Research On Cod Degradation And Fluoride Removing Of High Fluoride Industrial Wastewater

With the development of industry, COD content in wastewater increased and thebiodegradability became lower. Environmental pollution was aggravating, which led to greatharm to human health. Therefore, study on high fluoride-containing industrial wastewater anddegradation of COD as well as removal method was important for the protection of water andecological environment and human health.In this research, high COD and high fluoride wastewater from Chemical Industry Parkwas chosen as object. The system of UV/TiO₂, UV/Fenton and UV/Fenton-like were used tostudy the factors of influence on the removal rate of COD and find the optimum conditions.At the same time, using fly ash and Ca（OH）₂as the absorption materials, artificially preparedcontaining10000mg/L high fluoride wastewater as object, explored the affected factors andbest conditions under the treatment of fly ash and Ca（OH）₂. Using wastewater under the bestconditions of UV/TiO₂, UV/Fenton and UV/Fenton-like as samples, the fittest conditionsunder two treatments were verified, respectively. The main research results were as follows:1. The best conditions of UV/TiO₂method were: solution pH value of2, TiO₂dosage of0.9g/L, temperature of60°C, the distance between high pressure mercury lamp and thesurface was7cm. After reaction had carried out for120min under the best condition, CODvalue was17.54mg/L and COD removal rate was94.2%.2. The best conditions of UV/Fenton method were: solution pH value of2, the addedamount of Fe²⁺was5mmol/L, the addition of H₂O₂was200mmol/L, temperature of60°C,the distance between high pressure mercury lamp and the surface distance was7cm. Afterreaction had carried out for120min under the best condition, COD value was142.1mg/L andCOD removal rate was53.3%.3. The best conditions of UV/Fenton-like method were: solution pH value of2, theadded amount of Fe³⁺was5mmol/L, the addition of H₂O₂was100mmol/L, temperature of60°C, the distance between high pressure mercury lamp and the surface was7cm. Afterreaction had carried out for120min under the best condition, COD value is105.1mg/L, CODremoval rate is65.43%.4. The best conditions of fly ash treatment were: solution pH value of2, the dosage offly ash was300g/L, temperature of40°C, shocking30minutes in stable temperature.Under this condition, the amount of fluorine in artificial wastewater was19.51mg/L, and the removal rate of fluoride ion was99.6%. Under the above conditions, the wastewatercontaining fluoride which was treated under best conditions with UV/TiO₂system,UV/Fenton system and UV/Fenton-like system was used to verify the results. COD value andfluorine ion content in artificial wastewater were as follows: UV/TiO₂33.52mg/L,1952.36mg/L; UV/Fenton160.95mg/L,1937.1mg/L; UV/Fenton-like137.73mg/L,1967.71mg/L,respectively.5. The best conditions of Ca（OH）₂treatment were: solution pH value of1²,dosage of Ca（OH）₂was30g/L, reaction temperature of20°C, shocking15minutes. Underthis condition, fluorine content in the artificial wastewater was1.95mg/L, the removal rate offluoride ion was99.96%. Under the above conditions, the wastewater with fluorine whichtreated by UV/TiO₂, UV/Fenton, UV/Fenton-like system was used to verified. After treatment,the COD value and fluoride ion content were as follows: UV/TiO₂10mg/L,3.03mg/Lï¼›UV/Fenton40.35mg/L,3.24mg/Lï¼› UV/Fenton-like80.26mg/L,3.12mg/L, respectively.