A Portable Sensor With Disposable Electrodes for Water Bacterial Quality Assessment

Bacterial screening is very important in water environmental monitoring, because the presence of dangerous pathogens can seriously endanger human health. Microbial concentration detection is performed by standard plate count technique, which is reliable but is characterized by long response time and is not suitable to be implemented in automatic form. Based on impedance measurements, this paper presents a portable sensor implemented as an electronic embedded system featuring disposable measurement cells, which is suitable of measuring bacterial concentration in water samples. The system provides a much faster response than standard technique (3-12 h depending on the contamination level versus 24-72 h of the standard technique) and can be used for an in situ microbial test rather than taking samples to a laboratory for analysis. Water samples from different sources (such as rivers, wastewaters, watercourses) are tested using the presented system. Enriched medium is added to the sample to favor bacterial growth. Three different media are tested (Lauria Bertani, Mc Conkey Broth, and Lactose Broth) and data are compared with microbial growth rate and selectivity toward bacterial group (e.g., coliforms). The obtained experimental data show good correlation with the plate count technique.