Study On Treatment Of Wastewater From Aqueous Enzymatic Extraction Of Camellia Seed Oil

Camellia seed wastewater is a by-product of aqueous enzymatic extraction of camellia seed oil, which is rich in protein, carbohydrates and camellia saponin etc., if it is discharged directly that would cause serious pollution to the environment. Therefore, it is of great practical significance to carry on the purification treatment. Based on researches of other food processing wastewater treatment, this research focused on exploring and optimizing treatment technology of camellia seed wastewater. The main results are as follows:1. Analysis of main chemical components and water quality indexes of camellia seed wastewater. The main chemical components of camellia seed wastewater:camellia saponin content is 6.2%, protein content is 5.4%, polysaccharide content is 5.8%, and lipid content is 0.8%. The result of water quality index of camellia seed wastewater:COD concentration is 358300 mg/L, total phosphorus concentration is 40 mg/L, SS concentration is 12108 mg/L, ammonia nitrogen concentration is 432 mg/L, pH is 7.9 and the chroma is 2500 times.2. Treat camellia seed wastewater by acidification-coagulation-anaerobic. After 7 days of natural acidification, the camellia seed wastewater is coagulated by 10% concentration PAC (3% amount) and 3% concentration PAM (0.2% amount), then take supernatant to anaerobic digestion after standing, the time of anaerobic digestion is 5 days. The COD concentration of anaerobic effluent is 15000 mg/L, ammonia concentration is 452 mg/L and chroma is 500 times.3. The acidification-coagulation-anaerobic process effluent is further treated by Fenton to further reduce COD concentration. Optimized based on single factor, optimal conditions of Fenton reaction are:the initial pH was 3, dosage of FeSO4-7H2O is 30 g/L, the dosage of H2O2 is 30 g/L, and the reaction time is 4 h. The COD concentration of treated wastewater is 1000 mg/L, ammonia is 360 mg/L and chroma is 100 times.4. Biological contact oxidation treatment is used to further reduce the COD concentration. By a single factor test to get the best conditions for biological contact oxidation:HRT is 10 h, the influent pH is 8 and the amount of dissolved oxygen is 4 mg/L. The COD concentration of treated wastewater is 180 mg/L, ammonia is 320 mg/L and chroma is 50 times.5. Taking into account the higher nitrogen and phosphorus content of wastewater, first using the following conditions to get optimal parameters of denitrification:The reaction pH was 10.0, the dosage of MgCl2 is 20 g/L, the dosage of Na2HPO4 is 23.3 g/L and the reaction time is 3 h. After denitrification, the ammonia content in wastewater is reduced to 14 mg/L. Based on this, using three dephosphorization methods, they are:use alone FeCl3, use alone CaCl2, combined use FeCl3 and CaCl2. After a comparative analysis of the results shows that single addition of CaCl2 method most suitable for practical application, and when CaCl2 dosage is 4 g/L, total phosphorus concentration of wastewater is 0.2 mg/L, ammonia content is 13 mg/L, COD concentration is 85 mg/L, chroma is 5 times, up to the national "Integrated Wastewater Discharge Standard" (GB8978-1996) an emission standard.6. In the case of the best conditions and stable operation, COD concentration of combined process effluent during actual operation is 84 mg/L approximately, ammonia nitrogen content is 12 mg/L approximately, total phosphorus content is 0.22 mg/L approximately, SS content is 48 mg/L approximately, chroma is 5 times, up to the national "Integrated Wastewater Discharge Standard" (GB8978-1996) an emission standard.