人造沸石对低C/N污水中氮的去除性能及机理

Performance and mechanism of artificial zeolite on nitrogen removal from low C/N sewage

以人造沸石为吸附剂,处理低C/N高速服务区污水。考察了沸石投加量对人造沸石去除污水中氮效果的影响,利用正交实验探讨了影响人造沸石吸附污水中NH_(3)-N效果的因素,并结合吸附动力学和热力学、比表面积分析(BET)、扫描电子显微镜(SEM)等手段探讨了人造沸石去除NH_(3)-N的机理。结果表明:人造沸石可在短时间内实现对污水中NH_(3)-N和TN的显著去除,并可有效提升污水C/N,反应24 h后,40 g/L人造沸石可使污水中NH_(3)-N和TN分别降至(13.45±0.39)、(19.23±0.21)mg/L,去除率分别达到(91.14±0.32)%和(87.12±0.10)%,C/N由1.30±0.01提升至5.47±0.07;正交实验表明各因素影响人造沸石脱氮效果的程度表现为沸石投加量>曝气量>NH_(3)-N初始浓度;人造沸石对NH_(3)-N的吸附过程符合准二级反应动力学模型(R^(2)=0.990),且该吸附行为是吸热过程;BET和SEM显示,人造沸石对NH_(3)-N的高效去除主要得益于其较大的比表面积(493.23 m^(2)/g)以及以介孔为主且分布范围较宽的孔道,吸附后沸石表面的颗粒变得光滑、紧密且数量减少。

Artificial zeolite was used as an adsorbent to treat sewage with low C/N from an expressway service area.The effect of zeolite dosage on nitrogen removal from sewage was investigated.The factors affecting the adsorption ef⁃fect of NH_(3)-N by artificial zeolite were discussed by orthogonal experiments.The mechanism of NH_(3)-N removal by artificial zeolite was discussed by means of adsorption kinetics and thermodynamics,specific surface area analysis(BET)and scanning electron microscopy(SEM).The results showed that artificial zeolite could significantly remove NH_(3)-N and TN in sewage in a short time,and could effectively increase the C/N of sewage.After 24 h reaction,40 g/L artificial zeolite could reduce NH_(3)-N and TN in sewage to(13.45±0.39)mg/L and(19.23±0.21)mg/L,with the removal rates of(91.14±0.32)%and(87.12±0.10)%,respectively.Meanwhile,the C/N increased from 1.30±0.01 to 5.47±0.07.The orthogonal experiments showed that the effect of various factors on nitrogen removal of artificial zeolite was as follows:zeolite dosage>aeration volume>initial concentration of NH_(3)-N.The adsorption process of NH_(3)-N by artificial zeolite conformed to the quasi-secondary reaction kinetic model(R^(2)=0.990),and the adsorption was a heat-absorbing process.The efficient removal of NH_(3)-N by artificial zeolite was mainly due to its large spe⁃cific surface area(493.23 m^(2)/g)and its mesoporous pores with a wide distribution range.After adsorption,the par⁃ticles on zeolite surface became smooth,compact and reduced in number.