沸石吸附去除城市污水厂初沉池出水中氨氮的研究

直接向城市污水初沉池出水中投加沸石 ,利用沸石对氨氮的选择性交换去除其中的氨氮 ,并辅以实验室配制液作为对比。研究结果表明 :( 1)沸石对初沉池出水中的氨氮具有很强的选择性 ;( 2 )与实验室配制液相比 ,在城市污水初沉池出水中沸石的交换容量受其他离子和有机物的影响而有所下降 ,但下降并不明显 ;( 3 )沸石对初沉池出水中的COD也有一定的去除效果     

Formaldehyde oxidation on Pd/USY catalysts at room temperature: The effect of acid pretreatment on supports

The complete catalytic oxidation of formaldehyde (HCHO) to CO₂ and H₂O at room temperature is a green route for indoor HCHO removal. Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area, intricate pores and high adsorption capacity. However, the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature. In this work, we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation. Activity tests illustrated that HCHO could be completely oxidized to CO₂ and H₂O at a nearly 100% conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g∙hr) at 25°C, when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L. The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction. The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene (DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.     

沸石生物滴滤器处理分散式生活污水的性能及生物膜特征

构建沸石生物滴滤器处理农村生活污水,研究了滴滤器的挂膜启动特征、进水水力负荷对滴滤器处理生活污水性能的影响.滴滤器采用连续进水的方式挂膜,挂膜26d后,COD和氨氮去除率分别达到85%和68%以上,且COD和氨氮相邻两次监测结果的相对偏差均低于10%,表明滴滤器挂膜成功,并基本达到了稳定的运行状态.滴滤器表现出对进水水力负荷变化较强的适应性,水力负荷为300L/（m²·d）时,滴滤器对COD、氨氮、TN、TP的平均去除率分别达到90.8%、87.1%、67.2%、90.1%.滴滤器对有机物和氮磷的去除途径结果表明,微生物降解和转化作用对污水中COD、氨氮、TN的去除贡献率最大,填料的吸附则是TP去除的主要途径,铁屑的氧化是影响填料吸附去除TP的重要因素.生物量及生物膜的分布特征表明,滴滤器内生物膜中细菌的多样性十分丰富.     

NaCl改性沸石对水中氨氮的吸附机制

通过颗粒强度测定、扫描电镜分析（SEM）、X射线能谱分析（EDS）和零电点测定（pHPZC）考察改性前后沸石表面特性的变化,考察pH值、沸石投加量、初始氨氮浓度以及温度对吸附过程的影响,并通过吸附等温式和吸附动力学对吸附机制进行描述.经过NaCl改性后的沸石的颗粒强度明显增大,表面更加粗糙,孔径增大,钠离子通过交换作用进入到沸石内部.pH值为7,沸石投加量为8g/L,温度为35℃时吸附效果最好,平衡吸附量（qe）与氨氮初始浓度呈正相关性.Langmuir等温线比Freundlich等温线更适合描述实验数据,最大饱和吸附量为13.210mg/g.吸附动力学符合准二级动力学模型.实验表明NaCl改性沸石能够有效去除水中的氨氮.     

沸石及其改性材料硅炭素处理含铅废水

对沸石及其改性材料硅炭素(ANJ.SiC)处理含铅废水进行优化研究,结果表明,当废水中ρ(Pb)为10 mg/L,pH>4.62,吸附剂投加量为5 g/L,25 ℃处理30 min时,沸石及硅炭素对铅的去除率均可达到90%以上,且硅炭素的处理效果优于沸石.分别采用5种再生剂对饱和的沸石和硅炭素进行再生,NaOH再生效果最佳;经过5次再生,2种吸附剂的饱和容量呈现不同的衰减,硅炭素的再生效果较好,饱和容量从33.9 mg/L衰减到20.5 mg/L.通过扫描电镜(SEM)对沸石和硅炭素吸附前后的表面形貌进行观察发现,二者的除铅机理不尽相同,沸石主要是通过离子交换作用,使铅进入其结构内部;沸石经过改性,表面发生变化,硅炭素主要是通过材料表面与铅离子的反应达到除铅目的.      

活化沸石曝气生物滤池预处理微污染源水的研究

采用上流式活化沸石滤料曝气生物滤池(AZBAF)对杭州市某微污染地表源水进行生物预处理.结果表明,活化沸石的高效吸附作用可使AZBAF通过自然挂膜实现快速启动.在水力负荷1.2m/h,气水比为(3~1):1条件下,AZBAF对TOC和CODMn的去除率分别为40%~60%和10%~27%,尤其对小分子量(MW<1kDa)有机物具有良好的降解作用.同时系统对NH3-N的去除率保持在90%以上.污染物的去除主要发生在滤池30cm以下部分,这与其中微生物的数量和活性分布规律一致.暂时停运(5~10d和35d)对生物过滤影响较小,系统重启后可在6~8h和24h内基本恢复至原有处理水平.     

