Metals In Industrial Effluents Research Articles

Isolation and Characterization of Heavy Metal-Tolerant Bacterial Isolates from Industrial Effluents in Uttar Pradesh, India

Industrial activities over the past century have significantly increased human exposure to pollutants such as heavy metals. Industrial emissions of heavy metals, which are carcinogenic, mutagenic and toxic, contaminate natural water supplies and the agricultural environment. Due to the high concentration of heavy metals in industrial effluents, the bacteria present there naturally develop resistance to heavy metals. The aim of this study is to isolate and characterize bacteria resistant to heavy metal, lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), and nickel (Ni) from sites contaminated by industrial effluents in Uttar Pradesh, India. A total of 58 bacterial isolates were isolated from 9 samples according to their various morphological parameters and 32 isolates were found positive for all heavy metals, which revealed that samples contained metal-resistant bacterial diversity. Two isolates were identified up to species level based on their physiological, biochemical and molecular characterization as Comamonas testosteroni (S4C1) and Bacillus cereus (S5C3). Both isolates are highly resistant to lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), and nickel (Ni) and they show different MICs against the above heavy metals at different levels. A growth experiment showed that the presence of heavy metals concentration had no discernible impact on the growth rate among the isolates. Gel analysis showed interesting patterns of protein expression were observed in the presence of various heavy metals. MALDI-TOF analysis found that specific proteins (S layer protein, F0F1ATP synthase subunit b, Flagellin, 50S ribosomal protein L4, Molecular chaperone) were overexpressed in the presence of heavy metals. As a result, identifying the heavy metal resistance bacteria and their proteins study could be useful as a preliminary investigation for the development of prospective bioremediation agents of potentially hazardous waste treatment technology.

Trace metal transfer to passerines inhabiting wastewater treatment wetlands

Wastewater treatment wetlands are cost-effective strategies for remediating trace metals in industrial effluent. However, biogeochemical exchange between wastewater treatment wetlands and adjacent environments provides opportunities for trace metals to cycle in surrounding ecosystems. The transfer of trace metals to wildlife inhabiting treatment wetlands must be considered when evaluating wetland success. Using passerine birds as bioindicators, we conducted a multi-tissue analysis to investigate the mobilization of zinc, copper, and lead derived from wastewater to terrestrial wildlife in treatment wetlands and surrounding habitat. In addition, we evaluate the strength of relationships between metal concentrations in non-lethal (blood and feathers) and lethal (muscle and liver) sample types for estimation of toxicity risk. From July 2020 to August 2021, 177 passerines of seven species were captured at two wetlands constructed to treat industrial wastewater and two reference wetlands in the coastal plain of South Carolina. Feather, blood, liver, and muscle samples from each bird were analyzed for fourteen metals using inductively coupled plasma mass spectrometry and direct mercury analysis. Passerines inhabiting wastewater treatment wetlands accumulated higher concentrations of zinc in liver, copper in blood, and lead in feathers than passerines in reference wetlands, but neither blood nor feather concentrations were correlated with internal tissue concentrations. Of all the detected metals, only mercury in the blood showed a strong predictive relationship with mercury in internal tissues. This study indicates that trace metals derived from wastewater are bioavailable and exported to terrestrial wildlife and that passerine biomonitoring is a valuable tool for assessing metal transfer from treatment wetlands. Regular blood sampling can reveal proximate trace metal exposure but cannot predict internal body burdens for most metals.

