Microwave Irradiation in Technologies of Wastewater and Wastewater Sludge Treatment: A Review

Abstract

Every year, the human impact on the world’s water sources becomes more pronounced. One of the triggers to this increase is the use of ineffective wastewater and sludge treatment systems. Recently, the number of studies of microwave processing in handling liquid municipal and industrial waste has increased. This paper discusses heat treatment, change in properties, decomposition of substances, removal of metals, demulsification, pyrolysis, biogas processing, disinfection, and other topics. The findings of European, Chinese, Russian, and other authors are summarised and presented in this review. In addition, the most notable Russian patents for microwave installations/devices and reactors suitable for a wide variety of applications are discussed. In this article, the authors look at microwave wastewater and sludge treatment from the perspective of practical application in various fields of human economic activity.

Study and application status of the nonthermal effects of microwaves in chemistry and materials science – a brief review

“…The researchers who advocate for the existence of nonthermal effects of MWs always make their claims by comparing experimental phenomena that are caused by MW heating and CH. According to previous studies, the nonthermal effects of MW can be reected in various aspects, such as (1) variations in solution conductivity, (2) variations in substance microstructure, (3) variations in the composition and nutritional quality of food, and (4) the generation of H 2 O 2 in water and physiological solutions. Typical studies are summarized in Table 1, and some typical gures are given as well.…”

“…Microwaves (MWs) are a part of the electromagnetic spectrum, and their frequency range is from 0.3 GHz to 300 GHz, which corresponds to a wavelength range of 1 m–1 mm. 1 In commercial applications, the allowed MW frequencies are 2.45 and 0.915 GHz, which correspond to wavelengths of 122 and 328 mm, respectively. These frequencies must be used to avoid interference with military applications.…”

“…Opponents argue that MWs are oen associated with higher temperature and are too weak to cause molecular self-organizing behaviour, while proponents argue that open systems far from equilibrium can self-organize due to the exchange of matter and energy. In order to solve the dispute, two aspects must be improved: (1) standard experimental conditions and equipment; (2) strict experimental means and methods, especially ne measurement of temperature spatial distribution under MW irradiation. 20 In this review, we summarize the studies that detect nonthermal effects of MWs, propose an operating mechanism for these effects, and introduce the applications of and the harms that are caused by these effects based on published reports from various elds.…”

Detection and Treatment of Persistent Pollutants in Water: General Review of Pharmaceutical Products

“…Among the drug removal technologies biological processes [11][12][13] are the most commonly used techniques in conventional wastewater treatment plants. Recently, advanced oxidation processes (AOP), [14][15][16][17] which are typically more efficient, but more expensive, are expected to offer potential relief to expanding contamination issues. However, AOP are proving to be difficult to scale up from their application in a pilot plant.…”

Synergistically enhanced solar light‐driven degradation of hazardous food colorants by ultrasonically derived MgFe2O4/S‐doped g‐C3N4 nanocomposite: A Z‐scheme system‐based heterojunction approach

“…[18] Conventionally, the eradication of such toxic colorants from the waste water streams relies on numerous techniques including biodegradation, [22] adsorption, [23,24] photocatalysis, [25][26][27] coagulation, flocculation, [28] reverse osmosis, [29] sedimentation, piezocatalysis, [30,31] and microwave catalysis. [32][33][34] However, the majority of the mentioned methods are economically unfavoured, less efficient, technically complicated, or require special operational conditions for the removal of by-products/ secondary waste products. [18] Each of the mentioned method has its own set of benefits and drawbacks, not just in terms of cost but also in terms of effectiveness, practicality and environmental impact.…”