Study On The Disinfection Test Of Potassium Ferrate Based On Control Disinfection By-products

Disinfection is the last barrier in the process of drinking water treatment,which is very important for the health of drinking water.Chlorine disinfection is still the most commonly used disinfection method in water works.With the development of the economy,the water quality of the water source is polluted to different degrees,which leads to the increase of microorganism and organic matter in the water,and the separate chlorine disinfection process can not meet the health requirements of drinking water.Potassium ferrate,as a new agent,is a combination of oxidation,flocculation,deodorization,germicidal and algae removal.It will not produce toxic and harmful substances.It is a kind of green multifunctional water treatment agent.Potassium ferrate is used in drinking water treatment.It is of great significance to the improvement of drinking water safety and disinfection process.This paper studied the inactivation effect of Potassium Ferrate on bacteria and total coliform bacteria used the filtered water of the Ji'nan snow mountain water plant,and studied the control effect of Potassium Ferrate on the organic matter and the chlorine disinfection by-products in the water.The main contents and results of the experimental study are as follows.?1?The effects of disinfectant dosage,pH and reaction time on the inactivation of bacteria and total coliform bacteria were studied by plate counting and multi tube fermentation.The results showed that when pH and reaction time were fixed,the inactivation rate of bacteria and total coliform bacteria increased with the increase of potassium ferrate dosage.When the dosage was 1.5 mg/L,the total number of bacteria reached the requirements of"Hygienic standard for drinking water"?GB5749-2006?,"the total number of bacteria is less than 100cfu/mL".When the dosage was 3 mg/L,the inactivation rate of Escherichia coli reached100%.When the dosage of potassium ferrate and pH were fixed,the inactivation rate of the two bacteria decreased with the increase of pH,which indicated that the strong oxidation of potassium ferrate was more beneficial to the removal of microbes under the acid condition.When the dosage and pH of potassium ferrate were fixed,the inactivation rate of the two bacteria decreased with the increase of reaction time.The total number of residual bacteria had reached"sanitary standard for drinking water"?GB5749-2006?when the reaction time was2 min,and the bacteria could be removed to a stable and higher level in the reaction time of 15min.The total coliform group had a 100%inactivation rate at 15 min.?2?The kinetic analysis of potassium ferrate disinfection was carried out.The results showed that the inactivation rate of bacteria and total coliform group was in accordance with Chick's law with the dosage of potassium ferrate.The fitting equations are-ln?N/N₀??28?.10212c?10?.27770and-ln?N/N₀??28?.10773c?10?.26975respectively.The fitting equations of bacteria and total coliform bacteria inactivation rate and reaction time were-ln?N_t/N₀??28?.3866?10?.0083x-0.002x²and-ln?N_t/N₀??28?.3353?10?.0357x-.0015x²respectively.?3?The effect of Potassium Ferrate on the removal of organic matter TOC and UV₂₅₄ in water and the change of the fluorescence intensity of each component of the water samples after the oxidation of potassium ferrate were studied.The results showed that TOC gradually decreased with the increase of the dosage of K₂FeO₄,and the UV₂₅₄ increased gradually with the increase of the dosage of K₂FeO₄.The fluorescence peaks of organic matter in water mainly consist of tryptophan,fulvic acid and humic substances.They decrease with the increase of K₂FeO₄ dosage.?4?The study of the generation potential?DBPsFP?of the disinfection by-product?DBPsFP?showed that when the dosage of chlorine was added to 5 mg/L and the reaction time was 72 h,the production of halogen and haloacetic acid reached the maximum.In order to ensure the concentration of residual chlorine in water is about 5 mg/L,the amount of disinfection by-products generated by chlorine dosage of 10 mg/L and reaction time 72 h is selected as DBPsFP.?5?The effects of K₂FeO₄ dosage,pH,concentration of organic matter,ammonia nitrogen and Br-concentration on THMFP and HAAFP were studied by the purge and trap GC-MS method and GC-ECD method.The results showed that potassium ferrate could control THMFP significantly,but had a promotion effect on HAAFP.The overall THMFP increased with the increase of pH,and the overall HAAFP decreased with the increase of pH.Under the acidic condition,the formation of HAAs was better than that of THMs.The THMFP and HAAFP increased linearly with the increase of TOC concentration,and THMFP was greater than HAAFP;The concentration of ammonia nitrogen in water increases with the oxidation of nitrogen containing organic compounds in potassium ferrate.The presence of ammonia nitrogen has a certain control effect on DBPs.THMFP increases with the increase of Br-concentration.Among them,the formation of CHCI₃ gradually decreases,CHBr₃ increases obviously,CHBrCI₂ and CHBr₂CI also increase,HAAFP decreases gradually with the increase of Br-concentration.