Comprehensive pollution and ecological risk of heavy metals in an industrial region of south-west Bangladesh

Deterioration of water, soil and sediment due to industrial operation is well known. This study aimed to evaluate physicochemical properties of surface water and heavy metals in industrial effluent (n = 13), river water (n = 14), pond water (n = 5), soil (n = 11) and sediment (n = 19) collected from an industrial zone in south-west Bangladesh. Among the physicochemical parameters, pH and dissolved oxygen (DO) indicated relatively higher values in most of the samples than their respective lower guideline values of 6 and 4.5 mg L-1 and showed significant variation across environments. Based on the average concentration, none of the heavy metals in any environment surpassed the guideline values in the study area, except, Cr in both industrial effluent (0.034 ± 0.055 mg L-1) and river water (0.011 ± 0.005 mg L-1), Cd in both soil (1.11 ± 0.47 mg kg−1) and sediment (1.41 ± 1.04 mg kg−1). Possibly, continuous discharge of industrial effluents might increase the heavy metal concentrations in the effluent receiving environment. Concentration of others heavy metals were below the respective guideline values but varied significantly among the environments. Depth-wise variation was negligible which might be dependent on metal chemistry in soil and sediment. A very high pollution and ecological risk were observed for Cd, specifically in soil and sediment. Multivariate statistics showed strong correlation among heavy metals, which indicated considerable contribution from industrial effluent. Industrial operations control physicochemical properties of surface water, but temperature is dependent of meteorological conditions. This study concludes that the lower concentrations of heavy metals than guideline values in environmental samples still pose significant levels of pollution and ecological risks.

Physicochemical characterization and heavy metals analysis from industrial discharges in Upper Awash River Basin, Ethiopia

The recent expansion of industries in Addis Ababa is causing additional environmental pollution through wastewater discharges; this is becoming a critical concern. Addis Ababa is located in the upper Awash River basin, and is the main source of industrial pollutants to the river. In this study, physicochemical parameters, nutrients and heavy metal content of wastewaters released from 16 factories, 6 tanneries, 6 beverages and 4 diverse factories, and the Akaki-Kality central wastewater treatment plant in Addis Ababa, were sampled to assess the level of pollutants. Heavy metals were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Analysis of nutrients were conducted using Palintest Photometer. Physicochemical characteristics were measured either in situ using a portable micro meter or in the laboratory. Among the measured physicochemical properties, critical issues were observed with electrical conductivity, total dissolved solids and total hardness. Effluents from all of the tanneries, and a number of other factories, were found at levels higher than the maximum limits of various guideline standards. In addition, samples from two of the tanneries (T1 and T5), two beverage factories (B3 and B6) and the central wastewater treatment plant showed elevated concentrations of PO4 3-, which violated the limit (10mg/l) set by Environmental Protection Agency of Ethiopia (ETHEPA). The two tanneries (T1 and T5) also contained higher SO4 2- than the guideline limit of 1000mg/l. On the other hand, only one factory, one brewery (B3), exhibited NO3 - above the standard limit of 20mg/l. Whereas NH3, NH4 +, Cl-, S2- and NO2 - were within the limits in all of the samples. Severe pollution was found in wastewaters from tanneries, where half of them (T1, T5 and T6) contained Cr beyond the maximum limit of 2000µg/l. Furthermore, a third of the tanneries (T1 and T5) and a beverage factory (B5) contained Fe, Mn, Zn and Cu, higher than the ETHEPA limits of 10000, 5000, 5000 and 2000µg/l, respectively. Waste disposal from factories without proper treatment can cause great harm to the local people and the environment. Hence, the results of this study call for regulatory bodies to pay close attention to factories, particularly tanneries, in Addis Ababa in implementing adequate treatments of their wastewater discharges.

Bioremoval of Different Heavy Metals in Industrial Effluent by the Resistant Fungal Strain Aspergillus niger

Developing countries are increasingly concerned with pollution due to toxic heavy metals in the environment. Unlike most organic pollutants which can be destroyed, toxic metal ions released into the environment often persist indefinitely circulating and eventually accumulating throughout the food chain thus posing a serious threat to mankind. The use of biological materials for heavy metal removal or recovery has gained importance in recent years due to their good performance and low cost. Among the various sources, both live and inactivated biomass of organisms exhibits interesting metal binding capacities. Their complex cell walls contain high content of functional groups like amino, amide, hydroxyl, carboxyl, and phosphate which have been implicated in metals binding. In the present study, Aspergillus niger was used to analyze the metal uptake from an aqueous solution. The determination of Cu+2, Pb+2, Cd+2, Zn+2, Co-2 and Ni+2 in samples was carried out by differential Pulse Anodic Voltammetry (DPASV) and the Voltammograms. Production of oxalic acid was carried out by submerged fermentation. The organism used in the present study has the ideal properties to sequester toxic metals and grow faster.

