Treatment of nitrate contaminated water using an electrochemical method

School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, China.
Bioresource Technology (Impact Factor: 4.49). 04/2010; 101(16):6553-7. DOI: 10.1016/j.biortech.2010.03.076
Source: PubMed


Treatment of nitrate contaminated water which is unsuitable for biological removal using an electrochemical method with Fe as a cathode and Ti/IrO(2)-Pt as an anode in an undivided cell was studied. In the absence and presence of 0.50 g/L NaCl, the nitrate-N decreased from 100.0 to 7.2 and 12.9 mg/L in 180 min, respectively, and no ammonia and nitrite by-products were detected in the presence of NaCl. The nitrate reduction rate increased with increasing current density, with the nitrate reduction rate constant k(1) increasing from 0.008 min(-1) (10 mA/cm(2)) to 0.016 min(-1) (60 mA/cm(2)) but decreasing slightly with increasing NaCl concentration. High temperature favoured nitrate reduction and the reaction followed first order kinetics. The combination of the Fe cathode and Ti/IrO(2)-Pt anode was suitable for nitrate reduction between initial pH values 3.0 and 11.0. e.g. k(1)=0.010 min(-1) (initial pH 3.0) and k(1)=0.013 min(-1) (initial pH 11.0). Moreover, the surface of all used cathodes appeared rougher than unused electrodes, which may have increased the nitrate reduction rate (4-6%).

Download full-text


Available from: Zhenya Zhang, Apr 11, 2014
  • Source
    • "Nitrite and ammonia are the main products formed during ER of nitrate ion [11] [12]. Direct 5e − reduction of nitrate to nitrogen gas has been claimed in some reports, supported by the mechanism which deals with the formation of nitrogen gas during chemical reduction of nitrate using Al and Fe powders [13] [14] [15] [16] [17]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: This study is focused on the mechanism of nitrate removal from aqueous solutions by electrochemical denitrification process (EDN) in an undivided electrolytic cell. The sacrificial (Fe and Al) electrodes and Inert (graphite (Gr)) electrode are employed for evaluation of operational parameters, namely current density, electrolysis time and sodium chloride concentration. The experimental results reveal that nitrate-N removal efficiency of 92% for Al–Fe (anode-cathode) and 80% for Fe–Fe are achieved at a current density of 25 mAcm−2 and 180 min electrolysis time in 100 ppm of NaCl when the initial nitrate-N concentration is 100 ppm. However, during this process approximately 20 ppm of ammonia-N is also formed. Ammonia-N generated is significantly lower compared to the amount of nitrate-N removal. It can be attributed to the fact that nitrate ion can be removed by both electrocoagulation (EC) and electrochemical reduction (ER) processes simultaneously. Experiments using Al, Fe and Gr as cathodes as well as anodes indicate that the contribution of EC increases when dissolving anodes are used. Further confirmation of nitrate-N removal by EC pathway is obtained by quantitative estimation of nitrate present in the sludge. During EDN, pH of the solution also increases with ammonia generation.
    Full-text · Article · Jun 2015 · Journal of Water Process Engineering
  • Source
    • "Extractive methods like reverse osmosis and ion exchange resins [8] [9] produce a large amount of effluent contains high concentration of nitrate, which result in the second pollution, so it must be treated later and therefore increase the overall cost of the process. Electrochemical denitrification has been focused on by a large number of researchers recently [10] [11] [12] [13] [14] [15] [16] [17] [18], as it has high treatment efficiency, no sludge production , small area occupied and relatively low investment costs. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Electrochemical reduction of nitrate in an undivided cell was studied in the present experiments. The optimization of the influencing factors on electrochemical reduction of nitrate by response surface methodology (RSM) was also studied. An ideal condition of performing both cathodic reduction of nitrate and anodic oxidation of the formed by-product in the presence of NaCl was achieved in the present experiment. The Box–Behnken design can be employed to develop mathematical models for predicting electrochemical nitrate removal geometry. The removal is sensitive to the current density and time in the present study. The value of R2>0.99 for the present mathematical model indicates the high correlation between observed and predicted values. The optimal NaCl dosage, current density and electrolysis time for nitrate removal in the present experiment are 0.47gL−1, 26.06mAcm−2, and 111.88min, respectively, at which the nitrate nitrogen (nitrate-N) and ammonia nitrogen (ammonia-N) concentration in the treated solution are 9.80 and 0mgL−1, respectively, which will meet the standards for drinking water.
    Full-text · Article · Dec 2010 · Electrochimica Acta
  • [Show abstract] [Hide abstract]
    ABSTRACT: A simple and fast electroanalytical method for the detection of nitrate at an in situ copper-modified glassy carbon electrode (GCE) in an acidic media is proposed on the basis of square wave voltammetry. Since the fresh copper-modified electrode was formed in situ and the signals of nitrate were recorded in time, the whole experiment does not require sample preparation and oxygen removal from the solution degassed with nitrogen. Finally, a procedure for on-line electrochemical cleaning, the surface of GCE was employed to keep the copper film fresh. The whole experiment was rapid, in no more than 10 min. Under the optimal conditions, nitrates could be quantitatively determined in the range extending from 10 to 300 μM, a very good linear correlation (R = 0.9996) can be observed when analyzing the relationship between the peak current and the ion concentration. In addition, the interferential effects of some common anions in water samples on the nitrate determination were also investigated. The results show that only nitrite ions could produce a distinct peak current at the same potential as nitrate does. When applying this method to detect nitrate in real water samples, the results exhibit good sensitivity. The procedure was also verified by the standard optical method.
    No preview · Article · Aug 2013 · Ionics
Show more