A Novel Wastewater Treatment Method Using Electrical Pulsed Discharge Plasma over a Water Surface

Electrical pulsed discharge plasma produces various powerful oxidizing agents, such as hydroxyl radicals and ozone, which have high oxidation potential. These species play an important role in the decomposition of persistent organic compounds in wastewater. Because highly concentrated oxidants are directly produced inside the plasma, plasma realizes high-speed wastewater treatment without pretreatment of samples, such as pH adjustment. The pulsed discharge plasma generated over the water surface and inside bubbles is highlighted as a highly efficient method for plasma generation and radical supply into wastewater. In this paper, the physical and chemical properties of the discharge plasma generated over a water surface are described. The decomposition of persistent organic compounds dissolved in wastewater, such as 1,4-dioxane, formic acid, and dichloromethane, by plasma discharge is demonstrated, and their mechanisms are discussed. These persistent compounds, which have strong toxicity and stability, can be efficiently decomposed and removed quickly from solutions by plasma treatment. Furthermore, the treatment of nutrient solutions used in hydroponic systems for plant cultivation is also introduced as a novel application of plasma, and the effects of bacterial inactivation, decomposition of allelochemicals, and improvement in plant growth by plasma are demonstrated.

Presence and concentration of polycyclic aromatic hydrocarbons (PAHs) in sediments and organisms from Tampamachoco coastal lagoon and Tuxpan River, Veracruz; México.

Polycyclic aromatic hydrocarbons (PAHs) have carcinogenic and mutagenic properties and their main origin in the environment is the burning of fossil fuels and organic material and they are considered high priority Persistent Organic Compounds (POPs). In the present study (March and August 2018) the concentrations of the 16 priority PAHs were analyzed in sediments and organisms (fish and oysters) in the estuarine-lagoon system Tuxpan-Tampamachoco, Veracruz; Mexico.The analysis of these compounds was carried out by means of gas chromatography-FID and mass spectrometry. In March (dry season) the average concentration of PAHs in sediments was 0.86 ± 0.39 μg/g and in August (rainy season) it was 1.14 ± 0.45 μg/g. During both collections, chrysene presented the highest total concentrations and a domain of the compounds with 4 benzene rings was observed, therefore, pyrolytic sources of contribution predominated. The highest concentrations of PAHs occurred in 2 stations located in the Tuxpan riverbed and both exceeded the threshold concentration to cause adverse effects to the benthic community.The analysis of PAHs in organism tissues was carried out in 4 species of fish and one mollusk. In march, the species with the highest concentration was Bagre marinus with 88.87 μg/g and in august it corresponded to the Caranx hippos species with 26.82 μg/g and the compound determined with the highest presence was benzo(b)fluoranthene.Finally, the tendency of accumulation of PAHs in the evaluated matrices was: fish> sediments> mollusks.

The Dual Role of Microplastics in Marine Environment: Sink and Vectors of Pollutants

This review is a follow-up to a previous review published in Journal of Marine Science and Engineeringon the issues of accumulation, transport, and the effects of microplastics (MPs) in the oceans. The review brings together experimental laboratory, mathematical, and field data on the dual role of MPs as accumulators of hydrophobic persistent organic compounds (POPs), and their release-effect in the marine ecosystem. It also examines the carrier role, besides POPs, of new emerging categories of pollutants, such as pharmaceuticals and personal care products (PPCPs). This role becomes increasingly important and significant as polymers age and surfaces become hydrophilic, increasing toxicity and effects of the new polymer-pollutant associations on marine food webs. It was not the intention to provide too many detailed examples of carriers and co-contaminants, exposed marine species, and effects. Instead, the views of two different schools of thought are reported and summarized: one that emphasizes the risks of transport, exposure, and risk beyond critical thresholds, and another that downplays this view.

Carbon Nanotubes based Nanocomposites as Photocatalysts in Water Treatment

The shortage of worldwide clean water and the increasing water demand are now ubiquitous problems around the world. Thus, efficient water treatment is an important research topic, of which phocatalysis is known as simplest and efficient technique utilized in the photocatalytic degradation of all major water pollutants, including heavy metal ion, organic and inorganic pollutants. In this context, the use of one- dimensional carbon nanotubes-based nanocomposites in water treatment have been widely demonstrated to be capable of removing persistent organic compounds due to their unique physical and electronic properties, large surface area, tunable morphology, biocompatible and chemical-environmental-thermal stability. This chapter begins with the discussion of the importance and properties of carbon nanotubes, and then briefs about the types and methods of preparation of carbon nanotubes-based nanocomposites in detail. The next section emphasizes the fundamentals of photocatalysis phenomenon and its proposed mechanism for the photocatalytic degradation of pollutants. The last section highlights the recent development in the carbon-based nanocomposites as photocatalyst in water treatment systems, supported by comprehensive literature account. Finally, the remaining challenges and perspectives for using carbon nanotubes-based nanocomposites are discussed.

Interaction of Environmental Pollutants with Microplastics: A Critical Review of Sorption Factors, Bioaccumulation and Ecotoxicological Effects

Microplastics have become one of the leading environmental threats due to their persistence, ubiquity and intrinsic toxic potential. The potential harm that microplastics impose on ecosystems varies from direct effects (i.e., entanglement and ingestion) to their ability to sorb a diversity of environmental pollutants (e.g., heavy metals, persistent organic compounds or pharmaceuticals). Therefore, the toxicological assessment of the combined effects of microplastics and sorbed pollutants can produce in biota is one of the hottest topics on the environmental toxicology field. This review aims to clarify the main impacts that this interaction could have on ecosystems by (1) highlighting the principal factors that influence the microplastics sorption capacities; (2) discussing the potential scenarios in which microplastics may have an essential role on the bioaccumulation and transfer of chemicals; and (3) reviewing the recently published studies describing toxicological effects caused by the combination of microplastics and their sorbed chemicals. Finally, a discussion regarding the need for a new generation of toxicological studies is presented.