What Is Powdered Activated Carbon & How Is It Used for Water Treatment

PFAS are now detectable in an estimated 45% of US drinking water, and these forever chemicals could create a healthcare burden of between $5.5 billion and $63 billion over Americans' lifetimes.

As contamination from industrial activity and agricultural waste spreads through water sources, utilities face increasing pressure to protect public health and comply with stricter regulations. 

Technologies used for drinking water treatment, wastewater treatment, and PFAS absorption and remediation are helping address these challenges, with sustainable activated carbon among the most widely used solutions. 

This article explains what powdered activated carbon is, how it works, and where it fits into modern water treatment systems.

What Is Powdered Activated Carbon?

The American Society for Testing and Materials (ASTM) defines powdered activated carbon (PAC) as activated carbon with particle sizes predominantly between 80 mesh (0.180 mm) and 500 mesh (0.025 mm). It is highly porous and is produced by thermally or chemically processing organic precursors until they develop an exceptionally large internal surface area. Think of PAC's internal structure like a sponge at a microscopic scale. 

That fine particulate size is what sets it apart from granular activated carbon (GAC) and pelletized forms of the same material.

A single gram can have a surface area exceeding 1,000 square meters, depending on the feedstock and activation method, thereby giving contaminants an enormous number of binding sites even during short contact times.

How PAC Is Made and Where It Comes From

PAC starts as a carbon-rich raw material subjected to either steam activation or chemical activation at high temperatures. 

Steam activation pushes superheated steam through the material, burning away volatile compounds and opening up the porous structure responsible for adsorption. 

Chemical activation takes a different route by using agents such as phosphoric acid before heat treatment to develop porosity at lower temperatures.

Traditional feedstocks include coal, wood, and coconut shell, each producing a slightly different pore distribution. More recently, biomass-based production using agricultural byproducts has emerged as a sustainable alternative, reducing dependence on nonrenewable fossil fuel feedstocks.

Key Physical Properties of PAC

When you're selecting a PAC product for your treatment system, four properties matter most: 

• Particle size

• Surface area

• Pore volume

• Pore size distribution

Finer particles expose more surface area to surrounding water and reduce the distance contaminants must travel to reach an adsorption site. 

Micropores under 2 nm target small organic molecules and some PFAS compounds, while mesopores between 2 and 50 nm handle larger molecules like natural organic matter and disinfection byproducts.

What Is Powdered Activated Carbon Used for in Water Treatment?

Taste and Odor Control

If a local community has ever complained about its tap water smelling like dirt or algae, there’s a good chance geosmin and 2-methylisoborneol (MIB) are the culprits. 

Both are produced by cyanobacteria during seasonal algal blooms and are detectable by humans at concentrations as low as a few nanograms per liter. 

Water treatment plants dose PAC directly into raw water at intake points during bloom events, allowing rapid adsorption before conventional filtration removes the carbon and adsorbed compounds together.

Organic Compounds and Disinfection Byproducts

Agricultural runoff carries herbicides, pesticides, and industrial solvents into surface water, and PAC adsorbs all of them effectively. 

It also targets disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs), which form when chlorine reacts with natural organic matter already in your source water. 

Pre-dosing PAC before primary disinfection reduces the precursor load available for DBP formation, so you're not just treating the problem after the fact.

PFAS Removal

There is strong evidence to suggest that PAC achieved higher short-term reductions of PFOS and PFOA than GAC in batch testing, while a comparative assessment in ACS ES&T Water found that a conventional dose of 10 mg/L eliminated 40% of total PFAS within 10 minutes. 

If your municipality is managing compliance timelines while a longer-term GAC system is being designed or funded, PAC is a realistic first-response option that slots into your existing infrastructure without major capital disruption. 

The EPA recognizes activated carbon adsorption as among the most studied and effective technologies for PFAS removal from drinking water.

Microplastics Removal

Research into activated carbon and microplastics removal is still developing, but early findings are encouraging. 

PAC can adsorb microplastic particles and the hydrophobic organic pollutants coating their surfaces. 

