Showing papers on "Effluent published in 2022"

Brine management (saline water & wastewater effluents): Sustainable utilization and resource recovery strategy through Minimal and Zero Liquid Discharge (MLD & ZLD) desalination systems

Abstract: Brine is a saline water present in the natural environment and produced by desalination and other process industries such as the oil & gas, textile, leather, food, dairy, agriculture, and pharmaceutical industries. Although brine was designated to be discharged in the early stages of the brine management strategy, its environmental impacts have recently prompted the adoption of a new management approach. This change is the shift from disposal to utilization and resource recovery. Apart from being a source of freshwater, brine can also be a source of salts, minerals, metals, chemicals, bioactive compounds, and even energy (known as ‘osmotic power’, ‘salinity gradient power’ or ‘blue energy’). Minimal Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) systems can be employed for the treatment and recovery of valuable resources. This review article is the first to investigate and evaluate the potential of recovering all of the resources present in brine through its treatment and utilization in MLD/ZLD systems. Overall, the challenges, research gaps, and future prospects are identified through this analysis, with the ultimate goals of decarbonized and sustainable brine management.

Key Points of Advanced Oxidation Processes (AOPs) for Wastewater, Organic Pollutants and Pharmaceutical Waste Treatment: A Mini Review

Abstract: Advanced oxidation procedures (AOPs) refer to a variety of technical procedures that produce OH radicals to sufficiently oxidize wastewater, organic pollutant streams, and toxic effluents from industrial, hospital, pharmaceutical and municipal wastes. Through the implementation of such procedures, the (post) treatment of such waste effluents leads to products that are more susceptible to bioremediation, are less toxic and possess less pollutant load. The basic mechanism produces free OH radicals and other reactive species such as superoxide anions, hydrogen peroxide, etc. A basic classification of AOPs is presented in this short review, analyzing the processes of UV/H2O2, Fenton and photo-Fenton, ozone-based (O3) processes, photocatalysis and sonolysis from chemical and equipment points of view to clarify the nature of the reactive species in each AOP and their advantages. Finally, combined AOP implementations are favored through the literature as an efficient solution in addressing the issue of global environmental waste management.

Microalgal-based biochar in wastewater remediation: Its synthesis, characterization and applications

Abstract: Microalgae are drawing attentions among researchers for their biorefinery use or value-added products. The high production rate of biomasses produced are attractive for conversion into volatile biochar. Torrefaction, pyrolysis and hydrothermal carbonization are the recommended thermochemical conversion techniques that could produce microalgal-based biochar with desirable physiochemical properties such as high surface area and pore volume, abundant surface functional groups, as well as functionality such as high adsorption capacity. The characterizations of the biochar significantly influence the mechanisms in adsorption of pollutants from wastewaters. Specific adsorption of the organic and inorganic pollutants from the effluent are reviewed to examine the adsorption capacity and efficiency of biochar derived from different microalgae species. Last but not least, future remarks over the challenges and improvements are discussed accordingly. Overall, this review would discuss the synthesis, characterization and application of the microalgal-based biochar in wastewater.

Process Parameters Optimization, Characterization, and Application of KOH-Activated Norway Spruce Bark Graphitic Biochars for Efficient Azo Dye Adsorption

Abstract: In this work, Norway spruce bark was used as a precursor to prepare activated biochars (BCs) via chemical activation with potassium hydroxide (KOH) as a chemical activator. A Box–Behnken design (BBD) was conducted to evaluate and identify the optimal conditions to reach high specific surface area and high mass yield of BC samples. The studied BC preparation parameters and their levels were as follows: pyrolysis temperature (700, 800, and 900 °C), holding time (1, 2, and 3 h), and ratio of the biomass: chemical activator of 1: 1, 1.5, and 2. The planned BBD yielded BC with extremely high SSA values, up to 2209 m2·g−1. In addition, the BCs were physiochemically characterized, and the results indicated that the BCs exhibited disordered carbon structures and presented a high quantity of O-bearing functional groups on their surfaces, which might improve their adsorption performance towards organic pollutant removal. The BC with the highest SSA value was then employed as an adsorbent to remove Evans blue dye (EB) and colorful effluents. The kinetic study followed a general-order (GO) model, as the most suitable model to describe the experimental data, while the Redlich–Peterson model fitted the equilibrium data better. The EB adsorption capacity was 396.1 mg·g−1. The employment of the BC in the treatment of synthetic effluents, with several dyes and other organic and inorganic compounds, returned a high percentage of removal degree up to 87.7%. Desorption and cyclability tests showed that the biochar can be efficiently regenerated, maintaining an adsorption capacity of 75% after 4 adsorption–desorption cycles. The results of this work pointed out that Norway spruce bark indeed is a promising precursor for producing biochars with very promising properties.

