Fate and Behavior of Tetracycline Resistance Genes in Activated Carbon Adsorption

The accessibility of tetracycline resistance gene (tetG) into the pores of activated carbon (AC), as well as the impact of the pore size distribution (PSD) of AC on the uptake capacity of tetG, were investigated using eight types of AC (four coal-based and four wood-based). AC showed the capability to admit tetG and the average reduction of tetG for coal-based and wood-based ACs at the AC dose of 1 g·L-1 was 3.12 log and 3.65 log, respectively. The uptake kinetic analysis showed that the uptake of the gene followed the pseudo-second-order kinetics reaction, and the uptake rate constant for the coal-based and wood-based ACs was in the range of 5.97 × 10-12 - 4.64 × 10-9 and 7.02 × 10-11 - 1.59 × 10-8 copies·mg-1·min-1, respectively. The uptake capacity analysis by fitting the obtained experiment data with the Freundlich isotherm model indicated that the uptake constant (KF) values were 1.71 × 103 - 8.00 × 109 (copies·g-1)1-1/n for coal-based ACs and 7.00 × 108 - 3.00 × 1010 (copies·g-1)1-1/n for wood-based ones. In addition, the correlation analysis between KF values and pore volume as well as pore surface at different pore size regions of ACs showed that relatively higher positive correlation was found for pores of 50 - 100 Å, suggesting ACs with more pores in this size region can uptake more tetG. The findings of this study are valuable as reference for optimizing the adsorption process regarding antibiotic resistance-related concerns in drinking water treatment.

Evaluation of alum-based water treatment residuals used to adsorb reactive phosphorus

Excess reactive phosphorus(PO4)in waterways can lead to eutrophication.A low-cost approach to reducing PO4 levels in surface water was evaluated using the alum-based water treatment residual(Al-WTR)or Al-WTR augmented with powdered activated carbon(PAC-WTR).Batch adsorption-desorption and continuous flow column experiments were performed to assess the specific adsorption capacities under various concentration and flow conditions.Both Al-WTR and PAC-WTR exhibited the ability to adsorb PO4.The overall,cumulative sorbed amount after a 28-d desorption step for Al-WTR was 33.93 mg/kg,significantly greater than the PAC-WTR value of 24.95 mg/kg(p<0.05).The continuous flow column experiments showed a theoretical PO4 uptake of 9.00 mg/g for Al-WTR and 7.14 mg/g for PAC-WTR over 720 h.When surface water was used,the Al-WTR and PAC-WTR columns removed 67.4%and 62.1%of the PO4,respectively.These results indicated that Al-WTR was more effective for in-field evaluation.

Application of Green Technology Using Biological Means for the Adsorption of Micro-Pollutants in Water

It is true that the world we have today is not the world we use to know. The Covid-19 pandemic has paralyzed all sector, hence the need for safety and enabling environment for mankind is of high importance. Adsorption technology is far the best and cheapest treatment technology for water and has extensively proven its worth for the uptake of micro-pollutant from surface, ground and water which are the major channels of home water. Over the years activated carbon is considered as the most common and universally used adsorbent for the eradication of different types of micro-pollutants from water. The contamination of surface water by micro-pollutant is a potential threat for the production of high quality and safe drinking water. Adsorption operation onto granulated activated carbon (GAC) in fixed-bed filters is often applied as a remedying step in the synthesis of safe and drinkable water. Activated carbon actively tends to act as a carrier material for a thin usually resistant layer of microorganisms (mostly bacteria) that forms on the coat of various surfaces (biofilm), hence biological simplification can be an alternative removal approach that can be adopted in granulated activated carbon filters. To evaluate the capacity of biofilm to biologically simplify micro-pollutants, it is very imperative to distinguish adsorption from biological simplification (biodegradation) as a removal mechanism. Experiment was carried out under the operating condition of a temperature range of 6?C to 20?C with biologically activated and autoclaved GAC to assess the biological simplification by the biofilm adsorbed on the GAC surface. Five micro-pollutants were selected as model compounds, of which some of them were biologically simplified by the GAC biofilm. Additionally, we observed that temperature can increase or decrease adsorption. Conclusively, comparison was made on the adsorption capacity of granulated activated carbon used for more than 50,000 beds.

Experimental Design Technique on Removal of Hydrogen Sulfide using CaO-eggshells Dispersed onto Palm Kernel Shell Activated Carbon：Experiment,Optimization,Equilibrium and Kinetic Studies

This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon（PKSAC） through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be： 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors（calcination temperature of impregnated activated carbon（IAC）, the calcium solution concentration and contact time of calcination） on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield（IACY, %） and removal efficiency（RE, %） were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows： calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.