While it isn't yet a standard dedicated treatment for microplastics in most US utilities, its role in coagulation-flocculation-sedimentation processes means it contributes to the physical removal of suspended particles, including microplastics, as part of a broader treatment train.

Wastewater Treatment

Municipal wastewater carries pharmaceuticals, personal care products, and industrial chemicals that biological treatment largely leaves behind. 

Adding PAC to secondary or tertiary treatment stages catches these residuals before discharge or water reuse. 

The Water Research Foundation is actively studying PAC efficacy and infrastructure costs for PFAS removal across different wastewater facility configurations. 

This will help utilities make more informed decisions about where and how to integrate PAC into their systems.

Why PFAS Contamination Is Driving Demand for PAC

The Scale of PFAS Contamination Across US Water Systems

The EPA tested more than 22,500 samples from roughly 3,800 of the country's 154,000 public drinking water systems.

The result? They found detectable PFAS in approximately 22% of those systems, with around 16% exceeding standards finalized in 2024.

Farms across the US have unknowingly spread PFAS-laden sewage sludge onto fields for decades, creating a persistent contamination problem that flows directly into the source waters municipal utilities depend on.

Tightening EPA Regulations and Compliance Deadlines

In April 2024, the United States Environmental Protection Agency (EPA) finalized the first-ever National Primary Drinking Water Regulation for PFAS, setting enforceable maximum contaminant levels for PFOA and PFOS at 4 parts per trillion. 

Public water systems were initially required to reach compliance by April 2029, though the Trump administration has since proposed an opt-in process allowing eligible systems to apply for up to two additional years.

The Harvard Environmental and Energy Law Program (EELP) has noted that PFAS regulatory status remains dynamic. 

That uncertainty makes it even more important to have flexible, deployable treatment options available while your long-term compliance strategy takes shape.

The Rising Cost of Inaction for Municipal Governments

The cost of doing nothing is not abstract. Researchers at New York University (NYU) Grossman School of Medicine estimated that PFAS-attributable disease costs for the US population range from $5.52 billion to $62.6 billion, covering conditions including:

• Childhood obesity

• Kidney cancer

• Thyroid disease

• Infertility and reproductive disorders

On the compliance side, the EPA estimates meeting PFAS drinking water standards will cost public water systems approximately $1.55 billion annually.

The American Water Works Association (AWWA) puts that figure closer to $3.8 billion per year. Total nationwide PFAS cleanup costs are estimated at approximately $400 billion. 

Against those numbers, investing in proven treatment technology isn't optional but the financially responsible path.

How Powdered Activated Carbon Works in Water Treatment

The Adsorption Mechanism

 

The mechanism behind powder-activated carbon water treatment is adsorption: dissolved contaminants bind to the surface of carbon particles rather than being broken down chemically. 

When you add PAC to water, contaminants diffuse through the liquid phase, pass through a thin film surrounding each carbon particle, and travel through the internal pore network until reaching an available binding site.

Nonpolar and weakly polar organic molecules, including many PFAS compounds, are strongly attracted to the nonpolar carbon surface, making adsorption thermodynamically favorable. 

Even a small dose of PAC brings an enormous surface area into contact with your water, meaning millions of binding events occur at once across a single treatment cycle. 

Once adsorption is complete, the PAC particles, now carrying the bound contaminants, are removed from the water stream through conventional clarification or filtration, leaving behind treated water that meets your target quality standards.

Hyera’s PAC Solution for Maximum Adsorption

Our American Engineered Carbon (AEC) PAC is a fine powder with particle sizes under 0.18mm, purpose-built for direct-dose contaminant removal. 

When dosed into your water stream, it exposes contaminants to an enormous number of active adsorption sites simultaneously. 

That binding action pulls them out of solution before they move further through your treatment system. 

More surface area contact in less time means faster removal and more consistent performance across each treatment cycle. 

It's manufactured from 100% renewable biomass using carbon-negative processes rather than coal or coconut shells, so your utility addresses contamination without adding to its environmental footprint.

For municipal governments managing billions in PFAS-related health and compliance costs, that consistency translates into lower dosing rates and less spent carbon to dispose of. 

If your municipality is navigating PFAS compliance, contact us to find out how AEC PAC can support your treatment program.

