Toxic Inorganic Compounds Research Articles

Thermoelectric Performance of Hybrid Inorganic/Organic Composites Based on PEDOT:PSS/Tin(II) Oxide.

PSS(poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate))-based composites often exhibit remarkable characteristics regarding high electrical conductivity and great processability, being a suitable candidate for thermoelectric (TE) applications. To increase its performance, PEDOT:PSS is commonly blended with scarce and toxic inorganic compounds based on Se, Te or Bi. In this work we propose the use of one p-type metal oxide semiconductor (MOs): tin(II) oxide (SnO), motivated by its abundance and low toxicity. Hybrid PEDOT:PSS/SnO composites were obtained by firstly blending Ethylene glycol (EG) with PEDOT:PSS and then by adding p-type SnO, previously synthesized by a chemical route. The mixture was deposited via spin-coating onto glass substrates. The Power Factor (PF) of the composites increased by a factor of 300 with the combined EG/SnO composition.

The use of different carbon sources to maintain water quality and growth performance of sangkuriang catfish (Clarias gariepinus) in the biofloc aquaculture system

ABSTRACT Intensive cultivation of sangkuriang catfish (Clarias gariepinus) has the potential to increase toxic inorganic compounds. Biofloc is one way to offset the negative impact of the large amount of ammonia being converted into floc by utilizing heterotrophic bacteria with the addition of a carbon source. This study analyzes the effect of carbon type on water quality and growth performance of sangkuriang catfish. Used a completely randomized design with three treatments and three replications: probiotics + molasses, probiotics + wheat flour, and probiotics + sugar. The results of the research show that wheat flour and sugar could substitute molasses carbon as seen from the results of the carbon content tested which shows high values for wheat flour (46.16%), sugar (43.65%), and molasses (23.16%). Water quality and growth performance of sangkuriang catfish were not significantly different (p > 0 .05). The addition of carbon sources had a positive effect on ammonia, nitrite, total intestinal bacteria, and floc volume (p < 0 .05).

Microalgae, a current option for the bioremediation of pharmaceuticals: a review.

In this review, research on the use of microalgae as an option for bioremediation purposes of pharmaceutical compounds is reported and discussed thoroughly. Pharmaceuticals have been detected in water bodies around the world, attracting attention towards the increasing potential risks to humans and aquatic biota. Unfortunately, pharmaceuticals have no regulatory standards for safe disposal in many countries. Despite the advances in new analytical techniques, the current wastewater treatment facilities in many countries are ineffective to remove the whole presence of pharmaceutical compounds and their metabolites. Though new methods are substantially effective, removal rates of drugs from wastewater make the cost-effectiveness ratio a not viable option. Therefore, the necessity for investigating and developing more adequate removal treatments with a higher efficiency rate and at a lower cost is mandatory. The present review highlights the algae-based removal strategies for bioremediation purposes, considering their pathway as well as the removal rate and efficiency of the microalgae species used in assays. We have critically reviewed both application of living and non-living microalgae biomass for bioremediation purposes considering the most commonly used microalgae species. In addition, the use of modified and immobilized microalgae biomass for the removal of pharmaceutical compounds from water was discussed. Furthermore, research considering various microalgal species and their potential use to detoxify organic and inorganic toxic compounds were well evaluated in the review. Further research is required to exploit the potential use of microalgae species as an option for the bioremediation of pharmaceuticals in water.

Catalytic systems for neutralization of exhaust gases from diesel engines: modern challenges and technological solutions to improve a diesel oxidation catalyst

Diesel vehicles are responsible for the emission of not only soot and NОx to the environment, but also various organic and inorganic toxic compounds. The review provides a detailed discussion of the place of oxidation catalyst in the modern system for purification of exhaust gases from diesel engines, the ways to improve and optimize the oxidation catalysts intended for the neutralization of carbon monoxide and hydrocarbons according to the accepted standards, and the methods for decreasing the content of Pt group metals in the indicated catalytic systems.