Microalgae-based wastewater treatment: Mechanisms, challenges, recent advances, and future prospects

Abstract: The rapid expansion of both the global economy and the human population has led to a shortage of water resources suitable for direct human consumption. As a result, water remediation will inexorably become the primary focus on a global scale. Microalgae can be grown in various types of wastewaters (WW). They have a high potential to remove contaminants from the effluents of industries and urban areas. This review focuses on recent advances on WW remediation through microalgae cultivation. Attention has already been paid to microalgae-based wastewater treatment (WWT) due to its low energy requirements, the strong ability of microalgae to thrive under diverse environmental conditions, and the potential to transform WW nutrients into high-value compounds. It turned out that microalgae-based WWT is an economical and sustainable solution. Moreover, different types of toxins are removed by microalgae through biosorption, bioaccumulation, and biodegradation processes. Examples are toxins from agricultural runoffs and textile and pharmaceutical industrial effluents. Microalgae have the potential to mitigate carbon dioxide and make use of the micronutrients that are present in the effluents. This review paper highlights the application of microalgae in WW remediation and the remediation of diverse types of pollutants commonly present in WW through different mechanisms, simultaneous resource recovery, and efficient microalgae-based co-culturing systems along with bottlenecks and prospects.

Efficient dye degradation strategies using green synthesized ZnO-based nanoplatforms: A review

Abstract: Organic pollutants in industrial waste must be handled with viable and eco-friendly approaches. In particular, releasing toxic effluents like dyes into the environment pollutes water bodies, causing fatal diseases in humans and is hazardous to aquatic life. It necessitates the removal of effluent dyes before being discharged into the water bodies. The photocatalytic degradation method using metal oxide nanoparticles is the preferred choice amongst various dye remediation strategies. However, state-of-the-art metal oxide nanoparticle-based dye remediation involves developing non-toxic, economic, and eco-friendly metal oxides using green chemistry. Plant-mediated ZnO-based nanoplatforms exhibited substantial photocatalytic properties, non-toxicity, biocompatibility, and cost-effectiveness, possessing the potential to replace conventional dye remediation strategies. This review focuses on the development and performance of green synthesized ZnO nanoparticles towards degrading various dyes for wastewater remediation. It comprehensively summarizes the state-of-the-art green ZnO nanoparticle fabrication from various plant extracts (like leaves, seeds, juice, and fruits), illustrates their dye removal efficacies, and details their photocatalytic dye degradation mechanism. This review aims to serve as a fundamental structure to guide future research on green ZnO-based nanoplatforms for wastewater treatment, where photocatalytic attributes and green chemistry are prerequisites.

Multiple Roles of Dissolved Organic Matter in Advanced Oxidation Processes

Abstract: Advanced oxidation processes (AOPs) can degrade a wide range of trace organic contaminants (TrOCs) to improve the quality of potable water or discharged wastewater effluents. Their effectiveness is impacted, however, by the dissolved organic matter (DOM) that is ubiquitous in all water sources. During the application of an AOP, DOM can scavenge radicals and/or block light penetration, therefore impacting their effectiveness toward contaminant transformation. The multiple ways in which different types or sources of DOM can impact oxidative water purification processes are critically reviewed. DOM can inhibit the degradation of TrOCs, but it can also enhance the formation and reactivity of useful radicals for contaminants elimination and alter the transformation pathways of contaminants. An in-depth analysis highlights the inhibitory effect of DOM on the degradation efficiency of TrOCs based on DOM's structure and optical properties and its reactivity toward oxidants as well as the synergistic contribution of DOM to the transformation of TrOCs from the analysis of DOM's redox properties and DOM's transient intermediates. AOPs can alter DOM structure properties as well as and influence types, mechanisms, and extent of oxidation byproducts formation. Research needs are proposed to advance practical understanding of how DOM can be exploited to improve oxidative water purification.