First principle investigation of boron functionalized graphene to detect the presence of “arsenic” in water

Heavy metals in industrial effluents create severe water pollution, leading to adverse effects on human beings. Thus, to save mankind from the ill effects of these heavy metals and to monitor its’ concentration within the permissible limits, effective sensors are required to be marked in terms of sensitivity, selectivity, and simplicity. In this work, boron functionalized graphene (BG) has been examined for its sensing ability towards Arsenic (As) by analyzing its band structure, density of states, and current–voltage characteristics in both vacuum and aqueous environments. The findings of the vacuum environment reveal that the arsenic interacts strongly with BG sheet owing to its high binding energy −2.63eVthat results in an opening of a bandgap of ~0.206 eV, infers the sensing ability of the sheet towards arsenic. Further, to comprehend the effect of an aqueous environment on the sheet's sensitivity, calculations are carried out in the presence of water molecule. The findings show that the BG sheet can detect the As in water with a sensitivity of ~15% at a low applied voltage of 400 mV.

A Review on the Synergetic Effect of Plant Extracts on Nanomaterials for the Removal of Metals in Industrial Effluents

Aim: The review paper aims to explore the effect of plant extracts on nanomaterial adsorbent for the removal of toxic metals present in industrial effluents. Background: Water plays a major role in the sustainability of human life and its existence. Rapid industrialization and urbanization lead to an increase in the pollution and accumulation of hazardous substances which causes the degradation of the aquatic ecosystem. Heavy metals are considered to be a major threat to the environment. Among various metals, the International Union of Pure applied chemistry (IUPAC) has characterized heavy metals based on their intensity of toxicity and hazardous effects. Nanoparticles, due to their unique properties of particle size, exist in the range between 1- 100nm, which represents the possibility to introduce modified chemical groups on their surface functioning as capping agents. Nanoparticles with the increased surface area have specified functional groups which induce the capability of the catalytic reduction reaction and their optical characteristics impact the industrial, agricultural and environmental sectors. Objective: Magnetic nanoparticles incorporated with the enzymes and metallic sites have been widely used in both the synthesis of bio valuable products as well as in the degradation of many hazardous substances like dyes, phenolic compounds, etc. Also, they are used in the removal of metal ions present in wastewater. Methods: Superparamagnetic support nanomaterials (SPIONs) are prepared using the compounds of Fe, Cu, Ni, Mn and Mg for the distinct and unique characteristics of reusability. These metallic nanomaterials are coated with distinct materials like mesoporous and amorphous silica, polyvinyl alcohol and pyrrolidine, polyethylene glycol, polystyrene, chitosan, dextran, starch, gelatin, polystyrene, polyacrylic acid, and polymethyl methacrylate to enhance the stability of the nanomaterials. Results: In comparison to the different nanomaterials, metal oxide NPs possess increased stability, magnetic inertness, optical and electrical properties. Nanomaterials that are used in the medical applications are also used as the adsorbents to remove heavy metals from the industrial wastewater. The presence of polyphenolic compounds and flavonoids makes the plant extracts effective antimicrobial agents that impact pathogens. Moreover, these plant extracts, coupled with other nanomaterials, play a significant role in the removal of toxic pollutants from the environment. Conclusion: Polyphenolic compounds present in plant extract function as natural reducing agents; hence, integrating plant extract with metal/metal oxide nanoparticles proves to be efficient in comparison with the catalysts synthesized by using other chemical methods. These surface modified nanocatalysts tend to possess enhanced stability and specific reactivity in the system and are used in the elimination of organic and inorganic pollutants in the industrial wastewater.