Coupling Plant Biomass Derived from Phytoremediation of Potential Toxic-Metal-Polluted Soils to Bioenergy Production and High-Value by-Products—A Review

Phytoremediation is an attractive strategy for cleaning soils polluted with a wide spectrum of organic and inorganic toxic compounds. Among these pollutants, heavy metals have attracted global attention due to their negative effects on human health and terrestrial ecosystems. As a result of this, numerous studies have been carried out to elucidate the mechanisms involved in removal processes. These studies have employed many plant species that might be used for phytoremediation and the obtention of end bioproducts such as biofuels and biogas useful in combustion and heating. Phytotechnologies represent an attractive segment that is increasingly gaining attention worldwide due to their versatility, economic profitability, and environmental co-benefits such as erosion control and soil quality and functionality improvement. In this review, the process of valorizing biomass from phytoremediation is described; in addition, relevant experiments where polluted biomass is used as feedstock or bioenergy is produced via thermo- and biochemical conversion are analyzed. Besides, pretreatments of biomass to increase yields and treatments to control the transfer of metals to the environment are also mentioned. Finally, aspects related to the feasibility, benefits, risks, and gaps of converting toxic-metal-polluted biomass are discussed.

Overview on Bioconversion of Domestic Wastewater Sewage Sludge into Green Energy: Biogas and Hydrogen

Municipal wastewater treatment plants generate large amounts of sludge after a set of unit processes. The sewage sludge is an important resource for energy production because of its high level of biodegradability. Sewage sludges are generally made of non-toxic and biodegradable organic compounds mixed with a small fraction of non-toxic and toxic inorganic compounds having a very low biodegradability. The large fraction of biodegradable matter constitutes a pool for green/clean energy to be used for industrial and domestic applications. The generated energy can also be used in the wastewater treatment plant. Currently, fossil fuels are leading the energy world, however, they are being depleted and are considered to be among the main causes contributing to climate change and global warming. Domestic sewage sludge can be converted sustainably into bio-hydrogen and bio- methane. This conversion is achievable through anaerobic digestion, combustion, pyrolysis and gasification. With regard to the last three conversion processes, the organic and inorganic toxic compounds are eliminated. Production of biogas from sewage sludge is being undertaken worldwide on small, medium, and large scales. However, hydrogen production from sludge is still developing. There is an existence of substantial knowledge in this field, the production of hydrogen and biogas from sewage sludge is gaining interest. This study analyses various possibilities of sewage sludge conversion into clean energy. The analysis focuses on the technology strengths, weaknesses and gaps to be improved in future studies.

A review natural polymeric coagulants in wastewater treatment

Fresh-water comes from the rain which finally goes into the ocean via rivers. The human beings store this water and use it in a variety of purposes such as drinking, washing, irrigation and in industries etc., Wastewater is generated after the utilization of pure water in domestic, industrial, agricultural, municipal and other activities. The growing population and urbanization are the principal reason of continuous increase in wastewater generation. Wastewater contains a number of contaminants like organic materials, biological components and toxic inorganic compounds which cause adverse effect on the human health. Many inorganic chemicals are conventionally used as coagulant for the treatment of wastewater. Theses coagulants have the ability to change the physico-chemical properties of the treated water. In this review paper, we have described the used of naturally-occurring polymers as coagulants in wastewater treatment. These coagulants have more potential for coagulation and are also eco-friendly and biodegradable in nature; moreover, these coagulants do not adversely affect the human health and do not induce change in the physico-chemical properties of treated water.

