Water Pollution Sources and Purification: Challenges and Scope

Nowadays, the whole world is facing water containment issues caused by anthropogenic sources, including household waste, agricultural waste, and industrial waste. There is a huge impact of wastewater on the environment; hence, the public concern over it has been increased. This led researchers to be motivated and find radical and cheap solutions to overcome this problem. Several conventional techniques, including boiling, filtration, sedimentation, and chlorination, are used for wastewater treatment; however, they have limited scope. Some other methods like coagulation, flocculation, biological treatment, Fenton processes, advanced oxidation, membranebased processes, ion exchange, electrochemical, adsorption, and UV-based processes have been applied to remove pollutants, but there are still some limitations. This review chapter sheds some light on these traditional and modern methods applied for water treatment, along with their advantages and disadvantages. These methods have the potential to remove pollutants from wastewater, such as natural organic matter, heavy metals, inorganic metallic matter, disinfection byproducts, and microbial chemicals. The potential threats and challenges of using water treatment methods for safe water production have also been discussed in this chapter.

Fluoride in drinking water has become a global problem that has a profound effect on teeth and bones, fostering various health problems. Adsorption is a potential defluoridation technique because of flexibility, cost-effectiveness, environmental friendliness, simplicity in design, relative ease of operation, and capability of producing high water quality. Although activated alumina is an appropriate adsorbent, it has a narrow favorable pH range, a tendency to form toxic aluminum fluoride complexes, and the problem of aluminum metal leaching. This article critically reviews the applicability of activated alumina and its modification by metal oxides, rare earth elements, organic materials, alkaline earth metals, and acid treatment. The effect of process parameters like pH, contact time, adsorbent dose, initial fluoride concentration, and the presence of coexisting ions on the adsorption capacity of fluoride ions is discussed. The adsorption reaction rates were discussed by fitting various rate models into the experimental data and the model equations. The adsorption isotherm models like Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich tested on the adsorption equilibrium data to identify the best fit model for adsorption isotherm are discussed in this chapter. The chapter finally discusses the advantages, disadvantages, and future prospects of all the adsorbents in order to improve their fluoride removal capacity.

The existence of organic acids in aqueous waste continues to be an important environmental concern because of the odor and toxicity they impart to water. The photochemical degradation of benzoic acids (BA) and some of the substituted benzoic acids (SBA), which act as environmental pollutants, are studied in the present investigation using the Advanced Oxidation Processes (AOPs) and combinations of different oxidants and UV irradiation (UV/H2O2, UV/TiO2, UV/ZnO, and Fe(III)- oxalate complex). The photo-oxidative degradation of these pollutants was followed by studying their concentration decay over the period of exposure to the UV-oxidant combination. The degradation kinetics of substituted benzoic acids (SBA) is observed to be dependent on the directory nature of the substituent groups, analyzed by the Hammett constant (σ), where electron-withdrawing groups (EWGs) show positive values and electron-donating groups (EDGs) account for its negative values. These observations figured out the processes that can be efficiently used for the system. Thus, this paper aims to examine parameters that affect the photocatalytic degradation of substituted benzoic acids.

