Research On Resource Recovery And Purification Technology Of Vessel Oily Sewage

The annual output of oily sewage from a dock reaches 400,000 tons and the emulsification of sewage is serious.The fluctuation of water volume between different batches of oily sewage is fierce and the water quality varies greatly.At present,it is urgent to propose a complete set of oily sewage treatment program to ensure that the effluent reaches the national A-level emission standard.In this study,the water quality analysis,oil-water separation technology,flocculation technology,and oxidation technology were carried out to analyze and treat oily sewage.The main evaluation indicators were the water content of oil phase,COD and petroleum content.At the same time,key indicators like ammonia nitrogen,total nitrogen,total phosphorus were measured to make a comprehensive evaluation of the treatment effect of each technical aspect and determined the best technology and conditions.On this basis,the feasibility of the removal of biological nitrogen and phosphorus was studied and a complete set of sewage treatment process was finally obtained.In order to reduce the water content in the oily phase of the sewage,the oil-water separation experiment chemical agents were used for the oil-water separation test.The optimum value of PR-3 inorganic demulsifier coagulant addition was 150 mg/L,PR-11organic demulsifier coagulant addition was 1.5 mg/L,ultrasonic time 20 min,ultrasonic power 700W,ultrasonic frequency 45 kHz and temperature 35°C.The pH value of the oily sewage was adjusted to 9 after oil-water separation experiment and allowed to stand at a constant temperature for 7 h.Finally,the water content of oil phase was1.10%,which reached the test target of the moisture of the recovered oil below 2%.After the oil-water separation treatment,there was still a large amount of dissolved oil and emulsified oil in the sewage.The results of chemical flocculation experiments showed that under the constant temperature of 35°C,when the pH value of the SY Water was adjusted to 9,and the inorganic flocculant XN-1 addition was 200 mg/L and the organic flocculant XN-2 addition was 2.0 mg/L,the flocculation of the SY Water had satisfactory performance.The effluent was bright and translucent and the content of COD and petroleum in the test water were significantly reduced.In order to improve the biodegradability of the sewage and meet the conditions of biochemical treatment influent,the molar ratio of Fe²⁺to H₂O₂?1:9?,the dosage of Fe²⁺?4 mmol/L?,and the dosage of H₂O₂?36 mmol/L?and reaction time?3 h?were detemined.The COD content was 308mg/L and the petroleum content was 1 mg/L,which indicated the oxidation effect was the best.Through the biodegradability evaluation and biochemical treatment process of oily sewage,it was found that the biodegradability of the oily sewage was significantly improved after a series of treatment,and the sewage had good biochemical ies.The content of COD,nitrogen and phosphorus in oily sewage meeted the influent index of the multi-level AO process after Fenton oxidation treatment.Meanwhile,the effluent of this type of sewage treated by the multi-level AO process in the engineering examples was superior to the national A-level emission standard.