Cost of Purifying Municipal Waste Waters by Distillation

摘要

Desk top studies of the cost of distillation of waste water are made with the types of equipment proposed for use with sea water. The estimates are based upon those for sea water, but are modified to conform with the differences in composition of sea water and waste water, and differences in the modes of operation for the two feeds. The smaller concentration of scaling materials in waste water should allow distillation to be carried out at a higher temperature than can be used with sea water. The smaller total contaminant concentration results in a smaller boiling-point elevation. Because of the need to dispose of the blowdown permanently it is necessary to concentrate to a far greater extent than in the case of sea-water distillation. Three types of equipment: Multi-stage flash, multiple-effect, and recompression-flash, appear economically promising. For all types of equipment the cost for the distillation step alone is somewhat less than for sea water, but inclusion of costs for feed pretreatment and ultimate disposal of blowdown, bring the cost up to about that for sea water. (Author)