铁锰复合氧化物的制备及其吸附除砷性能

采用共沉淀法制备了新型铁锰复合氧化物吸附剂,并对其表面特性及除砷性能进行了初步研究.ξ电位测试表明,铁锰复合氧化物pHzpc在6.0附近,SEM/EDX表征证明吸附剂表面Fe和Mn的相对摩尔比为3∶1;铁锰复合氧化物对As(Ⅴ)和As(Ⅲ)均表现出很强的吸附能力,并且吸附速度快,在60min内即可达到平衡吸附容量的80%;该吸附剂在天然水环境pH范围内均有良好吸附除砷能力,磷酸根、硅酸根、碳酸根等阴离子对除砷效果有不同程度的影响,其余共存阴、阳离子及天然有机物在中性水环境中对除砷效果影响不大;采用Langmuir吸附等温线能较好地描述铁锰复合氧化物吸附As(Ⅴ)的过程(R2=0.997),而Freundlich方程能较好地拟合As(Ⅲ)的吸附过程(R2=0.989),对As(Ⅴ)与As(Ⅲ)的饱和吸附容量分别达到227mg·g-1和312 mg·g-1.  

Characterization of the Songhua River sediments and evaluation of their adsorption behavior for nitrobenzene

The explosion at a plant of the Jilin Petrochemical Corporation on 13 November,2005,and the spill of an estimated 100 t of toxic substances (nitrobenzene as the main component) into the Songhua River received worldwide attention.This study has focused on the adsorption behavior of nitrobenzene that spilled onto sediments along the Songhua River,which was one of the efforts to evaluate the fate of nitrobenzene after the spillage event.The organic carbon contents of these sediments along the Songhua River ...  

铁锰复合氧化物同时吸附锑镉性能研究

以五价锑（Sb（V））和镉（Cd²⁺）为对象，考察了二者单独存在和共存体系下铁锰复合氧化物（FMBO）对其吸附性能，探讨了Sb（V）（或Cd²⁺）的吸附对Cd²⁺（或Sb（V））吸附的影响.研究发现，单独存在体系下Sb（V）和Cd²⁺的吸附常数K_F分别为0.48和1.13 L·mg^-1，而共存体系下则分别提高至1.88和1.51 L·mg^-1；Elovich动力学模型可较好地描述共存条件下Cd²⁺与Sb（V）在FMBO表面的吸附，表明该体系的吸附为多层吸附且为非均相扩散过程；吸附48 h后Sb（V）和Cd²⁺的最大吸附量分别达到0.32和1.43 mmol·g^-1；Sb（V）在偏酸性而Cd²⁺在偏碱性pH范围具有较好的吸附效果.Sb（V）（或Cd²⁺）通过改变FMBO表面ζ电位和反应平衡pH等机制影响Cd²⁺（或Sb（V））的吸附.此外，XPS和吸附后水相铁锰浓度结果显示，Cd²⁺可能与FMBO体相中Mn²⁺进行晶格置换并促进Mn²⁺的溶出，进而促进了Sb（V）的吸附.  

Practical performance and its efficiency of arsenic removal from groundwater using Fe-Mn binary oxide

A treatment unit packed by granular adsorbent of Fe-Mn binary oxide incorporated into diatomite (FMBO(1:1)-diatomite) was studied to remove arsenic from anaerobic groundwater without any pre-treatment or post-treatment. The raw anaerobic groundwater containing 35-45 μg/L of arsenic was collected from suburb of Beijing. Arsenic(Ⅲ) constituted roughly 60%-80% of the total arsenic content. Approximately 7,000 bed volumes (ratio of effluent volume to adsorbent volume) treated water with arsenic concentration below 10 μg/L were produced in the operation period of four months. The regeneration of FMBO(1:1)-diatomite had been operated for 15 times. In the first stage, the regeneration process significantly improved the adsorption capacity of FMBO(1:1)-diatomite. With increased loading amount of Fe-Mn binary oxide, the adsorption capacity for arsenic decreased 20%-40%. Iron and manganese in anaerobic groundwater were oxidized and adsorptive filtrated by FMBO(1:1)-diatomite efficiently. The final concentrations of iron and manganese in effluents were nearly zero. The continued safe performance of the treatment units proved that adsorbent FMBO(1:1)-diatomite had high oxidation ability and exhibited strong adsorptive filtration.  

