Study Of Grains Wastewater Treated By Anaerobic Degradation-photocatalysis Oxidation

Firstly, in the thesis, the basic research achievements and applications concerning the photocatalytic oxidation of organic pollutants in wastewater were reviewed. The mechanisms, the dynamic reaction principles and the influencing factors of TiO₂ photocatalytic oxidation were also described. Secondly, the treatments of grains wastewater by photocatalytic oxidation technology using the anatase nanosized TiO₂ were studied systematically .The main contents of experiment were as follows:(1) High-level organic wastewater, i.e., grains wastewater was treated in self-designed anaerobic biological reactor. The results shows that COD_Cr content was cut down from 40000 60000mg/L to 500 1200mg/L.(2) The effluent water from anaerobic biological treatment were treated in self-designed photcatalytic reactor using anatase nanometer TiO₂ as photocatalyst. The influencing factors of photcatalytic reaction, such as the dosages of TiO₂ photocatal yst, the intensity and time of UV irradiation, the concentrations and pH values of raw water and the aeration flows were studied to choose the optimum processing conditions.(3) On the bases of single-factors experiment, the influencing factors such as the dosage of catalyst, irradiation time, initial concentration and pH value of raw water were choosed to proceed four-factor three-level L₉ (4³) orthogonal experiments.And the optimum conditions of grains wastewater treatment were determined as: TiO₂ 2 mg/L; initial pH value 9.0; intial concentration of wastewater COD_cr 600 -700mg/L; UV irradiation time 6h. Under these processing condition, the value of CODcr, BOD5, SS, color and pH of effluent were up to the concentration standard of wastewater ofalcohol industry of nation.(4)Bacteriologic test and the experiment on reduplicate using tim of TiO₂ were carried out. After photocatalytical treatment, the total bateria in the water was less or equal to two per milliliter and coliform group was less or equal to two per liter. The nanosized TiO₂ catalyst could be used three times and therefore the cost of treatment would be reduced.In this study, photocatalytic oxidation technology was applied to treat actual grains wastewater for the first time and showed its advanced aspects. The research results can provide the theoretical and experimental foundations for deep-going study and application of the technology afterwards.