Alonda - Alarm-Based Automatic Mobile Sampling Unit
From Drinking Water
Alonda is a mobile sampling unit that can be placed in conjunction with central nodes in the mains and automatically take samples in case of aberrant water quality. Alonda can be activated by any sensor and take water samples at the same time a given sensor detects a value above the threshold.
In the event of an alarm, Alonda automatically takes four different samples, which in each case can contribute with important knowledge about the pollution
A random test: When a threshold value for a sensor connected to Alonda is exceeded, a water test (1 liter) is taken. This test ensures a sample of the water that has triggered the alarm from the sensor for subsequent analysis. If more Alonda is located stratically in the grid, these can be triggered at the same time, and knowledge gained about which parts of the grid are affected by the same contamination.
A time-tested sample: After activation a water sample is collected in small volumes over a period to a total volume of 1 liter. The time-integrated test provides information on whether the contamination is decreasing or increasing over time when compared to the instant test. The period during which the time-integrated sample is collected is optional.
Two membrane filters: Alonda activates two membrane filters, for example, 100 liters of water are filtered over 24 hours (filtration volume and filtering period are optional). One filter can be used to determine the bacterial concentration with very low detection limit. If 100 liters are filtered, the detection limit can reach up to 0.001 bacteria per. 100 ml. With the low detection limit, it is possible to find and follow a contamination that would otherwise not be available with standard methods. This could be useful in particular if Alonda is activated by a sensitive sensor, where the low detection limit can provide an indication of whether the alarm from the sensor is a false positive or a 'early warning' of a contamination.
The second filter can extract DNA from DNA analysis in connection with source tracking.
The prototype prior to Alonda was developed with support from the Water Sector Technology Fund and valuable academic sparring from all participants in the project group: Jørn-Ole Andreasen (Aarhus Water), Tammes Lund Jepsen (Aarhus Water), Jane Bloch Hansen (Aarhus Water), Kim Kusk Mortensen Aarhus University) and Carsten Jensen (Sønderlev Vandværk).