By 2020, it is expected that more than 3.5 billion of people might live in regions with hydric stress [1], that is, regions where the available water cannot fulfil the demand required for basic domestic, agricultural and industrial purposes. Under this scenario, the use of non-conventional water resources, as the regeneration and reuse of treated wastewater, is expected to be an alternative option for increasing the available water resources [2].
Nevertheless, the reuse of wastewater also presents many drawbacks that have to be addressed. For instance, it is mandatory to perform a disinfection of water previous to its reuse. The chlorination is the most common and cheapest used disinfection agent, but its utilization to treat wastewater is not recommended by the generation of disinfection by-products as trihalomethanes. Nowadays, new technologies have emerged as alternative. This is the case of Advanced Oxidation Processes (AOPs) based on the generation of highly reactive species, such as hydroxyl (OH•) and sulfate radicals (SO4•-). These short-lived radicals are characterized by a high oxidation potential, being able to inactivatebacteria and to remove recalcitrant organic matter and micropollutants [3]. Sulfate radical basedAOPs (SR-AOPs) could involve the use of peroxymonosulfate (PMS; HSO5-) anion. But, PMS is not an effective disinfectant at low dosages, so it requires to be activated in combination with: i) heat; ii) UV-radiation; and/or iii) the addition of a transition metal cation [4]. In this regard, the use of Fe2+,Co2+, Ni2+, another cations allowing a homogeneous catalytic activation has been widely reported by different authors [4, 5]. However, there exists legal restrictions concerning the amount of metals present in solution and they have to be removed from water previous to the reuse. For this reason, the use of a heterogeneous catalysts that can be recovered and reused is an eco-friendly alternative.
By 2020, it is expected that more than 3.5 billion of people might live in regions with hydric stress [1], that is, regions where the available water cannot fulfil the demand required for basic domestic, agricultural and industrial purposes. Under this scenario, the use of non-conventional water resources, as the regeneration and reuse of treated wastewater, is expected to be an alternative option for increasing the available water resources [2].
Nevertheless, the reuse of wastewater also presents many drawbacks that have to be addressed. For instance, it is mandatory to perform a disinfection of water previous to its reuse. The chlorination is the most common and cheapest used disinfection agent, but its utilization to treat wastewater is not recommended by the generation of disinfection by-products as trihalomethanes. Nowadays, new technologies have emerged as alternative. This is the case of Advanced Oxidation Processes (AOPs) based on the generation of highly reactive species, such as hydroxyl (OH•) and sulfate radicals (SO4•-). These short-lived radicals are characterized by a high oxidation potential, being able to inactivatebacteria and to remove recalcitrant organic matter and micropollutants [3]. Sulfate radical basedAOPs (SR-AOPs) could involve the use of peroxymonosulfate (PMS; HSO5-) anion. But, PMS is not an effective disinfectant at low dosages, so it requires to be activated in combination with: i) heat; ii) UV-radiation; and/or iii) the addition of a transition metal cation [4]. In this regard, the use of Fe2+,Co2+, Ni2+, another cations allowing a homogeneous catalytic activation has been widely reported by different authors [4, 5]. However, there exists legal restrictions concerning the amount of metals present in solution and they have to be removed from water previous to the reuse. For this reason, the use of a heterogeneous catalysts that can be recovered and reused is an eco-friendly alternative. Read More
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