黄河中下游沉积物对磷酸盐的吸附动力学研究

研究了黄河中下游10个不同表层沉积物在黄河水体中对磷酸盐（P）的吸附动力学及其影响因素和吸附机理。结果表明：（1）不同黄河沉积物对P的吸附能力各不相同,但吸附量随时间的变化具有相同的变化趋势,吸附速率均在前8h内较快,以后逐渐趋缓,在48h时基本达到吸附平衡。不同黄河沉积物对P的吸附量均随P初始质量浓度的增加而增大,随沉积物含量增大而减小;（2）不同沉积物在不同P初始质量浓度下对P的吸附动力学均符合Lagergren二级吸附动力学模型及Weber-Morris扩散方程,求得二级吸附速率常数和扩散速率常数分别在11.9866～157.55g·mg^-1·h^-1和0.0005～0.0119mg·g^-1·h^-1/2之间,吸附过程由P在沉积物内扩散控制。     

黄河上游沉积物对磷酸盐的吸附动力学研究

研究了黄河上游10个不同表层沉积物在黄河水体中对磷酸盐（P）的吸附动力学及其影响因素和吸附机理。结果表明：不同黄河沉积物对P的吸附能力各不相同,但吸附量随时间的变化具有相同的趋势,吸附速率均在前8 h内较快,以后逐渐趋缓,在48 h时基本达到吸附平衡。不同黄河沉积物对P的吸附量均随P初始质量浓度的增加而增大,随沉积物质量浓度增大而减小,且也受水体pH值的影响,在pH为6.0~9.0范围内吸附量比较大。不同沉积物在不同P起始质量浓度下对P的吸附动力学均符合Lagergren二级吸附动力学模型及Weber–Morris扩散方程,求得二级吸附速率常数和扩散速率常数分别在10.85~229.29 g.mg-1.h-1和0.7×10-3~5.2×10-3 mg.g-1？h-1/2）之间,吸附过程由P在沉积物内的扩散控制。     

黄河上中游水体沉积物对磷酸盐的吸附/释放行为

研究了黄河上中游8个沉积物磷酸盐的吸附/释放动力学,比较了不同沉积物吸附磷的差别,分析了沉积物磷形态对磷吸附特征的影响.结果表明,沉积物对磷酸盐的吸附与释放均主要在前8 h内完成,在前0.5 h内对磷的吸附和释放速率均最快,在24 h内吸附基本达到平衡;沉积物对磷的等温吸附曲线既符合线性方程和Freundlich模型,同时也较好地符合Langmuir模型.据Langmuir模型计算得出沉积物对磷的最大吸附容量为0.095～0.272 mg·g-1,且最大吸附容量与沉积物总磷、可交换态磷和有机质含量呈显著正相关;沉积物在相应的上覆水中对磷酸盐的吸附过程存在一个吸附/解吸平衡点,对应的吸附/解吸平衡质量浓度为0.009～0.031 mg·L-1,均大于相应上覆水体中磷浓度,说明沉积物有向上覆水释磷的趋势.     

螺蛳壳和鱼骨混合物对水中磷酸盐的去除作用

通过试验研究了螺蛳壳、鱼骨以及螺蛳壳和鱼骨混合物对水中磷酸盐的去除作用。结果表明,当磷酸盐初始质量浓度C0为20 mg·L-1、pH值为7、T为303 K条件下,螺蛳壳投加量为4 g·L-1时对水中磷酸盐的去除率在36 h时达最大值86%;鱼骨投加量为2 g·L-1时,在不存在钙离子的情况下鱼骨对磷酸盐的去除率较低,当反应时间为5 h时仅为36%左右;螺蛳壳和鱼骨混合物可以有效去除水中的磷酸盐,特别是较短时间内(12 h以内)其去除能力明显优于单独投加螺蛳壳或鱼骨,投加量为6 g·L-1时其对水中磷酸盐的去除率在12 h时达最大值96%。pH值,水中共存的Cl-、SO42-、Na+、K+和Mg2+对螺蛳壳和鱼骨混合物去除水中磷酸盐的影响较小,HCO3-会抑制螺蛳壳和鱼骨混合物对水中磷酸盐的去除,而Ca2+则会促进螺蛳壳和鱼骨混合物对水中磷酸盐的去除。螺蛳壳和鱼骨混合物对水中磷酸盐的主要去除机制包括螺蛳壳和鱼骨对磷酸盐的表面吸附作用以及钙磷化合物沉淀作用。鱼骨可以为钙磷化合物沉淀的异质成核提供核心,促进钙磷化合物沉淀的生成;螺蛳壳和鱼骨所释放出来的钙离子可以为钙磷化合物沉淀的形成提供钙源。     

