Biosorption of zinc(Ⅱ) from aqueous solution by dried activated sludge

The biosorption potential of dried activated sludge as a biosorbent for zinc（Ⅱ） removal from aqueous solution was investigated.The effects of initial pH,contact time,initial zinc ion concentration,and adsorbent dosage on the biosorption processes were determined,and the equilibrium data were modeled by the Langmuir and Freundlich isotherms.The Langmuir isotherm model （R 2=0.999） was proved to fit the equilibrium data much better than the Freundlich isotherm model （R 2=0.918）.The monolayer adsorption capacity of dried activated sludge for zinc（Ⅱ） was found to be 17.86 mg/g at pH of 5 and 25°C.The kinetic data were tested using pseudo firstand second-order models.The results suggested that the pseudo second-order model （R 2 〉 0.999） was better for the description of the adsorption behavior of zinc（Ⅱ） onto the dried activated sludge.Fourier transform infrared spectral analysis showed that the dominant mechanism of zinc（Ⅱ） biosorption onto the dried activated sludge was the binding between amide groups and zinc ions.

A restoration-promoting integrated floating bed and its experimental performance in eutrophication remediation

Numerous studies on eutrophication remediation have mainly focused on purifying water first, then restoring submerged macrophytes. A restoration-promoting integrated floating bed （RPIFB） was designed to combine the processes of water purification and macrophyte restoration simultaneously. Two outdoor experiments were conducted to evaluate the ecological functions of the RP1FB. Trial 1 was conducted to compare the eutrophication purification among floating bed, gradual-submerging bed （GSB） and RPIFB technologies. The results illustrated that RPIFB has the best purification capacity. Removal efficiencies of RPIFB for TN, TP,NH4＋-N, NO3-N, CODcr, Chlorophyll-a and turbidity were 74.45%, 98.31%, 74.71%, 88.81%, 71.42%, 90.17% and 85%, respectively. In trial 2, influences of depth of GSB and photic area in RPIFB on biota were investigated. When the depth of GSB decreased and the photic area of RPIFB grew, the height of Potamogeton crispus Linn. increased, but the biomass of Canna indica Linn. was reduced. The mortalities of Misgurnus anguillicaudatus and Bellamya aeruginosa in each group were all less than 7%. All results indicated that when the RPIFB was embedded into the eutrophic water, the regime shift from phytoplankton-dominated to macrophyte-dominated state could be promoted. Thus, the RPIFB is a promising remediation technology for eutrophication and submerged macrophyte restoration.

Performance of biotrickling filters packed with structured or cubic polyurethane sponges for VOC removal

Two identical bench-scale biotrickling filters （BTFs）, BTF 1 and BTF 2, were evaluated for toluene removal at various gas empty bed contact times （EBCTs） and organic loadings. BTF 1 and BTF 2 were packed with structured and cubic synthetic polyurethane sponges, respectively. At a constant toluene loading of 16 g/（m3.hr）, toluene removal efficiencies decreased from 98.8% to 64.3% for BTF 1 and from 98.4% to 74.1% for BTF 2 as gas EBCT decreased from 30 to 5 sec. When the toluene loading increased from 35 to 140 g/（m3.hr） at a gas EBCT of 30 sec, the removal efficiencies decreased from 99.1% to 77.4% for BTF 1 and from 99.0% to 81.5% for BTF 2. The pressure drop for both BTFs increased with increased air flow rate, and did not significantly vary while the toluene loading was increased under similar operation conditions. BTF 1 and BTF 2 could start up successfully within 19 and 27 days, respectively, when packed with fresh sponge media, and the performances could be restored in 3-7 days after biomass was removed and wasted from the media. BTF 2 displayed higher removal efficiency even under shorter EBCT or higher loading rate than BTF1 when other operation conditions were similar, while it showed lower pressure drop than BTF 1 during the whole period of operation. These results demonstrated that both BTFs could treat waste gas containing toluene effectively.

