Advanced Oxidation Processes for Wastewater Remediation: Fundamental Concepts to Recent Advances

Industrialization and modernization in recent times have led to a water crisis across the world. Conventional methods of water treatment like physical, chemical and biological methods which comprise of many commonly used techniques like membrane separation, adsorption, chemical treatment etc. have been in use for many decades. However, problems like sludge disposal, high operating costs etc. have led to increased focus on Advanced Oxidation Processes (AOPs) as alternative treatment methods. AOPs basically involve reactions relying on the high oxidation potential of the hydroxyl (OH•) free radical. They have the potential to efficiently treat various toxic, organic pollutants and complete degradation of contaminants (mineralization) of emerging concern. Many different types of homogenous as well as heterogenous AOPs have been studied viz: UV/H2O2, Fenton, Photo-Fenton, Sonolysis, Photocatalysis etc. for treatment of a wide variety of organic pollutants. Different AOPs are suitable for different types of wastewater and hence proper selection of the right technique for a particular type of pollutant is required. The inherent advantages offered by AOPs like elimination of sludge disposal problems, operability under mild conditions, ability to harness sunlight, non selective nature (ability to degrade all organic and microbial contamination) etc. have made it one of the most actively researched areas in recent times for wastewater treatment. Despite the benefits and intense research, commercial applicability of AOPs as a practical technique for treating wastewater on a large scale is still far from satisfactory. Nevertheless, positive results in lab scale and pilot plant studies make them a promising water treatment technique for the future. In the present chapter, an attempt has been made to discuss all aspects of AOPs beginning with the fundamental concepts, classification, underlying mechanism, comparison, commercialization to the latest developments in AOPs.

Introduction to Conventional Wastewater Treatment Technologies: Limitations and Recent Advances

The rapid growth of the industries and population leads to increasing generation of industrial and municipal wastewater. This wastewater threatens directly or indirectly the human health and industrial processes. Therefore, it is necessary to develop a rapid, simple, eco-friendly, effective, and efficient method for eliminating pollutants from industrial and municipal wastewater. The wastewater treatment aims to remove pollutants including particles, organic/inorganic substances, and pathogenic microorganisms, and finally returned to the cycle. This chapter presents a brief introduction to the issue associated with municipal and industrial wastewater. Also, this chapter presents detailed information about the conventional wastewater treatment methods. Specifically, it discusses the steps involved in the wastewater treatment viz. primary, secondary, and tertiary treatment.

The Applicability of Eggshell Waste as a Sustainable Biosorbent Medium in Wastewater Treatment – A Review

The exemplary properties of eggshell waste have gained a lot of attention due to its chemical composition and bio-degradable features making it a suitable choice to be used in wastewater treatment. The use of biosorption as an alternate treatment technology to conventional processes such as chemical precipitation and ion exchange is seen as a promising solution to the many drawbacks experienced by conventional processes. Furthermore, due to higher imposed environmental legislations, eco-friendly and low-cost considerations have set the momentum in the search for biosorbents of this nature. With the circular economy being the focal point of industrial operations, eggshell waste is a highly promising biosorbent due to its non-toxicity properties and its ability to be converted from a waste material to a valuable product. In this review paper, fundamental aspects of biosorption will be discussed where the main focus will lie in qualitatively examining the properties of eggshell waste, binding mechanisms, kinetics and isotherm modelling that make it an attractive option to be used in the biosorptive process. Finally, a summary of the important considerations for future research work in this field is presented.

New Class of Flocculants and Coagulants

Coagulation is a kind of efficient water treatment method commonly used in domestic anhydrous and industrial wastewater treatment. Inorganic polymer coagulants (polyvalent metal salts) are widely used because of their low cost and ease of use. However, due to the low flocculation effectiveness and the presence of residual metal concentrations in the treated water, their application is limited. Organic synthetic flocculant has been widely used due to its higher flocculation efficiency at lower dosage. However, it has limitations in applicability due to its molecular structure which is less biodegradable and less disperse in water. Therefore, flocculants based on natural polymers have attracted extensive attention from researchers due to their advantages such as biodegradability and environmental friendliness. This paper summarizes the overview of the development of various types of flocculants that were used for industrial wastewater treatment. In addition, the characteristics and application of flocculant is reviewed with their behavior.

Removal of PAHs from Wastewater Using Powdered Activated Carbon: A Case Study

The aim of this study was to develop immobilized microorganism carrier for effectively degradation of petroleum hydrocarbons (PAHs), especially pyrene. Powdered activated carbon (PAC) was used to immobilize the bacterial consortium (Klebsiella pneumoniae and Pseudomonas aeruginosa) with binder CaCl2 and sodium alginate (SA) for improving mass transfer rate of the pyrene pollutants. Mass transfer properties, embedding ratio, and mechanical strength were inspected for the immobilization particles. Mechanical strength of SA beads was more influenced by proportion of SA and CaCl2 than by proportion of PAC. The optimum proportion of SA, CaCl2 and PAC were 2.5%, 2% and 0.5% for immobilization SA beads. The degradation of bacterial consortium (Pa+Kp) had the best degradation rates at 48.2% on 14 days. SA embedding immobilization by adding PAC can obviously enhanced effect of pyrene degradation because of bacterial absorption ability and nutrient permeability being improved.

Treatment and Analysis of Arsenic Contaminated Water

The presence of arsenic in as many as 245 minerals makes it an indispensable waste in the metal refining industry. Hydraulic fracturing, underground drilling, pesticides, herbicides, electronic industries are also linked to arsenic contamination. Natural processes such as volcanic emissions, hydrothermal ores, and river flow through arsenic rich sediments also contribute to arsenic contaminated water. The consumption of arsenic contaminated water leads to various types of cancer such as dermatological, respiratory, gastrointestinal, cardiovascular, hepatic, neurological, renal, and mutagenesis. Thus, remediation and testing of arsenic contaminated water becomes ubiquitous. Arsenic removal methods include precipitation, filtration, membrane technology and bioremediation. Quantitative arsenic analysis includes several colorimetric, luminescence, spectroscopic, atomic absorption, mass spectrometric and biosensor-based techniques. In this chapter, we present an overview of the various sources linked with arsenic contaminated water followed by a discussion on the available treatment and monitoring technologies for waterborne arsenic.

Degradation of Pharmaceutical Pollutants under UV Light using TiO2 Nanomaterial Synthesized through Reverse Micelle Nanodomains

Controlling water pollution are huge challenges throughout the world especially concerning pharmaceutical pollutants. Common practices at industrial wastewater treatment facilities need to be upgraded with advanced wastewater treatment techniques. TiO2 based photocatalytic processes have shown great potential for removal of these aqueous pharmaceutical pollutants. Reverse micelle based modified sol-gel method is utilized for the synthesis of TiO2 nanomaterial. Generated reverse micelle nanodomains have controlled size and particle size distribution (PSD) of synthesized TiO2 nanomaterial, as revealed by SEM and DLS analysis. Thermal behaviour of synthesized sample is characterized by TGA analysis. TiO2 photocatalyst is also characterized through XRD, BET surface area, and UV-Vis spectroscopy. TiO2 photocatalyst is used for degradation of three model pharmaceutical pollutants viz. Levofloxacin hemihydrate (LFX), Metronidazole (MNZ) and Ketorolac tromethamine (KRL) under a UV light source. Reverse micelle mediated modified sol-gel method synthesized TiO2 nanomaterial has shown excellent photocatalytical performance, where degradation efficiency of LFX, KRL and MNZ were found to be 99.6%, 98% and 91.4% respectively within a little as 60 minutes.