锆负载量对锆镁改性膨润土吸附水中磷酸盐的影响

制备了锆氧化物(ZrO_2)含量分别为2.98%、7.81%、13.73%和33.70%的4种锆镁改性膨润土,并考察了锆负载量对锆镁改性膨润土吸附水中磷酸盐的影响.结果表明,较高的吸附剂投加量有利于水中磷酸盐被锆镁改性膨润土所吸附去除.锆镁改性膨润土吸附水中磷酸盐的动力学过程符合准二级动力学模型.锆镁改性膨润土对水中磷酸盐的吸附等温行为可以采用Langmuir、Freundlich和Dubinin-Redushckevich (D-R)等温吸附模型进行描述.增加溶液pH值不会导致锆镁改性膨润土对水中磷酸盐吸附能力的下降.锆镁改性膨润土对水中磷酸盐的吸附能力随其锆含量的增加而增加.但是,从总体上,锆镁改性膨润土中单位质量ZrO_2对水中磷酸盐的最大吸附量则随其锆含量的增加而降低.研究结果说明,锆镁改性膨润土适合作为一种吸附剂去除水中的磷酸盐,较高的锆负载量有利于增强锆镁改性膨润土吸附水中磷酸盐的能力,而较低的锆负载量则有利于提高锆镁改性膨润土中单位质量ZrO_2对水中磷酸盐的吸附能力.     

活性炭纤维对水中敌草隆的吸附性能

探讨了活性炭纤维对水中敌草隆的吸附．结果表明,在pH=2．9时,吸附量最大;活性炭纤维的吸附能力随着温度的升高而升高;Redlich．Peterson方程更适合描述敌草隆的吸附行为;Gibbs自由能（△G0）值小于零,说明此吸附过程是自发进行的吸附过程;假二级方程更适用于描述活性炭纤维对水中敌草隆的吸附动力学过程．     

层状双氢氧化物负载生物炭对磷酸盐的吸附性能研究进展

层状双氢氧化物负载生物炭（layered double hydroxides functionalized biochar, LDHs@BC）对水体中磷酸盐具有优异的吸附性能,近年来受到了广泛关注.本文详细介绍了LDHs@BC的制备方法以及制备条件对其理化性质的影响,探讨了LDHs@BC对水体中磷酸盐的吸附性能及机制,并且阐述了生物炭和层状双氢氧化物对磷酸盐吸附的协同作用及其机制,以期通过优化制备工艺参数定向调控LDHs@BC性能,显著提升LDHs@BC对磷酸盐的吸附效率.本文展望了LDHs@BC的应用前景,以期进一步推动LDHs@BC在水体修复中的应用和推广.     

活性炭纤维对水中罗丹明B的吸附性能

研究了活性炭纤维对水中罗丹明B的吸附.结果表明,pH=2时,罗丹明B的吸附量最大,并随着pH的增高吸附量随之降低;离子强度对吸附的影响不大;Langmuir等温线更适合于描述罗丹明B的吸附行为;活性炭纤维对罗丹明B的吸附量随着温度的升高逐渐增加;热力学数据表明,较高温度下,活性炭纤维对罗丹明B的吸附是自发行为,且为吸热反应;吸附动力学符合假二级动力学模型;吸附过程可以很好地用内扩散模型来说明.     

聚苯乙烯电纺纳米纤维对水中苯系物的吸附性能

采用高效液相色谱法研究了静电纺聚苯乙烯纳米纤维对水中苯系物有机污染物的吸附性能,探究了纳米纤维对苯、对氯苯、硝基苯的吸附容量随浓度和时间的变化规律.通过实验得到静电纺纳米纤维对苯、对氯苯、硝基苯的平衡吸附容量平均值分别为9.82,5.57和4.4mg.g-1,静态吸附4h后基本达到平衡.实验结果表明,静电纺聚苯乙烯纳米纤维能够较好地吸附苯类物质,并能多次重复利用,对水中较低浓度的苯类物质吸附是一种比较合适的吸附材料.     

