Study On Purification Of Black And Odorous Water By Tower Bipolar Electro Flocculation

Nowadays electrocoagulation technology has been concerned by many researchers,because it’s suitable for the treatment of complex water body with high efficiency,and is applicable to various environmental conditions.The arrangement of electrodes is one of the research hotspots in this technology,bipolar- electrocoagulation is considered to be a promising electrocoagulation mode due to its unique advantages.The black-odorous water is a complex pollution system,so the electrocoagulation can be considered as a good choice for the treatment of black- odorous water.In this study bipolar-electrocoagulation was used to treat simulated black-odorous water,a tower bipolar-electrocoagulation reactor was designed for removing COD,turbidity,S^2-and PO₄^3-,and oxygen enrichment.The results are as follows.（1）The treatment effect of small-scale bipolar electrocoagulation reactor shows bipolar-electrocoagulation can removal turbidity,phosphate and sulphion of black-odorous water effectively.When the voltage is 40 V and the length of sacrificial electrode is 7 cm,the removal rate of turbidity,S^2-and PO₄^3-in iron sacrificial electrode experimental group is 66.3%,100%and 100%respectively,while aluminum sacrificial electrode can completely remove these three pollutants.However,due to the poor effect of electrocoagulation on the removal of soluble organic matter,the COD removal rate in this experiment is only 29.71%,and the remaining COD concentration is 194.01 mg/L.In addition,there is a bypass current in the two-stage mode,which leads to unnecessary energy loss.（2）The sacrificial electrodes made of iron and aluminum in the tower electric flocculation reactor can completely remove S^2-and PO₄^3-,at the same time,the oxygen production of MMO anode at the bottom shows a good oxygen enrichment effect on the water body,which makes the dissolved oxygen in the water body rise to4.14 mg/L and 6.40 mg/L respectively.In addition,the microbial community structure of the treated water body changed to some extent.After electrocoagulation,the proportion of Gammaproteobacteria and Clostridia decreased from 30.76%and30.28%to 16.61%and 12.96%,respectively.In addition,the number of Campylobacteria flora,which plays an important role in sulfide oxidation,increased from 13.14%to 33.34%.These changes reflect the improvement of water environment.（3）In the experiment,the effect of bipolar electrocoagulation of aluminum and iron electrodes is compared.Because the effect of iron flocculation is affected by the redox potential of water,it is necessary to generate trivalent iron through the reaction of dissolved oxygen in water to produce better flocculation effect.Therefore,the flocculation effect and the elevation of dissolved oxygen concentration of the experimental group using iron sacrificial electrodes in anaerobic water environment are not as good as that of aluminum sacrificing,only can reach 4.14 mg/L.In addition,ferroelectric flocculation can form iron flocs that are difficult to precipitate,so the removal rate of turbidity of ferroelectric flocculation is relatively low,and the highest can only reach 88.1%. The results show that the tower bipolar electrocoagulation reactor has good electrocoagulation,electro flotation effect and water oxygen enrichment effect.This study provides a reference for the development of electrocoagulation technology and the treatment of black-odorous water.