[lemma=□]
[lemma=divalent]
CFBW settled water quality could be achieved through the addition of the divalent cations , thereby adjusting the monovalent to divalent ( M :D ) ratios of the wastewater . Na super ( + ) , K super ( + ) ) and added divalent cations ( i.e. Ca super ( 2 + ) , Mg super ( 2 + ) ) aided in the settling mechanism through charge neutralisation - precipitation . The increase in divalent cation concentrations within the waste residual stream promoted destabilisation of the negatively charged colour molecules within the CFBW , thereby causing the colloidal content to become more hydrophobic . VERSENE 100 chelating agent is recommended for the control of hardness ions above a pH of 6.0 ; most divalent heavy metal ions throughout the pH range ; and ferric ions to below a pH of 8.0 .