Study On The Treatment Of Wastewater From Enzymatic Extraction Of Camellia Oil By Coagulation + UASB + A/O Process

Aqueous enzymatic extraction is a new method for extracting vegetable oil.It does not need complicated refining processes such as deacidification,decolorization and deodorization,the indexes such as acid value,iodine value,saponification value,peroxide value and volatile matter of the obtained vegetable oil are not lower than the quality standard of the first-class pressed Camellia Oleifera seed oil.Based on this,this method has been widely concerned by scholars,and a large number of related researches have been done.The plant oil extracted by this method will produce a lot of waste water,and it is rich in organic matter such as protein and carbohydrate.The chemical oxygen demand（COD）can reach up to one hundred of thousands even hundred of thousands.If direct discharge of the waste water will cause serious pollution to the environment,which result in the application of aqueous enzymatic method in the extraction of vegetable oil is limited.In order to solve this problem,this study took the wastewater from the process of extracting camellia seed oil by water enzymatic method as the research object,and carried out the following researches on the treatment of the wastewater by coagulation pretreatment+UASB+combined A/O process:The water quality of the wastewater from the self-made water enzymatic extraction of camellia seed oil was as follows:COD was 135000-141000 mg/L,ammonia nitrogen concentration was 120-130 mg/L,p H was 4.5-5.0,suspended solids（suspended solid,SS）is 3021 mg/L.The coagulation pretreatment study of process wastewater showed that:through the combined treatment of 7%polyaluminum chloride（PAC）with a concentration of10%and 0.2%polyacrylamide（PAM）with a concentration of 3%,after 4 days of precipitation,The COD in the effluent of the primary sedimentation pool was 57800mg/L,and the removal rate was 57%;the ammonia nitrogen was 89.7 mg/L,the removal rate was 27%;the SS was 598 mg/L,and the removal rate was 80.2%.Start-up and operation characteristics of UASB:After 18 days,the system was successfully started;when the volume load was 8.5 kg/m³·d,and the RT was 10 days,the COD of effluent was 1445-7500 mg/L,and the average removal rate was 91%.The highest was 97.5%;The average gas production of the system reaches the highest value of 6.8 m³/m³·d;The p H value of the effluent was maintained between 7.0-8.8,and the effluent ammonia nitrogen was always higher than the influent ammonia nitrogen,up to 224.7 mg/L,and the average was 142.3 mg/L;The highest removal rate of SS by the system is only 10%.A/O process treatment effect:the system was started successfully for 24 hours;in the stable operation stage,the average effluent COD was 111.4 mg/L,the average COD removal rate was 85.5%,and the anoxic tank was 70.6%.The aerobic tank was14.8%;the average ammonia nitrogen was 12.7 mg/L,the average removal rate was95.3%,the anoxic tank was 19.1%,and the aerobic pool was 80.9%;The average SS concentration was 98.6 mg/L,the average removal rate was 81.3%,and the highest was 93.2%.The effluent reaches or gets close to the national"Comprehensive Sewage Discharge Standard"（GB 8978-1996）first-class discharge standard.The research on the distribution of microbial flora of anaerobic granular sludge showed that:after long-term operation,the bacterial abundance of anaerobic granular sludge increases and the flora structure was more complex,indicating that the wastewater was rich in nutrients and suitable for the growth and reproduction of various microorganisms;and Compared with the anaerobic granular sludge seed sample,the bacterial dominant flora in the anaerobic granular sludge sample did not change on the 60^thday,but the relative abundance increased;The bacteria with regard to the degradation of organic matter,especially macromolecular organic matter,increased.The abundances were all increased,indicating that a favorable environment for the degradation of macromolecular organic matter was formed in the UASB anaerobic reactor,and the degradation of organic matter may be dominated by the production of acetic acid;The relative abundance of Methanosaeta increased to66.7%,became the main archaea,indicating that the environment dominated by acetic acid created a good nutrient environment for the mass reproduction of acetic acid methanogenic archaea,so that the anaerobic granular sludge gradually developed towards the simplification of Methanosaeta.