Study On Treatment Technology Of High Salt And High Ammonia Nitrogen Wastewater From Thermal Power Plant

High salinity wastewater is a certain kind of wastewater with a high mass fraction of salt which is at least 1%.Usually,high salinity wastewater contains a variety of ionic compositions.The total amount of high salinity wastewater is huge and shows increasing trend year by year.In view of the differences among the industry and the production process,apart from a large number of inorganic salts,the main pollutants in high salt wastewater are of great differences.In this paper,we mainly focus on the high salt wastewater in which ammonia nitrogen acting as the main pollutant.In order to explore the possibility of treat the high salt high ammonia nitrogen wastewater via biochemical method directly,the chemical precipitation?MAP?pretreatment&salt tolerant denitrifying bacteria A/O biochemical treatment and ozone oxidation technology combined process was applied,in which complex salt tolerant nitrogen removal agent was inoculated and salt tolerant nitrogen and biochemical process as the main body in removing salt,dilution conditions.The experimental results showed that treated wastewater had reached the discharge standard of 0.2 mg L^-1.Furthermore,inspired by the unique characteristics of anammox bacteria,the advantage of anaerobic ammonium oxidation process in the treatment of high ammonia nitrogen wastewater was discussed,and the salinity tolerance experiment of anammox bacteria was accordingly carried out.This wastewater treatment process is expected to greatly reduced the operation cost and energy consumption in the future.Through a series of experimental studies,the suitable technological conditions are preliminarily proved.The results show that:1.Using struvite precipitation,through single factor experiment,the obtained optimal process parameters are pH 9.5,HRT=30 min and n?Mg?:n?NH₄⁺-N?:n?P?=1.1:1:1,slowly adding Mg²⁺and PO₄^3-and alkali at the same time.Under this condition,the effluent ammonia removal rate reached 95.2%.2.Controlling the temperature between 28 and 30?,salt tolerant denitrifying bacteria were used to treat the high salt and high ammonia nitrogen wastewater in A/O reactor;the pH of the anaerobic reactor is about 7.0⁷.5 and the pH of aerobic reactor is at around 8.0⁸.4;the DO of aerobic reactor is at 3⁴ mg·L^-1,the nitrification liquid reflux ratio is between 150%and 250%,sludge reflux ratio is at 50%-100%,hydraulic the residence time is 48 h,the effluent ammonia concentration held steady at less than 2mg·L^-1.3.Ozone oxidation process was used to treat biochemical effluent.When the pH of wastewater was 7.5,keep the ozone production at 10 g·h^-1,the gas flow rate at 160 L·h^-1and the reaction time of 120 mins,the ammonia nitrogen concentration of effluent could be controlled at below 0.2 mg·L^-1,and TOC concentration realized 10 mg·L^-1.4.After the sewage treatment station accepts high salt and high ammonia nitrogen waste water,it runs steadily and verifies the denitrification performance of microorganism in high salt environment.5.CSTR reactor was used to enrich anammox,at the temperature of 35?and the pH of 7.5-8.0,NLR increased gradually,the TN removal rate was above 86.1%,considerable nitrogen removal was achieved.With the promotion of salinity,the removal rate of TN gradually decreased.After acclimation for a period of time,the TN removal rate was stabilized.When the salinity conditions are at 1%-2%,the removal rate of TN was stable between 77%and 80%.Therefore,using chemical precipitation?MAP?pretreatment&salt tolerant denitrifying bacteria A/O biochemical treatment and ozone oxidation technology combined process to treat high salt and high ammonia nitrogen wastewater is feasible and effective,it also provides a theoretical basis for the design and application of practical engineering.After acclimation,the obtained anammox bacteria can survive and further assist the denitrification under 1%-2%salinity,but the time of enrichment and acclimation last a little longer.