High removal of phosphate from wastewater using silica sulfate

This report shows that silica sulfate is removing phosphate from wastewater very efficiently. Phosphorus removal and recovery from wastewater is a worldwide issue due to pollution of natural waters by phosphate and depletion of phosphate ores. Adsorption is a process that can remove phosphate at low concentrations. Adsorption also allows the recovery of phosphate for possible re-use. Here, we studied the adsorption of phosphate from wastewater using commercial Zr ferrite, Zr-MCM 41 and silica sulfate. We calculated equilibrium isotherms, kinetic models and thermodynamic effects under conditions similar to real wastewaters. We found that the equilibrium data for the adsorption of phosphate were best fitted to the Freundlich model. The results show that the maximum uptake of phosphate was 3.36 mg g⁻¹ for Zr-MCM, 27.73 mg g⁻¹ for Zr ferrite and 46.32 mg g⁻¹ for silica sulfate. The kinetic results of the three adsorbents were satisfactorily predicted using a pseudo-second-order model. We found that silica sulfate provided excellent characteristics in terms of the maximum adsorption and rate constant for the adsorption of phosphate. The thermodynamic data showed that increasing the temperature enhanced the adsorption of phosphate onto silica sulfate. Our findings will help to define efficient methods to remove phosphate from wastewater.     

煤气化废水中有机物对磷酸铵镁结晶法去除氨氮的影响

研究了杂环类(吡啶、喹啉)和酚类(间甲酚、二甲酚、苯酚)有机物对磷酸铵镁结晶法(MAP,magnesium ammonium phosphate)处理废水中氨氮的影响.研究表明,杂环和酚类有机物均对MAP法的除氮效果产生抑制作用,杂环类有机物的抑制作用大于酚类有机物,其中加入吡啶、喹啉、间甲酚、二甲酚、苯酚相比于对照组(21 mg·L-1),氨氮残余浓度分别升高45.17、56.66、43.01、50.68、49.72 mg·L-1.因为络合作用和吸附作用,多组分体系MAP晶体产生的抑制作用强于单一组分体系.     

Occurrence and removal of N-nitrosodimethylamine and its precursors in wastewater treatment plants in and around Shanghai

Six wastewater treatment plants （WWTPs） were investigated to evaluate the occurrence and removal of N-nitrosodimethylamine （NDMA）, NDMA formation potential （FP） and four specific NDMA precursors, dimethylamine （DMA）, trimethylamine （TMA）, dimethyl- formamide （DMFA） and dimethylaminobenzene （DMAB）. DMA and tertiary amines with DMA functional group commonly existed in municipal wastewater. Chemically enhanced primary process （CEPP） had no effect on removal of either NDMA or NDMA FP. In WWTPs with secondary treatment processes, considerable variability was observed in the removal of NDMA （19%-85%） and NDMA FP （16%-76%）, moreover, there was no definite relationship between the removal of NDMA and NDMA FP. DMA was well removed in all the six surveyed WWTPs; its removal efficiency was greater than 97%. For the removal of tertiary amines, biologic treatment processes with nitrification and denitrification had better removal efficiency than conventional activated sludge process. The best removal efficiencies for TMA, DMFA and DMAB were 95%, 68% and 72%, respectively. CEPP could remove 73% of TMA, 23% of DMFA and 36% of DMAB. After UV disinfection, only 17% of NDMA was removed due to low dosage of UV was applied in WWTP. Although chlorination could reduce NDMA precursors, NDMA concentration was actually increased after chlorination.     

High zinc removal from water and soil using struvite-supported diatomite obtained by nitrogen and phosphate recovery from wastewater

Zinc is known as an essential element of human life. However, excessive zinc discharge into water and soil causes water pollution, leading to serious health issues such as septicemia, meningitis and iron-deficiency anemia. Here, a novel material made of struvite-supported diatomite was obtained from eutrophic water treated by mesoporous MgO-modified diatomite. This material was applied for zinc remediation in aqueous solutions and contaminated soils to test the reuse of P-containing products. Struvite-supported diatomite was characterized by field emission scanning electron microscopy and X-ray diffraction. Results show that the maximum removal efficiency of Zn(II) from wastewater streams reached 90.54% at an initial pH of 5 and struvite-supported diatomite dosage of 0.3 g/L. Moreover, the X-ray diffraction patterns of precipitates after Zn(II) sorption show that the combination between zinc and the phosphate group played a key role for zinc removal in solution. For Zn-contaminated soils amended with 10% struvite-supported diatomite, available Zn decreased by 65.38% and acid soluble Zn decreased by 56.9% after 56 days.     