A highly efficient nanoscale tapioca starch prepared by high‐speed jet for Cu2+ removal in simulated industrial effluent

AbstractBACKGROUNDNanoscale tapioca starch (NTS) was successfully developed by high‐speed jet in our previous study. In this study, the adsorption capacity of Cu2+ onto NTS was further discussed. The optimal adsorption conditions (pH, contact time, contact temperature, initial Cu2+ concentration, and adsorbent concentration), adsorption kinetics, isotherms, and thermodynamic were also evaluated.RESULTSThe results showed that NTS exhibited excellent performance in adsorption of Cu2+, with adsorption capacities of 122.31 mg g−1 for Cu2+ (pH 7, 0.04 g L−1, 0.2 g L−1, 313.15 K and 10 min). The pseudo‐second‐order and Langmuir isotherms models could be used to explain the adsorption kinetics and adsorption equilibrium, respectively. The thermodynamic results showed that the adsorption process was spontaneous and endothermic with an increase in entropy. Cu2+ was adsorbed onto NTS, which was confirmed by energy dispersive spectrometry analysis.CONCLUSIONThese findings indicated that NTS might be an effective, environment‐friendly and renewable bio‐resource adsorbent for removing heavy metals in industrial effluent. © 2021 Society of Chemical Industry

Influence of Operating Environments on Adsorptive Removal of Lead (Pb (II)) Using Banana Pseudostem Fiber: Isotherms and Kinetic Study

ABSTRACT Natural fiber as adsorbents is an emerging trend in effluent treatments as the fibers are environmental friendly, abundantly available and superior to polymeric-based materials. In this study, fiber extracted from the banana pseudostem was tested as an adsorbent. The lead (Pb (II)) removal was assessed with various parameters, namely, pH, agitation speed, adsorbent dosage and contact time. Removal efficiency was found maximum in alkaline conditions (pH 10) with a contact time of 140 min. Its efficiency was further optimized for adsorbent dosage and agitation speed. Between the isothermic model and Temkin isotherm model predicted the conditions better by providing the highest respective coefficient of determination (R2 – 0.9942). Similarly, the kinetics for adsorption was fitted well with pseudo-second-order kinetic model. Banana pseudostem fiber (BPF) could be a promising source and low-cost adsorbent to remove toxic heavy metals in industrial effluents.

Reduction of toxic elements in marine environment using nano adsorbent materials

Due to large scale industrialisation and indiscriminate discharge of effluents with high BOD, sulphuric acid, oil, toxic metals and particulate matter reach the aquatic environment, either directly or indirectly. Living organisms consist less than one percent of heavy metals, and their different density cause to some disorders. Surface waters and also acidic rains can transfer these metals to oceans via washing polluted environment. Heavy metals naturally exist in very little amount in watery places. Metal pollution of the sea is less than other types of water pollution but its effects on marine ecosystems and humans are very extensive. Industrial wastes in aquaculture because toxic effects in aquatic organisms especially in fishes. Aquatic organisms absorb the pollutants directly from water and indirectly from food chains. Some of the toxic effects of heavy metals on fishes and aquatic invertebrates are; reduction of the developmental growth, increase of developmental anomalies, reduction of fishes survival- especially at the beginning of exogenous feeding or even cause extinction of entire fishes population in polluted reservoirs. The objective of this project is to investigate the heavy metals in industrial effluents and reducing it by using Nano Adsorbent of Vetiveriazizanioides. This method is more efficient than any other method for reducing heavy metals from industrial effluents, because it is biodegradable. The results obtained from this attempt shows that heavy metals reduction by this Nano adsorbent is in the range of decreases like Hg > As > Cd > Pb.

