P removal from surface water in Belgium at a water production center of De Watergroep
Granulated sorbents from Al
VITO has produced a granulated sorbent from aluminum sludge, which is a by-product from the drinking water treatment process. At De Watergroep, the material was used in a downflow sorption set-up to treat 200 l/h of surface water, with a contact time of 10 minutes. To avoid clogging a back-washing regime was installed. Samples of the raw water going to the filter as well as samples of the filter outlet (taken automatically on a daily basis) were analyzed in the lab for phosphorous concentration.
In the first days of testing, removal yields of > 85% of ortho-phosphate (concentration in untreated water: 1.4 mg PO4-P/l) were obtained (figure above). In the following months, removal yields dropped due to lower phosphate concentrations in the raw water and lower water temperatures. However, the ortho-phosphate concentrations of the treated water were generally kept < 0.2 mg PO4-P/l. Furthermore, it was proven that after a “resting period” (a period without water flow) of a few days, the removal yield of the column increased again.
The sorption column is still running with the original sorbent material, while a second column is filled with new material (figure below).