Electrochemical removal of nitrate in industrial wastewater

A number of recent studies have demonstrated that electrochemical technologies, including electroreduction (ER), electrocoagulation (EC), and electrodialysis (ED), are effective in nitrate elimination in wastewater due to their high reactivity. To obtain the maximal elimination efficiency and current efficiency, many researchers have conducted experiments to investigate the optimal conditions (i.e., potential, current density, pH value, plate distance, initial nitrate concentration, electrolyte, and other factors) for nitrate elimination. The mechanism of ER, EC and ED for nitrate removal has been fully elucidated. The ER mechanism of nitrate undergoes electron transfer and hydrogenation reduction. The EC pathways of nitrate removal include reduction, coagulation and flotation. The ED pathways of nitrate include redox reaction and dialysis. Although the electrochemical technology can remove nitrate from wastewater efficiently, many problems (such as relatively low selectivity toward nitrogen, sludge production and brine generation) still hinder electrochemical treatment implementation. This paper critically presents an overview of the current state-of-the-art of electrochemical denitrification to enhance the removal efficiency and overcome the shortages, and will significantly improve the understanding of the detailed processes and mechanisms of nitrate removal by electrochemical treatment and provide useful information to scientific research and actual practice.

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Highly efficient and selective removal of phosphate from wastewater of sea cucumber aquaculture for microalgae culture using a new adsorption-membrane separation-coordinated strategy

● A new adsorption-membrane separation strategy is used for phosphate removal. ● PVC/Zr-BT shows a selective adsorption ability to low-concentration phosphate. ● Low concentration of P below 0.05 mg/L was achieved in actual wastewater treatment. ● Algal biomass production served as a demonstration of phosphorus recycling. Enhanced phosphorus treatment and recovery has been continuously pursued due to the stringent wastewater discharge regulations and a phosphate supply shortage. Here, a new adsorption-membrane separation strategy was developed for rational reutilization of phosphate from sea cucumber aquaculture wastewater using a Zr-modified-bentonite filled polyvinyl chloride membrane. The as-obtained polyvinyl chloride/Zr-modified-bentonite membrane was highly permeability (940 L/(m²·h)), 1–2 times higher than those reported in other studies, and its adsorption capacity was high (20.6 mg/g) when the phosphate concentration in water was low (5 mg/L). It remained stable under various conditions, such as different pH, initial phosphate concentrations, and the presence of different ions after 24 h of adsorption in a cross-flow filtration system. The total phosphorus and phosphate removal rate reached 91.5% and 95.9%, respectively, after the membrane was used to treat sea cucumber aquaculture wastewater for 24 h and no other water quality parameters had been changed. After the purification process, the utilization of the membrane as a new source of phosphorus in the phosphorus-free f/2 medium experiments indicated the high cultivability of economic microalgae Phaeodactylum tricornutum FACHB-863 and 1.2 times more chlorophyll a was present than in f/2 medium. The biomass and lipid content of the microalgae in the two different media were similar. The innovative polyvinyl chloride/Zr-modified-bentonite membrane used for phosphorus removal and recovery is an important instrument to establish the groundwork for both the treatment of low concentration phosphate from wastewater as well as the reuse of enriched phosphorus in required fields.     

芦苇人工湿地对农村生活污水磷素的去除及途径

构建了芦苇(Phragmites australis)水平潜流人工湿地处理农村生活污水中的磷素,考察了湿地除磷效果以及地上植物吸磷量。结果表明,人工湿地对磷素的去除随水力停留时间的延长而增加,停留时间大于5.3 d时,芦苇湿地除磷效率可以高于88%。湿地进水TP负荷与磷去除速率之间有较好的线性关系(R2>0.91)。湿地植物在11月份收割时,地上生物量为1.65 kg.m-2,芦苇地上部分吸收磷量为3.68 g.m-2.a-1。分析了湿地除磷途径,在试验条件下,湿地填料的吸附和沉淀等作用是水平潜流人工湿地除磷的主要途径,植物吸收仅占湿地总磷去除量的9.1%,但是湿地水生植物是人工湿地重要组成部分,可以通过影响湿地的其他条件间接影响湿地除磷效果。试验证明,人工湿地是适用于农村地区的优良的污水处理技术。