Fate, Transport, Removal and Modeling of Traditional and Emerging Pollutants in Water

1. Special Issue Information

The scope of discussion of this Special Issue includes, but is not limited to, understanding the fate, transport, removal, and modeling of traditional and emerging pollutants in water. Every day, a greater concentration of pollutants is found not only in water bodies but also in different compartments, such as air, soil and sediments.

Natural and anthropogenic factors can lead to a reduction in clean drinking water supplies. For instance, long droughts, surges in annual rainfall, and natural disasters impact the quality and availability of our water sources. On the other hand, the overexploitation of natural resources, the use of pesticides, the presence of chlorinated solvents, the lack of new regulations to address emerging pollutants, processes that are not sustainable for the environment, and the lack of or incomplete life cycle analyses are examples of serious human-made threats for the current and coming generations.

At this point, it is relevant to identify, understand, and re-evaluate several of the important environmental effects of water pollutants on humans and ecosystems. In addition to developing recommendations, regulations and appropriate methodologies are required to identify, track, and remediate concentrations of pollutants in water. This Special Issue will update the state of the art and partially fill the knowledge gap on these contaminants in water.

2. Introduction

In this Special Issue, the presence, fate, transport, remediation, toxicity, health risks, and environmental risk assessments of pollutants in various environmental compartments, such as soil, water, and sediments, were investigated. Special emphasis was placed on pollutants, including pharmaceuticals (emerging pollutants), toxic aromatics (regulated pollutants), and microbial pathogens in drinking water, surface water, industrial water, and wastewater.

The articles include different kinds of methodologies, such as kinetic, batch and dynamic column experiments, plus modeling methods such as principal component analysis (PCA), self-organizing maps (SOMs), positive matrix factorization (PMF), and Monte Carlo simulation for data analysis, visualization, and interpretation.

The results of the manuscripts underscore the need for a deeper understanding of the behavior and impacts of pollutants and environmental stressors across different compartments to quantify ecological effects; the development of effective treatments or the enhancement of existing ones to remove contaminants; the strict regulation and monitoring of pollutants released into the environment; and the importance of long-term assessments to adequately estimate environmental risks.

3. Main Contribution of This Special Issue/An Overview of Published Articles

Based on a rigorous peer-review, five papers were ultimately published in this Special Issue. A summary of their key findings is provided below:

“Enhancing Point-of-Use Sand Filters through Integration of Copper Mesh”, written by Kasaraneni et al. (contribution 1), showed the potential of Cupper (Cu) to enhance sand filters to remove bacteria using batch and columns reactors. The results showed that 1 g of copper mesh was enough to inhibit typical concentrations of bacteria between 10² and 10⁶ CFU/100 mL. The findings present a viable strategy with potential to reduce waterborne disease in developing countries.

“Source-Oriented Health Risks and Distribution of BTEXS in Urban Shallow Lake Sediment: Application of the Positive Matrix Factorization Model”, written by Trajković et al. (contribution 2), studied the polluting effect of Benzene, Toluene, Ethylbenzene, and Xylenes (BTEXs) on sediments through the health risk quantification using self-organizing maps (SOMs), positive matrix factorization (PMF), and Monte Carlo simulation. The results showed Toluene was the main congener, followed by m,p-xylene, benzene, ethylbenzene, o-xylene and styrene; however, the carcinogenic and non-carcinogenic health risks were below the permissible limits. The results allow for a better understanding of the dynamics and impacts of BTEX in lake sediments.

“Peroxydisulfate Persistence in ISCO for Groundwater Remediation: Temperature Dependence, Batch/Column Comparison, and Sulfate Fate”, written by McGachy et al. (contribution 3), studied the impact and persistence of peroxydisulfate anion (S₂O₈²⁻) in soil to design effective in situ chemical oxidation treatments (ISCO) for groundwater. Through batch, dynamic, and PCA methods, the authors found the ability of some systems to partially accumulate produced SO4²⁻ and the relevant role of total organic carbon (TOC), Ni, Mo, Co, and Mn to be key factors influencing the decomposition rate under varying soil conditions. These findings are relevant to improve ISCO treatments for groundwater remediation.

“The Effect of pH on Aniline Removal from Water Using Hydrophobic and Ion-Exchange Membranes”, written by Filian et al. (contribution 4), found that up to 97% of charged aniline can be removed using hydrophobic and ion-exchange membranes (IEMs). The results could improve the treatment of industrial wastewater effluents.

“Toxicity of the Antiretrovirals Tenofovir Disoproxil Fumarate, Lamivudine, and Dolutegravir on Cyanobacterium Microcystis novacekii”, written by Souza-Silva et al. (contribution 5), studied the inhibitory effect and environmental risk of pharmaceutical residues in three types of antiretrovirals (ARVs)—tenofovir (TDF), lamivudine (3TC), and dolutegravir (DTG)—on the cyanobacterium Microcystis novacekii. The toxicity results and environmental risk assessments showed that the highest toxicity effect was caused by DTG and moderate-to high environmental risk at typical environmental concentrations was observed for TDF and 3TC. The previous findings allow for a better understanding of the ecotoxicological impacts of ARVs and the determination of the best methods to estimate their environmental risks.

4. The Perspective for Future Directions

Future research on the fate, transport, and remediation of pollutants in water should adopt a holistic approach that considers the prevention, generation, monitoring, quantification, interaction, and removal or remediation of the pollutants throughout the whole system. Educational programs for children, teenagers, and parents are needed to raise awareness about pollutants that can be generated at home and explain the correct way to dispose of them. In addition, workshops should be held for companies to present updates on how to process and minimize generated pollutants. These efforts should also incorporate updates on regulatory changes, the identification of emerging pollutants, the implementation of comprehensive recycling programs, and life cycle assessments to effectively evaluate, control, and reduce the generation of pollutants.

Additionally, enhanced analytical techniques are required to accurately detect and quantify the pollutants generated/released, as well as long-term assessments of the environment. A deeper understanding of pollutant interactions, including their persistence, mobility, transformations, and impact, is essential, not just in isolation but across different environmental categories, such as soil, air, and sediments.

Data analysis and modeling capabilities are required to process complex environmental data, predict the impact of pollutants guide the design of sustainable treatment with low cost, energy-efficient, and nature-based solutions, such as effective phytoremediation technologies and biochar-enhanced filtration, alongside innovations in nanomaterials. In parallel, tools such as Monte Carlo simulations, SOMs, PCA, PMF, and probabilistic risk assessments can enhance the understanding of complex pollutant behavior across spatial and temporal scales and will become increasingly important for incorporating uncertainty and informing regulatory decisions.

Interdisciplinary efforts that bridge environmental science, engineering, data analysis and interpretation, and environmental policy will be essential to advancing holistic strategies for protecting water resources for both current and future generations.