Study On The Biologic Contact Oxidation Process For High Salinity Wastewater

The high concentration sodium thiosulfate wastewater has the characteristics of high COD, and high pH value. It belongs to petroleum chemical wastewater which difficult to be degraded. According to the characteristics of the high concentration sodium thiosulfate wastewater, the Bio-contact oxidation craft has proposed for this kind of wastewater.The high concentration of sodium thiosulfate in the wastewater has certain toxic action to the microorganism. Especially when the sailnity density suddenly changes, the toxicity is more serious. Therefore, the first step is improving the sailnity gradully to enable the microorganism adapting this of high-salt environment. In the experiment, the microorganism was domesticated by gradually increasing the concentration of sodium thiosulfate .The results of the experiment are as follows: when the salinity is increasing, the microorganism needs a period to adapt the salinity stock. With normal temperature among 20℃～35℃and adequate dissolved oxygen, the biochemical system should to be acclimated about 30~40 days before regular operation . And the results also show that we controlled the hydraulic residence time to be 36 hours and pH value of the inlet water among 8.8～12.25, aerated sufficiently , when the concentration of sodium thiosulfate, COD in the inlet water is among 573mg/L～5680mg/L , 1000 mg/L～2500mg/L respectively , the COD in the effluent water could be reduced to 50mg/L～200mg/L, and we could get the removing rate of COD as 90%～95%; when the concentration of sodium thiosulfate, COD in the inlet water is among 5680mg/L～14812mg/L , 2500 mg/L～6000mg/L respectively , the COD in the effluent water could be reduced to 100mg/L～400mg/L, and we could get the removing rate of COD as 90%～97%. The Bio-contact oxidation system also has the ability to handling ammonia. It will get the removing rate of ammonia as 45%～75%in stable operation period.When the Bio-contact oxidation system was subjected to attack load, it would recover rapidly, about within 3~5 periodicities.In addition , we researched the mechanism of the removing course of sodium thiosulfate by the Bio-contact oxidation process , and got the reaction mode of the degradation of organisms as :...