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.