稀土荧光粉回收利用技术研究现状与发展趋势

中国是稀土资源最为丰富的国家之一,但随着稀土消费需求的增加、大量廉价出口和长期掠夺式开采等因素的影响,近年来中国的稀土储量锐减.因此,迫切需要对废旧稀土产品进行高效回收再利用.综述了直接萃取、CO2超临界萃取分离、离心分离、浮选分离、湿法浸取分离这几种主要的稀土荧光粉回收利用技术的研究现状,并对不同方法的优缺点进行了比较,最后指出了未来的发展方向.     

OGO工艺处理城市污水的脱氮除磷效能与水力特性的试验研究

在OCO反应器的基础上改进得到了OGO反应器.在反应器改进前后脱氮除磷效能对比试验的基础上,进行了反应器水力特性的试验研究.城市污水对比试验研究结果表明,OGO工艺较改进前具有更为稳定、良好的生物同时脱氮除磷效果,工艺出水的平均值COD为22mg·L-1、NH4 -N为4.8mg·L-1、TN为11.2 mg·L-1、TP为0.80mg·L-1.反应器流态特征的试验结果表明,改进后形成的OGO反应器内,缺氧环区形成了良好的DO浓度梯度分布,且OGO反应器内推流流态所占比例从改进前的5.9%提高到改进后的12.9%,有效提高了反应器内推流流态的容积利用率和反应器效率.同时,反应器改进后能明显改善混合区水力条件,并有效避免了混合区内侧液流涡旋停滞造成的污泥沉积问题.     

Characteristics of anoxic phosphors removal in sequence batch reactor

The characteristics of anaerobic phosphorus release and anoxic phosphorus uptake were investigated in sequencing batch reactors using denitrifying phosphorus removing bacteria （DPB） sludge. The lab-scale experiments were accomplished under conditions of various nitrite concentrations （5.5, 9.5, and 15 mg/L） and mixed liquor suspended solids （MLSS） （1844, 3231, and 6730 mg/L）. The results obtained confirmed that nitrite, MLSS, and pH were key factors, which had a significant impact on anaerobic phosphorus release and anoxic phosphorus uptake in the biological phosphorous removal process. The nitrites were able to successfully act as electron acceptors for phosphorous uptake at a limited concentration between 5.5 and 9.5 mg/L. The denitrification and dephosphorous were inhibited when the nitrite concentration reached 15 mg/L. This observation indicated that the nitrite would not inhibit phosphorus uptake before it exceeded a threshold concentration. It was assumed that an increase of MLSS concentration from 1844 mg/L to 6730 mg/L led to the increase of denitrification and anoxic P-uptake rate. On the contrary, the average P-uptake/N denitrifying reduced from 2.10 to 1.57 mg PO4^3--P/mg NO3^--N. Therefore, it could be concluded that increasing MLSS of the DEPHANOX system might shorten the reaction time of phosphorus release and anoxic phosphorus uptake. However, excessive MLSS might reduce the specific denitrifying rate. Meanwhile, a rapid pH increase occurred at the beginning of the anoxic conditions as a result of denitrification and anoxic phosphate uptake. Anaerobic P release rate increased with an increase in pH. Moreover, when pH exceeded a relatively high value of 8.0, the dissolved P concentration decreased in the liquid phase, because of chemical precipitation. This observation suggested that pH should be strictly controlled below 8.0 to avoid chemical precipitation if the biological denitrifying phosphorus removal capability is to be studied accurately.     

SUFR系统在低温影响下处理效果的试验分析

全面分析低温(8—20℃)对螺旋升流式反应器(spiral Up-Flow Reactor,SUFR)系统处理效果的影响．低温时利用SUFR系统进行试验研究的结果表明,该系统耗氧有机物(以COD计)和TN处理效果虽然随着温度的降低有所下降,但是耗氧有机物(以COD计)及TN去除率仍分别达到86％、70％以上．TP的去除率一直在92％以上．低温时该系统的活性污泥一时难于压缩、沉降．然而在未采取任何措施的情况下,污泥沉降性能可以在较短时间内自行恢复．这说明,接近活塞流特征的SUFR系统可以减轻低温对污水处理的负影响．该系统具有更宽的温度适宜范围．     

