Activated carbon options

Because industrial wastewater operators face regulations and many contaminants in their work, making treatment and compliance challenging, activated carbon has been an effective treatment option for years and can be used to remove contaminants from wastewater streams.

Challenges

Industrial wastewater treatment operations constantly contend with new regulations, while current regulations become more stringent. Meeting the requirements of these regulations and doing so in a way that is both cost-effective and accommodating to a facility’s operations can prove challenging. Planning for future regulations, which potentially impact the current design and operational needs of facilities in the industry, must also be included.

Many guidelines in the regulations mentioned above focus on the proper removal of organic matter such as FOG, BOD, PPCP, EDC and DBPs. Under the Clean Water Act, the U.S. Environmental Protection Agency (EPA) established the National Pollutant Discharge Elimination System permitting program as way to control the discharge of wastewater to surface water supplies and prevent the discharge of toxic materials to waterways. As wastewater quality parameters changed from chemical-specific to include toxicity-based limits, more time and effort are required to study and test solutions.

To address these challenges and regulations, operators must rely on the combination of experience from engineering firms and equipment suppliers that are familiar with pollutants and contaminants. This ensures the completion of the proper research and testing needed to select the right treatment solution.

Operators are also encouraged to review the EPA’s “Best Available Treatment” document, which summarizes the available treatment options and maximum containment level goals for regulated contaminants.

Glossary of terms

BOD – biological oxygen demand

DBPs – disinfection byproducts

EDC – endocrine disrupting compounds

FOG – fats, oils and grease

GAC – granular activated carbon

NPDES – National Pollutant Discharge Elimination System

PAC – powdered activated carbon

PPCP – pharmaceutical personal care products

UV – ultraviolet

A treatment solution

PAC and GAC remove organic chemicals and reduce toxicity in some wastewaters to allow for safe discharge into surface water and are a widely accepted technology for treating and removing organics, free chlorine, color and many other impurities. For some industrial wastewaters, secondary treatment following activated carbon may be required.

Powdered activated carbon

PAC is defined by the American Society for Testing Materials as particles passing through an 80-mesh sieve (0.177 millimeter) and smaller. By varying manufacturing conditions, internal pore structures are created by imparting unique adsorption properties specific to each product. The choice for a specific application varies because of differing impurities and proprietary process conditions. PAC can also be used as an as-required treatment objective to accommodate batch processes or seasonal issues.

PAC is typically dosed directly into the stream or holding tank to remove contaminants and is subsequently filtered from the stream. PAC requires a filtration system, either a clarifier, filter press or rotary vacuum filter, and it cannot be reactivated. It is often disposed by the generator in a landfill or an incinerator. The removal of contaminants to low treatment objectives requires a high dosage of PAC, which makes it less economical than GAC from a carbon-use perspective.

Granular activated carbon

The porous nature and large surface area of GAC make it specifically ideal for physical adsorption and other treatment techniques. GAC has the capacity to remove a broad range of organics and can improve water quality for discharge or reuse. It can be reused through reactivation, which is an attractive option for facilities that want to improve their sustainability. GAC can be produced using different materials, methods and degrees of activation to produce activated carbons designed to meet and exceed the demands of a many applications.

While GAC can often be more economical for lower treatment objectives, it can be reactivated (recycled), reducing potential disposal costs and long-term liability costs affiliated with landfill disposal.

The EPA and most state-based health departments consider adsorption by GAC to be an instrumental technology for the removal of many organic materials in surface water. On its own, or paired with an ultraviolet (UV) disinfection system, GAC can facilitate the removal of:

DBPs associated with chlorine and alternative disinfectants
EDC
PPCP
Taste and odor-causing compounds
Organic materials from decaying plants and other naturally occurring matter that serve as the precursors for DBPs

The future of industrial wastewater

Wastewater treatment is a vital component of any industrial process because it ensures that water meets the discharge criteria and/or meets the process requirements for the water to be reused at a facility. As water reuse becomes increasingly important from a sustainability position, activated carbon will become a central component of the water treatment train because of its versatility. For some industrial wastewaters, additional treatment efforts, such as UV disinfection, reverse osmosis or ultrafiltration, may be required for reuse and for release to surface waters.

John Matthis is an applications engineer with the Industrial and Food Business Unit (IFBU) at Calgon Carbon Corporation. In this position, He is involved in design, troubleshooting and product recommendations for industrial process and activated carbon applications, which include wastewater treatment. Matthis may be reached at [email protected].