Biofilm growth in response to various concentrations of biodegradable material in drinking water

Biological stability is one of the most important aspects of safe drinking water. It depends crucially on the availability of biodegradable organic carbon (BDOC). Measurement of BDOC is time-consuming and only performed if an increase is suspected. In this study, a fibre optical sensor (FOS) was used to detect changes in BDOC, detected as an increase in biofilm growth. The FOS consists of a sending and a receiving optical fibre, the latter connected to a detector. When material is deposited at the tip of the fibre, an increase of backscattered light is detected. In a system fed with drinking water, the signal was correlated to biofilm growth which was confirmed by independent surface colonisation determination. When 1 and 3mgL(-1) of BDOC respectively was added, the increment of the FOS signal over a period of 1 week could be distinguished. Interference by planktonic components and humic substances could be excluded. The biofilm on the FOS could be used as a means to detect changes in BDOC in drinking water and the signal has an early warning capacity.