预氯化对铝盐混凝铜绿微囊藻过程中溶解性有机物和残余铝的影响

以铜绿微囊藻为对象,研究了预氯化过程中藻胞内代谢物释放及铝盐混凝除藻过程中残留铝的变化规律.结果表明,氯投量对胞内物质释放量和释放有机物特征有重要影响.与未投加氯的对照体系相比,在较低氯投量时(1~2 mg·L-1),水中有机物浓度升高26%~31%,UV254值升高46%~49%,且有机物主要为中等分子量(2191、2830和3168 Da)和高芳香度的有机物.增大氯投量至3~4 mg·L-1,水中有机物浓度和UV254值有所下降;就不同分子量有机物而言,大分子量有机物(16304 Da)浓度升高而中等分子量有机物(2830、3168和6163 Da)浓度下降,且出现少量小分子量有机物(180 Da).分子量较大或芳香度较高的溶解性有机物在铝盐混凝中可被优先去除.释放到水中的蛋白质能与铝盐形成可溶性蛋白质-混凝剂复合物,从而导致出水铝浓度升高,但增大铝投量可在一定程度上降低残留铝浓度.  

Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation

This study focuses on the effects of pH and fluoride at different molar ratios of fluoride to Al (RF:_Al) on the removal of cadmium (Cd²⁺) and phosphate by Al coagulation. Fluoride at RF:_Al ≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high RF:_Al of 10:1 whereas at lowered RF:_Al (i.e., ≤6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at pH 7 and 8 and that of phosphate at pH 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated RF:_Al. The Al fluoride interactions include the formation of Al-F complexes and the adsorption of fluoride onto Al(OH)₃ precipitates, i.e., the formation of Al(OH)nFm. Al-F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower pH. Al-F complexes at high RF:_Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low RF:_Al shows little effect on Al coagulation behavior towards Cd²⁺ and phosphate, and the spent defluoridation adsorbent, i.e., aluminum (Al) hydro(oxide) with adsorbed fluoride at RF:_Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved.  

Development of systems for detection, early warning, and control of pipeline leakage in drinking water distribution: A case study

The integrated system for the detection, early warning, and control of pipeline leakage has been successfully developed to manage the pipeline networks of Beijing.  

Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation

This study focuses on the effects of pH and fluoride at different molar ratios of fluoride to Al (R_F:Al) on the removal of cadmium (Cd²⁺) and phosphate by Al coagulation. Fluoride at R_F:Al ≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R_F:Al of 10:1 whereas at lowered R_F:Al (i.e., ≤ 6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at pH 7 and 8 and that of phosphate at pH 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R_F:Al. The Al fluoride interactions include the formation of Al–F complexes and the adsorption of fluoride onto Al(OH)₃ precipitates, i.e., the formation of Al(OH)_nF_m. Al–F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower pH. Al–F complexes at high R_F:Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R_F:Al shows little effect on Al coagulation behavior towards Cd^2 + and phosphate, and the spent defluoridation adsorbent, i.e., aluminum (Al) hydro(oxide) with adsorbed fluoride at R_F:Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved.  

Preferential binding between intracellular organic matters and Al_(13) polymer to enhance coagulation performance

Coagulation is the best available method for removing intracellular organic matter(IOM),which is released from algae cells and is an important precursor to disinfection by-products in drinking water treatment. To gain insight into the best strategy to optimize IOM removal, the coagulation performance of two Al salts, i.e., aluminum chloride(AlCl_3) and polyaluminum chloride(PACl, containing 81.2% Al_(13)), was investigated to illuminate the effect of Al species distribution on IOM removal. PACl showed better removal efficiency than AlCl_3 with regard to the removal of turbidity and dissolved organic carbon(DOC), owing to the higher charge neutralization effect and greater stability of pre-formed Al_(13) species. High pressure size exclusion chromatography analysis indicated that the superiority of PACl in DOC removal could be ascribed to the higher binding affinity between Al_(13) polymer and the low and medium molecular weight(MW) fractions of IOM. The results of differential log-transformed absorbance at 254 and 350 nm indicated more significant formation of complexes between AlCl_3 and IOM, which benefits the removal of tryptophan-like proteins thereafter. Additionally,PACl showed more significant superiority compared to AlCl_3 in the removal of 5 kD a and hydrophilic fractions, which are widely viewed as the most difficult to remove by coagulation.This study provides insight into the interactions between Al species and IOM, and advances the optimization of coagulation for the removal of IOM in eutrophic water.  

Review on water leakage control in distribution networks and the associated environmental benefits

Water supply is the primary element of an urban system. Due to rapid urbanization and water scarcity, maintaining a stable and safe water supply has become a challenge to many cities, whereas a large amount of water is lost from the pipes of distribution systems. Water leakage is not only a waste of water resources, but also incurs great socio-economic costs. This article presents a comprehensive review on the potential water leakage control approaches and specifically discusses the benefits of each to environmental conservation. It is concluded that water leakage could be further reduced by improving leakage detection capability through a combination of predictive modeling and monitoring instruments, optimizing pipe maintenance strategy, and developing an instant pressure regulation system. The environment could benefit from these actions because of water savings and the reduction of energy consumption as well as greenhouse gas emissions.