Phytoremediation of landfill leachate waste contaminants through floating bed technique using water hyacinth and water lettuce

Abstract

In the present study, the effectiveness of water hyacinth and water lettuce was tested for the phytoremediation of landfill leachate for the period of 15?days. Fifteen plastic containers were used in experimental setup where aquatic plants were fitted as a floating bed with the help of thermo-pole sheet. It was observed that both plants significantly (p?<?0.05/p?<?0.01/p?<?0.001) reduce the physicochemical parameters pH, TDS, BOD, COD and heavy metals like Zn, Pb, Fe, Cu and Ni from landfill leachate. Maximum reduction in these parameters was obtained at 50% and 75% landfill leachate treatment and their removal rate gradually increased from day 3 to day 15 of the experiment. The maximum removal rate for heavy metals such as for Zn (80–90%), Fe (83–87%) and Pb (76–84%) was attained by Eichhornia crassipes and Pistia stratiotes. Value of bioconcentration and translocation factor was less than 1 which indicates the low transport of heavy metals from roots to the above-ground parts of the plants. Both these plants accumulate heavy metals inside their body without showing much reduction in growth and showing tolerance to all the present metals. Therefore, results obtained from the study suggest that these aquatic plants are suitable candidate for the removal of pollution load from landfill leachate.     

黄河口盐地碱蓬湿地土壤-植物系统重金属污染评价

以黄河口盐地碱蓬湿地为例,评价了淹水和非淹水区湿地表层土壤As、Cd、Cu、Cr、Pb和Zn 6种重金属的污染程度及其在土壤-植物系统中的迁移、富集特征,分析了不同积水深度和土壤理化性质对研究区土壤重金属含量的影响.研究结果表明,与土壤或沉积物质量标准相比,黄河口盐地碱蓬湿地土壤受As和Cd污染最严重,而其它重金属污染较轻;非淹水土壤Cd、Cr和Zn含量高于淹水湿地,而As、Cu和Pb则较低;而且淹水土壤As含量随积水深度增加而呈下降趋势,但积水深度对其他重金属含量的影响不明显.相关性分析结果表明,按照受土壤关键影响因子的不同重金属(除As外)可以分为两类:第一类为Cd、Cr和Zn,这些重金属含量受土壤pH值和盐分影响较大,且相互间存在显著正相关关系,表明它们可能有相同的来源;第二类为Pb和Cu,它们受土壤pH值、盐分和有机质的影响,且Pb和Cu之间存在显著正相关关系.除Cr、Cu和Zn外,重金属在盐地碱蓬的根系内一般不发生显著富集,但绝大多数重金属都表现出地上部分的含量比根系更高的现象.     

Health Risk Assessment of Exposure to Metals in a Nigerian Water Supply

This article reports the health risk associated with chronic intake of metals in the municipal water supplies of Eleyele and neighboring towns in the Ibadan metropolitan area of Nigeria. A total of 42 composite samples, consisting of treated water from the water treatment facility and residential areas receiving personal-use water (i.e., tap water) directly from the facility, as well as raw water from the treatment facility's water supply dam were sampled twice every month for 7 months. Concentrations of the metals were determined by atomic absorption spectrophotometry. Among the metals studied, Cd, Co, Cr, and Pb were detected at concentrations higher than maximum regulatory limits. Cd, Co, Cr, and Pb concentrations in treated water at the treatment facility ranged from 0.08–0.10, 0.14–0.16, 0.04–0.22 and 0.07–0.36 mg L^?1, respectively, while personal-use water ranged from 0.08–0.11, 0.15–0.29, 0.02–0.29, and 0.12–0.65 mg L¹, respectively. Likewise, concentrations of the metals at the dam ranged from 0.06–0.08, 0.17–0.20, 0.13–0.37, and 0.03–0.15 mg L¹, respectively. It is estimated that exposure to the metals in the water supply results in oncological and non-oncological systemic health risks higher than is generally acceptable for drinking water.     

