity removal rate can reach as high as 99.3%, Compared with other flocculants, it is less affected by salts, temperature, and pH, and also less amount.Remix experiments among cactus, sulfate gel, polyferric sulfate, and polyacrylamide are designed in this dissertation. The results show that, the cacti -polyacrylamide is the best flocculation, cacti-sulfate take second place considering the turbidity removal rate, size of alumina flower, the clarity. The best pH range of Cactus-sulfate is 5.0 to 9.0; it is less affected on water temperature. The effect on the flocculation of Cactus-polyacrylamide is lower both the pH and the water temperature; salts has negative impact on both of them.In addition, the practical application has been studied in the dissertation. As an example of realistic domestic wastewater treatment, the results show that when adding 2.14 mg/L of cacti, the turbidity removal rate of real-life sewage will reached 88% whereas adding Cactus-sulfate, cacti-polyacrylamide the turbidity removal will reach to 95.44% and 96.33 % respectively. That's to say using the remix flocculation is better than using cactus only. Furthermore, the cactus has a better on the removal of COD on sewage, when remix with sulfate the COD removal rate can reach to 72.99%.