Enhanced efficiency of cadmium removal by Boehmeria nivea(L.) Gaud. in the presence of exogenous citric and oxalic acids

Boehmeria nivea（L.） Gaud. is a potential candidate for the remediation of Cd contaminated sites. The present investigation aims to explore Cd tolerance threshold and to quickly identify the role of exogenous organic acids in Cd uptake and abiotic metal stress damage.Elevated Cd levels（0–10 mg/L） resulted in an obvious rise in Cd accumulation, ranging from268.0 to 374.4 in root and 25.2 to 41.2 mg/kg dry weight in shoot, respectively. Citric acid at1.5 mmol/L significantly facilitated Cd uptake by 26.7% in root and by 1-fold in shoot,respectively. Cd translocation efficiency from root to shoot was improved by a maximum of66.4% under 3 mmol/L of oxalic acid. Citric acid exhibited more prominent mitigating effect than oxalic acid due to its stronger ligand affinity for chelating with metal and avoiding the toxicity injury of free Cd ions more efficiently. The present work provides a potential strategy for efficient Cd remediation with B. nivea.

Feasibility of bioleaching combined with Fenton oxidation to improve sewage sludge dewaterability

A novel joint method of bioleaching with Fenton oxidation was applied to condition sewage sludge. The specific resistance to filtration（SRF） and moisture of sludge cake（MSC） were adopted to evaluate the improvement of sludge dewaterability. After 2-day bioleaching, the sludge p H dropped to about 2.5 which satisfied the acidic condition for Fenton oxidation.Meanwhile, the SRF declined from 6.45 × 1010 to 2.07 × 1010s2/g, and MSC decreased from91.42% to 87.66%. The bioleached sludge was further conditioned with Fenton oxidation. From an economical point of view, the optimal dosages of H2O2 and Fe2＋were 0.12 and 0.036 mol/L,respectively, and the optimal reaction time was 60 min. Under optimal conditions, SRF,volatile solids reduction, and MSC were 3.43 × 108s2/g, 36.93%, and 79.58%, respectively. The stability and settleability of sewage sludge were both improved significantly. Besides,the results indicated that bioleaching-Fenton oxidation was more efficient in dewatering the sewage sludge than traditional Fenton oxidation. The sludge conditioning mechanisms by bioleaching-Fenton oxidation might mainly include the flocculation effects and the releases of extracellular polymeric substances–bound water and intercellular water.

Enhanced removal of ethylbenzene from gas streams in biotrickling filters by Tween-20 and Zn(Ⅱ)

The effects of Tween-20 and Zn（II） on ethylbenzene removal were evaluated using two biotrickling filters（BTFs）, BTF1 and BTF2. Only BTF1 was fed with Tween-20 and Zn（II）.Results show that ethylbenzene removal decreased from 94% to 69% for BTF1 and from 74%to 54% for BTF2 with increased organic loading from 64.8 to 189.0 g ethylbenzene/（m3·hr） at EBRT of 40 sec. The effect of EBRT（60–15 sec） at a constant ethylbenzene inlet concentration was more significant than that of EBRT（30–10 sec） at a constant organic loading. Biomass accumulation rate within packing media was reduced significantly.

Shellac-coated iron oxide nanoparticles for removal of cadmium(Ⅱ) ions from aqueous solution

This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy （TEM） imaging showed shellac-coated magnetic nanoparticle （SCMN） adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg]g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration.

Adsorption of 17β-estradiol from aqueous solution by raw and direct/pre/post-KOH treated lotus seedpod biochar

Five biochars derived from lotus seedpod(LSP)were applied to examine and compare the adsorption capacity of 17β-estradiol(E2)from aqueous solution.The effect of KOH activation and the order of activation steps on material properties were discussed.The effect of contact time,initial concentration,p H,ionic strength and humic acid on E2 adsorption were investigated in a batch adsorption process.Experimental results demonstrated that the pseudo second-order model fitted the experimental data best and that adsorption equilibrium was reached within 20 hr.The efficiency of E2 removal increased with increasing E2 concentration and decreased with the increase of ionic strength.E2 adsorption on LSP-derived biochar(BCs)was influenced little by humic acid,and slightly affected by the solution p H when its value ranged from 4.0 to 9.0,but considerably affected at p H 10.0.Low environmental temperature is favorable for E2 adsorption.Chemisorption,π–πinteractions,monolayer adsorption and electrostatic interaction are the possible adsorption mechanisms.Comparative studies indicated that KOH activation and the order of activation steps had significant impacts on the material.Post-treated biochar exhibited better adsorption capacity for E2 than direct treated,pretreated,and raw LSP biochar.Pyrolyzed biochar at higher temperature improved E2 removal.The excellent performance of BCs in removing E2 suggested that BCs have potential in E2 treatment and that the biochar directly treated by KOH would be a good choice for the treatment of E2 in aqueous solution,with its advantages of good efficiency and simple technology.