Assessing the influence of water and substratum quality on benthic macroinvertebrate communities in a metal-polluted stream: an experimental approach

SUMMARY 1. Field and laboratory experiments were conducted to assess the relative influence of water quality and substratum quality on benthic macroinvertebrate communities in the Animas River, a metal-polluted stream in south-western Colorado (U.S.A.).
2. A community-level in situ toxicity test measured direct effects of Animas River water on benthic invertebrates collected from a reference stream (Elk Creek). The effects of metal-contaminated biofilm were examined by comparing macroinvertebrate colonisation of clean and contaminated substrata placed in Elk Creek. A feeding experiment with the mayfly Baetis tricaudatus Dodds (Ephemeroptera: Baetidae) examined metal bioaccumulation and effects of metal-contaminated biofilm on growth and survival.
3. Animas River water was acutely toxic to most taxa, with greatest effects observed on mayflies (Heptageniidae, Ephemerellidae) and stoneflies (Taeniopterygidae and Capniidae).
4. Although Animas River biofilm was characterised by high concentrations of metals and low algal biomass, most taxa colonised substratum from the reference stream and the Animas River equally. The exceptions were Ephemerellidae, Taeniopterygidae and Simuliidae, which were less abundant on Animas River substratum. Mayflies grazing Animas River biofilm accumulated significantly more metals and showed reduced growth compared with organisms feeding on Elk Creek biofilm.
5. Results of our experiments demonstrated that effects of heavy metals on benthic community structure in the Animas River were complex, and that responses to metals in water and contaminated substratum were species-specific. Predicting recovery of benthic communities following remediation requires an understanding of these species-specific responses.     

Trace metal fractionation in water and sediments of an urban river stretch

Abstract

In this study, the fractionation and ecotoxic potential of Cr, Ni, Cu and Pb in water and sediments of the river Yamuna (Delhi stretch) is presented. The river water is used for various purposes such as irrigation, industrial, domestic and drinking. The investigations suggest that the availability of metals in water follows the sequence Ni>Cr>Pb>Cu whereas a different pattern (Pb>Cu>Ni>Cr) is observed in sediments. Statistically significant spatial variations are indicated by two-way ANOVA in different geochemical forms of the metals and physicochemical parameters of water and sediments of the river Yamuna. Principal component analysis (PCA) suggests a similar source for all four metals probably from the sewage from municipal drains. PCA also indicates some independent sources of Cu and Pb. The hot spots were identified using hierarchical cluster analysis considering bioavailable forms of the metals in water and sediments as objects and the sampling sites as variables. Risk assessment code analysis indicates that metals generally pose medium to high risk at different sites. However, at a few locations either Ni or Pb cross the level of very high ecological risk.     

Concurrent removal and accumulation of heavy metals by the three aquatic macrophytes

Under the present investigation effectiveness of three aquatic macrophytes Pistia stratiotes L. (water lettuce), Spirodela polyrrhiza W. Koch (duckweed) and Eichhornia crassipes were tested for the removal of five heavy metals (Fe, Zn, Cu, Cr and Cd). These plants were grown at three different concentrations (1.0, 2.0 and 5.0mgl(-1)) of metals in laboratory experiment. Result revealed high removal (>90%) of different metals during 15 days experiment. Highest removal was observed on 12th day of experiment, thereafter it decreased. Results revealed E. crassipes as the most efficient for the removal of selected heavy metals followed by P. stratiotes and S. polyrrhiza. Results from analysis confirmed the accumulation of different metals within the plant and a corresponding decrease of metals in the water. Significant correlations between metal concentration in final water and macrophytes were obtained. Plants have accumulated heavy metals in its body without the production of any toxicity or reduction in growth. Selected plants shown a wide range of tolerance to all of the selected metals and therefore can be used for large scale removal of heavy metals from waste water.     

