Comparison of CNT-PVA membrane and commercial polymeric membranes in treatment of emulsified oily wastewater

CNT-PVA membrane was fabricated and compared with polymeric membranes. The separation performance was evaluated by homemade and cutting fluid emulsions. The three membranes show similar oil retention rates. CNT-PVA membranes have higher permeation fluxes compared with polymeric membranes. CNT-PVA membrane shows higher fouling resistance. Membrane separation is an attractive technique for removal of emulsified oily wastewater. However, polymeric membranes which dominate the current market usually suffer from severe membrane fouling. Therefore, membranes with high fouling resistance are imperative to treat emulsified oily wastewater. In this study, carbon nanotube-polyvinyl alcohol (CNT-PVA) membrane was fabricated. And its separation performance for emulsified oily wastewater was compared with two commercial polymeric membranes (PVDF membrane and PES membrane) by filtration of two homemade emulsions and one cutting fluid emulsion. The results show that these membranes have similar oil retention efficiencies for the three emulsions. Whereas, the permeation flux of CNT-PVA membrane is 1.60 to 3.09 times of PVDF membrane and 1.41 to 11.4 times of PES membrane, respectively. Moreover, after five consecutive operation circles of filtration process and back flush, CNT-PVA membrane can recover 62.3% to 72.9% of its initial pure water flux. However, the pure water flux recovery rates are only 24.1% to 35.3% for PVDF membrane and 6.0% to 26.3% for PES membrane, respectively. Therefore, CNT-PVA membrane are more resistant to oil fouling compared with the two polymeric membranes, showing superior potential in treatment of emulsified oily wastewater.     

Recovery of Ni(II) from real electroplating wastewater using fixed-bed resin adsorption and subsequent electrodeposition

Resin adsorption and subsequent electrodeposition were used for nickel recovery. Treated wastewater can meet the Electroplating Pollutant Discharge Standard. The spent resin is completely regenerated by 3 BV of 4% HCl solution. 95.6% of nickel in concentrated eluent was recovered by electrodeposition. Effective recovery of high-value heavy metals from electroplating wastewater is of great significance, but recovering nickel ions from real electroplating wastewater as nickel sheet has not been reported. In this study, the pilot-scale fixed-bed resin adsorption was conducted to recover Ni(II) ions from real nickel plating wastewater, and then the concentrated Ni(II) ions in the regenerated solution were reduced to nickel sheet via electrodeposition. A commercial cation-exchange resin was selected and the optimal resin adsorption and regeneration conditions were investigated. The resin exhibited an adsorption capacity of 63 mg/g for Ni(II) ions, and the average amount of treated water was 84.6 bed volumes (BV) in the pilot-scale experiments. After the adsorption by two ion-exchange resin columns in series and one chelating resin column, the concentrations of Ni(II) in the treated wastewater were below 0.1 mg/L. After the regeneration of the spent resin using 3 BV of 4% (w/w) HCl solution, 1.5 BV of concentrated neutral nickel solution (>30 g/L) was obtained and used in the subsequent electrodeposition process. Using the aeration method, alkali and water required in resin activation process were greatly reduced to 2 BV and 3 BV, respectively. Under the optimal electrodeposition conditions, 95.6% of Ni(II) in desorption eluent could be recovered as the elemental nickel on the cathode. The total treatment cost for the resin adsorption and regeneration as well as the electrodeposition was calculated.     

海洋酸化与重金属、有机污染物和人工纳米颗粒的联合毒性效应研究进展

由于大量人类活动的影响,大气CO_2浓度持续增加,其中约1/3被海洋吸收,导致表层海水pH值降低和碳酸盐平衡体系波动,即"海洋酸化"现象。污染物的海洋环境效应一直是全球环境科学领域研究的热点。在实际环境中,海洋酸化往往与污染物共同存在并作用于海洋生态系统,且海洋酸化极有可能改变污染物的海洋环境行为从而影响其毒性效应。但现有研究大多针对海洋酸化或者污染物单独作用下的毒性效应展开,对海洋酸化与污染物的联合毒性效应的研究不足、亟待加强。为此,综述了近年来海洋酸化与典型污染物(重金属、有机污染物)及新型污染物(人工纳米颗粒)的相关文献,重点阐述了海洋酸化对污染物环境行为的影响和海洋酸化与污染物对海洋生物的联合毒性效应,指出当前的研究不足,并对未来的研究方向进行了展望。     

