China
Africa
Explore chapters and articles related to this topic
Chemistry in Wastewater Treatment
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
Sonali Sengupta, Chandan Kumar Pal
In situ chemical oxidation (ISCO) is remedial measure that is practiced with an aim to transform groundwater or soil contaminants into less harmful chemical species. It involves the introduction of a chemical oxidant into the subsurface (29, 30). The most common oxidants used in chemical oxidation are permanganate (MnO4-), hydrogen peroxide (H2O2), iron (Fe: Fenton-driven, or H2O2-derived oxidation), persulfate (S2O82-), and ozone (O3). The success of the technique depends on the persistence of the reagent in the injected subsurface and its diffusive transport toward the targeted affected zone. Unlike usual chemical oxidation there is only limited scope of removal of the transformed oxidized product here, which is also to be taken into consideration. Like all other technological innovations, this too has its advantages and limitations. The major indicators in these arena are listed in the following sections.
General Types of Contaminated Site Restoration Methods and Technologies
Published in Kofi Asante-Duah, Management of Contaminated Site Problems, 2019
In situ chemical oxidation (ISCO) refers to a general group of specialty remediation techniques or technologies in which chemical oxidants are delivered to the subsurface to rapidly degrade organic contaminants, with each variant technology representing unique combinations of oxidants and delivery techniques. Broadly speaking, it involves the application of a strong oxidizing agent in the ground via well injection or a specially designed injection tool. The oxidants degrade the target contaminants by converting them to benign compounds, usually H2O, CO2, and mineral salts. Specific primary oxidants commonly used for ISCO include hydrogen peroxide (H2O2); Fenton’s reagent (i.e., an iron-catalyzed hydrogen peroxide—a liquid composed of Fe2+ + H2O2); permanganate (MnO4−)—typically potassium and sodium permanganate (usually, KMnO4 in liquid form); and ozone (viz., O3 gas). Each oxidant chemical is generally uniquely effective for different contaminants.
In situ soil remediation: The reactor approach
Published in Katalin Gruiz, Tamás Meggyes, Éva Fenyvesi, Engineering Tools for Environmental Risk Management – 4, 2019
For chemical or biological transformation of poorly mobilizable soil contaminants (typically aged contaminants with large molecular weight that are dominantly sorbed on a solid), GCW-aided delivery can be applied. The additives, nutrients, or reagents (which can enhance the chemical or biological availability and transformation) are injected into the well and spread via the hydrolytically controlled water circulation. This way the additives and reagents get more easily to their destination and in contact with the target molecules (even if they are sorbed on solid surfaces). As a result, the efficiency of the key process can be enhanced. An intensifying effect occurs mainly in the impact area of the well, and to a lesser extent downstream from the well. In such applications the cycled water is the carrier medium and is responsible for additive or reagent delivery to the place of use. For example, in situ chemical oxidation (ISCO) can be intensified this way: the dissolved reagent is injected into the well, and the hydrolytically controlled water cycling delivers and uniformly spreads permanganate or peroxide into the contaminated soil.
Fast Direct Oxidation of All Alkanes in Soil by Hydrophilic Fe-SOM
Published in Soil and Sediment Contamination: An International Journal, 2023
Jinlan Xu, Lu Liu, Qihang Shi, Zezhuang Cao, Yuetong Rong, Fengsen Li
Growing energy demand and innovations in oil extraction technologies have rapidly increased crude oil extraction, refining, and use globally (Yuan et al. 2018). Because petroleum’s mobility and permeability made the soil less fertile, with altered physicochemical properties and high human hazards, petroleum hydrocarbon-contaminated soil must be treated (Kiamarsi et al. 2020; Usman, Hanna, and Faure 2018; Zhen et al. 2021). Fenton oxidation, a kind of in situ chemical oxidation (ISCO), has become an economical and efficient remediation technology, which referred to the production of •OH by using the solution of H2O2 and Fe2+ (Laurent et al. 2012; Usman et al. 2022). Due to the high oxidation potential of •OH(Eo = 2.80 V) (Cheng et al. 2016; Ma et al. 2018), non-selected oxidation of total petroleum hydrocarbons (TPHs) in soil could be achieved (Paixão et al. 2020; Usman and Ho 2020). Moreover, previous reports indicated that needle ferrite (FeOOH) as high-potential iron could also lead to Fenton reactions with H2O2, showing excellent oxidation efficiency (Pervez etal. 2021; Tsai et al. 2009). Compared to bioremediation, chemical oxidation can oxidize TPHs in soil within a few hours to achieve the desired remediation effect (Huguenot et al. 2015; Martínez-Pascual et al. 2015; Pan et al. 2020).