Surfactin production using papaya peel aqueous extract as substrate and its application for iron adsorption

The presence of metals in industrial effluents has become a major environmental problem since these residues are often disposed of in lakes or rivers. Aiming to recover contaminated areas the remediation by washing using biosurfactants appears as an alternative technique that features low toxicity to the environment. This paper aims to evaluate the efficiency in iron removal within a synthetic effluent, utilizing a biosurfactant. This was produced in a bioreactor (37°C, 200 rpm, 0.5 vvm) derived from a papaya peel aqueous extract and the Bacillus subtilis UFPEDA strain 86. The fermentation tests revealed that this Bacillus is a great producer for the biosurfactant. The tests also displayed that the papaya peel extract is a viable substrate for the production of biosurfactant by this strain. Among the results found, in 24 hours of cultivation, the highest concentration of biomass and product was obtained, of 2.17 ± 0.04 g.L-1 and 2.88 ± 0.01 g.L-1, respectively. The biosurfactant provided a Critical Micellar Concentration (CMC) of 20 mg.L-1. The batch method was used in the obtainment of removal data, in which a series of solutions at different concentrations of iron ions were exposed to different amounts of biosurfactant, both raw and purified, at a temperature of 25 °C, under agitation (200 rpm) and pH ~ 6.3. A multivariate experimental design was carried out in the presence of crude and purified biosurfactant. The results demonstrated significant interactions involved for the following independent variables: concentration of iron ions, concentration of biosurfactant and the treatment time. The iron removal percentages varied between 47.2% and 95.82% in the presence of the raw biosurfactant, and between 37.01% to 91.94% in the presence of the purified surfactant. The Langmuir adsorption model was the better adjusted, providing a maximum adsorption capacity at approximately 10 mg.g-1.

Effect of Industrial Effluents on Rice Growth, Yield and Soil Chemical Properties

Toxic pollutants and heavy metals in industrial effluents and city waste water are massive concern among the researchers, development worker, media personnel and policy makers. Keeping this in view-a pot experiment was conducted at the Bangladesh Rice Research Institute (BRRI), net house during T. Aman 2010 (wet season) and Boro 2011 (dry season) rice aimed to determining the effect of different industrial effluents on rice growth, yield and soil chemical properties. The irrigation effect of industrial effluents on rice production was more prominent in dry season (Boro) rice than wet season (T. Aman) rice. Perceptible changes in soil properties occurred through the effluents irrigation in rice-rice cropping pattern. Pharmaceutical and tannery effluents increased soil pH, EC, total N (%) available P (mg/kg). Exchangeable K, Ca, Mg and Na (cmol/kg) were increased due to irrigation with dyeing, pharmaceutical and tannery effluents. Dyeing, beverage, tannery and city waste water reduced percent soil organic carbon. Micronutrients (Zn, Fe, Cu and Mn) were increased significantly by the irrigation with dyeing, pharmaceutical and tannery effluents in both wet and dry season rice. Heavy metals like Pb, Cd, Ni and Cr in soils were increased significantly through irrigation with effluents in rice-rice cropping pattern.

Hexavalent Chromium Removal Using Filamentous Fungi: Sustainable Biotechnology

To advance sustainable, safe biotechnologies for removal of heavy metals in industrial effluents, we evaluated two filamentous fungi isolated from chromium-contaminated soil (Aspergillus fumigatus ...

