Explore chapters and articles related to this topic
Soil Washing Treatability Studies
Published in Donald F. Lowe, Karen L. Duston, Carroll L. Oubre, C. Herb Ward, Douglas A. Hlousek, Thomas A. Phillips, of Firing Range Impact Berms, 2016
Donald F. Lowe, Karen L. Duston, Carroll L. Oubre, C. Herb Ward, Douglas A. Hlousek, Thomas A. Phillips
Vat and agitation leach processes use oxidation-reduction and acid-base reactions to dissolve lead soil contamination into aqueous solutions. The major lead contaminants in the soil are lead metal (Pb) and lead oxide (PbO). Acceptable lixiviants that have been used to dissolve the lead compounds are nitric acid (HNO3), hydrochloric acid (HCl), acetic acid (CH3COOH), and citric acid [COOHCH2COHCOOHCH2COOH or (CH2)2COH(COOH)3]. Dilute acidic solutions of nitric acid can also act as an oxidizing agent for lead metal probably forming nitric oxide gas [NO(g)]; however, this oxidizing reaction could be quite slow. Other oxidizing agents that have been used are hydrogen peroxide (H2O2) and calcium peroxide (CaO2). The main chemical reactions and their stoichiometry that dissolve the lead metal and lead oxide are as follows:
Influence of calcium compounds as a compression framework on activated sludge dewaterability and calorific value
Published in Environmental Technology, 2018
Yang Yu, Huangzhao Wei, Yonghui Yu, Li Yu, Sen Wang, Chenglin Sun
Li [18] studied the influence of additives (CaCl2, AlCl3 and FeCl3) on activated sludge flocculation mechanism. It was found that the binding ability of Ca2+ was different from Al3+ and Fe3+. Yu [19] reported the role of temperature and CaCl2 in activated sludge dewatering under hydrothermal treatment. It was found that an increase in temperature and dosage of CaCl2 till 60 mg/g dry sludge (DS) allowed a continuous improvement of dewaterability. Chen [20] studied the enhancement of activated sludge dewaterability using calcium peroxide pre-oxidation, and sludge filtration performance was enhanced by calcium peroxide oxidation. Calcium compounds contain several anions and we need to know which calcium compound is the best additive to decrease the cost. However, the effect of different calcium compounds on activated sludge dewatering by compressed filtration has not been investigated. Furthermore, most of the previous studies have investigated the dewaterability of high-moisture-content sludge (above 95%), and a few studies [21,22] have focused on the dewaterability of sludge, from 80% to 60% moisture content.
In situ sodium persulfate/calcium peroxide oxidation in remediation of TPH-contaminated soil in 3D-sand box
Published in Environmental Technology, 2018
Hao Wu, Lina Sun, Hui Wang, Xiaoxu Wang
As seen from Figure 16, the addition of calcium peroxide did not increase the pH of the surface layer soil. Changes of pH in the upper layer were relatively small. For instance, for probe P7 30 days after the reaction, soil pH values decreased from 7.1 to 6.8, representing only a reduction of 0.3. For Probe P8 14 days after the reaction, pH values were slightly elevated to 7.5, and 30 days after the reaction, the soil pH decreased to 7.1. This may be due to the uneven mixing of soil and calcium peroxide. In practical applications, plans should be taken to ensure the most effective mixing possible of the reagent and the soil, so as not to affect the treatment process and avoid waste of the oxidant.
Persulfate activated with calcium peroxide to remediate RAFT soil contaminated with diesel in Arctic northern villages: on-site pilot scale study
Published in Environmental Technology, 2023
Taillard Vincent, Martel Richard, Pasquier Louis-César, Blais Jean-François, Mercier Guy
Sodium Persulphate (> 99%) was manufactured by PeroxyChem (Philadelphia, MA, USA) and bought from Chemco Inc. (Québec, QC, Canada). Calcium peroxide > 75% (< 25% Calcium hydroxide) was bought from Chemco Inc. ACS methylene chloride (99.9%) and ACS hexane (95%) were provided by Fisher Chemical. Diesel was provided by FCNQ and was sampled from the main vessel tank (lot MTL-18-9351) in charge of refuelling Nunavik’s northern villages in September 2018.