Accumulation of heavy metals in epidermal glands of the waterlily (Nymphaeaceae)

This study investigates the anatomical aspects of heavy-metal accumulation in the waterlily (Nymphaea `Aurora', Nymphaeaceae). Epidermal glands were identified by light microscopy on the abaxial side of the leaf laminae and on the epidermis of the rhizome; glandular trichomes were observed in the petiole epidermis. Glands were not observed in the roots. Accumulation of heavy metals in these glands was monitored using a scanning electron microscope equipped for energy-dispersive spectroscopy. Further experiments showed maximal cadmium and calcium accumulation in the mature leaf lamina in daylight, and this accumulation was inhibited by the herbicide 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. These results suggest that, in Nymphaea, heavy metals are accumulated primarily in association with glands found in plant organs that have direct contact with water or mud. Deposition and storage of heavy metals by these glands may represent a stage in the sequestration and detoxification of the metals. Our results raise the possibility of utilizing waterlilies for the removal of heavy metals from polluted environments. Received: 29 April 2000 / Accepted: 8 June 2000     

Metal Sources for Freshwater Invertebrates: Pertinence for Risk Assessment

Ecological risk assessments are likely to be more effective if they are built upon knowledge of from where and in what manner animals take up contaminants. We discuss the relative importance of various metal sources for aquatic invertebrates. First, we address the question do sediment-dwelling animals take up their metals from the overlying water compartment or the sediment compartment or both (both compartments include water and particles). We find that the overlying water column is more important as a metal source for insects, whereas the sediment compartment is more important for oligochaete worms. We explain this tendency by the behaviors of the animals involved. Second, we ask the question do animals take up their metals from food or water within a given compartment. Through case studies on three widespread freshwater invertebrates, we conclude that for some predatory insects food is their major source of several metals, whereas for the crustacean Hyalella both food and water appear to be important depending on the metal involved and the experimental protocol used to study the question. We conclude that ignoring food as a metal source could severely underestimate metal exposures for some animals. We suggest that integrating these complexities into laboratory tests and risk assessment protocols will improve their meaningfulness and thus their ability to protect aquatic ecosystems.     

The resorption of zinc from scales of sea trout (Salmo trutta) during the upstream spawning migration

SUMMARY. The concentration of zinc in the scales of unripe, prespawning, estuarine sea trout was compared to that in the scales of sea trout about to spawn in fresh water. Zinc concentrations in scales from estuarine sea trout were in agreement with a published concentration factor but those from fresh water were not — a 43–52% reduction in the zinc concentration of the scales was observed. This withdrawal of trace metals from scales was also likely for iron but these data were less conclusive. This reclamation of trace metals from scales may represent the withdrawal of stored nutrients from body reserves to be used in gonad development and maturation.     

Uptake and transformation of metals and metalloids by microbial mats and their use in bioremediation

Summary Constructed microbial mats, used for studies on the removal and transformation of metals and metalloids, are made by combining cyanobacteria inoculum with a sediment inoculum from a metal-contaminated site. These mats are a heterotrophic and autotrophic community dominated by cyanobacteria and held together by slimy secretions produced by various microbial groups. When contaminated water containing high concentrations of metals is passed over microbial mats immobilized on glass wool, there is rapid removal of the metals from the water. The mats are tolerant of high concentrations of toxic metals and metalloids, such as cadmium, lead, chromium, selenium and arsenic (up to 350 mg L^–1). This tolerance may be due to a number of mechanisms at the molecular, cellular and community levels. Management of toxic metals by the mats is related to deposition of metal compounds outside the cell surfaces as well as chemical modification of the aqueous environment surrounding the mats. The location of metal deposition is determined by factors such as redox gradients, cell surface micro-environments and secretion of extra-cellular bioflocculents. Metal-binding flocculents (polyanionic polysaccharides) are produced in large quantities by the cyanobacterial component of the mat. Steep gradients of redox and oxygen exist from the surface through the laminated strata of microbes. These are produced by photosynthetic oxygen production at the surface and heterotrophic consumption in the deeper regions. Additionally, sulfur-reducing bacteria colonize the lower strata, removing and utilizing the reducing H₂S, rather than water, for photosynthesis. Thus, depending on the chemical character of the microzone of the mat, the sequestered metals or metalloids can be oxidized, reduced and precipitated as sulfides or oxides. For example precipitates of red amorphous elemental selenium were identified in mats exposed to selenate (Se-VI) and insoluble precipitates of manganese, chromium, cadmium, cobalt, and lead were found in mats exposed to soluble salts of these metals. Constructed microbial mats offer several advantages for use in the bioremediation of metal-contaminated sites. These include low cost, durability, ability to function in both fresh and salt water, tolerance to high concentrations of metals and metalloids and the unique capacity of mats to form associations with new microbial species. Thus one or several desired microbial species might be integrated into mats in order to design the community for specific bioremediation applications.     

