Evaluation of a Vapor Compression Distillation Unit for Laundry Wastewater Reuse.

摘要

A nominal 6 gallon per hour vapor compression distillation unit (VCDU) fabricated by Chemtric, Inc. of Rosemont, Illinois, was evaluated. The unit was designed to distill wastewater using less than 300 watt-hours of energy per gallon of recovered water. The object of the evaluation was to measure product water quality and energy use rates, and to monitor operation and maintenance over an extended run period. Operational time of 432 hours was accumulated on the VCDU over a 16-week period using laundry wastewater as the feed. Compared to tap water, product water quality from the laundry wastewater feed was lower in turbidity, total solids, and conductivity, but higher in total organic carbon and chemical oxygen demand. Energy use was very dependent on the operation of the storage tank heater. If all make up heat could be supplied solely by vapor compression, energy use was minimum. If it was necessary to add the storage tank heater, energy use was maximum. Actual operation used the storage tank heater part of the time and energy use averaged 655 watt-hours per gallon of water produced. Energy use rates for the VCDU were high because of intermittent operation of the unit, lack of adequate operator controls, and maintenance problems. Maintenance problems proved to be a source of considerable difficulty. Operation of the VCDU was terminated when foam from the concentrated wastewater began to carry-over into the product water.