Enhanced nitrogen removal reliability and efficiency in integrated constructed wetland microcosms using zeolite

The purpose of this study is to reduce the seasonal fluctuation and enhance the efficiency of nitrogen removal in vertical flow-horizontal subsurface flow (VF-HSF) constructed wetlands. Two sets of VF-HSF constructed wetlands were built, VF1-HSF1 and VF2-HSF2, and a zeolite section was placed in VF2. The results showed that VF2-HSF2 compared to VF1-HSF1 was not only a more reliable nitrogen removal method, but also enhanced the nitrogen removal efficiency by 50%. The average apparent rate of nitrogen removal in VF2-HSF2 reached to 2.52 gN·m^-3·d^-1, which doubled the rate in VF1-HSF1. Plant uptake and organic nitrogen sediment accounted for 12% and 6% of the total nitrogen removal in VF1-HSF1, respectively, and 10% and 4% in VF2-HSF2, respectively. Biologic nitrogen removal was the dominant mechanism, which accounted for 79% and 87% of the total nitrogen removal in VF1-HSF1 and VF2-HSF2, respectively. Ammonia adsorbed by zeolite during the cold seasons was desorbed, and then nitrified in warm seasons, which resulted in a bioregeneration efficiency of 91%. Zeolite in VF was capable of transferring ammonia from cold seasons to warm seasons as well as enhancing nitrification, which was accompanied by high potential denitrification in HSF that reinforced the efficiency and relieved seasonal fluctuation of nitrogen removal in VF-HSF.     

改性斜发沸石处理高浓度氨氮废水

采用NaOH碱熔法对缙云斜发沸石进行处理,采用正交实验对碱熔法改性沸石的最佳条件进行了选择;并对改性前后的沸石进行粉末X射线衍射(XRD)、电感耦合等离子体发射光谱法(ICP-AES)和扫描电镜(SEM)表征;详细研究了所得改性沸石在氨氮废水处理中的净化性能.结果表明,处理沸石的水热温度对氨氮去除效果的影响最显著;碱熔法处理可使缙云斜发沸石转变为低硅铝比的Na-P型分子筛,它对氨氮废水的NH4+-N具有优异的吸附性能.当改性沸石投加量为5 g,对100 mL浓度为1000 mg.L-1氨氮溶液,氨氮去除率可达77.8%,改性沸石吸附NH4+-N是一快速吸附过程,且能较好地符合Langmuir吸附等温模式,偏向于单分子层的吸附.     

Comparative study between using natural and synthetic zeolites for the improvement of soil salinity and crop yield

The effects of natural zeolite (clinoptilolite, NZ) and synthetic zeolite (Y, SZ) on salinity and the presence of the harmful salts in the soil were compared on Raphanus sativus L. Nine soil treatments were studied: 1 (control), 2 (NaCl), 3 (Na₂SO₄), 4 (NZ), 5 (SZ), 6 (NZ?+?NaCl), 7 (SZ?+?NaCl), 8 (NZ?+?Na₂SO₄), and 9 (SZ?+?Na₂SO₄). Five radish seeds were planted in each pot. Each treatment was repeated 10 times. After 50 days under equal conditions some parameters consisting of the number of leaves (NL), total leaf area (TLA), total fresh weight (TFW), total dry weight (TDW), root fresh weight (RFW), air fresh weight (AFW), root dry weight (RDW) and air dry weight (ADW) were determined. Results showed that adding either NZ or SZ to salinic soil (treatments NZNaCl, NZNa₂SO₄, SZNaCl and SZNa₂SO₄) increased AFW, TFW and TDW. Using both NZ and SZ in normal soil increased the weight of plants by developing AFW. Further NZ was more effective on soil with NaCl than SZ.     

Immobilization of some metals in contaminated sludge by zeolite prepared from local materials

In this study, zeolite was prepared from cheap local Egyptian clay (kaolin) and characterized by X-ray diffraction, X-ray fluorescence spectroscopy, SEM. The prepared zeolite was used as a binder for immobilization of the metals Cd²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in contaminated sewage sludge. Different leaching tests were conducted to determine the efficiency of the prepared zeolite for metal stabilization. The leaching of the metals from stabilized sludge decreased as the zeolite amount increased. It was found that 10% of zeolite is sufficient for the stabilization of all metal ions under investigation. It was suggested that the metal uptake mechanism by zeolite was by an ion-exchange mechanism. Examination of the solidified sample for its compressive strength after curing for 28 days yielded a value of 0.83?MPa, which indicates that the treated sludge was well solidified and safe to be used in a wide variety of applications, for instance as a raw material for pavement blocks.