Optimization And Application Of The Treatment For Salt Industrial Wastewater

Salt chemical industry refers to the process that salt or bittern resources is processed into sodium chlorate, soda, chloride, caustic soda, hydrochloric acid, chlorine, hydrogen, sodium and the processes that these products are further processed and comprehensively utilized. A lot of pollutions in salt chemical wastewater were brought into the environment, and the difficulty of the salt chemical wastewater treatment is great because of the complicated composition and huge emissions.In this paper, the treatment of salt chemical wastewater was researched based on the reconstruction project of40000tons/day wastewater treatment of Tianjin Dagu Chemical Co., Ltd... The treatment processes were selected and optimized based on the original treatment process in order to make the water quality of the effluent met the secondary emission standards of 《Tianjin Integrated Wastewater Discharge Standard》(DB12/356-2008). Based on the bench and pilot test, the scientific basis was provided for the reconstruction project. The activated carbon catalytic ozonation, moving bed biofilm reactor (MBBR), hydrolytic acidification, break-point chlorination and many-point-water-inflow activated sludge were used.Experimental results show that:(1) With the effluent of the original treatment process as the influent of the activated carbon catalytic ozonation oxidation method, experiments were conducted in the device of activated carbon catalytic and ozone oxidation. COD, SS, Chloride and pH of the influent were40-200mg/L,18-40mg/L,10000-15000mg/L,7.0-8.0respectively. The results showed that COD of the effluent was higher than the influent, and the contact time had no significant influence on the treatment effect by the activated carbon catalytic ozonation.(2) Hydrolysis acidification unit was added behind the first sedimentation pond of the original process, and the original contact oxidation pond was transformed to the MBBR. The results of the bench and pilot tests showed that COD of the effluent of the process was below than60mg/L and the ammonia was higher than8mg/L when HRT of the hydrolysis acidification unit was4h, and HRT of the MBBR was21h.(3) The defect of the organic distribution was conquered after the single-point-inflow activated sludge was transformed to many-point-water-inflow activated sludge. The difficulty of the follow-up treatment was reduced.(4) The ammonia nitrogen content of the effluent was not below8mg/L with nitrification and denitrification because the wastewater contained high content Chloride. The break-point chlorination was used to remove ammonia nitrogen and the reaction rate of the method was high. The standard of ammonia nitrogen content of the effluent could be met with The proper dose of the reagent added into the wastewater according to the ammonia nitrogen of the effluent from the biochemical unit wastewater.On the basis of results of a lot of experiments, the secondary emission standards of 《Tianjin Integrated Wastewater Discharge Standard》(DB12/356-2008) could be met by using the combination process of many-point-inflow activated sludge, hydrolysis acidification, MBBR and break-point chlorination to treat the salt industrial wastewater.