| Three dimensional electrode biofilm reactor is a new type of water treatment technology,it has the advantage of high nitrogen removal rate,stable and easy to control.Due to the different structure of the reactor has great effect on the nitrate removal efficiency and energy consumption,and the structure of the reactor at different materials are different,we developed a novel reactor structure on the basement of data analysis and the preliminary study of the research group.Then the removal efficiency and influencing factors of nitrate in water were studied under the action of single electrochemical and hydrogen autotrophic denitrifier.Through inoculateing and cultureing hydrogen autotrophic bacteria,we initiated the three-dimensional biofilm electrode reactor.Based on this mature reactor,the nitrate removal effect and its influencing factors were investigated.Finally we get the main conclusions as follows:(1)The three dimensional biofilm electrode reactor has a part of the removal of nitrate nitrogen by the electrode,but the proportion is very low,the maximum is about 13%;(2)The experiment of hydrogen autotrophic denitrification shows that nitrate nitrogen removal needs to meet a certain amount of hydrogen.with the hydrogen supply / nitrate nitrogen(mass ratio)α increasing,the removal rate of nitrate rise up rapidly,when α is equal to 9.84,the rate of can reach 97%.,which means the mass ratio of the hydrogen production of the cathode in the three-dimensional biofilm reactor with the influent nitrate nitrogen should be 9.84 at least.The autohydrogentrophic three-dimensional biofilm electrode reactor cathode hydrogen production and quality of influent nitrate nitrogen than the minimum should meet 9.84.In addition,through the experiment of hydrogen supply method,it was found that the increase of the dispersion of hydrogen was beneficial to the reduction of nitrite and nitrite,and decrease the nitrite accumulation.This result also shows that the hydrogen produced by the electrochemical cathode has a catalytic effect on autotrophic bacteria denitrification.(3)The start-up of the reactor was divided into two stages: the film-filling stage and the acclimation stage.After 15 days of filming,a thin film attached to the surface of the particle electrode and cathode.Domestication stage established a stable biofilm cathode by controlling the parameters of the five phases,the effluent nitrate concentration of nitrate can be stable at 4mg/L,the removal rate reached 89%,the effluent nitrite concentration at 1.2mg/L,the effluent ammonia concentration was stable at 2.5mg/L.(4)When the current intensity is 40 m A,the removal rate of nitrate was 89%,the concentration of nitrite was 1.43 mg / L,and the effluent ammonia concentration was 1.90 mg / L in the mature three-dimensional biofilm reactor.(5)The influent pH has certain effects on the nitrogen removal process.The removal rate of nitrate nitrogen increases to 83% when the pH increases to 6.86,then the removal rate of decreases.With the increase of influent pH,the concentration of nitrite in effluent decreases firstly,then increases and the pH value of inflexion is 6.86.The concentration of ammonia nitrogen in effluent increases firstly and then decreases,and the inflexion pH is 8.5.(6)HRT <10h,the nitrate removal rate increases linearly with the increase of hydraulic retention time.When the HRT> 10 h,the removal rate is basically constant or even decreases slightly.When the HRT is 10.17 h,the maximum removal rate of nitrate is 90%.With the increase of hydraulic retention time,the concentration of nitrite in effluent decreases and the concentration of ammonia nitrogen in effluent increaseds slightly,ranging from 0.90-1.33 mg / L. |
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