Pollution load, rising population, and scarcity of water have drawn special attention for the management of water resources such as pond water. The present investigation was carried out at Dulahra and Ved ponds in Ratanpur, Bilaspur District. The seasonal deviations in water such as transparency, temperature, pH, dissolved oxygen, nitrate, phosphate, biological oxygen demand (BOD), total dissolved solids (TDS), and total suspended solids (TSS) were evaluated. In the contemporary study, the BOD standards were considerably higher than World Health Organization (WHO) standards (5 mg/l). The water samples were collected from each site at outer (about 100-150 meters) and internal (10 m from the shoreline) localities. The highest mean value of BOD, i.e., 32±4.6, was found at the north peripheral S-1 in the summertime. In the summer season, maximum mean BOD 39±2.1 was found at S-2 (West peripheral) in Ved Pond. It indicates the biological pollution load on the water body in the site of North peripheral in Dulhara pond and West peripheral in Ved Pond in the summer season. Low Secchi depth readings such as 20±1.0 at S-2 North peripheral site during summer seasons are indicative of reduced water clarity that is habitually related to the existence of suspended particles and algal tinges. We also found the maximum value of total suspended solids on the north side of the pond, where the transparency of water was also very low. A transparency value of 37.0±0.40 was noted at S-1 in the East marginal sites and 30±0.22 at the East inner sites in the rainy period at the Ved pond. The transparency of the water physique is exaggerated by the elements like planktonic growth, rainfall, the sun’s location in the sky, the angle of incidence of rays, cloudiness, electiveness, and turbidity due to deferred inert particulate material. Our outcomes suggest that the lowermost water transparency value was 16.0 ± 0.41 at S-1 in the North marginal sites for the duration of summer. The concentration of Calcium ions was much above the WHO recommended value of 75 mg/l at almost all the sites and both ponds during the study period. Numerous indicators and catalogues have been established in this particular study to evaluate water quality in intermediate water bodies. For transparency studies,low-cost Secchi disk was used.

Advanced oxidation process (AOP) degrades a number of non-degradable organic compounds in low concentrations, saving time and energy. Benzoic acid and its derivatives are readily used in pharmacy, textile, and dyes industries. Through these applications, benzoin acid enters the ecosystem, which leads to its accumulation and various health hazards. In the present study, the degradation of Benzoic acid was studied using Iron nanoparticles as heterogeneous photocatalyst and hydrogen peroxide as an oxidizing agent. This paper also discusses the synthesis of Fe nanoparticles via hydrothermal process at ordinary temperature and elevated temperature. The powder samples were characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Energy dispersive analysis of X-rays (EDAX). The percentage degradation of benzoic acid using goethite (α-FeOOH) and hematite (α-Fe2O3) was 49.02% and 90.90% with the nano concentrations of 0.07g and 0.05g, respectively using visible light, in addition, the hydrothermal model of nanoparticle synthesis proved affordable, efficient and eco-friendly.

This paper presents an exhaustive study of modern methods used to purify water with the support of nanomaterials. For deriving maximum benefits from nanotechnology, the environmental sustainability of the nano-particles must be assessed. Nanoparticles possess useful characteristics contributing to water treatment and the removal of numerous pollutants. Materials such as zeolites, chitosan, MWCNT, nano-composites (Fe3O4/TiO2, GO/FeO·Fe2O3, etc.), nano-oxides (ZnO, TiO2, Al2O3, Fe2O3, Fe3O4, etc.) and MOF (MOF-808, Cu-terephthalate, CoFe2O4 /MIL-100(Fe), UiO-66-NHC(S) NHMe, etc.) have been included in the study including their apparent functionality in treating contaminated water streams. Additionally, known methods to synthesize these nano particles from diverse sources have been studied. The review highlights the removal of pollutants (non-biodegradable, heavy metals, inorganics, and organics) by adsorption using photo nano adsorbents. Devoid of any recognized standards, the performance of the nanomaterials in wastewater treatment needs further research. With the further advancement of nano technology, ideological guidelines along with general cons and future challenges affecting humans and the ecosystem have been reported to provide further scope for research in this domain.

The availability of pure drinking water to individuals reflects the progress of any region, which is linked directly with the quality of life across the globe. Variations in the quality and quantity of water systems control all aspects of human life. Both its shortage and excess affect the growth and development of the community. The utilization and conservation of our water world must be an integral part of sustainable development and should be appealed to by all sectors. While effective wastewater treatment has the tendency to recover the water, integration of all policies with periodic improvement using research outcomes is still essential. In order to tackle the challenges in the coming decades, it is important that all stakeholders are sensitized about the current scenario, future needs, and the need for a proper scientific and rational approach to moderate the issues and challenges collectively. Integrated Water Conservation Techniques are acknowledged as the only sustainable solution to water scarcity.