Holistic insight mechanism of ozone-based oxidation process for wastewater treatment.

The world is facing water crises because freshwater scarcity has become a global issue due to rapid population growth, resulting in the need for more industries, agriculture, and domestic sectors. Therefore, it is challenging for scientists and environmental engineers to treat wastewater with cost-effective treatment techniques. As compared to conventional processes (physical, chemical, and biological), advanced oxidation processes (AOP) play an essential role in the removal of wastewater contaminants, with the help of a powerful hydroxyl (OH•) through oxidation reactions. This review study investigates the critical role of O3-based Advanced Oxidation Processes (AOPs) in tackling the complex difficulties of wastewater treatment. Effective treatment methods are critical, with wastewater originating from various sources, including industrial activity, pharmaceutical manufacturing, agriculture, and a wide range of toxins. O3-based AOPs appear to be powerful therapies capable of degrading a wide range of pollutants, including stubborn organics, medicines, and pesticides, reducing environmental and human health risks. This review sheds light on their efficacy in wastewater treatment by explaining the underlying reaction mechanisms and applications of several O3-based AOP processes, such as O3, O3/UV, and O3/H2O2. Ozone, a powerful oxidizing agent, stimulates the breakdown of complex chemical molecules by oxidation processes, which are aided further by synergistic combinations with ultraviolet (UV) radiation or hydrogen peroxide (H2O2). Notably, while ozonation alone may not always produce the best outcomes, it acts as an essential pretreatment step prior to traditional treatments, increasing total treatment efficiency. Furthermore, O3-based AOPs' transformational capacity to convert organic chemicals into simpler, more stable inorganic forms with little sludge creation emphasizes its sustainability and environmental benefits. This study sheds light on the processes, uses, and benefits of O3-based AOPs, presenting practical solutions for sustainable water management and environmental protection. It is a valuable resource for academics, engineers, and politicians looking for new ways to combat wastewater contamination and protect water resources.

Challenges towards the Sustainability and Enhancement of the Indian Sundarban Mangrove's Blue Carbon Stock.

The Sundarban is the world's largest contiguous mangrove forest and stores around 26.62 Tg of blue carbon. The present study reviewed the factors causing a decline in its blue carbon content and poses a challenge in enhancing the carbon stock of this region. This review emphasized that recurrent tropical cyclones, soil erosion, freshwater scarcity, reduced sediment load into the delta, nutrient deficiency, salt-stress-induced changes in species composition, mangrove clearing, and anthropogenic pollution are the fundamental drivers which can potentially reduce the total blue carbon stock of this region. The southern end of the Ganges-Brahmaputra-Meghna Delta that shelters this forest has stopped its natural progradation due to inadequate sediment flow from the upper reaches. Growing population pressure from the north of the Sundarban Biosphere Reserve and severe erosion in the southern end accentuated by regional sea-level rise has left minimal options to enhance the blue carbon stock by extending the forest premises. This study collated the scholarly observations of the past decades from this region, indicating a carbon sequestration potential deterioration. By collecting the existing knowledge base, this review indicated the aspects that require immediate attention to stop this ecosystem's draining of the valuable carbon sequestered and, at the same time, enhance the carbon stock, if possible. This review provided some key recommendations that can help sustain the blue carbon stock of the Indian Sundarban. This review stressed that characterizing the spatial variability of blue carbon with more sampling points, catering to the damaged trees after tropical cyclones, estuarine rejuvenation in the upper reaches, maintaining species diversity through afforestation programs, arresting coastal erosion through increasing sediment flow, and combating marine pollution have become urgent needs of the hour. The observations synthesized in this study can be helpful for academics, policy managers, and decision makers willing to uphold the sustainability of the blue carbon stock of this crucial ecosystem.

How environmentally significant is water consumption during wastewater treatment? Application of recent developments in LCA to WWT technologies used at 3 contrasted geographical locations.

Environmental impact assessment models are readily available for the assessment of pollution-related impacts in life cycle assessment (LCA). These models have led to an increased focus on water pollution issues resulting in numerous LCA studies. Recently, there have been significant developments in methods assessing freshwater use. These improvements widen the scope for the assessment of wastewater treatment (WWT) technologies, now allowing us to apprehend, for the first time, a combination of operational (energy and chemicals use), qualitative (environmental pollution) and quantitative (water deprivation) issues in wastewater treatment. This enables us to address the following question: Is water consumption during wastewater treatment environmentally significant compared to other impacts? To answer this question, a standard life cycle inventory (LCI) was performed with a focus on consumptive water uses at plant level, where several WWT technologies were operating, in different climatic conditions. The impacts of water consumption were assessed by integrating regionalized characterization factors for water deprivation within an existing life cycle impact assessment (LCIA) method. Results at the midpoint level, show that water deprivation impacts are highly variable in relation to the chosen WWT technology (water volume used) and of WWTP location (local water scarcity). At the endpoint level, water deprivation impacts on ecosystem quality and on the resource damage categories are significant for WWT technologies with great water uses in water-scarce areas. Therefore, our study shows the consideration of water consumption-related impacts is essential and underlines the need for a greater understanding of the water consumption impacts caused by WWT systems. This knowledge will help water managers better mitigate local water deprivation impacts, especially in selecting WWT technologies suitable for arid and semi-arid areas.