Removal of Pb2+ and Ni2+ by bio-sludge in sequencing batch reactor (SBR) and granular activated carbon-SBR (GAC-SBR) systems

Living bio-sludge from domestic wastewater treatment plant was used as adsorbent of heavy metals (Pb(2+), Ni(2+)) and its adsorption capacity was about 10-30% reduced by autoclaving at 110 degrees C for 10 min. The living bio-sludge acclimatized in synthetic industrial estate wastewater (SIEWW) without heavy metals showed the highest Pb(2+) and Ni(2+) adsorption capacities at 840+/-20 and 720+/-10 mg/g bio-sludge, respectively. The adsorbed Pb(2+) and Ni(2+) were easily eluted (70-77%) from bio-sludge by washing with 0.1 mol/l HNO(3) solution. The heavy metals (Pb(2+), Ni(2+)) removal efficiency of both SBR and GAC-SBR systems were increased with the increase of hydraulic retention time (HRT), or the decrease of organic loading. The SBR system showed higher heavy metals removal efficiency than GAC-SBR system at the same organic loading or HRT. The Pb(2+), Ni(2+), BOD(5), COD and TKN removal efficiencies of GAC-SBR system were 88.6+/-0.9%, 94.6+/-0.1%, 91.3+/-1.0%, 81.9+/-1.0% and 62.9+/-0.5%, respectively with industrial estate wastewater (IEWW) with 410 mg/l glucose, 5 mg/l Pb(2+) and 5 mg/l Ni(2+) under organic loading of 1.25 kg BOD(5)/m(3) d (HRT of 3 days). The bio-sludge quality (sludge volume index: SVI) of the system was less than 80 ml/g. The excess sludge from both SBR and GAC-SBR systems with SIEWW under the organic loading of 1.25-2.50 kg BOD(5)/m(3) d contained Pb(2+) and Ni(2+) at concentrations of 240-250 mg Pb(2+)/g bio-sludge and 180-210 mg Ni(2+)/g bio-sludge, respectively.     

Identification and characterization of heavy metal-resistant unicellular alga isolated from soil and its potential for phytoremediation

A unicellular alga displaying a high growth rate under heterotrophic growth conditions was isolated from soil and identified as Chlorella sorokiniana. The optimal temperature for growth was 35 degrees C and the optimal pH was 6.0-7.0. Glucose, sucrose, galactose, maltose, and soluble starch served as carbon sources supporting growth under dark conditions. The cell yield was 50 g/l (wet weight) in a heterotrophic medium containing 3% glucose. Isolated unicellular algae were highly resistant to heavy metals such as Cd(2+), of which the minimal inhibitory concentration was 4 mM. Algae were capable of taking up the heavy metal ions Cd(2+), Zn(2+) and Cu(2+) at 43.0, 42.0 and 46.4 microg/mg dry weight, respectively. Growth inhibition of Oryza sative shoots by 5 ppm Cd(2+) in hydroponic medium was completely prevented by the addition of 0.25 mg of wet Chlorella cells. These results indicated that this isolate was potentially useful for phytoremediation by preventing environmental dispersion of heavy metals.     

Alleviation of heavy metal stress in Spilanthes calva L. (antimalarial herb) by exogenous application of glutathione

To evaluate the role of exogenous application of a phytochelating agent glutathione in increasing resistance against different heavy metals stress, nodal explants excised from 28-day-old in vitro seedlings of Spilanthes calva L. were cultured on Murashige and Skoog’s medium supplemented with 10 μM benzyl adenine and five different concentrations (1, 5, 50, 100, or 200 mg/l) of four heavy metals: As₂O₃, CuSO₄, ZnSO₄, or Pb(NO₃)₂. Data were recorded for percent survival, shoot number, and shoot length after 28 d of heavy metal treatment. All four heavy metals severely inhibited growth and morphogenesis. Pb proved most inhibitory whereas Zn was least effective. Pb was further selected to study the reversal effect of glutathione on morphogenesis. The addition of different concentrations (1, 5, 10, or 25 mg/l) of glutathione to media containing the Pb resulted in a significant improvement in almost all growth parameters. Inclusion of glutathione at 10 mg/l was optimum for maximum reversal of the negative effects of heavy metals on morphogenesis.     

