Adsorption of ammonium in wastewater from fertilizer plant by different kinds of soils

The dischar ge of ammonium2co nt aining w astewater fr om fertilizer plants may cause g ro undwater contamination. T he adsor pt ion by soil in the vadose zo ne is an important pr ocess t o prevent ammonium from entering the aquifer. We select ed four typical so il samples at differ ent depths in a vadose zo ne, and co nducted batch labor ator y experiments to study the adso rption ki2 netics and iso thermal adsor ption char acteristics of the soils w ith reg ard to ammo nium in wastew ater fr om fertilizer plants. T he ammonium sulfat e solution was prepa red fo r the ex periments. Results show ed that ammonium can be adso rbed easily by v arious so il particles. Some materia ls such as o rg anic matters in the wastew ater can pr olong the adso rptio n equilibrium time, and affect the adsor ption capacity of soils to ammo nium; specifically , they will incr ease the capacity in low2concentr atio n ammo nium so lu2 tion, but their effects in hig h2concent ratio n ammonium so lutio n depend o n the soil or ganic matt er co ntent. Soils w ith differ ent textures have differ ent adso rptio n behav iors. Generally , the adsor ption ca pacity o f co hesiv e so il is better than that of sandy soil. Compar ed w ith the Freund lich and L angmuir iso thermal, BET adsorptio n iso thermal can better f it the ex perimental adso rptio n data. This verifies the feasibility of apply ing BET formula to the study of isotherma l adsor ption of ammonium and indicates t hat the adsor ption of ammonium in soil particles is multi2mo lecular layer adso rption.

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