The use of some microorganisms to remove heavy metals from contaminated industrial wastewaters may represent an innovative purification process. Several aspects must be taken into consideration for complete process development. Standardisation of the experimental procedures, equilibrium and kinetic modelling and related statistical data analysis represent in general the first steps of these studies. Screening experimental tests have to be performed in order to characterise the microbial strains and verify the ability of microorganisms to adsorb heavy metals: protonation and titration tests have been discussed as useful preliminary tests for microorganism selection. The effect of the age of microbial strain, the presence of other ions that must be introduced into the experimental systems to control pH, or initially present in wastewater (i.e. Na and K) has to be investigated in order to optimise the experimental conditions. An original and advantageous experimental procedure useful for equilibrium studies, named subsequent addition method (SAM), has been proposed and tested from the theoretical and experimental point of view. Moreover, the problems of equilibrium data analysis have been considered because an incorrect approach has been highlighted in the statistical regression analysis described in many papers reported in the available literature. For this reason some guidelines have been proposed and discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.