Dual augmentation for aerobic bioremediation of MTBE and TCE pollution in heavy metal-contaminated soil

In this work we isolated from soil and characterized several bacterial strains capable of either resisting high concentrations of heavy metals (Cd²⁺ or Hg²⁺ or Pb²⁺) or degrading the common soil and groundwater pollutants MTBE (methyl-tert-butyl ether) or TCE (trichloroethylene). We then used soil microcosms exposed to MTBE (50 mg/l) or TCE (50 mg/l) in the presence of one heavy metal (Cd 10 ppm or Hg 5 ppm or Pb 50 or 100 ppm) and two bacterial isolates at a time, a degrader plus a metal-resistant strain. Some of these two-membered consortia showed degradation efficiencies well higher (49–182% higher) than those expected under the conditions employed, demonstrating the occurrence of a synergetic relationship between the strains used. Our results show the efficacy of the dual augmentation strategy for MTBE and TCE bioremediation in the presence of heavy metals.     

乌鲁木齐市道路林带土壤抗重金属细菌的筛选及重金属去除能力

【背景】道路重金属污染问题日益严峻,寻找高效的微生物资源用于环境修复已迫在眉睫。【目的】从乌鲁木齐市道路林带土壤中筛选抗重金属菌株,并对其重金属去除能力进行探究。【方法】使用含5种重金属离子(铅、镉、锌、铜、镍)的4种培养基进行抗性菌株筛选,通过形态学特征和16S rRNA基因序列进行鉴定,采用电感耦合等离子体发射光谱仪(inductively coupled plasma optical emission spectrometer,ICP-OES)检测分离株对重金属离子的去除情况。【结果】4种分离培养基中,TSA是抗重金属菌株筛选的最适培养基,共筛选出16株抗重金属菌,其中4株抗Pb菌、4株抗Cd菌、4株抗Zn菌、3株抗Cu菌和1株抗Ni菌,其抗性分别高达3 000、800、600、300和400mg/L,16株菌中以芽孢杆菌属(Bacillus)数量最多。在初始浓度为700mg/L Pb²⁺下,菌株Pb6的去除率高达92.48%,菌株Pb11、Pb3和Pb9的去除率分别为27.70%、40.37%和58.88%;在200mg/L Cd²⁺...     

The humoral immune response of Salmo trutta L. and Cyprinus carpio L. exposed to heavy metals

Salmo trutta L. and Cyprinus carpio L. were exposed to low levels of waterborne heavy metals, 0.75 mg Ni dm^-3, 1.06mg Zn dm^-3, 0.29 mg Cu dm^-3 and 1.01 mg Cr dm^-3, at pH 7.83, water hardness 206.9 mg CaCO, dm^-3, and water temperature 15.5° C. During a 38 week exposure period, the humoral antibody response to MS2 bacteriophage was followed using a 50% viral neutralization assay (SD₅₀) method. A suppression of the immune response was observed in fish exposed to the four heavy metals. Total suppression of the humoral antibody response was found only in C. carpio exposed to Cu or Cr, and these fish exhibited symptoms of acute toxicosis. The time for the primary blood clearance of live bacteriophage was increased in S. trutta exposed to the heavy metals, with the exception of Zn-exposed fish, and in C. carpio exposed to Cu. Following the suppressed primary responses, the Ni-exposed S. trutta and Zn-exposed C. carpio exhibited an adjuvant-like response to the second bacteriophage challenge.     

Temporal and spatial fluctuations of heavy metals in Opa Reservoir,Ile-Ife,Nigeria

The Opa Reservoir, established for water supply to the Obafemi Awolowo University community, over the years has received direct linkage to township drains as a result of the widening and dredging of its river channels. The current study aimed at documenting monthly heavy metal loads at its riverine, transition and lacustrine zones in 2012–2013. Most of the heavy metals, analysed using an atomic absorption spectrophotometer, occurred within wide ranges, with coefficients of variation ranging from 60% to 300%, although the differences in heavy metal loads between the different zones were statistically insignificant at both the surface and bottom levels. The overall order of dominance of the metals was Ni > Cu > Fe > Zn > Cd = Cr > Pb, with nickel concentration being very high throughout. Heavy metal total mean concentration was higher during the rainy season (1.889 mg l?1) than the dry season (1.503 mg l?1) irrespective of sampling sites, having highly significant seasonal differences (p < 0.001) in Ni, Cd, Fe and Cu concentrations. The mean concentrations of Zn (0.074 mg l?1), Fe (0.176 mg l?1), Cu (0.507 mg l?1) and Pb (0.004 mg l?1) were within the WHO acceptable limit. However, the recorded levels of toxic elements Cd (0.031 mg l?1) and Ni (0.905 mg l?1) pose potential health risk to water consumers.     