Effects of silver nanoparticles with different dosing regimens and exposure media on artificial ecosystem

Due to the wide use of silver nanoparticles(AgNPs) in various fields, it is crucial to explore the potential negative impacts on the aquatic environment of AgNPs entering into the environment in different ways. In this study, comparative experiments were conducted to investigate the toxicological impacts of polyvinylpyrrolidone-coated silver nanoparticles(PVP-AgNPs) with two kinds of dosing regimens, continuous and one-time pulsed dosing, in different exposure media(deionized water and XiangJiang River water). There were a number of quite different experimental results(including 100% mortality of zebrafish,decline in the activity of enzymes, and lowest number and length of adventitious roots) in the one-time pulsed dosing regimen at high PVP-AgNP concentration exposure(HOE)compared to the three other treatments. Meanwhile, we determined that the concentration of leached silver ions from PVP-AgNPs was too low to play a role in zebrafish death. Those results showed that HOE led to a range of dramatic ecosystem impacts which were more destructive than those of other treatments. Moreover, compared with the continuous dosing regimen, despite the fact that higher toxicity was observed for HOE, there was little difference in the removal of total silver from the aquatic environment for the different dosing regimens. No obvious differences in ecological impacts were observed between different water columns under low concentration exposure. Overall, this work highlighted the fact that the toxicity of Ag NPs was impacted by different dosing regimens in different exposure media, which may be helpful for assessments of ecological impacts on aquatic environments.

Sustainable H2 production from ethanol steam reforming over a macro-mesoporous Ni/Mg-Al-O catalytic monolith

macro-meso-porous 整体的基于 Ni 的催化剂作为模板用聚苯乙烯泡沫经由一条受精线路被准备然后在乙醇改过生产 H2 富有的气体的蒸气使用了。Ni/Mg-Al 催化剂有一层次地由相片和扫描电子显微镜学(SEM ) 显示了的 macro-meso-porous 结构。催化剂的表面区域是 230

Photodegradation of amoxicillin by catalyzed Fe^(3+)/H_2O_2 process

Three oxidation processes of UV-Fe3＋（EDTA）/H2O2（UV：ultraviolet light;EDTA：ethylenediaminetetraacetic acid）,UV-Fe3＋/H2O2 and Fe3＋/H2O2 were simultaneously investigated for the degradation of amoxicillin at pH 7.0.The results indicated that,100% amoxicillin degradation and 81.9% chemical oxygen demand（CODCr） removal could be achieved in the UV-Fe3＋（EDTA）/H2O2 process.The treatment efficiency of amoxicillin and CODCr removal were found to decrease to 59.0% and 43.0% in the UV-Fe3＋/H2O2 process;39.6% and 31.3% in the Fe3＋/H2O2 process.Moreover,the results of biodegradability（biological oxygen demand（BOD5）/CODCr ratio） revealed that the UV-Fe3＋（EDTA）/H2O2 process was a promising strategy to degrade amoxicillin as the biodegradability of the effuent was improved to 0.45,compared with the cases of UV-Fe3＋/H2O2（0.25） and Fe3＋/H2O2（0.10） processes.Therefore,it could be deduced that EDTA and UV light performed synergetic catalytic effect on the Fe3＋/H2O2 process,enhancing the treatment efficiency.The degradation mechanisms were also investigated via UV-Vis spectra,and high performance liquid chromatography-mass spectra.The degradation pathway of amoxicillin was further proposed.

Spectroscopic studies of dye-surfactant interactions with the co-existence of heavy metal ions for foam fractionation

The interaction between a cationic dye Methylene Blue （MB） and an anionic surfactant sodium dodecyl sulfate （SDS） with the presence of Cd2＋ was investigated spectrophotometrically in a certain concentration range. The spectrophotometric measurements of dye-metal ion-surfactant system were carried out. The results indicated that the SDS concentration had a significant influence on the dye spectrum, while the addition of Cd2~ hardly caused change of the maximum value of absorbance. According to this observation, we concluded that electrostatic and hydrophobic interaction between dye and surfactant occurred up to a certain level, and the homo-ions Cd2＋ almost exerted no effect on the dye-surfactant complexation, establishing a theoretical foundation for simultaneous removal of organic dye and heavy metal using foam fractionation. Meanwhile, the effects of their interaction on foam performance were investigated. The results showed that the addition of Cd2＋ favored the tendency to ameliorate foam properties just contrary to MB. The feasibility of foam separation for dye and heavy metal removal from simulated wastewater was also confirmed using a continuous foam fractionator. In the simultaneous removal process, with the initial SDS concentration ranging from 0.5 to 5.0 retool/L, the maximum removal efticiencies of MB and Cd2＋ were obtained as 99.69% and 99.61%, respectively. The enrichment ratios were reduced from 24.34 to 7.65 for MB and from 22.01 to 3.35 for Cd2＋.

