Study On The Disposal Of Gelatin Production Wastewater By PSB

Manufacturing of gelatin needs large amounts of water and generates serious pollution. Because there are high contents of organics,calcium and alkalines in the waste water, it is very difficult to treat it. Based on the existing technology, the cost of building up acceptable waste water treating facilities is no less than that of building a middle sized gelatin factory. The key to solve the problem of pollution generated in gelatin manufacturing is to cut down the cost.Works covered in this thesis is based on the production engineering. Water analysis and water volume calculation have been done in every waste water-producing procedure. Split-stream treating technique has been put forward, which is diffracting several thousand tons of waste water produced in the process of manufacturing 1 ton gelatin firstly, after treating the less polluted water with flocculation or precipitant, it is acceptable to discharge it or reuse it; water needing advanced treatment is only hundreds of tons, reduced nearly 80%. At the same time, water treating expenditure is cut down.Waste water generated in such procedures as recycle of calcium hydrophosphate; pickling and water washing; soaking in lime, etc. needs advanced treating. The method put forward in this thesis is treating by photosynthetic bacteria. What we concern about are :how do the factors such as compatible pH range for this method, reacting time,illumination, dissolved oxygen, amount of bacteria etc. influence the treating effect; what we can choose as the carrier of photosynthetic bacteria; what are the different effects by using different carriers. For the waste water generated from the procedures of recycle of calcium hydrophosphate and soaking in lime, comparision between the effects of traditional activated sludge method and photosynthetic bacteria method is given. COD, ammonia nitrogen and orthophosphate are choosen as the indicators of treating effect. Modern measuring and test instruments such as IR spectrum is used to analyze and evaluate the treating process.Reacting conditions are decided by treating waste water generated from the procedure of pickling, because it is not so difficult to treat as the others. The treating of phosphor and calcium water and soaking in lime water is carried out under the decided conditions. Results of this study are listed below:Illumination and certain amount of dissolved oxygen are favorable to this method.There are a wide adaptive PH range, 5.5-10. Within this range, we can remove more than 80% COD using this method. But PH 6.5 is best for reacting time and the recycling of calcium hydrophosphate. When the concentration of bacteria is above 3 billion per ml and the volume ratio of waste water to photosynthetic bacteria liquid is in the range of 1:1 to 9:1, bacteria dosage can have no obvious influence to the treating effect.Adsorption and embedding are chosen to fix the bacteria. We use calcium hydrophosphate deposit, acticarbon, saw dust as absorbent, algin and agar as embedding material seperately, and the treating effects are tested. We can see from the result that calcium hydrophosphate is the best to absorb photosynthetic bacteria. It has little influence on the activity of bacteria and can ensure the acceptable treating effect. What more, by adjusting the value of pH, it can deposit very easily. By treating with photosynthetic bacteria, COD can be removed more than 90% in the phosphor and calcium water, more than 95% in the lime soaking water. But photosynthetic bacteria can use limited amount of nitrogen and phosphorous, we can not use this method in denitrify and dephosphor.