Hydrocarbon Degradation and Biosurfactant Production by an Acenaphthene-degrading Pseudomonas Species

An acenaphthene-degrading bacterium putatively identified as Pseudomonas sp. strain KR3 and isolated from diesel-contaminated soil in Lagos, Nigeria was investigated for its degradative and biosurfactant production potentials on crude oil. Physicochemical analysis of the sampling site indicates gross pollution of the soil with high hydrocarbon content (2100 mg/kg) and detection of various heavy metals. The isolate grew luxuriantly on crude oil, engine oil and acenaphthene. It was resistant to septrin, amoxicillin and augmentin but was susceptible to pefloxacin, streptomycin and gentamycin. It was also resistant to elevated concentration of heavy metals such as 1–15 mM lead, nickel and molybdenum. On acenaphthene, the isolate exhibited specific growth rate and doubling time of 0.098 day^?1 and 3.06 days, respectively. It degraded 62.44% (31.2 mg/l) and 91.78% (45.89 mg/l) of 50 mg/l acenaphthene within 12 and 21 days. On crude oil, the specific growth rate and doubling time were 0.375 day^?1 and 1.85 days with corresponding percentage degradation of 33.01% (903.99 mg/l) and 87.79% (2403.71 mg/l) of crude oil (2738.16 mg/l) within 9 and 18 days. Gas chromatographic analysis of residual crude oil at the end of 18 days incubation showed significant reductions in the aliphatic, alicyclic and aromatic fractions with complete disappearance of benzene, propylbenzene, pristane, phytane, and nC₁₈-octadecane fractions of the crude oil. The isolate produced growth-associated biosurfactant on crude oil with the highest emulsification index (E₂₄) value of 72% ± 0.23 on Day 10 of incubation. The partially purified biosurfactant showed zero tolerance for salinity and had its optimal activity at 27°C and pH 2.0.     

The effect of landfill age on municipal leachate composition

The influence of municipal landfill age on temporal changes in municipal leachate quality on the basis of elaboration of 4 years monitoring of leachate from landfill in Wysieka near Bartoszyce (Poland) is presented in this study. In leachate, concentrations of organic compounds (COD, BOD(5)), nutrients (nitrogen, phosphorus), mineral compounds, heavy metals and BTEX were investigated. It was shown that the principal pollutants in leachate were organics and ammonia - as landfill age increased, organics concentration (COD) in leachate decreased from 1,800 mg COD/l in the second year of landfill exploitation to 610 mg COD/l in the sixth year of exploitation and increase of ammonia nitrogen concentration from 98 mg N(NH)/l to 364 mg N(NH4) /l was observed. Fluctuation of other indexes (phosphorus, chlorides, calcium, magnesium, sulfate, dissolved solids, heavy metals, BTEX) depended rather on season of the year (seasonal variations) than landfill age. Moreover, the obtained data indicate that despite of short landfill's lifetime some parameters e.g. high pH (on average 7.84), low COD concentration (<2,000 mg COD/l), low BOD(5)/COD ratio (<0.4) and low heavy metal concentration, indicated that the landfill was characterized by methanogenic conditions already at the beginning of the monitoring period.     

Removal of heavy metals by an enriched consortium

An enriched consortium obtained from lake-sediment was developed for the removal of heavy metals such as Cu, Pb, Cr, Ni, and Zn from heavy metal-contaminated water. The removal efficiency of heavy metals in a shaking condition was generally higher than that in the static state. After the fifteenth enrichment with assorted heavy metals, the removal efficiencies in the shaking and static condition at an average concentration of 100 mg/L of each heavy metal were approximately 99 approximately 100% and 95 approximately 100%, respectively, depending on the type of heavy metal. An aerobically grown, pure culture isolated from an enriched culture was analyzed by 16S rRNA sequencing and identified as Ralstonia sp. HM-1. This strain was found to remove various heavy metals with an efficiency of approximately 97 approximately 100% at an average concentration of 200 mg/L of each heavy metal.     

