A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1987

The phenomenon of cadmium transport to the ground water was studied by modelling it as a fixed bed adsorption system. Since, most of the cadmium waste recharge will take place on a low permeable soil such as clay, a "plug-flow" type model incorporating solute transport, mass transfer and sorption was proposed to simulate the spatial and temporal variation of cadmium concentration in the soil matrix. Batch adsorption experiments were conducted to evaluate the model parameters (Freundlich isotherm constants) and to monitor the influence of pH and competing cations on the adsorption of cadmium by a soil media . Column adsorption experiments were conducted in order to validate the proposed mode l. Additionally, the head loss development was monitored in these experiments to check whether a significant head loss develops during the adsorption process. Except at a higher pH conditions, the head loss development was found to be negligible. Due to the constraints imposed by t he lab-scale equipments, the superficial velocity of t he cadmium feed in the column experiments could not be maintained at a very low level as required in the model. Hence experimental data obtained from past technical literature with a very low so lute flux, was used to evaluate the adequateness of the model simulation. This has given fairly reasonable results, indicating that further study on this subject is warranted.