Use of Granular Regenerable Carbon for Treatment of Secondary Effluent. Engineering Design and Economic Evaluation

摘要

Indicative capital and operating cost estimates have been prepared for plants to treat effluent from activated sludge plants with granular regenerable activated carbon. The treatment objective has been the removal of organic materials but because alkyl benezene sulfonate was considered as representative of the compounds of interest and because data on its adsorption kinetics was found to be adaptable to engineering calculations, the reduction of this compound from 4 to 0.5 ppm was the criteria of design. Realization of this objective will be accompanied by a reduction of other soluble organic contaminants. Resultant effluent is clear, non-foaming and of low color and odor. The capital cost estimates are based on plants in typical locations, with allowances for site development, provisions for services, engineering design, contractors' profit and in accordance with the general quality of construction of municipal sewage works. A process design formula was developed that relates the rate of adsorption to the liquor concentration and to the fractional saturation of the carbon. A technique was developed to apply this rate equation to the calculation of carbon usage per unit of waste water flow at various residence times and concentrations and with various degress of countercurrent flow in the asorber beds. Calculated economics show an unconventional design involving a quasi-countercurrent flow of carbon and waste water to be slightly more favorable than a two-stage countercurrent system. (Author)