The recycling of rare earths from waste tricolor phosphors in fluorescent lamps: A review of processes and technologies

Rare earths have become the most important strategic resources, widely used as functional materials in industry and many other aspects of life due to its optical, electrical, and magnetic characteristics. As a consequence, a considerable number of wastes containing rare earths such as abandoned fluorescent lamps are generated and lost. Considering the scarcity in availability and supply of certain raw materials, waste tricolor phosphors are viewed as potential resources that can be mined in urban areas for their reutilization as rare earths. A number of studies in this area have been carried out all over the world.The purpose of this paper is to review the current status of recycling technologies of rare earths from waste tricolor phosphors in fluorescent lamps. The main characteristics of the tricolor phosphors were introduced, and also a detail review of the typical single recycling and reusing technologies with regard to waste tricolor phosphors was carried out in present paper. After that, several combined recycling processes and technologies were evaluated. Based on the review, the prospects of recycling technologies were suggested.     

亚热带丘陵区流域不同土地利用系统磷素径流输出特征

土地利用的环境影响是目前生态系统研究中的重要课题。以位于亚热带低山丘陵地区的安徽省宣城市梅村中2个相邻的支流域为实例,研究了具有不同土地利用结构的农－林生态系统地表径流水的磷素含量和输出。结果表明：林地－水塘－农田－村庄系统水溶性磷（DP）含量＞＞林地－水塘系统DP含量和林地－农田系统DP含量,后二者间没有显著性差异;林地－水塘－农田－村庄系统悬浮泥粒结合态磷（PAP）含量＞＞林地－农田系统PAP含量＞林地－水塘系统PAP含量,三者存在显著性差异。总磷的输出量为：林地－水塘－农田－村庄系统＞＞林地－农田＞林地－水塘系统。土地利用类型和结构对磷素输出有明显影响,村庄的存在显著地影响下游的水质,农田（水稻田）显著地增加悬浮颗粒和颗粒含磷的输出。流域磷素主要是随土壤泥粒的流失而输出,在3个系统中磷素的含量都以PAP的含量为主,占水中全磷量的73％－99％,平均为90％。流域3种土地利用系统地表径流水中的PAP的含量（PAP＜400mg/L时）均与悬浮泥粒的含量有一定的线性相关关系,而只有林地－水塘－村庄系统中DP含量与PAP含量存在对数相关关系。     

Visible light driven mineralization of spiramycin over photostructured N-doped TiO2 on up conversion phosphors

A novel visible light-active photocatalyst formulation(NdT/OP) was obtained by supporting N-doped TiO_2(NdT) particles on up-conversion luminescent organic phosphors(OP). The photocatalytic activity of such catalysts was evaluated for the mineralization process of spiramycin in aqueous solution. The effect of NdT loading in the range 15–60 wt.% on bulk and surface characteristics of NdT/OP catalysts was investigated by several chemicophysical characterization techniques. The photocatalytic performance of NdT/OP catalysts in the removal of spyramicin from aqueous solution was assessed through photocatalytic tests under visible light irradiation. Total organic carbon(TOC) of aqueous solution,and CO and CO_2 gas concentrations evolved during the photodegradation were analyzed. A dramatic enhancement of photocatalytic activity of the photostructured visible active NdT/OP catalysts,compared to NdT catalyst,was observed. Only CO_2 was detected in gas-phase during visible light irradiation,proving that the photocatalytic process is effective in the mineralization of spiramycin,reaching very high values of TOC removal. The photocatalyst NdT/OP at 30 wt.% of NdT loading showed the highest photocatalytic activity(58%of TOC removed after 180 min irradiation against only 31% removal after 300 min of irradiation of NdT). We attribute this enhanced activity to the high effectiveness in the utilization of visible light through improved light harvesting and exploiting. OP particles act as "photoactive support",able to be excited by the external visible light irradiation,and reissue luminescence of wavelength suitable to promote NdT photomineralization activity.     

气相色谱法测定水中甲萘威

通过改进预处理方法,采用带氮磷检测器的毛细柱气相色谱仪测定水中甲萘威的含量,得到了较好的精密度和准确度。