Electro-oxidation Technology For Ammonia Removal And Itsapplication In Swine Wastewater

Swine wastewater coniains large content of ammonia nitrogen,and has thecharacteristics of carbon nitrogen ratio imbalance. The conventional biologicaltreatment could not meet the national discharge standards GB18596-2001. Inthis paper, we studied the factors that affected ammonia electro-oxidation and itsapplication in treatment of swine wastewater.The influence factors was assessedby measuring the removal rate of ammonia nitrogen in synthetic wastewater.Electrode electro-oxidation reaction is the main influence factors and corecomponents, so the electrodes were characterized, and got the surfacemorphology and electrochemical properties of electrodes. Feasibility analysiswas carried out on the electro-oxidation treatment of swine wastewater, as wellas the electro-oxidation of swine wastewater composition changes before andafter the analysis. The results presented in this study can be used as a startingpoint for the evaluation of the process with real swine wastewater. The mainstudy results and conclusions are as follows：(1) Current density, chloride concentration and electrode material were themain factors for ammonia electro-oxidation. Under alkalescence condition, thechloride ion would transform in a circle, it was favourable for ammonia removal.Metal ion such as Mg2+、Al3+、Fe2+、Ca2+, and anion such as HCO-2-3and CO3had little effect on ammonia electro-oxidation removal,but SO2-4had significanteffect. COD and ammonia can be removed simultaneously by electrochemicaloxidation.(2) The SEM and XRD of the electrode materials show thatTi/Mn-Ni/SnO2-Sb-CeO2electrode almost no crack and the particles wassmallest. Open circuit potential, polarization curves of oxygen evolution,strengthening the electrode life test based on the preparation of the electrode. From the above five aspects of the analysis, we can concluded thatTi/Mn-Ni/SnO2-Sb-CeO2electrode is relatively the best electrode.Taking2-hydroxy terephthalic acid as hydroxyl radical (·OH) capture agent,fluorescence spectrum technique was employed to examine whether·OH couldbe produced during the electrochemical degradation process or not. The resultsproved that·OH was produced on the electrode during the degrading processand the quantity of·OH was produced in the direct ratio of the time. And also, itwas further proved that fluorescence method, which possesses convenience, andefficiency, could be used in·OH detection during electrochemical degradation process.(3)The raw and biologically pretreated swine wastewater was treated usingTi/Mn-Ni/SnO2-Sb-CeO2anode under optimal process conditions. Ammonianitrogen,COD and TP concentration could meet requirement of dischargestandard(GB18596-2001) when the current density was20mA/cm2and chlorideconcentration was3g/L，chromaticity went to zero.(4)The mechanism of electro-oxidation had shown that organic pollutantswere degraded. The organic molecular weight distribution showed that theelectro-oxidation could convert macromolecular organics into smallorganicmolecules, with the removal of some small organic molecules. TheGC-MS results showed that the pollutants peak position of electro-oxidationeffluent were different of the raw water’s. The polycyclic organic matters werecompletely converted to organic compounds of a single ring or straight-chainstructure. In the electro-oxidation process, biodegradable organic matters werechanged into easily degradable middle product.