| Funding: | BMWi (Lufo IV), Airbus |
| Duration: | 01.08.2012 - 31.01.2015 |
project management / project work: | Dr. B. Bendinger / Dr. A. Höckendorf |
Situation: | In this project decalcification procedures with organic acids and their impact on water quality are investigated in a mobile drinking water facility. In mobile drinking water facilities, e.g. on board of aircrafts, fuelling of water with different scaling potentials and heating of the water in the kitchen may lead to partially strong scale deposits. This causes constrictions in water distribution, breakdown of devices for hot water production, and finally an off time of the transport vehicle, when the whole facility has to be decalcified. Conventionally, for decalcification of the potable water system organic acids like acetic acid or citric acid are used. Thereby, the risk of microbial growth arises because bacteria are able to utilize not completely rinsed acid as a food source and consequently their growth is promoted. |
| Methodology: | For comparable conditions in the decalcification experiments a special facility had been built. Herein pipes can be calcified under defined conditions resulting in reproducible solid calcite deposits in stainless steel tubes. In a true-to-original mobile drinking water facility these calcified pipes are decalcified with acids in various concentrations and subsequently rinsed with potable water. Afterwards, the facility is operated with a flow-stagnation-program and the water phase is examined under operation conditions in the following weeks. Diverse chemical and microbiological parameters are analyzed including total and dissolved organic carbon (TOC and DOC), calcium carbonate precipitation potential (Dc), total cell count, and colony counts at 20 °C and 36 °C according to the german drinking water directive 1990. The aim of this study is to find an optimized decalcification procedure which provides a more efficient decalcification performance without microbial regrowth after restart of operation. The existing decalcification instruction will be critically examined and evaluated and in addition recommendations for decalcification will be developed.
Figure 1: (A) Calcified pipes, such as those used for decalcification, (B) pipes after decalcification |
| Outcomes: | The results of this study impact the existing decalcification procedure in the sort and concentration of the applied acid as well as in the quantity and intensity of the rinsing steps with drinking water following the acid treatment. Based on these findings a new decalcification instruction for mobile drinking water systems may be defined. |
