Impact of Surface to Water Volume Contact Ratio on the Biomass Production Potential of Products in Contact with Drinking Water

摘要

The biomass production potential (BPP) test is a semi-static test for assessment of growth promoting properties of construction products in contact with drinking water (CPDW) under defined conditions. The test is performed at the product¿s surface to water volume contact ratio (S/V) of 0.16 cm-1, that is quite different from the practice in buildings and domestic installations.The goal of this study was to evaluate the importance of the S/V ratio for performance of the BPP test and for correct determining the enhancement of microbial growth by CPDW. The BPP of 10 pipe products were compared under the S/V ratios of 0.16 cm-1 and 1.6 cm-1 in two consecutive trials. Our study found out that the BPP test at the originally proposed S/V contact ratio is a reliable approach for assessment of growth promoting properties of CPDW. The data showed that under the S/V ratio of 0.16 cm-1 the test achieves similar results for the BPP of the tested pipe materials as with a more realistic S/V ratio of 1.6 cm-1. However, the S/V ratio showed a significant effect on the planktonic biomass concentration and heterotrophic plate count in the test waters in contact with the tested pipe materials and that stronger effect on the water quality can be important from hygienic point of view. Therefore, the impact of the S/V contact ratio on drinking water quality should be taken into consideration for assessment of the products in contact with drinking water. For acceptance of the CPDW, besides a Pass/Fail Criterion for the BPP, a second criterion for evaluation of materials on their effect of drinking water quality needs to be developed and the planktonic biomass concentration could be useful one for this purpose.