Implementation research of new phosphorus free antiscalant at an aerobic ground water RO plant

摘要

Antiscalants are used to prevent scaling in the membrane filtration processes NF and reverse osmosis (RO). Current generation antiscalants are stable in the process equipment and slowly biodegradable in the receiving surface water. These types of antiscalants are optimized with respect to biological inertness in process equipment and biodegradable in a limited time frame in the receiving surface water. However, the phosphorus from these antiscalants can cause undesirable eutrophication in the receiving surface water and this will result in restrictions for concentrate disposal. A solution to this problem is the use of stable antiscalants without phosphorus groups. 4 Aqua BD25 is a phosphorous free carboxy methyl inulin based antiscalant that is first applied at a drinking water RO in Dinxperlo, the Netherlands. Before the application in practice, biofouling tests with membrane fouling simulator's had shown that biofouling was not aggravated by BD25. After those preliminary tests BD25 was dosed to one of the four stacks of the RO treatment and meanwhile the mass transfer coefficient (MTC) in the stack was checked with a Scale Guard on the concentrate. Beside that the MTC and normalized pressure difference of each stage of the stack was monitored and checked. The stable MTC shows that no scaling has occurred. After a half year of tests is decided to apply 4 Aqua BD25 at all stacks of the RO plant. 4 Aqua BD 25 is drinking water approved by Kiwa assessment on toxicological aspects and NSF standard 60. Right now a phosphorus and assimilable organic carbon free antiscalant is available for application.