Anaerobic digestion of cattail with rumen culture in the presence of heavy metals

The anaerobic digestion of cattail by rumen cultures in the presence of Cu(II), Cd(II) or Cr(VI) was investigated in this study. Three cases were respectively observed for the different metal dosages: promoted cattail degradation and methane production at a low heavy metal concentration, e.g., Cu(II) 2.4 mg/l, Cd(II) 1.6 mg/l, Cr(VI) 4.0 mg/l; reduced cattail degradation efficiency and methane production at a middle metal level; a severe inhibition to the cattail degradation at a high heavy metal dosage. The inhibition kinetics of Cu(II) on the digestion of cattail by rumen cultures was also analyzed and a simplified Andrews equation was used to describe such an inhibition. The inhibition constants for Cu(II) on the degradation of cattail, production of volatile fatty acids and formation of methane were estimated as 7.4, 9.5 and 6.4 mg/l, respectively. Comparative experimental results suggest that the order of toxicity degree of the tested metals on the rumen cultures was: Cd(II) > Cu(II) > Cr(VI).     

Potential treatment alternative for laboratory effluents

The Chemical Analysis Laboratory under study weekly generates 46.5 L effluent with low pH (0.7), high COD concentration (6535 mg O2/L), sulphate (10390 mg/L) and heavy metals (213 mg Hg/L, 55 mg Cr/L, 28 mg Al/L, 22 mg Fe/L, 10mg Cu/L, 4 mg Ag/L). A treatment sequence has been proposed using a physical chemical step (coagulation/flocculation or chemical precipitation) followed by a biological step (anaerobic treatment). Removals of COD (18%), turbidity (76%) and heavy metals (64-99%) were attained only after adjusting pH to 6.5, without requiring the addition of Al2(SO4)3 and FeCl3. Due to the low COD:sulphate ratio (0.9-1.3), it was possible to efficiently operate the UASB reactor (at the biological step) only upon mixing the effluent with household wastewater. COD, sulphate and heavy metals removals of 60%, 23% and 78% to 100%, respectively, were attained for 30% effluent in the reactor feed. The results pointed to the need of a pretreatment step and mixing the effluent in household wastewater prior to the biological step. This alternative is feasible as this can be achieved using sanitary wastewater generated in the university campus.     

天山土壤微量(类)重金属的来源解析及潜在生态危害评估

从天山山地3个区段(巴里坤-伊吾、乌鲁木齐-阿克苏、昭苏-特克斯)采集土壤样品,测定了其中(类)重金属Pb、Ni、Cd、Co、Hg、Cu、Mn、Zn、Cr和As的含量.运用经典统计学与多元统计方法分析了这些(类)重金属的来源;同时采用污染指数法与潜在生态风险指数法,并结合天山及新疆土壤背景值、国家土壤质量标准开展了区域土壤微量(类)重金属生态风险的评价.结果表明： 所测10种(类)重金属的平均含量均高于天山或新疆土壤背景值.从变异系数来看,均为中等变异.总体上看,天山山地土壤中10种(类)重金属的含量均较低;主成分分析显示,10种元素可以辨识出 2 个主成分,主成分1(PC1,包括Cd、Pb、Hg、Mn和Zn)为人为源因子,主成分2(PC2,包括Cu、Ni、Cr、Co和As)为自然源因子.Mn 和As在PC1和PC2上均有较大载荷,主要受人为源和自然地质背景的共同控制;污染评价表明, 重金属Hg、Cd在天山中部的乌鲁木齐-阿克苏区段、As在天山西部的昭苏-特克斯区段的单因子污染指数(P_i)属于警戒等级,其他均属于安全等级和清洁水平.从综合污染(P_z)指数来看,天山中部乌鲁木齐 阿克苏区段土壤中10种(类)重金属元素的综合污染程度均属于轻度污染,其他两个区段均属于清洁水平;生态风险评估表明,重金属Hg、Cd在天山中部乌鲁木齐 阿克苏区段,As在天山西部昭苏 特克斯区段的潜在生态风险系数(E_i^r)和生态危害指数(RI)相对较高.     

