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Advanced Risk-Based Biodegradation Study Using Environmental Information System and the Holistic Macroengineering Approach
Published in Donald L. Wise, Debra J. Trantolo, Edward J. Cichon, Hilary I. Inyang, Ulrich Stottmeister, Remediation Engineering of Contaminated Soils, 2000
Stergios Dendrou, Basile Dendrou, Mehmet Tumay
Abiotic reactions are typically not complete and often result in the formation of intermediate by-products that may be at least as toxic as the original contaminant. The most common reactions are hydrolysis (a substitution reaction) and dehydrohalogenation (an elimination reaction). Other possible reactions include oxidation and reduction. However, no abiotic oxidation reactions involving typical halogenated solvents have been reported. Also, reduction reactions (which include hydrogenolysis and dihaloelimination) are commonly mediated microbially, although some abiotic reduction reactions have been observed. In general, attributing changes in either the presence or absence of halogenated solvents or the concentrations of halogenated solvents to abiotic processes is usually difficult. Often, chlorinated solvents may be undergoing both biotic and abiotic degradation, and discerning the relative contribution of each mechanism on the field scale is very difficult, if possible at all. As another example, to substantiate that hydrolysis is occurring, the presence of nonhalogenated breakdown products such as acids and alcohols should be established. In general, these products are more easily biodegraded than their parent compounds and can be difficult to detect.
Elimination Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
When a highly ionizing medium such as water is present and substitution is slow, elimination can occur via a carbocation intermediate. Typically, E2 reactions are faster in protic solvents, but a first-order elimination reaction, termed E1, can occur under certain conditions. When 2-bromo-2-methylpropane reacts with KOH in dry ethanol, is carbocation formation possible?
Chemical Destruction
Published in Domenic Grasso, Hazardous Waste Site Remediation, 2017
E1 is the elimination mechanism that involves one molecule in the rate determining step. E2 is the elimination mechanism that involves two molecules in the rate determining step. These mechanisms are relatively similar to their nucleophilic substitution counterparts SN1 and SN2.
Combined process of chemically enhanced sedimentation and rapid filtration for urban wastewater treatment for potable reuse
Published in Environmental Technology, 2022
Cleber Pinto da Silva, Sandro Xavier de Campos
In general, for most of the available post-treatment technologies, the final effluent may still contain pathogenic microorganisms, requiring disinfection depending on its reuse [17]. Chlorine is widely used for this purpose [26], being commercially available as aqueous sodium hypochlorite or solid calcium hypochlorite [27]. The rate of elimination depends on treatment conditions such as temperature, pH and organic matter content [28]. Chlorine disinfection processes for urban effluents are widespread around the world, being used in conjunction with several direct or indirect reuse technologies (i.e. activated sludge; anaerobic reactors; oxidation ponds) used in sewage treatment plants in the city of Uttarakhand - India, the effluent being released in the Ganges river or used for agricultural irrigation purposes [29].