Research On Oxidation-decreasing Technology For Sudden Pollution Of Intake Of Drinking Water Resources

Recent years, sudden pollution accidents in water source places happen frequently, which have greatly threaten the urban water supply system.Taking the sudden pollution of Huang-pu river as the background, this study investigated the emergency oxidation treatment efficiency of phenol, diesel oil and atrazine by KMnO₄ and NaClO, through bench and pilot tests.The oxidation power of different oxidants and the influence of oxidants dose, oxidation time and oxidation temperature on organic pollutants treatment efficiency were investigated through bench scale tests. The optimal oxidation conditions were determined. Then on the basis of the bench scale tests, pilot scale tests were carried out to determine the removal efficiency of phenol, diesel oil and atrazine. and the corresponding elixir dosing quantity.Bench scale tests results show that: KMnO₄ and NaClO were appropriate oxidants and their maximum allowable dosage are separately 2.0 mg/L and 50 mg/L. Phenol and atrazine's best oxidation time are 20 min and diesel oil's is 25 min,which close to total retention time of pollutants staying in former pool and surge tank and ensure phenol, diesel oil and atrazine completely responsing with oxidants.Because the removal efficiency of phenol and atrazine could be influenced by the reaction temperature, so in the field application, the dosage of oxidant should be properly adjusted to get a higher removal efficiency in different seasons. But the removal efficiency of diesel oil is influenced little by the reaction temperature, there is no need to consider seasonal effects in the field application.Pilot scale tests results show that: dosing KMnO₄ and NaClO to inlet of former pool or dosing PAC to inlet of former pool and KMnO₄ to inlet of former surge tank in the same time, there is no need to add other sewage treatment facilities to remove pollutants in raw water.When the initial concentration of phenol in raw water below 50μg/L, the added oxidants of 2.0 mg/L KMnO₄ or 2.0⁶.0 mg/L NaClO could remove phenol to less than 12.5 times of standard value and further removed in the waterworks. When the initial concentration was 50²50μg/L, added 10⁴0 mg/L PAC in former pool and 2.0 mg/L KMnO₄ in surge tank in the same time, could decrease effluent concentration to less than 12.5 times of standard value. When 250 500μg / L phenol pollution occurred, 40⁵0 mg/L PAC in former pool and 2.0 mg/L KMnO₄ in surge tank were added, effluent concentration could be decreased to 7.5²5 times of standard value. But when initial concentration exceeded 500μg/L, even added 50 mg/L PAC in former pool and 2.0 mg/L KMnO₄ in surge tank, effluent concentration still exceeded 50 times of standard value.Diesel oil could be directly removed when its initial concentration below 0.50 mg/L. When initial concentration in raw water were 0.5 ⁵.0 mg/L, added 2.0mg/L KMnO₄ or 6.0¹0.0 mg/L NaClO could decrease diesel oil concentration to below 5 times of standard value.When 2.0 mg/L KMnO₄ or 5¹0 mg/L NaClO were put in, atrazine with initial concentration of below 20μg / L could be removed to below 5 times of standard value. When atrazine initial concentration were 20¹00μg/L, Even if the maximum dosage levels of KMnO₄ or NaClO dosage were added, effluent concentration still exceeded 30 times of standard value. Used the process of PAC adsorption combined with KMnO₄ oxidation and added 30⁵0 mg/L PAC in former pool and 2.0 mg/L KMnO₄ in surge tank, effluent concentration of atrazine could be decreased to below 12 times of standard value. When 100μ 200μg/L atrazine pollution occurred, added 40⁵0 mg/L PAC in former pool and 2.0 mg/L KMnO₄ in surge tank could decrease the effluent concentration to less than 12 times of standard value. But if atrazine initial concentration exceeded 200μg/L, even added 50 mg/L PAC in former pool and 2.0 mg/L KMnO₄ in surge tank, effluent concentration of atrazine still exceed 12 times of standard value.