Photocatalytic Reduction of Nickel using Synthesized nano Titanium Oxide - Acidified neem saw dust Composite from Battery waste

The heavy metals, present in the battery waste water released from industries are extremely toxic and pose a serious threat to public health. The physical adsorption methods are effective, but require an additional adsorbent regeneration step. The degradation of heavy metals in industrial effluents through chemical remediation has also gained tremendous attention due to its enormous applications. Photo catalytic degradation using renewable UV / sun light is one of the most promising techniques due to its simplicity and economy. Till date, various metallic/bimetallic oxides such as TiO2, ZnO, Fe2O3 have been tested for degradation of photo catalytic components due to their superior activity, low price. Attempts have been made to study the photo catalytic degradation of heavy metals using nano Titanium Oxide and Acidified neem saw dust (nTO/ANSD) composite as a photo catalyst.In this present research, nTO/ANSD composite was synthesized and assessed for photo-chemical degradation of nickel in presence of UV light. It was observed that 96.4% Nickel was reduced using photo catalytic process. The X-Ray Diffraction(XRD) and Scanning Electron Microscopy (SEM) for nTO/ANSD studies were also performed. The recovery process of the nTO/ANSD composite photo catalyst is easier and reusability studies shows that the catalyst can be reused to remove the traces of heavy metals with slight reduction in efficiency.

XANTHATION OF SAWDUST WASTE FOR ADSORPTION OF LEAD IONS FROM AQUEOUS SOLUTIONS

Heavy metals in industrial effluents have contaminated natural waters compromising the health of humans and animals. Traditional methods eliminate these metals from wastewater but they are costly or ineffective at low metal concentrations for which alternative methods are required. We investigated the adsorption of lead on xanthated sawdust (CS2 treatment). Kinetic and pH tests, adsorption isotherms and infrared spectroscopy were performed. Kinetic studies indicated that adsorption equilibrated at 120 min following a kinetic model of pseudo-second order. The adsorption capacity was 72 mg Pb2+ g-1 (maximum at pH 5, Freundlich type isotherm, 98% adsorption). This product obtained from raw materials without commercial value, can be used for environmental remediation as an alternative to its expensive dumping into landfills.

Simultaneous removal of Pb(II), Cd(II) and Cu(II) from aqueous solutions by adsorption on Triticum aestivum - a green approach

The presence of heavy metals in industrial effluents as a single component is generally very rare. The present study provides information about adsorption behaviour of lead, cadmium and copper in single and multi-component system using triticum aestivum (wheat straw) as adsorbent. It has been shown that adsorption of a certain metal ion is greatly affected by the presence of other metal ions. Effects of process parameters (adsorbent dose, contact time, pH, agitation speed etc.) have been studied. pH 4-6 have been found suitable for metal removal. Adsorption mechanism has been evaluated using five adsorption isotherm models (Langmuir, Freundlich, Temkin, Harkin- Jura and Halsey Isotherms). Removal of cadmium in multi-component system is greater as compared in single component system indicating the metal competition for adsorption sites. Kinetic and thermodynamic parameters have also been calculated and obtained results were found closely related to the reported literature. Positive values of ?H° for lead, cadmium and copper shows feasibility of the process and the spontaneous nature of adsorption.

Vulnerabilidade Sócio Ambiental de Pescadores e Marisqueiras em S. Francisco do Conde/Ba

A partir da identificação dos determinantes socioambientais em saúde, este estudo tem como objetivo mapear aspectos relativos aos riscos e vulnerabilidade social e ambiental de um grupo de pescadores e marisqueiras no município de São Francisco do Conde, região metropolitana de Salvador, Ba. Com o propósito de colaborar na formulação de políticas públicas voltadas a promoção da qualidade de vida das marisqueiras e pescadores artesanais, tomou-se como base 2 diagnósticos complementares: o ambiental e sócio demográfico. Foi verificado a qualidade microbiológica das águas, presença de metais pesados nos sedimentos, mariscos e peixes; contaminantes microbiológicos do esgoto doméstico e 6 metais pesados mais comuns nos efluentes industriais. O diagnóstico sócio demográfico levantou as condições de trabalho e habitação além de aspectos relativos à saúde. Aliados à observação de campo e estudos similares, constatou-se que o oficio da pesca e coleta de mariscos, vem sofrendo declínio enquanto atividade ligada a tradição, despertando pouco interesse das gerações mais jovens, além das características artesanais que restringem sua inserção no modo de produção capitalista. Resultados indicam comprometimento do ecossistema costeiro, o manguezal, pela contaminação por metais pesados e coliformes fecais que potencializam os agravos de ordem ocupacional, decorrentes da ergonomia e exposição à contaminação. Refere-se ainda as condições de habitabilidade destes sujeitos e sua condição de invisibilidade que recorrentemente fortalece e amplia o grau de vulnerabilidade social e ambiental. Assim, as raízes negras do município, manifestadas na composição da população, encontra-se ameaçada face a vulnerabilidade social das comunidades, grupos remanescentes e seus descendentes.