Investigation of Vetiver Grass Capability in Phytoremediation of Contaminated Soils with Heavy Metals (Pb,Cd, Mn,and Ni)

ABSTRACT

Soil contamination with heavy metals has become a worldwide concern. A sustainable technology to mitigate heavy metal contamination is extremely important. Phytoremediation is a cost-effective method, environmentally friendly, and esthetically pleasing. The aim of this study was to investigate the potential of Vetiver phytoremediation of soils contaminated with heavy metals. This research was conducted as a factorial design with four different heavy metals (lead, cadmium, manganese, and nickel) with three varying levels and also three replications for each treatment. Statistical analysis of data was performed using SPSS19 software and analysis of variance, Duncan and Pearson correlation tests. The results showed that, the highest uptake rate was related to lead metal with 282.45 mg/kg of dry soil and 83.4% uptake percentage. Then, the mean and percentage of adsorption for cadmium, nickel and manganese were 248.3 mg/kg (53.2%), 69.4 mg/kg (65.5%), and 63.29 mg/kg (61%), respectively. Lead was found to be the main component of uptake by Vetiver plant. It was found that the roots of the plant have absorbed more heavy metals than the shoots. And at the roots in total 1089.05 and on average 363.01 mg/kg and at the shoots 901.19 and on average 300.39 mg/kg, the metals used were adsorbed on three levels and four treatments. The results of analysis of variance, Duncan test and Pearson correlation showed that the effect of applied treatments on lead uptake in roots and shoots increased significantly (P ≤ 0.05) with increasing levels of treatments. The biological concentration factor was more than one, and the transfer factor was close to one. Therefore, it can be used as a phytostablization plant. The results showed that Vetiver can be considered as a refining plant due to its vegetative characteristics, cost-effectiveness and high adaptation to environmental conditions.     

Multi-metal biosorption and bioaccumulation by Exiguobacterium sp. ZM-2

The present work deals with the biosorption performance of dried and non-growing biomasses of Exiguobacterium sp. ZM-2, isolated from soil contaminated with tannery effluents, for the removal of Cd²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ from aqueous solution. The metal concentrations studied were 25 mg/l, 50 mg/l, 100 mg/l, 150 mg/l and 200 mg/l. The effect of solution pH and contact time was also studied. The biosorption capacity was significantly altered by pH of the solution. The removal of metal ions was conspicuously rapid; most of the total sorption occurred within 30 min. The sorption data have been analyzed and fitted to the Langmuir and Freundlich isotherm models. The highest Q_max value was found for the biosorption of Cd²⁺ at 43.5 mg/g in the presence of the non-growing biomass. Recovery of metals (Cd²⁺, Zn²⁺, Cu²⁺ and Ni²⁺) was found to be better when dried biomass was used in comparison to non-growing biomass. Metal removal through bioaccumulation was determined by growing the bacterial strain in nutrient broth amended with different concentrations of metal ions. This multi-metal resistant isolate could be employed for the removal of heavy metals from spent industrial effluents before discharging them into the environment.     

Heavy metals (Cd, Pb, Zn, Ni, Cu and Cr(III)) removal from water in Malaysia: post treatment by high quality limestone

This paper presents the results of research on heavy metals removal from water by filtration using low cost coarse media which could be used as an alternative approach to remove heavy metals from water or selected wastewater. A series of batch studies were conducted using different particle media (particle size 2.36-4.75 mm) shaken with different heavy metal solutions at various pH values to see the removal behaviour for each metal. Each solution of cadmium (Cd), lead (Pb), zinc (Zn), nickel (Ni), copper (Cu) and chromium (Cr(III)) with a concentration of 2 mg/L was shaken with the media. At a final pH of 8.5, limestone has significantly removed more than 90% of most metals followed by 80% and 65% removals using crushed bricks and gravel, respectively. The removal by aeration and settlement methods without solid media was less than 30%. Results indicated that the removal of heavy metals was influenced by the media and not directly by the pH. Investigations on the removal behaviour of these metals indicated that rough solid media with the presence of carbonate were beneficial for the removal process. Adsorption and precipitation as metals oxide and probably as metals carbonate were among the two mechanisms that contributed to the removal of metals from solution.     

Mytilus trossulus hsp70 as a biomarker for arsenic exposure in the marine environment: laboratory and real-world results.

