Summary

The principal objective of wastewater treatment is generally to allow human and industrial effluents to be disposed of without danger to human health or unacceptable damage to the natural environment. Typical processes that are investigated and applied to wastewater treatment can be the following: biological, adsorption, flocculation, oxidation, membranes, filtration, etc. This entry collection features information about many processes of wastewater treatment and many other related issues such as reuse, cost, fluid aspects, plants, etc.

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Topic Review
Water Treatment Residues and Methanogenic Activity in Wastewater-Sludge
The effect of adding alum water treatment residues (WTR) on the methanogenic activity in the digestion of primary domestic wastewater sludge was evaluated through laboratory experiments in sedimentation columns, using total suspended solids (TSS) concentrations from 0.37 to 1.23 g/L. The addition of WTR to primary clarifiers can benefit its effluent water quality in terms of colour, turbidity, chemical oxygen demand (COD), and TSS. However, the presence of WTR can negatively influence the production of methane gas during organic sludge digestion in primary clarifiers, for concentrations of TSS between 14.43 and 25.23 g/L and of VSS between 10.2 and 11.85 g/L. The activity of the Methanothrix sp., curved bacilli, methanococci, and Methanosarcina sp. decreases considerably after 16 days of anaerobic digestion, and methane production seems to only be associated with fluorescent methanogenic bacilli.
  • 728
  • 17 Mar 2022
Topic Review
Structural and Thermal Characterization of Resins
The synthesis of poly(vinylbenzyl pyridinium salts) fabricated through poly(vinylbenzyl halogene-co-divinylbenzene) quaternization of N-decyloxy-1-(pyridin-3- or -4-yl)ethaneimine was verified by the FTIR spectra of the final quaternized products, in comparison with the spectra of the initial copolymers.
  • 454
  • 17 Mar 2022
Topic Review
Electrospun Polymer Nanofibers in Photocatalytic Hybrid Materials
A wide variety of materials, strategies, and methods have been proposed to face the challenge of wastewater pollution. The most innovative and promising approaches include the hybrid materials made of polymeric nanofibers and photocatalytic nanoparticles. Electrospun nanofibers with unique properties, such as nanosized diameter, large specific surface area, and high aspect ratio, represent promising materials to support and stabilize photocatalytic nanosized semiconductors. Additionally, the role performed by polymer nanofibers can be extended even further since they can act as an active medium for the in situ synthesis of photocatalytic metal nanoparticles or contribute to pollutant adsorption, facilitating their approach to the photocatalytic sites and their subsequent photodegradation. 
  • 737
  • 10 Mar 2022
Topic Review
Integrated Green Hydrogen Production Processes
The thermochemical water-splitting method is a promising technology for efficiently converting renewable thermal energy sources into green hydrogen. Thermochemical water splitting uses a high-temperature source, e.g., nuclear energy, waste heat, or concentrated solar systems, to convert water into hydrogen and oxygen through cyclic chemical reactions. Several promising routes have been proposed for hydrogen production through green technologies such as biological processes (such as CO gas-fermentation, dark fermentation, etc.), electrical (such as alkaline electrolysis cell, anion exchange membrane electrolysis cell, proton exchange membrane electrolysis cell, solid oxide electrolysis cell, etc.), photonic (bio-photolysis, photofermentation, etc.), thermochemical, etc.
  • 862
  • 01 Mar 2022
Topic Review
ZnO Photocatalysts for the Treatment of Wastewater
The presence of contaminants in wastewater, surface water, groundwater, and drinking water is a serious threat to human and environmental health. Their toxic effects and resistance towards conventional water treatment methods have compelled the scientific community to search for an environmentally friendly method that could efficiently degrade toxic contaminants. In this regard, visible light active photocatalysts have proved to be efficient in eliminating a wide variety of water toxins. A plethora of research activities have been carried out and significant amounts of funds are spent on the monitoring and removal of water contaminants, but relatively little attention has been paid to the degradation of persistent water pollutants. In this regard, nanoparticles of doped ZnO are preferred options owing to their low recombination rate and excellent photocatalytic and antimicrobial activity under irradiation of solar light. 
  • 2.4K
  • 18 Feb 2022
Topic Review
Bacterial Potential in Degradation of Azo Dyes
The use of dyes dates to ancient times and has increased due to population and industrial growth, leading to the rise of synthetic dyes. These pollutants are of great environmental impact and azo dyes deserve special attention due their widespread use and challenging degradation. Among the biological solutions developed to mitigate this issue, bacteria are highlighted for being versatile organisms, which can be applied as single organism cultures, microbial consortia, in bioreactors, acting in the detoxification of azo dyes breakage by-products and have the potential to combine biodegradation with the production of products of economic interest. These characteristics go hand in hand with the ability of various strains to act under various chemical and physical parameters, such as a wide range of pH, salinity, and temperature, with good performance under industry, and environmental, relevant conditions. 
  • 910
  • 11 Feb 2022
Topic Review
Non-Ferrous Metal Ions Removal by PIMs Doped 2-Alkylimidazoles
Polymer inclusion membranes (PIMs) are an attractive approach to the separation of metals from an aqueous solution. This study is concerned with the use of 2-alkylimidazoles (alkyl = methyl, ethyl, propyl, butyl) as ion carriers in PIMs. It investigates the separation of copper (II), zinc (II), cobalt (II), and nickel (II) from aqueous solutions with the use of polymer inclusion membranes. PIMs are formed by casting a solution containing a carrier (extractant), a plasticizer (o-NPPE), and a base polymer such as cellulose triacetate (CTA) to form a thin, flexible, and stable film. 
  • 559
  • 24 Jan 2022
Topic Review
Fouling Prevention in Membranes by Radiation-Induced Graft Copolymerization
The application of membrane processes in various fields has now undergone accelerated developments, despite the presence of some hurdles impacting the process efficiency. Fouling is arguably the main hindrance for a wider implementation of polymeric membranes, particularly in pressure-driven membrane processes, causing higher costs of energy, operation, and maintenance. Radiation induced graft copolymerization (RIGC) is a powerful versatile technique for covalently imparting selected chemical functionalities to membranes’ surfaces, providing a potential solution to fouling problems. 
  • 862
  • 17 Jan 2022
Topic Review
Soil and Food Crops Irrigated with Wastewater
Wastewater is actively used for irrigation of vegetable and forage crops in arid lands due to water scarcity and cost advantages. The objective of this review was to assess the effect of wastewater (mixture sources) reuse in irrigation on soil, crop (vegetable and forage crops), animal products, and human health. 
  • 1.6K
  • 31 Dec 2021
Topic Review
Autothermal Thermophilic Aerobic Digestion
Pembroke JT and MP Ryan.  Autothermal thermophilic aerobic digestion (ATAD) is a microbial fermentation process characterized as a tertiary treatment of waste material carried out in jacketed reactors. Heat is generated which selects a thermoduric microbial population. The process results in a stabilised, pasteurised sludge suitable for land application as a fertiliser. The microbial population biodegrades sludge contents, are unique in terms of diversity and have biotechnological potential as enzymes and proteins associated with the microbial population are thermostable. 
  • 1.0K
  • 24 Dec 2021
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