Enhancing the Removal of Sorbed Crude Oil from Soil Through Multiple Oxidation Steps in Stepwise Fenton Processes
Published in Soil and Sediment Contamination: An International Journal, 2018
Jinlan Xu, Chengwei Yang, Lu Li, Tinglin Huang, Rulei Huang
Crude oil-contaminated soil has become a major environmental issue and has aroused public attention around the world. Such contaminated soil not only damages soil and aquatic ecosystems (Trellu et al., 2016) but also poses a great threat to human health due to its high toxicity (Elsheshtawy et al., 2014) and carcinogenicity (Tang et al., 2011). Therefore, remediation of crude oil-contaminated soil is a major environmental challenge on a global scale. Currently, biological and chemical oxidation methods are used to remediate contaminated soil, but the biological remediation methods are time consuming and inefficient for remediation of heavily polluted sites (Margesin et al., 2007). In situ chemical oxidation (ISCO) is a simple and flexible soil remediation process that can rapidly restore heavily contaminated soil (Anna and Vi, 2015; Do et al., 2010, 2009; Lim et al., 2016; Mora et al., 2014; Rosas et al., 2014; Xu et al., 2016a, 2016b). This method can also be effectively combined with biological treatment, which is an area of active research (Sutton et al., 2014; J Xu et al., 2011a, 2016a, 2016b). Potassium permanganate, ozone, persulfate and Fenton reagents are oxidants commonly used in ISCO (Li et al., 2014; Oh and Shin, 2014). Fenton oxidation generates hydroxyl radicals (·OH) (Cheng et al., 2016; Martínez et al., 2011) that can effectively remove organic pollutants (Mater et al., 2006; Shi and Spence, 2004). This Fenton process is easy to apply and is therefore promising (Huang et al., 2017), but the short half-life of hydrogen peroxide (H2O2) is a severe limitation for ISCO.
Phase-transfer catalysis enhanced remediation of trichloroethylene polluted groundwater by potassium permanganate
Published in Environmental Technology, 2020
Some remediation techniques for removing TCE in soil and groundwater have been studied in lab-scale tests or pilot. Biodegradation and phytoremediation are in situ natural, solar driven and eco-friendly approaches, but many microorganisms used for bioremediation cannot survive high concentrations of contaminants, and they require more remediation time compared to most chemical remediation [7–9]. The application of pump and treat (P&T) is always difficult to completely remove contaminants and the long-term site management is needed because of rebound and tailing effects [10,11]. Contaminants in low-permeability zones (LPZs) may diffuse back into the transmissive zone after the transmissive regions have been treated and the oxidant has migrated down gradient, a phenomenon known as rebound. Moreover, tailing is due to the fact that the contaminants are still in LPZs while the concentration is lower in transmissive zones [12–14]. In situ chemical oxidation (ISCO) is a relatively mature technique for groundwater remediation. Unlike reductive dechlorination (such as in situ chemical reduction, ISCR), the oxidation of chlorinated solvents has no hazardous intermediate products, such as dichloroethylene and vinyl chloride generated [15]. Fenton reagent, ozone, potassium permanganate and persulfate [16] have been used as oxidizing agents. KMnO4 possesses superiorities of chemical stability, economical property and less toxicity of by-products when applied to contaminated sites, and it is effective over a wide range of pH [17] and in degrading various organic compounds, such as chlorinated solvents [18], chlorophene [19], triclosan [20] and bromophenols [21]. Potassium permanganate showed higher removal rates for some chlorinated solvents compared with Fenton’s agent [22]. The stability and durability of permanganate make it advantageous to the transport in porous media and contact with contaminant [23,24].