The highly conserved heat shock protein 70 (hsp70) is induced by heat and chemical toxins, particularly heavy metals such as arsenic (As). The use of Mytilus trossulus (bay mussel) hsp70 as a 'screening' biomarker for marine heavy metals contamination was assessed. Some studies have found high hsp70 sensitivity to heavy metals, while others have found the opposite. Few studies have realistically used low heavy metals exposures, and fewer have used real-world contamination exposures. Clean sub-tidal mussels from the Puget Sound, Washington State (WA), USA, were acclimatized for 2 weeks and exposed for 24 h to As-spiked seawater (n=9) or to contaminated seawater from an arsenical pesticide plant in Tacoma, WA (n=10) followed by a Western blot for hsp70. Hsp70 inductions were insignificant at 10 microg l(-1) As(III), but were strong at 100 microg l(-1) (p<0.05) and 1000 microg l(-1) (p<0.01), with the induction threshold estimated at 30-50 microg l(-1) As(III). Hsp70 induction roughly correlated with arsenical toxicity, with As(III) > As(V) > (CH(3))(2)As(V). Altogether, the inter-individual variability of hsp70 levels tends to mask inductions at low As concentrations, making it a crude toxicity biomarker. In addressing this problem, the following options could prove promising: (1) pre- or post-stressing specimens for greater hsp70 sensitivity, (2) use of internal protein controls such as actin, (3) use of hsp70-reporter gene constructs, and (4) detection with hsp60, heme oxygenase-1, metallothionein, CYP450, MXR or GPx.     

Increased removal of nickel and organics in the upflow anaerobic sludge bed filter reactor using sulfate and sulfide additions

Glucose (total organic carbon: 1,200 mg/l) and nickel (0 to 40 mg/l) were added to an anaerobic upflow sludge bed filter reactor. The removal efficiencies of total organic carbon and nickel were maintained to 95% and 98.5%, respectively, since nickel was precipitated with sulfide which was converted from sulfate added at 80 mg SO4-S/l by sulfate reducing bacteria. Sulfate therefore enhances its organic removal efficiency of AUBF reactor under the presence of heavy metal.     

中华绒螯蟹对Pb和Cd的富集与释放特性

应用生物富集双箱动力学模型模拟了中华绒螯蟹(Eriocheir sinensis)分别在Pb浓度为0.25、0.50、0.75mg/L,Cd浓度为0.025、0.050、0.075mg/L的单一水环境中暴露时,蟹鳃、肝胰腺、肌肉和血淋巴对Pb和Cd的生物富集与释放实验,并通过非线性拟合得到中华绒螯蟹对Pb和Cd的富集速率常数k1、排出速率常数k2、生物富集系数BCF、生物半衰期B1/2、富集平衡时生物体内Pb和Cd含量CAmax等动力学参数。结果表明:(1)中华绒螯蟹对Pb和Cd具有明显的富集,蟹鳃、肝胰腺和肌肉中Pb和Cd的含量与富集时间和水环境中Pb和Cd暴露浓度表现出了很好的正相关,血淋巴在富集阶段没有明显的规律。理论平衡状态下鳃、肝胰腺和肌肉中Pb和Cd含量CAmax随着暴露浓度的增大而增大,且成正相关。(2)Pb和Cd在中华绒螯蟹组织器官中的富集具有选择性,开始实验前,Pb在中华绒螯蟹体内的的分布规律为:肝胰腺>鳃>肌肉>血淋巴;Cd的分布规律为:鳃>肝胰腺>血淋巴>肌肉。在实验浓度的Pb和Cd水环境中暴露16d后,Pb的分布规律为:鳃>肝胰腺>肌肉>血淋巴;Cd的分布规律为:肝胰腺>鳃>肌肉>血淋巴。(3)中华绒螯蟹对Pb和Cd的生物富集和释放都较缓慢。经过16d的生物富集,各组织器官中Pb和Cd的含量均未达到稳态平衡。Pb和Cd在组织器官中的生物富集系数(BCF)范围分别为5-51和6-3148,中华绒螯蟹对Cd的富集能力明显高于Pb(P1/2)范围分别为4-9d和8-57d,中华绒螯蟹对Cd的排出能力明显低于Pb。