Synthesis and Application of Granular Activated Carbon from Biomass Waste Materials for Water Treatment:A Review

There is an increased global demand for activated carbon(AC)in application of water treatment and purification.Water pollutants that have exhibited a greater removal efficiency by AC included but not limited to heavy metals,pharmaceuticals,pesticides,natural organic matter,disinfection by-products,and microplastics.Granular activated carbon(GAC)is mostly used in aqueous so-lutions and adsorption columns for water treatment.Commercial AC is not only costly,but also obtained from non-renewable sources.This has prompted the search for alternative renewable materials for AC production.Biomass wastes present a great potential of such materials because of their availability and carbonaceous nature.This in turn can reduce on the adverse environmental effects caused by poor disposal of these wastes.The challenges associated with biomass waste based GAC are their low strength and attrition resistance which make them easily disintegrate under aqueous phase.This paper provides a comprehensive review on recent advances in production of biomass waste based GAC for water treatment and highlights future research directions.Production parameters such as granulation conditions,use of binders,carbonization,activation methods,and their effect on textural properties are discussed.Factors influencing the adsorption capacities of the derived GACs,adsorption models,adsorption mechanisms,and their regeneration potentials are reviewed.The literature reveals that biomass waste materials can produce GAC for use in water treatment with possibilities of being regenerated.Nonetheless,there is a need to explore 1)the effect of preparation pathways on the adsorptive properties of biomass derived GAC,2)sustainable production of biomass derived GAC based on life cycle assessment and techno-economic analysis,and 3)adsorption mechanisms of GAC for removal of contaminants of emerging concerns such as microplastics and unregulated disinfection by-products.

Competitive effects of humic acid and wastewater on adsorption of Methylene Blue dye by activated carbon and non-imprinted polymers

Natural organic matter（NOM）, present in natural waters and wastewater, decreases adsorption of micropollutants, increasing treatment costs. This research investigated mechanisms of competition for non-imprinted polymers（NIPs） and activated carbon with humic acid and wastewater. Three different types of activated carbons（Norit PAC 200,Darco KB-M, and Darco S-51） were used for comparison with the NIP. The lower surface area and micropore to mesopore ratio of the NIP led to decreased adsorption capacity in comparison to the activated carbons. In addition, experiments were conducted for single-solute adsorption of Methylene Blue（MB） dye, simultaneous adsorption with humic acid and wastewater, and pre-loading with humic acid and wastewater followed by adsorption of MB dye using NIP and Norit PAC 200. Both the NIP and PAC 200 showed significant decreases of 27% for NIP（p = 0.087） and 29% for PAC 200（p = 0.096） during simultaneous exposure to humic acid and MB dye. There was no corresponding decrease for NIP or PAC 200 pre-loaded with humic acid and then exposed to MB. In fact, for PAC 200, the adsorption capacity of the activated carbon increased when it was pre-loaded with humic acid by 39%（p = 0.0005）. For wastewater, the NIP showed no significant increase or decrease in adsorption capacity during either simultaneous exposure or pre-loading. The adsorption capacity of PAC 200 increased by 40%（p = 0.001） for simultaneous exposure to wastewater and MB. Pre-loading with wastewater had no effect on MB adsorption by PAC 200.

Pilot Study on Drinking Water Advanced Treatment by GAC-MF System

The pilot performance of the combined GAC-MF membrane process for drinking water advanced treatment was described. In the process of GAC adsorption, under the conditions of 20 min HRT and 6 m/h filtration rate, the removal efficiencies of UV254 and trichloromethane could reach 40% and 50%respectively and the UV254 and trichloromethane in system effluent was less than 0.015 cm-1 and 5 μg/L respectively. In the post MF membrane process, MF membrane effectively retained the particles and bacteria in raw water. The effluent turbidity was less than 0.2 NTU and no bacteria were detected at all in permeate. A computer-controlled system was enployed to control this system. The membrane operating parameters of backwash interval, duration and flux were studied. The backwash interval of 10-min, 20-min and 60-min was researched respectively, and the variation of trans-membrane pressure was also analyzed. Consequently short backwash interval was recommended under the same water consume.

Affordable Water Filtration Technology for Disinfection By-Product Control for Small Rural Communities by Using Carbon Extracted from Local Fly Ash

The fly ash generated from local pulp and paper industries was transformed into activated carbon (AC) through physical activation process in a high temperature tube furnace in this study. Effects of two factors including activation temperature and activation time were investigated. Iodine number (IN), methylene blue value (MBV), and surface microstructure were all analyzed to assess the adsorption capacity of different carbon samples. The surface area of the carbon sample increased significantly from 486.44 m2/g to 847.26 m2/g before and after activation. The jar tests revealed that the use of 0.5 g (AC)/L (water) has the highest adsorption effectiveness. Meanwhile, the column filtration experiment indicated more than 60% of the organic matter can be removed by the carbon barrier within 2 hours filtration. The follow-up chlorination experiment illustrated that the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) could be considerably prevented after filtration. Above all, the cost-effective carbon filtration technology developed in this study can potentially be applied as a pre-treatment technology for intake source waters for local communities.

