“…poly-aluminium chloride (PAC) and iron(III)chloride (Pan et al, 2011a;Lürling and Oosterhout, 2013;Waajen et al, 2016a;de Lucena-Silva et al, 2019), organic polymers like chitosan (Pan et al, 2006(Pan et al, , 2011bNoyma et al, 2016Noyma et al, , 2017 and cationic starch (Shi et al, 2016), synthetic organic coagulants like cationic polyacrylamides (Jančula and Maršálek, 2011) and cationic polyamine (Dai et al, 2015), or extracts derived from Moringa oleifera seeds (Oladoja and Pan, 2015;Camacho et al, 2017;de Oliveira Ruiz Moreti et al, 2019). Ballast compounds may be local soils, clay, bauxite, gravel (e.g., Pan et al, 2006Pan et al, , 2011aLi and Pan, 2015;Noyma et al, 2016Noyma et al, , 2017Miranda et al, 2017;de Lucena-Silva et al, 2019), or modified clays and products with P adsorption capacity (e,g., Lürling and Oosterhout, 2013;Noyma et al, 2016Noyma et al, , 2017Waajen et al, 2016a). The latter is a special case of "Floc and Sink" (Noyma et al, 2016) as it is also aimed at removing phosphate from a water column and reducing sediment P release: a "Floc and Lock" approach (Lürling and Oosterhout, 2013), which will be discussed in detail in the next section.…”