China
Africa
Explore chapters and articles related to this topic
Advanced Oxidation Process for Leachate Treatment: A Critical Review
Published in Maulin P. Shah, Sweta Parimita Bera, Günay Yıldız Töre, Advanced Oxidation Processes for Wastewater Treatment, 2022
Shilpa Mishra, Baranidharan Sundaram, S Muthukumar
Chen et al. (2019) found that the combination of AOPs with coagulation decreases the concentration of various organic compounds. It also improves wastewater biodegradability. Fenton with adsorption, photocatalysis with adsorption and US with adsorption were studied (Bell and Raman 2019). According to this study, some AOPs cannot degrade complex organic compounds completely. Some intermediate compounds may form, which may be more toxic than their parent compound. Therefore, the integration of AOP with adsorption helps mineralize these compounds into CO2, H2O and inorganic compounds. Various AOPs for landfill leachate treatment were reviewed in Pratibha Gautam et al. (2019). Figure 14.3 shows the percentage reduction in COD in leachate from HW landfill using different AOPs reviewed in this chapter. The maximum percentage reduction in COD is achieved by using electrochemical oxidation when compared with other AOPs.
Biodegradation kinetics of dichlorvos and chlorpyrifos by enriched bacterial cultures from an agricultural soil
Published in Bioremediation Journal, 2019
Omkar Gaonkar, Indumathi M. Nambi, Govindarajan Suresh Kumar
In this study, 3,5,6-trichloropyridinol (TCP) was found to be one of the intermediates detected in the early stage of degradation indicating that chlorpyrifos was hydrolyzed to form TCP with the removal of diethylthiophosphoric acid (DETP). The intermediate, TCP has a pyridinol ring with three chlorine atoms attached to it similar to the parent compound, chlorpyrifos. TCP is more water soluble than its parent molecule. The enriched culture was found to utilize TCP in addition to chlorpyrifos as a carbon and/or nitrogen source. A similar observation was made in the previous studies by (Jabeen, Iqbal, and Anwar 2015; Abraham, Shanker, and Silambarasan 2013). On the contrary, a study by Li et al. (2010) showed that TCP had antimicrobial property with a negative effect on chlorpyrifos degrading microbes but this was not observed in our study. TCP can undergo further ring cleavage by reductive dichlorination (Feng, Minard, and Bollag 1998). A study conducted by Gilani et al. (2016) has reported that mpd and opd genes present on chromosomes and plasmids are main genes for chlorpyrifos biodegradation. Further, they reported that organophosphorus hydrolase was the major enzyme which can hydrolyze chlorpyrifos. Few other metabolites obtained in this study were: 1-petanol-4-amino, 2-heptanol-6-amino-2-methyl and N-ethyl formamide (Table S3 Supplementary Information). Earlier, oxidation of chlorpyrifos metabolites has shown to result in the formation of inorganic phosphate, aliphatic amines, and carbon fragments, etc.(Singh and Walker 2006).
Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update
Published in Journal of Toxicology and Environmental Health, Part B, 2019
M.I. Banton, J.S. Bus, J.J. Collins, E. Delzell, H.-P. Gelbke, J.E. Kester, M.M. Moore, R. Waites, S.S. Sarang
It is not clear whether styrene, SO, some other styrene metabolite or some combination thereof is responsible for damaging the cochlea. Implication of a metabolite is suggested by the observation that co-exposure with ethanol (4 g/kg bw), an inducer of CYP2E1, both enhanced styrene metabolism and markedly potentiated its ototoxicity in rats (Loquet et al. 2000). This result is in striking contrast to that obtained in a similar experimental design with toluene, which is not capable of forming alkene-epoxide metabolites (Campo et al. 1998). Rats pretreated with the enzyme inducer phenobarbital exhibited enhanced metabolism of toluene and protection from ototoxicity, indicating that the parent compound is responsible for this effect (Pryor et al. 1991). Ethanol, a known competitive inhibitor of toluene metabolism (Sato, Nakajima, and Koyama 1981), slightly increased the ototoxicity of co-administered toluene, presumably due to the increase in circulating parent compound (Campo et al. 1998). Further support for a styrene metabolite’s role in cochlear damage is suggested by a study that found older rats (25–27 months of age) with presumed lower styrene metabolic capacity, were less sensitive to OHC loss and hearing threshold shift than young (3-month-old) rats exposed to 700 ppm for four consecutive weeks, with no evidence of recovery six weeks post-exposure (Campo et al. 2003). The older rats had heavier body weights (500 gm versus 300 gm for young rats) which could have impacted the findings of this study.
Micellar catalyzed hydrolysis of mono-2,3-dichloroaniline phosphate
Published in Journal of Dispersion Science and Technology, 2018
Nisha Chhetri, S. A. Bhoite, A. K. Singh
Mono-2,3-dichloroaniline phosphate was synthesized by the known method described in literature[18] by the reaction of parent compound (2,3-dichloroaniline) with phosphorylating agent phosphorus pentaoxide (P2O5) in 1:1 mole ratio. The parent compound was dissolved in benzene and stirred well for half an hour. Then, the phosphorous pentaoxide was added bit by bit during stirring. The whole reaction mixture was stirred for 12 hours at room temperature. After that, 100 ml of distilled water was introduced into the flask and shaken well. Two layers were separated. The benzene layer was rejected. To the aqueous layer, few drops of phenolphthalein were added. Then freshly prepared saturated solution of barium hydroxide was added drop by drop till pink color appeared. A white precipitate was obtained which was filtered and washed several times with distilled water having few drops of acetic acid to remove the inorganic phosphate. It was then dried to obtain Ba salt of mono-2,3-dichloroaniline phosphate.