Phytoremediation of Heavy Metals in Contaminated Water and Soil Using Miscanthus sp. Goedae-Uksae 1

The aim of this study is to characterize the heavy metal phytoremediation potential of Miscanthus sp. Goedae-Uksae 1, a hybrid, perennial, bio-energy crop developed in South Korea. Six different metals (As, Cu, Pb, Ni, Cd, and Zn) were used for the study. The hybrid grass effectively absorbed all the metals from contaminated soil. The maximum removal was observed for As (97.7%), and minimum removal was observed for Zn (42.9%). Similarly, Goedae-Uksae 1 absorbed all the metals from contaminated water except As. Cd, Pb, and Zn were completely (100%) removed from contaminated water samples. Generally, the concentration of metals in roots was several folds higher than in shoots. Initial concentration of metals highly influenced the phytoremediation rate. The results of the bioconcentration factor, translocation factor, and enrichment coefficient tests indicate that Goedae-Uksae 1 could be used for phytoremediation in a marginally contaminated ecosystem.     

Metal exchanges in the fauna-sediment system. The case of Nereis diversicolor and Scrobicularia plana in the Bou Regreg estuary (Morocco)

This study identifies the types and quantities of metals retained by Nereis diversicolor and Scrobicularia plana in a predominantly arid estuary environment.Certain abiotic parameters and a number of physiological processes linked to metabolic and reproductive functions play a decisive role in the seasonal influence of metal levels on the tissues of these organisms.Given the deposivoric diet of the organisms, the sedimentary bed would appear to be the principal source of metal accumulation.The following classification illustrates the bioaccumulation of metals: 209-1The possibility that these metals may be carried into the estuary by sewage water from the cities of Rabat and Sále should certainly not be ignored.     

Modelling Bioaccumulation and Toxicity of Metal Mixtures

Bioaccumulation of metals in mixtures may demonstrate competitive, anticompetitive, or non-competitive inhibition, as well as various combinations of these and/or enhancement of metal uptake. These can be distinguished by plotting (metal in water)/(metal in tissue) against metal in water and comparison to equivalent plots for single-metal exposure. For the special case of pure competitive inhibition where only one site of uptake is involved, inhibition of metal accumulation in any metal mixture can be predicted from bioaccumulation of the metals when present singly. This is consistent with the commonly used Biotic Ligand Model (BLM) but does not explain bioaccumulation of metals in Hyalella azteca. Options for modelling toxicity of metal mixtures include concentration or response addition based on metal concentrations in either water or tissues. If the site of toxic action is on the surface of the organism, if this is the same as the site of metal interaction for bioaccumulation, if there is only one such type of site, and if metal bioaccumulation interactions are purely competitive (as in the BLM), then metal toxicity should be concentration additive and predictable from metal concentrations in either water or tissues. This is the simplest toxicity interaction to model but represents only one of many possibilities. The BLM should, therefore, be used with caution when attempting to model metal interactions, and other possibilities must also be considered.     

