Study On The Treatment Of Ammonia Nitrogen Wastewater Using Microwave Technology

Traditional techniques to remove ammonia wastewater such as stripping andchemical precipitation have disadvantages such as high cost, low efficiency and difficultoperation. It is necessary to explore new ideas and methods. Microwave technology hasthe advantages of a short heating time and high degradation efficiency. At the same time,active carbon with excellent catalytic properties makes the combination of microwavecoupled with active carbon possible, becoming one of the hotspot aspects of environmentsewage wastewater treatment.This paper researched microwave technology treatment of ammonia wastewater,Experimental study drew the following main conclusions:（1） The single microwave method was studied to treat ammonia. Results showedthat factors such as pH, microwave irradiation time and microwave power affectedammonia removal mostly; In addition, aeration did not significantly affect removalefficiency of ammonia, and became effective only with low pH value, short microwaveirradiation time, and low microwave power. The impact of the initial ammoniaconcentration was small, but overall the amount of ammonia removed was proportionalincreased. The optimal conditions for single microwave treating ammonia wastewaterwere: pH=11, microwave time=4min, power=850W. Aeration enhanced conditions alittle, corresponding ammonia removal efficiency reached up to82.7%.（2） Results of the combined method showed that the removal effect of thecombination process of microwave and active carbon is better than single microwavemethod. Optimal active carbon dosage is2g/L, while the impact of active carbon dosageon the ammonia removal was little when the dosage is higher than2g/L. The optimalconditions of microwave-active carbon method dealing with ammonia wastewater, whichis almost the same as the single microwave method, were: pH=11, microwave time=4min, power=850W. When the dosage is2g/L, corresponding ammonia removalefficiency reached up to92.5%even without aeration, which is about10%higher thanthe single microwave method.（3） Through the calculation of balance of ammonia nitrogen material and thequalitative analysis of product, it is shown that the removal of ammonia and nitrogen inwastewater using microwave-active carbon combined technology is based on molecularform, so that the removal effect is relatively good in high pH conditions.（4） During the wastewater ammonia removal by microwave heating, thermal effect and non-thermal effect of microwave works simultaneously, and the thermal effect playsa leading role. By comparing the microwave heating and conventional heating, the authorfound that the microwave warmed up the wastewater in a very short time. To achieve thesame heat, conventional heating needs a period of15minutes or even longer, whichreveals the obvious advantage of microwave heating effect.（5） Comparing the iodine number of active carbon before and after microwavetechnology process, it was showed that active carbon may play a catalytic role in themicrowave technology process. Dynamics studies showed that the microwave processremoving ammonia wastewater is in line with the reaction kinetics equation of lgc=1.383-0.078t, with its R²=0.9524and removal rate constant K=0.078min^-1, whilemicrowave-active carbon method is in line with the reaction kinetics equation of lgc=1.325-0.088t, with its R²=0.9778and removal rate constant K=0.088min^-1.