Biodegradation of 3,5-dimethyl-2,4-dichlorophenol in saline wastewater by newly isolated Penicillium sp.yz11-22N2

In this study,the performance of 3,5-dimethyl-2,4-dichlorophenol（DCMX） degradation by a screened strain was investigated.18 S r DNA and the neighbor-joining method were used for identification of the isolated strain.The results of phylogenetic analysis and scanning electron micrographs showed that the most probable identity of the screened strain should be Penicillium sp.Growth characteristics of Penicillium sp.and degradation processes of DCMX were examined.Fourier transform infrared spectroscopy of the inoculated DCMX solution was recorded,which supported the capacity of DCMX degradation by the screened Penicillium sp.Under different salinity conditions,the highest growth rate and removal efficiency for DCMX were obtained at p H 6.0.The removal efficiency decreased from 100%to 66% when the DCMX concentration increased from 5 to 60 mg/L,respectively.Using a Box–Behnken design,the maximum DCMX removal efficiency was determined to be 98.4%.With acclimation to salinity,higher removal efficiency could be achieved.The results demonstrate that the screened Penicillium sp.has the capability for degradation of DCMX.

Growth inhibition and oxidative damage of Microcystis aeruginosa induced by crude extract of Sagittaria trifolia tubers

Aquatic macrophytes are considered to be promising in controlling harmful cyanobacterial blooms. In this research, an aqueous extract of Sagittaria trifolia tubers was prepared to study its inhibitory effect on Microcystis aeruginosa in the laboratory. Several physiological indices of M. aeruginosa, in response to the environmental stress, were analyzed. Results showed that S. trifolia tuber aqueous extract significantly inhibited the growth of M. aeruginosa in a concentration-dependent way. The highest inhibition rate reached 90% after 6 day treatment. The Chlorophyll-a concentration of M. aeruginosa cells decreased from 343.1 to314.2 μg/L in the treatment group. The activities of superoxide dismutase and peroxidase and the content of reduced glutathione in M. aeruginosa cells initially increased as a response to the oxidative stress posed by S. trifolia tuber aqueous extract, but then decreased as time prolonged. The lipid peroxidation damage of the cyanobacterial cell membranes was reflected by the malondialdehyde level, which was notably higher in the treatment group compared with the controls. It was concluded that the oxidative damage of M. aeruginosa induced by S.trifolia tuber aqueous extract might be one of the mechanisms for the inhibitory effects.

Interaction between Cu^(2+) and different types of surface-modified nanoscale zero-valent iron during their transport in porous media

This study investigated the interaction between Cu^2＋and nano zero-valent iron（NZVI）coated with three types of stabilizers（i.e., polyacrylic acid [PAA], Tween-20 and starch） by examining the Cu^2＋ uptake, colloidal stability and mobility of surface-modified NZVI（SM-NZVI） in the presence of Cu^2＋. The uptake of Cu^2＋ by SM-NZVI and the colloidal stability of the Cu-bearing SM-NZVI were examined in batch tests. The results showed that NZVI coated with different modifiers exhibited different affinities for Cu^2＋, which resulted in varying colloidal stability of different SM-NZVI in the presence of Cu^2＋. The presence of Cu^2＋ exerted a slight influence on the aggregation and settling of NZVI modified with PAA or Tween-20. However, the presence of Cu^2＋caused significant aggregation and sedimentation of starch-modified NZVI, which is due to Cu^2＋complexation with the starch molecules coated on the surface of the particles. Column experiments were conducted to investigate the co-transport of Cu^2＋ in association with SM-NZVI in water-saturated quartz sand. It was presumed that a physical straining mechanism accounted for the retention of Cu-bearing SM-NZVI in the porous media. Moreover, the enhanced aggregation of SM-NZVI in the presence of Cu^2＋ may be contributing to this straining effect.