煤质与木质活性炭吸附处理焦化RO浓水及再生试验研究

以某钢铁厂焦化RO浓水为研究对象,采用煤质颗粒活性炭与木质颗粒活性炭进行吸附处理,考察了活性炭投加量、pH值、吸附时间对吸附效果的影响,同时进行2种活性炭的Freundlich吸附等温线研究,研究了再生温度、再生时间、再生次数对活性炭再生后吸附性能及再生损失的影响。结果表明,在最佳吸附条件下,煤质和木质活性炭对废水中COD的去除率分别为61.1%、56.3%。最佳再生温度为500℃,煤质和木质活性炭最佳再生时间分别为1.5 h和1.0 h。多次再生试验证明,煤质活性炭可进行大于6次的再生,使用寿命优于木质活性炭。

基于净水厂废弃滤料的透水砖制作及性能研究

随着城市化发展,城市不透水表面日益增多,导致城市内涝频发,雨水径流污染加重。基于此提出以净水厂废弃滤料为主要材料,配以水泥、活性炭、粉煤灰等原料制作透水砖,并介绍了透水砖的制作方法和流程,研究并讨论了原材料的配合比对透水砖力学性能和净水性能的影响。结果表明,净水厂废弃滤料掺量77%、活性炭掺量10%的透水砖具备良好的性能,抗压强度为6.641 MPa,COD去除率为11.80%,TN去除率为23.24%,TP去除率为73.10%,TOC去除率为58.86%,各项数据都符合标准要求。采用净水厂废弃滤料制作透水砖不仅具有良好的实用价值,还能取得一定的经济效益和环保效益。

Preparation of Benzene Adsorption Materials Using Waste Activated Alumina

A new type of benzene adsorption material was prepared by using the airtight heat treatment method.This method can directly transform the organic impurities of the activated alumina waste into carbon with adsorption capability.The microstructure and carbon content of materials were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),BET(Brunauer Emmett Teller) surface area analysis and elemental analysis.The influences of heat treatment temperature on the properties of the composite materials were discussed.The benzene adsorption capability of the material was investigated.The experimental results show that the optimal heat treatment process condition is airtight heating at 400 ℃ for 2 h.The resulting sample has carbon mass fraction of 3.57%,specific surface area of 234.70 m 2 /g,pore volume of 0.41 m 3 /g,and average pore size of 6.59 nm.The samples show excellent benzene adsorption capability with an adsorption rate of 21.80%.

PACT+WAR工艺处理石化污水工程实例及分析

采用粉末活性炭活性污泥法(PACT)-湿式氧化再生(WAR)工艺处理某石化企业含油、含盐污水,处理规模均为500 m^(3)/h。针对装置运行过程中存在的问题进行了分析和优化,工程运行监测结果表明:该工艺脱氮除碳能力强且耐负荷冲击;含油污水处理后出水COD为36.8 mg/L,降低率为87.8%,氨氮平均质量浓度为0.3 mg/L,平均去除率为97.2%;含盐污水处理后出水COD为48.4 mg/L,降低率为89.9%,氨氮平均质量浓度为0.4 mg/L,平均去除率为98.0%,达到了装置出水水质指标要求;污水处理直接运行成本为3.07元m^(3),且实现了装置废气达标排放、生化剩余污泥近零排放,具有较好的示范作用。

活性炭对乙黄药的吸附研究

乙黄药是有色金属浮选常用的捕收剂,工业上常采用吸附法处理选矿废水中残留的乙黄药。文章以市售木质活性炭AC为吸附剂,研究其对乙黄药的吸附特性。通过元素分析、SEM、FT-IR、BET等方法对其进行表征,结果表明AC比表面积为1856.85 m^(2)/g,平均孔径为3.38 nm。单因素吸附实验发现AC用量为0.1 g,对100 mL初始浓度为100 mg/L的乙黄药,1 h去除率为97.21%;吸附过程更符合准二级动力学和Freundlich模型。AC循环再生4次后,对乙黄药去除率仍达82.82%,再生性能良好。

改性活性炭滤芯对饮用水中砷离子吸附性能的研究

探究了改性活性炭滤芯对饮用水中砷离子的吸附能力。利用溶胶-凝胶法制备TiO2溶胶并将其负载于活性炭粉末上,活性炭粉末与聚乙烯混合压制并烧结制备滤芯,测试其对饮用水中砷离子的吸附性能。采用动态吸附法,分别测试了进口流速、砷初始浓度、pH对吸附效果的影响。结果表明,流速从6 L/h升高到30 L/h时,三价砷离子去除率从95.8%降低到80.1%,五价砷离子去除率从96.3%降低到77.6%。初始砷浓度从200μg/L到350μg/L时,三价砷离子去除率从89.2%降低到78.9%,五价砷离子去除率从90.5%降低到89.3%。三价和五价砷离子分别在pH为9和4的条件下吸附效果最好。另外,Thomas模型能较好地描述改性活性炭滤芯对砷离子的动态吸附行为。改性活性炭滤芯相较于未改性的滤芯吸附效果显著提高,在流速为6 L/h,初始浓度为200μg/L时,砷离子出口浓度低于10μg/L,符合国家饮用水标准。

