Study On The Treatment Technology And Engineering For Photosensitive Wastewater

According to the " NATIONAL HAZARDOUS WASTES LIST ", the used developer, fixative, positive and negative film, photographic papers, photographic materials and medicines are HW16 photosensitive materials wastes, mainly coming from photographic chemicals, photographic materials manufacturers and publishers, newspapers, printings, the film works, photographs of the community, the department of irrigation and X-ray and CT scan rooms in hospitals. The fixative and developer contain many harmful components, such as silver, borax, phenol compounds and benzene compounds. Although the government has taken them in the Hazardous Waste Management System, there are still some weak links in environment management in the process of their production, emission, collection and disposition.In large and medium cities, the waste fixative and developer are directly discharged into sewerages or sewage treatment plants, which increases the difficulty of secondary sewage treatment. In rural areas and those townships without sewage treatment plant, the developer and fixative wastewater is discharged directly into rivers and lakes. It brings tremendous hazards to the atmosphere, soil and human health. At present, the treatment technology on this wastewater only emphasizes on the reuse of silver, and neglects the treatment of other harmful toxic substances. Because of its high concentration, disorder emissions into the environment and the serious environment impact , domestic environmental protection department gives more and more attention to photosensitive wastewater treatment. Many provinces have enacted various laws and regulations, in order to solve the wastewater treatment effectively .Currently, the mainly treatment techniques on photographic wastewater are settlement coagulation, ion exchange and other physical and chemical methods,chemical precipitation and chemical oxidation, and other chemical methods,activated sludge, anaerobic biological contact. These methods are not effective to photosensitive wastewater. The treatment technology and engineering has not been reported in the literatures. This essay based on projects of Jilin province environment protection bureau"PHOTOSENSITIVE WASTE WATER TREATMENT ENGINEERING", experimental study on biological treatment, pilot-plant design, equipment installation, test, and pretreatment.The main study contents are as follows.1. Based on the characteristics of photosensitive waste water, the technique development has been done in laboratory, and pretreatment process has been discussed and improved.2. Deep research on biological treatment techniques have been done to select the suitable method to the wastewater treatment.3. Engineering study on the wastewater treatment equipment has been done to find out available solution to projects in the process of resolving the problem, and train suitable micro-organisms. Pretreatment and biological treatment methods and engineering research has been done according to analysis of the character of the wastewater and the practical project. Conclusions are as follows:(1) Pretreatment of photographic wastewaterIn the pretreatment part, a wide range of physical and chemical treatments are carried out, including coagulation, adsorption, chemical oxidation (Fenton reagent), flocculation, micro-electrolysis, and the combination of experiments, etc. The final suitable pretreatment method of photographic wastewater is micro-electrolysis process. The best technical parameters are: iron ratio is 1:1, pH=6, aeration way of intermittent aeration, inflow:padding= 1:1, retention time is 30 min.(2) Study on biological treatment techniquesComparing the three contact oxidation - acid hydrolysis combination with activated carbon and biological treatment in high concentrations of photosensitive wastewater, the former is better than the latter in the effect .The three contact oxidation - acid hydrolysis process on the composition has better impact in stability, and it can effectively improve the treatment rate at a high temperature and the right pH range. The high capacity of sewage treatment process was established in total control of pollutants. The water treatment process on the high load may not reach the concentration of sewage discharge standards, but it can provide the corresponding reference data to the wastewater treatment. The polishing process was suggested to be employed after biological treatment process.(3) Engineering researchBased on the conclusion of experimental technique development, parameters were borrowed from similarity engineering, photosensitive wastewater treatment process were determined and designed, the process is as follows: micro-electrolysis as a pre-treatment, three of contact oxidation - acid hydrolysis process as a combination of biological treatment, activated carbon for follow-up treatment.â‘ In the course of running the project, the indicators were monitored in the entire system .The major monitoring indicators were CODCr, pH, temperature, biological observation phase, dehydrogenase activity, DO, nitrogen, phosphorus and so on. The data showed that the projects ran stably.â‘¡Effective solutions was find out in the process of running the unusual problem, such as excessive aeration, bubble, by a series of effective measures, the processing equipment resume to normal operation.â‘¢Enrichment culture was done to the microbial treatment plant ,in order to get the cultivation of microorganisms The degradation of the test results was done in order to cultivate the significantly degrading bacteria for use in actual results. The result showed that the train has a certain capacity to the wastewater, but also, experimental study was needed for further strain identification.