Impacts of Oil and Gas Production on Contaminant Levels in Sediments

Recent technological progresses have unlocked tremendous shale energy resources, leading to increased production of oil and gas and a variety of new environmental pollution issues in the United States. One such example is management of produced waters, which are often disposed of via deep well injection. Produced water injection has been linked to induced seismicity. Thus, there are strong incentives for alternative management strategies that come with new, uncertain environmental risks. This paper summarizes studies of sediment pollution due to oil and gas production. The goal is to highlight potential environmental risks associated with produced water management, including long-term contamination of sediments. Sediment contaminants from produced waters include organic and inorganic toxic compounds. Three different indicators have been developed for sediment pollution: the geoaccumulation index, pollution load index, and the enrichment factor. The main pollutants in sediments resulting from oil and gas production are heavy metals, salts, naturally occurring radioactive materials (NORMs), oil and grease (O&G), benzene, toluene, ethylbenzene and xylene (BTEX), total petroleum hydrocarbon (TPH), and polycyclic aromatic hydrocarbon (PAHs). These pollutants reach sediments and water resources via pipeline leaks, truck spills, improper waste disposal, and underground injection. Methods to decrease contaminant risks in sediments include surface capping, bioremediation, and phytoremediation. The shale oil and gas boom has exacerbated produced water management issues. As states consider regulation of treated produced waters, there is a strong need to consider potential contaminants of concern. Several case studies from the U.S., Middle East, Africa, Asia, and South America were used to assess levels of contamination around the world’s sediments in regions with high levels of oil and gas activity. Appropriate management of residual pollution from oil and gas operations should consider the nature of contaminants and sediments, the routes of contamination, the levels of contamination, the effect of contaminants on the sites, and methods for contaminant cleanup.

Removal Methods of Heavy Metals from Laboratory Wastewater

The removal of heavy metals from the environment is the special concern due to their persistence without degradation. Methods for treating laboratory and industrial wastewater containing heavy metals often involve technologies for reduction of toxicity in order to meet technology-based treatment standards. Physico-chemical removal processes such as; adsorption on new adsorbents, ion exchange, membrane filtration, electrodialysis, reverse osmosis, and ultrafiltration were discussed. Their advantages and drawbacks in application were evaluated. In the processes of biological treatments microorganisms play a role of settling solids in the solution. Activated sludge, trickling filters, stabilization ponds are widely used for treating industrial wastewater. Bioadsorption is a new biological method and various low cost bioadsorbents (agricultural waste, forest waste, industrial waste, algae etc.) are used for maximum removal of heavy metals from wastewater. Bioadsorption techniques are eco friendly best solutions for removing heavy metals from wastewater rather than physic-chemical methods. But chemical methods are most suitable treatments for toxic inorganic compounds produced from various industries which cannot removed from any biological and physical techniques. Keywords: Heavy metals; removal techniques; Bioadsorption; physico-chemical treatments DOI : 10.7176/JNSR/9-2-04

Applications of Natural Coagulants to Treat Wastewater − A Review

The natural water falls from the mountain is merging into the oceans. This water is preserved by humans that are consumed for agriculture, industrial, and municipal use. This water become wastewater after different usage, and finally, completes the hydrological cycle. The water becomes wastewater due to population growth, urbanization, industrialization, sewage from household, institutions, hospitals, industries and etc. Wastewater can be destructive for the public because it contains a variety of organic and inorganic substances, biological substances, toxic inorganic compounds and the presence of toxic materials. The coagulant chemicals and its associated products are resourceful but these may change the characteristics of water in terms of physical and chemical characteristics, this make matters worse in the disposal of sludge. An option of natural polymer can be used in water and wastewater in this review. The natural polymers are most efficient that provide several benefits such as; prolific, exempt from physical and chemical changes from the treated water.

Total Environmental Impact of Three Main Dietary Patterns in Relation to the Content of Animal and Plant Food.

Based on a review of the most recent available scientific evidence, the new Dietary Guidelines for Americans 2010 (USDA DG) provide information and advice for choosing a healthy diet. To compare the environmental impacts of, respectively, omnivorous (OMN), lacto-ovo-vegetarian (LOV) and vegan (VEG) dietary patterns as suggested in the USDA DG, we analyzed the three patterns by Life Cycle Assessment (LCA) methodology. The presence of animal food in the diet was the main determinant of environmental impact. The major impact always stemmed from land and water use. The second largest impact came from energy use. Emission of toxic inorganic compounds into the atmosphere was the third cause of impact. Climate change and acidification/eutrophication represented other substantial impacts.