Dietary Intakes and Health Risk of Toxic and Essential Heavy Metals through the Food Chain in Agricultural,Industrial, and Coal Mining Areas of Northern India

Minerals can enter the food chain through industrial and mining activities. Soil-to-vegetable transfer is higher than soil-to-cereal, but human consumption of metals is attributable to balanced diets containing both vegetables and cereals and drinking water. However, the impact of location on intakes of metals from predominantly cereal-based Indian diets is not clear. Hence, the present study was undertaken in selected Agricultural, Industrial, and Coal Mining Areas (AA, IA, CMA) around the Allahabad District in Northern India to compare transfer of toxic metals, Pb, Cd, Cr and essential metals, Fe, Zn, Cu, Co in soil and water to common crops: cereals (rice, wheat, maize) and vegetables (spinach, potato), and to assess Daily Intake of Metal (DIM) and consequent Health Risk Index (HRI). The overall content of all metals, except Cu, in water, soils, and crops followed the pattern CMA > IA > AA. Transfer factors (TFs) followed the sequence spinach > potato > cereals. Quantitatively, however, cereals contribute maximally to a balanced diet, so DIM and HRI were higher from cereals than vegetables. Even though spinach had the highest TFs, cereals contributed maximally to HRI. CMA had the highest metal content so locally grown cereals contributed significantly to intake of both toxic and essential metals.     

Isolation and characterization of heavy metal tolerant Gram-positive bacteria with bioremedial properties from municipal waste rich soil of Kestopur canal (Kolkata), West Bengal,India

The present study was conducted to determine the culturable bacterial profile from Kestopur canal (Kolkata, India) and analyze their heavy metal tolerance. In addition to daily sewage including solid and soluble wastes, a considerable load of toxic metals are released into this water body from industries, tanneries and agriculture, household as well as health sectors. Screening out microbes from such an environment was done keeping in mind their multifunctional application especially for bioremediation. Heavy metals are major environmental pollutants when present in high concentration in soil and show potential toxic effects on growth and development in plants and animals. Some edible herbs growing in the canal vicinity, and consumed by people, were found to harbour these heavy metals at sub-toxic levels. The bioconcentration factor of these plants being <1 indicates that they probably only absorb but not accumulate heavy metals. All the thirteen Grampositive bacteria isolated from these plants rhizosphere were found to tolerate high concentration of heavy metals like Co, Ni, Pb, Cr, Fe. Phylogenetic analysis of their 16S rDNA genes revealed that they belonged to one main taxonomic group — the Firmicutes. Seven of them were found to be novel with 92–95% sequence homology with known bacterial strains. Further microbiological analyses show that the alkaliphilic Bacillus weihenstephanensis strain IA1 and Exiguobacterium aestuarii strain CE1, with selective antibiotic sensitivity along with high Ni²⁺ and Cr⁶⁺ removal capabilities, respectively, can be prospective candidates for bioremediation.     

Heavy metal contamination in water,soil, and milk of the industrial area adjacent to Swan River,Islamabad, Pakistan

Trace heavy metals such as Cr(III), Ni(II), Cd(II), Zn(II), Pb(II), and Cu(II) are hazardous pollutants and are rich in areas with high anthropogenic activities. Their concentrations were analyzed using atomic absorption spectroscopy, and it was found that their concentrations were several fold higher in downstream Swan River water samples of the Kahuta Industrial Triangle as compared to upstream. Heavy metal soil concentrations taken from the downstream site were 149% for Cr, 131% for Ni, 176% for Cd, 139% for Zn, 224% for Pb, and 182% for Cu when compared to samples from the upstream site. Quantitative analysis concluded that these metals were higher in milk samples collected from downstream as compared to the samples from upstream water-irrigated sites. The order of metal in milk was as Zn > Cr > Cu > Cd > Pb = Ni. Heavy metal contaminations may affect the drinking water quality, food chain, and ecological environment. It was also suggested that the toxicity due to such polluted water, soil, and milk are seriously dangerous to human health in future.     

