Study On Nitrogen Removal From Aquaculture Tail Water By Pulse Double Anode Electrochemical Technology

With the rapid development of the aquaculture industry and the demand for ecological civilization construction,the discharge standard of aquaculture pond tail water will be more and more strict.Aquaculture tail water mainly contains ammonia nitrogen,nitrite nitrogen,nitrate nitrogen,organic nitrogen,and other pollutants.To promote the green development of aquaculture,it is urgent to establish an effective aquaculture tail water treatment system.Therefore,it is imperative to develop new technology for aquaculture tail water treatment and recycling.In this paper,based on the analysis of the current commonly used aquaculture tail water treatment technology,pulse electrochemical technology was selected to carry out the experimental study on nitrogen removal of aquaculture tail water.Taking aquaculture simulated tail water as the research object,the nitrogen removal efficiency of pulse electrochemical technology was investigated from three aspects of total nitrogen removal efficiency,power consumption,and plate loss.The effects of plate material,plate configuration,pulse power parameters,and tail water quality on nitrogen removal efficiency were explored.The experimental results show that:when titanium mesh,DSA plate as anode material,and brass(Cu Zn alloy)plate as cathode material are used to form a double anode electrochemical system,for the simulated tailwater with ammonia/nitrate concentration ratio of 1:1,pH value of 7 and total nitrogen concentration of 20 mg/L,when the current density is 8.88 mA/cm~2,the duty cycle of 50%and pulse frequency of 300 Hz,the reaction time is 180 min The results show that the total nitrogen removal rate is 82.9%,the total power consumption is 0.132 k W·h,the anode plate loss mass is 0.05 g,when the concentration ratio of ammonia nitrogen to nitrate nitrogen is 7:3,the total nitrogen removal rate is improved to87.6%.Based on the above experiments,the double anode pulse electrochemical system was used to treat the actual aquaculture tail water.When the reaction time was 180 min,the total nitrogen concentration decreased from 6.038 mg/L to 1.029 mg/L,the effluent quality reached the national first-class standard,the total nitrogen removal rate reached 83.0%,and the power consumption was 0.0182 k W·h/mg total nitrogen.At the same time,COD concentration decreased from 38.71 mg/L to 21.47 mg/L,and the removal rate was 44.5%.The cyclic voltammetry curve and steady-state polarization curve of the plate material were measured to study the electrochemical performance of the plate.The anodic titanium mesh and DSA plate appeared oxidation peaks at different positions.The oxygen evolution potential of the two plates was higher and the chlorine evolution potential was moderate,which was suitable for the double anode of the electrochemical system.The oxygen absorption corrosion potential of the cathode brass plate was higher,which was suitable for the cathode of the electrochemical system.By studying the influence of the ammonia nitrogen/nitrate nitrogen concentration ratio on the total nitrogen removal rate and detecting the change of pH value in the solution within the reaction time,the transformation of nitrogen-containing substances in the solution was analyzed.The proportion of ammonia nitrogen in the solution would affect the total nitrogen removal.When the ammonia nitrogen/nitrate nitrogen concentration ratio was 7:3,the degradation efficiency of ammonia nitrogen and nitrate nitrogen in the solution was similar,and the total nitrogen removal rate was higher.The corrosion of the electrode plate was studied by SEM and XRD.The results show that the corrosion degree of titanium mesh is low after electrochemical reaction,and the corrosion product of the electrode plate is determined to be titanium dioxide,while the DSA plate shows strong corrosion resistance.