Brackish water desalination in the Algerian Sahara—Plant design considerations for optimal resource exploitation

A huge geothermal aquifer is located in the northern Algerian Sahara, with brackish water free from toxic inorganic compounds and organic matter. Therefore, this water is appropriate for good quality potable water production after partial desalination. This paper deals with the basic desalination plant design considerations in the context of overall optimal aquifer exploitation. The main types of criteria for such optimization are economic and environmental. Implementing the concept of “blending” reservoir water (at appropriate proportion) with desalinated water, allows cost-effective and environmentally attractive resource exploitation; the latter would be achieved by reinjecting the retentate (after desalination) free from any chemicals that may degrade the reservoir water quality by accumulation over the years. Results are summarized of a typical case study based on low pressure reverse osmosis (RO) membrane desalination. Key RO membrane performance data from a pilot unit are employed in support of this study. The results highlight the main features and the constraints in plant design and desalinated water recovery; constraints are mainly imposed by the need to avoid membrane scaling with no use of undesirable synthetic anti-scalants. The proposed cost-effective plant configuration and operating mode are in accord with the overall optimum resource exploitation. A cost analysis is also performed for a typical potable water production plant. Finally, possibilities are outlined of integrated exploitation of this geothermal reservoir, whereby energy is extracted in addition to potable water production.

Levels and chemical speciation of arsenic in representative biota and sediments of a tropical mangrove wetland, India

The general concern for arsenic in the marine environment is associated with its wide distribution and potential toxicity. In the present work, concentrations and chemical speciation of arsenic were characterized in sediments and representative biota from the Indian Sundarban, the largest continuous mangrove tract formed at the mouth of the Hugli (Ganges) River estuary, northeastern part of the Bay of Bengal. Analyzed organisms included both shellfish (Macoma birmanica, Sanguinolaria acuminata and Meretrix meretrix) and finfish (Liza parsia, Liza tade, Harpodon nehereus and Eleutheronema tetradactylum). Arsenic concentrations in sediments did not exceed 4 μg g(-1) dry weight with the contribution of inorganic molecules (arsenate and arsenite) ranging from 61.7 to 81.3%. Total As (TAs) concentrations varied from less than 2 to 16 μg g(-1) in tissues of bivalves; the more elevated As accumulation was observed in gills and the mantle probably due to ion exchange properties of the mucous layer covering these organs, whereas adductor muscle and the podium showed limited values. Distribution of various arsenic compounds followed a quite similar trend in bivalve tissues; arsenobetaine (AsB) was the most dominant form followed by compounds such as dimethylarsinate (DMA), trimethyl arsine-oxide (TMAO), tetramethyl arsonium (TETRA) and arsenocholine (AsC), while inorganic arsenic (IAs) represented a minor constituent (0.2 to 6.9%). Among the fish, detritivorous/herbivorous species (L. parsia and L. tade) exhibited TAs concentrations of 10.8 and 9.71 μg g(-1) dry wt with a prevalence of AsB (52-67%) and TETRA (26-35%); higher concentrations of TAs were measured in the two carnivorous species (20.62 and 19.67 μg g(-1) dry wt, in H. nehereus and E. tetradactylum respectively) mostly as AsB (63.3-72.3%) and AsC (17.5-28.6%). The obtained results can be considered as baseline levels for arsenic in the investigated area, confirming the predominance of organoarsenicals in marine organisms compared to more toxic inorganic compounds. Considering the ecological importance of this ecosystem and the increasing anthropogenic impact, the distribution of arsenic through the food chain should be continuously monitored, using organisms of different feeding guilds as indicators.

Bacterial bio-resources for remediation of hexachlorocyclohexane.

In the last few decades, highly toxic organic compounds like the organochlorine pesticide (OP) hexachlorocyclohexane (HCH) have been released into the environment. All HCH isomers are acutely toxic to mammals. Although nowadays its use is restricted or completely banned in most countries, it continues posing serious environmental and health concerns. Since HCH toxicity is well known, it is imperative to develop methods to remove it from the environment. Bioremediation technologies, which use microorganisms and/or plants to degrade toxic contaminants, have become the focus of interest. Microorganisms play a significant role in the transformation and degradation of xenobiotic compounds. Many Gram-negative bacteria have been reported to have metabolic abilities to attack HCH. For instance, several Sphingomonas strains have been reported to degrade the pesticide. On the other hand, among Gram-positive microorganisms, actinobacteria have a great potential for biodegradation of organic and inorganic toxic compounds. This review compiles and updates the information available on bacterial removal of HCH, particularly by Streptomyces strains, a prolific genus of actinobacteria. A brief account on the persistence and deleterious effects of these pollutant chemical is also given.

