Despite twenty years of blue sky and commercial research having been conducted at the University of Aberdeen in microbial biosensor technology; the same fundamental constraints remain. These include: the cumbersome nature of the bioassay, carbon carry over from environmental samples, interference in complex matrices, ambiguous results with mixed contaminants, restricted pH performance range, osmotic stresses, limited sensitivity to hydrocarbons and at times poor replication. The construction of microbial biosensors is often carried out by biotechnologists that lack an appetite for genuine environmental applicability. As a consequence there are few genuine examples of rigorous case studies where appropriate sensors have been applied to genuine scenarios. In reviewing the literature, one of the first objectives was to assess why researchers have failed to make this connectivity and then to assess how this project could address these shortcomings. A complication that has hindered environmental applicability of biosensors has been the use of environmental matrices that requires the adoption of a robust and consistent extraction technique prior to assay exposure. To overcome this issue, this study used genuine wastewater and groundwater and translated laboratory scale findings, through mescosms to the field scale. This enabled a better understanding of factors. Samples were physically and chemically manipulated to enable the biosensor to interrogate bioavailable and potentially bioavailable fractions of contaminants associated with wastewater, groundwater and soil extracts. Complementary chemical analysis validated the results. The biosensor responses correlated closely with the measured chemical values and enabled a detailed assessment of the efficacy of the adopted treatment processes This study has successfully characterised nine biosensors and confirmed the optimisation of their bioassay for testing the response to genuine ground and wastewater samples. Non-exhaustive extraction techniques (NEETs)-biosensor procedures were developed and validated to enhance the ability of biosensors to predict bioremediation, biodegradation and immobilisation of organic and inorganic contaminants. The biosensors complemented routine chemical analysis of contaminants and further responded to the bioavailable fraction of the contaminants. Bacterial biosensors are useful tools for assessing the bioavailable fraction, prediction of biodegradation and providing information on the constraints to biodegradation. If the samples are manipulated then the biosensors can be applied to complex matrices and provide information on environmental hazard assessments. The transfer of the use of the biosensors from laboratory study to genuine field studies was achieved in this study.