Membrane Distillation of Industrial Wastewater

This paper presents the results of work undertaken to demonstrate the potential for a membrane distillation (MD) process to exploit waste heat from heavy industry to treat saline effluent, producing high quality water for on-site reuse. In partnership with City West Water, GWMWater, the Victorian Smart Water Fund and WQRA the project seeks to examine the viability of MD in an industrial setting by designing a MD pilot plant to operate unattended producing 10 to 20 L/hr of desalinated water over a 3 month period. In attempting to understand the factors affecting successful demonstration of the technology, an examination of potential industrial sites was carried out. Five organisations in Melbourne's west were surveyed for participation in the project which included: a plastic foam producer; a frozen food producer; an electricity generator; a chemical manufacturer; and a plastics manufacturer. Site visits indicated three sites presented a number of possible streams that would benefit from a de-salting process, and possessed some form of waste heat to drive the MD process. Effluent water samples from these sites were tested on a lab scale MD plant simulator to investigate potential membrane fouling and other site specific process issues. The results of the survey revealed that the plastic foam producer's effluent was not sufficiently saline to demonstrate MD's benefits, and the electricity producer's waste heat was not accessible for a short term trial. The plastics manufacturer however, possessed an accessible source of waste heat and a cooling tower blowdown stream that would benefit from a desalination treatment. Plant simulator experiments indicated that an antiscalant additive was necessary for management of membrane fouling and would greatly improve permeate flux over the on-site demonstration phase of the project.