Biodegradation Potential of Halo(alkali)philic Prokaryotes

Oil and gas exploitation and downstream processing may generate large volumes of contaminated aqueous wastewaters. Without treatment, the discharge of these streams into the environment would lead to considerable environmental problems. A combination of physicochemical and biological treatment processes are applied to treat such polluted streams (e.g., in conventional water purification plants). However, the application of microorganisms in these streams is rather limited streams to salt levels well below those of seawater. The potential of microorganisms to degrade various organic and inorganic pollutants at higher salinities was surveyed in the open literature. The advantage of biological treatment processes that operate at elevated salinities is that no dilution water is needed, which is particularly relevant for arid regions. The available literature is scarce, especially concerning truly halophilic bacteria that thrive at salt concentrations significantly higher than in seawater. The obvious trend of most of the publications indicates a significant inhibition of the biodegradation activity at salt concentrations above 10 wt.%. However, a specialized group of extremophilic microorganisms, called halo(alkali)philes, could replace freshwater or marine organisms in the biodegradation processes at salinities above 1.5 M and pH values above 9. They are present in natural hypersaline habitats and can be activated either directly in situ by addition of micronutrients and aeration, or introduced into engineered water treatment systems. In a number of studies, the possibility of microbial HC degradation up to 5 M NaCl has been mentioned. Relatively little is known about the removal of toxic inorganic compounds, such as H2S, CO, and CN−, at halo(alkaline) conditions. These compounds are clearly associated with the processing of oil, coal, and gas. An exception is the application of sulfur-cycling bacteria, as these organisms have been intensively studied during the last decade. Sulfur-oxidizing and sulfidogenic bacteria can function efficiently at extremely saline and alkaline conditions. The general conclusion from this survey is that many biodegradation routs are, in principal, possible at high salt/pH but more research is needed to make a real progress in the development of engineered processes that can be applied to protect the environment.

Engineered cells as biosensing systems in biomedical analysis

Over the past two decades there have been great advances in biotechnology, including use of nucleic acids, proteins, and whole cells to develop a variety of molecular analytical tools for diagnostic, screening, and pharmaceutical applications. Through manipulation of bacterial plasmids and genomes, bacterial whole-cell sensing systems have been engineered that can serve as novel methods for analyte detection and characterization, and as more efficient and cost-effective alternatives to traditional analytical techniques. Bacterial cell-based sensing systems are typically sensitive, specific and selective, rapid, easy to use, low-cost, and amenable to multiplexing, high-throughput, and miniaturization for incorporation into portable devices. This critical review is intended to provide an overview of available bacterial whole-cell sensing systems for assessment of a variety of clinically relevant analytes. Specifically, we examine whole-cell sensing systems for detection of bacterial quorum sensing molecules, organic and inorganic toxic compounds, and drugs, and for screening of antibacterial compounds for identification of their mechanisms of action. Methods used in the design and development of whole-cell sensing systems are also reviewed.

Efficacy and Reliability of Upgraded Industrial Treatment Plant at Porto Marghera, near Venice, Italy, in Removing Nutrients and Dangerous Micropollutants from Petrochemical Wastewaters

Chemical and petrochemical wastewaters contain a host of contaminants that require different treatment strategies. Regulation of macropollutants and micropollutants in the final discharge from industrial wastewater treatment plants (WWTPs) have become increasingly stringent in recent decades, requiring many WWTPs to be upgraded. This article presents an analysis of a WWTP treating petrochemicals in Porto Marghera, Italy, that recently was upgraded following legislative changes. Because of strict legal limits for macropollutants and micropollutants and a lack of space necessary for a full-scale WWTP overhaul, the existing activated sludge tank was converted into a membrane biological reactor. The paper presents experimental data collected during a five-month investigation showing the removal rates achieved by the upgraded plant for macropollutants (particularly nitrogen compounds) and micropollutants (heavy metals and organic and inorganic toxic compounds).

