Study On Ammonia Nitrogen Removal From Aquaculture Wastewater By Acrylic Acid-modified Magnetic Chitosan Particles

Chitosan magnetic particles can be adsorbents to remove ammonia nitrogen fromaquaculture wastewater. Adsorption removal will be safe, simple operation, stable andeasy to control. This article prepared acrylic acid-modified magnetic chitosanparticles. The preparation conditions were optimized by single factor and orthogonalexperiments, and then the particles was characterized. The removal efficiency ofshaken adsorption, standing adsorption and the dynamic adsorption was investigated.Also the adsorption kinetic model and the adsorption isotherm were fitted.The preparation conditions of the acrylic acid-modified magnetic chitosanparticles were optimized. The results as follows, the amounts of acrylic acid,magnetic particles, ammonium persulphate and glutaraldehyde were respectively4mL,0.75g,1g and1ml. The saturation magnetization of the particles was17.437emu/g, and the magnetic particles content was41.3%.The optimized shaken adsorption conditions pH value, adsorption time,adsorbent concentration were respectively5.0-6.0,10min and3g/L. under theseconditions, the adsorption kinetics and adsorption isotherm study results show that:lagrange second order kinetic model equation can describe the adsorption behaviorwell, the ammonia adsorption process is controlled by chemical adsorption; therate-limiting step of the adsorption process is liquid film diffusion; the Longmuirequation and Freundlich equation can explain the adsorption, and the calculatedmaximum adsorption capacity was77.16mg/g, which was much larger than thetraditional adsorbent.The adsorption conditions of standing adsorption, packed-bed adsorption anddynamic adsorption were optimized, and then under the optimum conditions, theammonia nitrogen wastewater with concentration of10mg/L and50mg/L weretreated. The results showed that, in the treatment of10mg/L ammonia wastewater,the removal efficiency of standing adsorption, packed bed adsorption and dynamicbed adsorption were respectively72%,64%, and86%. In the treatment of50mg/Lammonia wastewater, the removal efficiency of standing adsorption, packed bedadsorption and dynamic bed adsorption were respectively84%,82%,and92%. The removal efficiency of standing adsorption and packed bed adsorption were closed.The process of standing adsorption need a long time, but cost least. The process ofdynamic adsorption had the best removal efficiency, but cost highest. According todifferent treating requirements to chose different treating methods.