TY - JOUR AU - KPT Atta, AU - JP Maree, AU - MS Onyango, AU - L Mpenyana-Monyatsi, AU - M Mujuru , PY - 2020/10/27 Y2 - 2024/03/28 TI - Chemical phosphate removal from Hartbeespoort Dam water, South Africa JF - Water SA JA - WSA VL - 46 IS - 4 October SE - Research paper DO - 10.17159/wsa/2020.v46.i4.9074 UR - https://watersa.net/article/view/9074 SP - AB - <p>Phosphate is one of the major nutrients contributing to the increased eutrophication of lakes and natural waters. The feed water to the Hartbeespoort Dam amounts to 650 ML/d of mainly treated sewage.&nbsp; Phosphate levels in the dam water need to be lowered from the current 0.2 mg/L to less than 0.05 mg/L to control eutrophication.&nbsp; Chemicals such as iron(III), iron(II), aluminium(III) and lime can be used to precipitate phosphate as FePO<sub>4</sub>, Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>, AlPO<sub>4</sub> and Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>, respectively. OLI software was used to identify the most suitable chemical for phosphate removal. It was found to be Ca(OH)<sub>2</sub> as this only requires the pH to be raised to 9.5. FeCl<sub>3</sub>, FeCl<sub>2</sub> and AlCl<sub>3</sub> were found to be unsuitable due to the required pH and/or the extent to which they could remove phosphate. For lowering of phosphate levels from 0.2 mg/L (as P), the current concentration in the Hartbeespoort Dam water, to &lt;0.05 mg/L (as P), the minimum concentration that is needed to support algal growth, a lime dosage of 50 mg/L&nbsp; is required. The cost of lime treatment will amount to 0.15 ZAR/m<sup>3</sup>. It is thus recommended that eutrophication in the Hartbeespoort Dam be controlled by removal of phosphate through lime dosing.</p> ER -