含Cu-EDTA废水吸附法处理研究

用活性炭吸附法对Cu-EDTA废水的处理进行了工艺条件研究。结果表明,对含Cu40mg/L的络合剂废水,利用络合铜在酸性条件下的不稳定和活性炭表面电荷作用,在pH=5—6,采用活性炭进行搅拌吸附0.5h,铜的吸附率可达98％,出水残铜稳定在1mg/L以下。同时采用0.5mol/L H_2SO_4洗脱回收铜,且做到活性炭再生使用,铜的回收率为98％。为Cu-EDTA废水的处理提供了一个经济有效的方法。     

味精废水厌氧处理稳态运行的控制研究

就目前较难处理的高浓度味精废水用厌氧法进行了稳态运行的控制研究。在中温条件下,获得了高浓度味精废水高效稳态运行的控制参数。COD去除率可达70％以上,产气量可达10.5m~3/m~3·d,其中甲烷含量占58％以上。表明高浓度(谷氨酸)味精废水进行厌氧处理是可行的。     

工业废水催化湿式氧化处理的研究

采用系列贵金属-半导体氧化物催化剂,在高压釜中250℃液相条件下对焦化厂等工业废水以及由氨、吡啶等组成的模拟废水进行液相氧化试验。结果发现几种催化剂对不同污染物有不同序列的催化氧化活性,其净化作用有各自的选择性。WT-501催化剂对氨和有机污染物均有高活性,焦化废水经WT-501催化氧化处理后’COD、NH_3分別从9302mg/L和5230mg/L降至619mg/L和47mg/L,去除率高达93.2％和99％。     

土壤重金属污染的酶学诊断——紫色土中的镉、铜、铅、砷对水稻根系过氧化物酶的影响

通过四川酸性紫色土、中性紫色土,石灰性紫色土中不同浓度的Cd、Cu、Pb、As对水稻根系过氧化物酶的影响研究,揭示了过氧化物酶受抑制与产生抗性的过程.在低浓度时,上述元素对过氧化物酶的影响能反映土壤类型影响的差别.确定了三种紫色土中Cd、Cu、Pb、As的临界浓度.     

活性污泥法处理焦化污水监测值的统计特性

用活性污泥法处理焦化污水,将一年内监测的曝气池山水和入水中酚、氰、氨氮、COD等指标建立数据库,并进行时间序列、正态分布性、自相关和线性回归分析.统计分析结果表明,多数指标呈正态分布而周期性特征不明显;经多元线性回归分析,出水COD与入水COD、出水酚之间的关系较为密切.     

武汉东湖湖水的藻类生长潜力(AGP)测试

在东湖湖水样品中添加排入东湖的主要污水或营养物(氮和磷)进行藻类测试,观察它们对斜生橱藻(Scenedesmus obliquus)的生长促进作用.生长反应与添加的污水浓度成正比,其SC_(20)(促进20％增长的浓度)为0.5—4％.单独添加氮或磷,在高浓度情况下也很少促进藻类生长,但共同添加时大多有促进作用.东湖为一严重富营养型湖泊,为了控制其富营养化进程,污水截流应是首先要采取的一项措施.     

重金属和氯酚对霍甫水丝蚓的急性毒性及水环境安全评价

研究了Hg2+、Cr6+和Pb2+等重金属及2,4-二氯酚、2,4,6-三氯酚和五氯酚等氯酚类物质对霍甫水丝蚓(Limnodrilus hoffmeisteri)的急性毒性效应.结果表明, Hg2+、Cr6+和Pb2+对霍甫水丝蚓的96h-LC50分别为0.16,4.25,76.24mg/L;2,4-二氯酚、2,4,6-三氯酚和五氯酚对霍甫水丝蚓的96h-LC50分别为20.73,7.86,2.42mg/L. 根据6种污染物对霍甫水丝蚓的毒性实验结果,预测水体中Hg2+、Cr6+和Pb2+对霍甫水丝蚓的安全浓度SC分别为16,425,7624μg/L,最大允许浓度分别为1.6,42.5,762.4μg/L;2,4-二氯酚、2,4,6-三氯酚和五氯酚对霍甫水丝蚓的安全浓度SC分别为2073,786,242μg/L,最大允许浓度MPC分别为207.3,78.6,24.2μg/L.6种污染物的毒性评估结果显示,Hg2+对霍甫水丝蚓表现为极高毒性,Cr6+、2,4,6-三氯酚和五氯酚对其表现为高等毒性,Pb2+和2,4-二氯酚表现为中等毒性.3种重金属对其毒性顺序为:Hg2+ > Cr6+ > Pb2+;3种氯酚类物质对其毒性大小依次为:五氯酚 > 2,4,6-三氯酚 > 2,4-二氯酚.