Phosphorus removal with membrane filtration for surface water treatment Available to Purchase

Surface water such as aquifers, recreational waters and rivers are often loaded by inflows with low quality, so that drinking water production, swimming or ground water charging must be restricted. To ensure the long-term use it is necessary to treat the influents or the water used for ground water charging. The current treatment process for phosphorus and turbidity removal is a combination of precipitation/coagulation, flocculation, sedimentation and sand filtration. By using this conventional method it is possible to reduce the dissolved ortho-phosphate and the turbidity (particulate phosphorus) as well as the amounts of algae and pathogenic organisms to very low concentrations. The high degree of reduction in this process is only achieved by a relatively high dosage of coagulants and flocculants. Such a process has been used for nearly 20 years by the Berliner Wasserbetriebe. In this study a comparison will be made between this process, which represents the state-of-the-art, and the combination of precipitation/coagulation with dead-end membrane filtration (micro-/ultrafiltration) concerning water quality and costs. The results show that it is possible to reach similar levels of phosphorus removal as with floc filtration. However, floc filtration requires significantly higher amounts of chemicals (coagulants and flocculants). No flocculants are used for membrane filtration. But the estimated costs for the membrane based process are at 0.17 €/m³ probably a little more expensive. However, the excellent permeate quality is much better at the values of suspended solids and micro-biological organisms.