Delivery of Carbon Substrates for in-situ Bioremediation of Chlorinated Solvents using Jet Nebuliser and Ultrasonic Humidifier Technology

A major obstacle facing in-situ bioremediation of chlorinated solvents is the efficient and reliable delivery of carbon substrates to the indigenous microbes in the subsurface. The substrates act as electron donors for the reductive dechlorination of the solvents under anaerobic conditions. A novel solution to this problem is being investigated by atomising the liquid substrate into micron-sized droplets using medical jet nebulisers and an ultrasonic humidifier that may then be transported to the subsurface using sparging gases. Extensive droplet size distribution measurements of atomised carbon substrate, transported through columns of granular soil under both dry and field capacity saturation conditions have been taken using a laser diffraction particle sizer. Droplet size distribution of transported atomised substrate was found to be influenced by both porous medium particle size and degree of saturation. The results demonstrate the transportation of 1-12μm droplets through fine gravel and coarse sand and the consequent effect on the droplet size distribution of the transported substrate.