TABLE OF CONTENTS Granular activated carbon (GAC) treatment has been used successfully for decades in the treatment of wastewater, hazardous waste streams, and drinking water. GAC treatment is used primarily for the removal of organic compounds. To a limited extent, GAC is used for the removal of some metals and other inorganic compounds. GAC treatment is generally used when biological treatment alone is not sufficient or when the wastes are refractory and/or toxic. Many pesticides, for example, are not biodegradable and their waste products require carbon treatment as the best alternative. GAC is also used to assist in reducing whole effluent toxicity, especially for complex wastestreams where it is difficult to identify the precise pollutant(s) responsible for test species mortality.
A process flow schematic for a typical GAC system is shown in Figure 6.1. A raw water feed pump conveys wastewater to the GAC reactors in a either a sequential or parallel flow pattern. In sequential flow, the wastewater enters the top of Column 1, flows through the column to the top of Column 2, and sequentially through the entire train. In parallel flow, the wastewater is simultaneously pumped to the tops of Columns 1 4.
As wastewater passes through the column, soluble and insoluble wastewater contaminants are attracted to the carbon particles due to differences in electrochemical charges between the carbon and the contaminants. These contaminants are adsorbed onto the surface of the carbon particle, forming a very...
