6.2.5 Coagulation-flocculation
Coagulation flocculation, one of the conventional ways used for treating
wastewater, destabilizes the colloidal particles and then aggregates
them to form clumps, making them easier to remove (Teh et al., 2016).
Huerta-Fontela et al. (2011) reported using aluminium sulfate
[Al2(SO4)3], a
coagulant, along with sand filtration removed medicated compounds like
warfarin, betaxolol, and hydrochlorothiazide by 80%. This method has
also shown to be potent in eliminating some hydrophobic pharmaceuticals
like doxazosin and chlordiazepoxide but its efficiency drops to less
than 5% for compounds like estrone and estradiol (Bundy et al., 2007;
Le-Minh et al., 2010). It also demonstrated to remove musky compounds,
commonly found in skincare products and cosmetics. Suarez et al. (2009)
reported this process could achieve removal rates of 78%, 79%, and
83% for tonalide, galaxolide, and celestolide, respectively, in
hospital wastewater. Nyström et al. (2020) demonstrated the
effectiveness of this process in treating stormwater, it was effective
in lowering oil, polycyclic aromatic hydrocarbons (PAHs) and total
metals (90% reduction). Coagulation-flocculation is an efficient
technique for removing a variety of ECs from water and therefore is
widely applied attributing to its simplicity and ease.