Masters Theses

Dale R. Heron

Date of Award

3-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemical Engineering

Major Professor

J. M. Holmes

Committee Members

Gregory D. Reed, George C. Frazier

Abstract

The treatment of contaminated wastewater from a synthetic-fuel plant using coal as a feedstock represents a significant problem in pollution control. This is especially true for the removal of phenol due to the solubility of phenol in water.

Many different treatment processes are available for wastewater treatment such as biological oxidation, carbon adsorption, and Wet Air Oxidation, (WAG), but, since very few synthetic-fuel facilities have been constructed, it is not clear how these processes will perform with wastewaters from these facilities. The primary objective of this study was to evaluate the viability of one possible treatment system involving the combined processes of a proprietary solvent extraction system called Phenosolvan and Wet Air Oxidation to treat phenolic wastewaters from a synthetic-fuel plant processing 20,000 ton/day of coal. This combination offers the advantages of recovering phenol as a by-product which can be sold or burned and effective treatment for residual concentrations of many different organic contaminates. The secondary objective of this study was to evaluate the effectiveness of the Advance System for Process Engineering, (ASPEN), program in performing a mass and energy balance simulation and preparing a capital cost estimate for the combined treatment process.

The results from this study indicate that the combined process reduced concentrations of phenol in the wastewater stream from 7000 ppm in the aqueous feed stream down to 0.25 ppm in the discharge stream from the system. The removal of phenol provided a Chemical Oxygen Demand, (COD), reduction from 16,300 ppm to 0.72 ppm. The discharge value for phenol, however, is still above the expected pollution standard of 0.13 ppm indicating that additional post-treatment is needed. From the economic evaluation of the process, it was found that a capital investment of $126 MM, (1984), is needed to construct the process. In addition, it was found that using this process to treat wastewater from a 20,000 ton/day of coal synthetic natural gas facility resulted in a $0.28/MMBTU increase in the gas price or a cost of $20.52/MGAL of treated wastewater.

From the study, it was concluded that the combined process could treat phenolic wastewater to a significant degree at a reasonable cost increase to the product of only 3.4%. It was also concluded that ASPEN is a very valuable tool in the evaluation of chemical processes.

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