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Remediation of PFAS-Contaminated Soil
Published in David M. Kempisty, Yun Xing, LeeAnn Racz, Perfluoroalkyl Substances in the Environment, 2018
Konstantin Volchek, Yuan Yao, Carl E. Brown
Aly (2016) investigated the sorption of six PFAS onto Ottawa sand in the presence of four cationic coagulants: polyaluminum chloride, polyamine, polydiallyldimethyl ammonium chloride (polyDADMAC), and a tannin-based cationic polymer. These coagulants reportedly enhanced the sorption of PFAS onto the sand, with polyDADMAC performing the most effectively. Aly suggested that the addition of cationic coagulants may facilitate the remediation of groundwater. One can further speculate that this method might be useful for soil remediation to immobilize PFAS within the soil matrix. It is, however, an open question whether coagulation-enhanced sorption can be adopted for site remediation. Further studies are required to answer this question.
Application of response surface methodology (RSM) for optimizing coagulation process of paper recycling wastewater using Ocimum basilicum
Published in Environmental Technology, 2020
Mohammad Reza Mosaddeghi, Farshid Pajoum Shariati, Seyed Ali Vaziri Yazdi, Gholamreza Nabi Bidhendi
Inorganic chemicals, such as alum, iron-based salts, polyaluminium chloride (PAC), polyacrylamides (PAMs), and polydiallydimethylammonium chloride (polyDADMAC) have been previously used for the coagulation process of the wastewater treatment [8,15]. However, excessive use of these materials leads to high cost, health hazards, and the high volume of sludge [16,17]. Considering the complications associated with the chemical coagulants, the use of natural coagulants and their derivatives have recently been increased [18]. As natural coagulants, plant-based polymeric coagulants have properties such as non-toxicity, high biodegradability, and low volume sludge [19,20]. In addition, the plants generating these coagulants can be cultivated in the developing countries, which are more economical than chemical coagulants. The use of such natural products together with inorganic coagulants seems possible in the future [21,22].
Aqueous N-nitrosamines: Precursors, occurrence, oxidation processes, and role of inorganic ions
Published in Critical Reviews in Environmental Science and Technology, 2021
Tahereh Jasemizad, Peizhe Sun, Lokesh P. Padhye
It was found that chloramination of polymers containing tertiary amines, with DMA moiety, could form a significant amount of NDMA while chloramination of polymers containing quaternary amine functional group did not yield much NDMA (Mitch & Sedlak, 2004). A higher NDMA formation potential was observed for the low molecular weight polymers than the high molecular weight polymers by Park, Wei, et al. (2009). Moreover, polyDADMAC’s and polyamine’s use in a full-scale drinking water plant, practising preoxidation with chloramines, was found to yield NDMA at 6 ng/L and 14 ng/L, respectively (Krasner et al., 2018). Therefore, it is important to identify strategies to reduce nitrosamines’ formation from polymers on which water utilities rely to meet current regulatory standards. Although pretreatments with ozone, chlorine, or ultraviolet (UV) and activated carbon were effective for the removal of wastewater-derived NDMA precursors, they achieved inefficient removal for polymer-derived precursors (Zeng, Li, et al., 2016; Padhye et al., 2011). To inhibit the formation of nitrosamines from two commonly used polymers, polyDADMAC and epichlorohydrin-dimethylamine (Epi-DMA), Zeng, Li, et al. (2016) modified the structures of the polymers by two strategies: (1) using methyl iodide (MeI) to convert polymer-bound tertiary amine groups to less chloramine-reactive quaternary ammonium groups (∼75% reduction in NDMA formation), and (2) synthesis of polymers with dipropylamino substituents resulting in less chloramine-reactive quaternary ammonium groups (no NDMA formation but instead resulting in the formation of NDPA, with a 20-fold lower yield). Hence, high molecular weight polymers with quaternary ammonium groups are better suited to reduce the risk of NDMA formation in water treatment plants.
State-of-the-art of membrane flux enhancement in membrane bioreactor
Published in Cogent Engineering, 2018
O. Kulesha, Z. Maletskyi, H. Ratnaweera
The superior role of the neutralization mechanism in flocculation employing PolyDADMAC was discussed in the studies by Hahn, Hoffmann, and Ødegaard (1996) and Zahrim and Dexter (2016). Meanwhile, as discussed in the latter work, flocculation occurs through the bridging mechanism as well.