Bioaccumulation and rhizofiltration potential of Pistia stratiotes L. for mitigating water pollution in the Egyptian wetlands

The bioaccumulation and rhizofiltration potential of P. stratiotes for heavy metals were investigated to mitigate water pollution in the Egyptian wetlands. Plant and water samples were collected monthly through nine quadrats equally distributed along three sites at Al-Sero drain in Giza Province. The annual mean of the shoot biomass was 10 times that of the root. The concentrations of shoot heavy metals fell in the order: Fe < Mn < Cr < Pb < Cu < Zn < Ni < Co < Cd, while that of the roots were: Fe < Mn < Cr < Pb < Zn < Ni < Co < Cu < Cd. The bio-concentration factor (BCF) of most investigated heavy metals, except Cr and Pb, was greater than 1000, while the translocation factor (TF) of most investigated metals, except Pb and Cu, did not exceed one. The rhizofiltration potential (RP) of heavy metals was higher than 1000 for Fe, and 100 for Cr, Pb and Cu. Significant positive correlations between Fe and Cu in water with those in plant roots and leaves, respectively were recorded, which, in addition to the high BCF and RP, indicate the potential use of P. stratiotes in mitigating these toxic metals.     

Heavy metals contamination and accumulation in submerged macrophytes in an urban river in China

Deteriorating urban water quality has attracted considerable attention in China. We investigated the contamination levels and distribution of heavy metals (As, Cd, Cu, Ni, Pb, and Zn) in Yuxi River water and sediments, and assessed the heavy metal accumulation capability of five species of submerged macrophytes: Vallisneria natans (Lour.) Hara, Potamogeton pectinatus L., Hydrilla verticillata (L. f.) Royle, Myriophyllum spicatum L., and Potamogeton crispus L. Samples were collected from upstream and downstream locations in different season. The results showed that the levels of heavy metals in the downstream areas were higher than in the upstream areas. Heavy metal concentrations in the river water during the dry seasons were higher than those during the rainy seasons, and the opposite results appeared in sediments and submerged macrophytes. In general, the river was slightly contaminated by heavy metals, and the concentrations of Pb and Ni in this river should serve as a warning, while Cd and Zn pollution in the sediments desperately needs to be removed. Furthermore, Potamogeton pectinatus L. showed a higher accumulation capacity for these metals among the five native submerged macrophytes and could be defined as a hyperaccumulator for Cd. Therefore, the potential use of native aquatic plants in contaminated rivers is worth further exploration.     

Risk Assessment of the Abandoned Jukjeon Metal Mine in South Korea Following the Korean Guidelines

Toxic metal contamination in the vicinity of Korean abandoned metal mines has been reported. A risk assessment for these metals was performed for the inhabitants in the area of the abandoned Jukjeon metal mine. Soil, groundwater, and crop samples were collected around the mine. After pretreatment of these samples, metal concentrations were measured and then a risk assessment was performed using the Korean soil-contamination risk assessment guidelines. Phytoaccumulation of metals in crops was observed in soybeans (As and Zn), red peppers (Zn), sweet potatoes (As and Zn), and cabbage (Cu), which had higher metal concentrations than soils in the area. The metal intake rate was highest for inhalation of soil. Cancer risk was highest from ingestion of As-contaminated crops. The sum of carcinogenic risks was 6.29 × 10^–3. The non-carcinogenic risk was highest for ingestion of As-contaminated crops (8.17). Most of the risks were attributable to As, Pb, and Hg contamination, therefore these three metals must be considered as the principal metals toxic to human health in the sampled area. In particular, the inhalation of metal-contaminated soil should be considered for risk assessment along with ingestion of water and crops in abandoned mine areas.     

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.