Molecular biodiversity of arbuscular mycorrhizal fungi in trace metal‐polluted soils

We assessed the indigenous arbuscular mycorrhizal fungi (AMF) community structure from the roots and associated soil of Plantago major (plantain) plants growing on sites polluted with trace metals (TM) and on unpolluted sites. Uncontaminated and TM-contaminated sites containing As, Cd, Cu, Pb, Sn and Zn were selected based on a survey of the TM concentration in soils of community gardens in the City of Montréal. Total genomic DNA was extracted directly from these samples. PCR followed by denaturing gradient gel electrophoresis (PCR-DGGE), augmented by cloning and sequencing, as well as direct sequencing techniques, was all used to investigate AMF community structure. We found a decreased diversity of native AMF (assessed by the number of AMF ribotypes) in soils and plant roots harvested from TM-polluted soils compared with unpolluted soils. We also found that community structure was modified by TM contamination. Various species of Glomus, Scutellospora aurigloba and S. calospora were the most abundant ribotypes detected in unpolluted soil; ribotypes of G. etunicatum, G. irregulare/G. intraradices and G. viscosum were found in both polluted and unpolluted soils, while ribotypes of G. mosseae and Glomus spp. (B9 and B13) were dominant in TM-polluted soils. The predominance of G. mosseae in metal-polluted sites suggests the tolerance of this species to TM stress, as well as its potential use for phytoremediation. These data are relevant for our understanding of how AMF microbial communities respond to natural environments that contain a broad variety of toxic inorganic compounds and will substantially expand our knowledge of AMF ecology and biodiversity.

Effect of organic and inorganic toxic compounds on luminescence of luminous fungi

The possibility of the development of the solid phase bioluminescent biotest using aerial mycelium of the luminous fungi was investigated. Effect of organic and inorganic toxic compounds (TC) at concentrations from 10(-6) to 1 mg/ml on luminescence of aerial mycelia of four species of luminous fungi-Armillaria borealis (Culture Collection of the Institute of Forest, Siberian Branch, Russian Academy of Sciences), A. mellea, A. gallica, and Lampteromyces japonicus (Fungi Collection of the Botanical Institute, Russian Academy of Sciences)--has been studied. Culture of A. mellea was shown to be most sensitive to solutions of the model TC. It was demonstrated that the sensitivity of the luminous fungi is comparable with the sensitivity of the bacteria that are used for environmental monitoring. Use of the aerial mycelium of the luminous fungi on the solid support as a test object is a promising approach in biotesting for the development of continuous biosensors for air monitoring.

Potential of laser ablation and laser desorption mass spectrometry to characterize organic and inorganic environmental pollutants on dust particles

Stainless steel factories are known to release particles into the atmosphere. Such particulate matter contains significant amounts of heavy metals or toxic inorganic compounds and organic pollutants such as, for example, Cr(VI) and polycyclic aromatic hydrocarbons (PAHs). The investigation of Cr(VI) and PAHs is often complicated by the associated matrix. Organic and inorganic pollutants present in stainless steel dust particles have been investigated with the same laser microprobe mass spectrometer according to two original methodologies. These analytical methods do not require time-consuming pretreatment (extraction, solubilization) or preconcentration steps. More specifically, experiments are conducted with a Fourier transform ion cyclotron resonance mass spectrometer coupled to an ArF (193 nm) or a tripled frequency Nd-YAG (355 nm) laser. Experiments at 355 nm allow the nature of the most frequently occurring Cr(III)/Cr(VI) compounds in dust particles to be identified. Examination of PAHs at 193 nm is assisted by the formation of pi-complexes with 7,7',8,8'-tetracyanoquinodimethane to prevent their evaporation in the mass spectrometer during analysis and to ensure an increase in sensitivity.