处理废气脱硝脱硫的活性碳改性技术研究进展

活性炭广泛应用在工业废气的吸附、脱硝脱硫中,然而,传统活性炭微孔结构较少、孔隙分布不均匀、孔道内灰分较多造成阻塞等,脱硝脱硫效率不理想;在应用前常常需要通过改性手段处理活性炭来扩大其比表面积,提升孔隙率,改善表面官能团与掺杂原子的种类和数量,以此来提升吸附性能。综述了活性炭脱除废气中SO_(2)和NO_(x)的机理,研究了物理改性、化学改性对活性炭比表面积、孔结构、表面官能团等理化性质的影响,以及改性方法对活性炭吸附、脱除烧结废气中NO_(x)/SO_(2)效率的影响规律,展望了用于处理废气脱硝脱硫的活性炭改性趋势。

木焦油基活性炭的制备及其对亚甲基蓝的吸附性能

以甲醛化处理后的木焦油为前体,通过炭化-活化法制得了木焦油基活性炭(WAC)。利用FTIR、比表面积和孔结构分析仪、XPS、SEM以及XRD对WAC的结构进行了表征。以制备的WAC为吸附剂,考察了其对模拟废水中亚甲基蓝(MB)的吸附性能。结果表明,制备的多孔活性炭WAC比表面积可达1373 m^(2)/g,表面含有丰富的含氧官能团。WAC对MB具有良好的吸附性能,准二级动力学模型能更准确地描述WAC吸附MB的过程。吸附等温线更符合Langmuir等温吸附模型。WAC对MB的最大吸附容量可达559mg/g。热力学分析表明,MB在WAC上的吸附是放热和自发的。

改性活性炭吸附废水中污染物的性能与机理研究

酚类物质的污染物对水质的影响越来越严重,利用活性炭技术对其进行吸附处理成为最有效的方法之一。本文利用木质活性炭为吸附材料,对活性炭进行酸碱以及氧化还原等处理,并采用单一变量的方法,研究BPA的浓度对活性炭的吸附影响,并最终确定了吸附达到平衡时的吸附时间,并对废水中NO-3以及Hg2+的吸附情况进行了研究。

活性炭吸附再生技术在化工废水处理中的应用

化工废水由于生化性较差、盐分、硬度较高,其深度处理已经成为行业亟需处理的重要问题。化工废水的深度处理有生化法、高级氧化法、膜法和吸附法。吸附法具有操作简单,对各种污染物具有广谱适用性、处理效果好等优点。同时通过选择合适的再生工艺,解决活饱和性炭的再生问题,可极大的拓展该工艺的使用范围。本文着重讨论了活性炭对化工废水有机污染物的吸附、活性炭再生机理及各项设计参数,通过工程实际运用,进一步验证了该工艺的可行性。

焦化废水异味治理工艺及其效果评估

为解决煤化工公司在生产中焦化废水所产生异味对周围环境造成污染的问题,在对本公司污水处理工艺现状综合分析的基础上,提出对调节池、除油池、缺氧池以及厌氧池进行加盖处理,采用化学洗涤+低温等离子体技术+活性炭吸附工艺对废气进行治理的思路,在确定洗涤液和操作工艺参数后,对该异味治理工艺的效果进行综合评估,得到理想结论。

从不同视角优化饮用水处理技术

饮用水的质量以及卫生安全对人体健康有着极其重要的作用。目前,我国大部分地区仍然按常规饮用水处理技术处理生活饮用水,以降低饮用水中传染病传播的致病微生物、病毒,消除病原微生物给人们带来传染疾病为主要目标。进入20世纪70年代,随着工业化及农业生产的快速发展,各类污染物排放物及农药、杀菌剂、除草剂使用量增加,导致局部水环境以及水体本底发生重大变化,且情况越来越复杂化。在此背景下,应用膜进行水处理技术应运而生,使得水处理技术有了突破性进展。但是,通过应用实践与理论研究发现,即使应用膜技术进行饮用水处理,其工艺技术依然存在优化空间,例如饮用水中溶解盐浓度调节、建立无菌环境控制微生物二次污染、控制消毒剂残留及消毒剂危害消除等问题。经过深入研究,在现有饮用水处理技术的基础上,本文对此提出全新、系统性的解决方案。