Textile industrial effluent induces mutagenicity and oxidative DNA damage and exploits oxidative stress biomarkers in rats.

Exposure to complex mixtures like textile effluent poses risks to animal and human health such as mutations, genotoxicity and oxidative damage. Aim of the present study was to quantify metals in industrial effluent and to determine its mutagenic, genotoxic and cytotoxic potential and effects on oxidative stress biomarkers in effluent exposed rats. Metal analysis revealed presence of high amounts of zinc, copper, chromium, iron, arsenic and mercury in industrial effluent. Ames test with/without enzyme activation and MTT assay showed strong association of industrial effluent with mutagenicity and cytotoxicity respectively. In-vitro comet assay revealed evidence of high oxidative DNA damage. When Wistar rats were exposed to industrial effluent in different dilutions for 60 days, then activities of total superoxide dismutase and catalase and hydrogen peroxide concentration were found to be significantly lower in kidney, liver and blood/plasma of effluent exposed rats than control. Vitamin C in a dose of 50 mg/kg/day significantly reduced oxidative effects of effluent in rats. On the basis of this study it is concluded that industrial effluent may cause mutagenicity, in-vitro oxidative stress-related DNA damage and cytotoxicity and may be associated with oxidative stress in rats. Vitamin C may have ameliorating effect when exposed to effluent.

Bioremoval of heavy metals by bacterial biomass

Heavy metals are among the most common pollutants found in the environment. Health problems due to the heavy metal pollution become a major concern throughout the world, and therefore, various treatment technologies such as reverse osmosis, ion exchange, solvent extraction, chemical precipitation, and adsorption are adopted to reduce or eliminate their concentration in the environment. Biosorption is a cost-effective and environmental friendly technique, and it can be used for detoxification of heavy metals in industrial effluents as an alternative treatment technology. Biosorption characteristics of various bacterial species are reviewed here with respect to the results reported so far. The role of physical, chemical, and biological modification of bacterial cells for heavy metal removal is presented. The paper evaluates the different kinetic, equilibrium, and thermodynamic models used in bacterial sorption of heavy metals. Biomass characterization and sorption mechanisms as well as elution of metal ions and regeneration of biomass are also discussed.

The ability of crab and cockle shell to adsorb lead and chromium from industrial effluent

The ability of crab shell (Scylla serata) and cockle shell (Anadara granosa) to remove Pb, and Cr from industrial effluent was examined to determine its removal efficiency. This research was conducted under constant pH around 4 under room temperature and all samples were shacked to 150 rpm. Other factors like amount of adsorbent, types of adsorbent and time equilibrium was examined along this research. The highest uptake of heavy metals recorded is by crab shells compare to cockle shells. All heavy metals except chromium reached equilibrium after 60 minutes time. The most of heavy metals was adsorbed by amount of 1.0 g compare to other amount of adsorbent (0.5 g and 1.0 g). The amount of adsorbent and type of adsorbent were strongly correlated by amount of heavy metals adsorption. (p < 0.001). Chromium was the highest heavy metals that were removed in industrial effluent. The highest reading was recorded as 97.45%. CaCO3 and chitin play an important role to adsorb heavy metals in industrial effluent. Although, there are many other particles existed in industrial effluent but still crab shells and cockles can be used as biomass adsorbent to remove heavy metals in industrial effluent.