Factors That Affect PAC Performance in Water Treatment

PAC Type and Source Material

The feedstock and activation conditions determine pore size distribution, which determines which contaminants your carbon captures effectively. 

Wood-based and biomass-based carbons tend to develop more mesopores, making them better suited for larger molecular weight organics. 

On the other hand, coal-based carbons lean toward a micropore structure, which works better for smaller dissolved molecules. 

Hyera's biomass-based PAC is a sustainable alternative to coal and coconut shell sources. 

Its pore structures are tailored to the contaminant profiles municipal water treatment systems face most, including taste and odor compounds, organics, and PFAS.

Dosing Rate and Contact Time

Higher doses improve removal efficiency up to a threshold, beyond which returns diminish quickly. 

Under-dosing leaves contaminants in the water; overdosing increases sludge volumes and disposal costs without proportional benefit. 

For most PAC applications, 10 to 30 minutes of contact time before clarification is a reasonable starting range.

Though your specific contaminant profile, carbon type, and water chemistry will all affect the optimal window. Jar testing remains the most reliable way to establish site-specific parameters.

Competing Contaminants

Your source water is never carrying just one contaminant. Natural organic matter (NOM), present in virtually all surface water, competes with target pollutants for adsorption sites on PAC. 

Higher NOM concentrations reduce the proportion of PAC capacity available for PFAS or other priority compounds. 

Research confirms that dissolved organic concentration is inversely related to PFOS and PFOA removal efficiency when PAC is used. 

If your watershed carries high agricultural runoff, account for elevated NOM loads and plan to adjust dosing seasonally.

Background Organics

Background organics from algal activity, industrial discharge, and decomposing vegetation consume adsorption capacity that would otherwise target your priority contaminants. 

The practical result is that PAC dose requirements are higher in source water with elevated background organic loads than in cleaner water. 

Pilot testing and site-specific isotherm studies give you the data to quantify how much theoretical adsorption capacity will actually be available for your target contaminants under real operating conditions.

PAC vs. GAC in a Water Treatment Plant

Structural Differences Between PAC and GAC

Particle Size

PAC particles fall between 0.180 mm and 0.025 mm, while GAC particles range from approximately 0.2 mm to 5 mm.

The finer the particle, the more surface area is exposed to the surrounding water, and the faster contaminants can reach an adsorption site. This drives most of the operational distinctions between the two forms.

Surface Area

PAC's smaller particle size means contaminants have shorter diffusion distances to reach adsorption sites. This gives it faster kinetics and makes it more responsive when you need results quickly. 

GAC's larger particles require a longer contact time to achieve an equivalent adsorption depth.

Pore Configuration

Pore structure depends on feedstock and activation process rather than physical form alone. 

PAC is often produced from wood and biomass feedstocks that favor mesopore development. Many commercial GAC products are coal-based, leaning toward a microporous structure with pores under 2 nm.

Application Differences in Water Treatment Systems

When to Use PAC

PAC is the right choice when you need rapid contaminant response without the lead time or capital cost of a fixed-bed system. It works particularly well for:

• Algae bloom-driven taste and odor events

• Chemical spills in source water require an immediate response

• Short-term PFAS exceedances while a permanent solution is developed

• Facilities that lack infrastructure for fixed-bed GAC systems

No dedicated filter vessels are required, which keeps upfront costs low. The main trade-off is ongoing chemical cost, since PAC is not reused after a single treatment cycle.

When to Use GAC

GAC is the better fit for continuous, high-volume treatment where long contact time and carbon reusability are priorities. 

Fixed-bed GAC filters run without the batch-dosing complexity of PAC systems, and spent carbon can be thermally reactivated and returned to service. 

For long-chain PFAS removal targets, particularly PFOA and PFOS, fixed-bed GAC with appropriate empty-bed contact times generally achieves higher removal percentages than PAC at conventional dose rates. 

That makes it the foundation of most long-term PFAS compliance programs.

Cleaner Water Starts With the Right Carbon

Decades of agricultural contamination have left municipal water systems managing a PFAS crisis that carries costs in public health, regulatory pressure, and ratepayer burden. 

PAC is one of the most practical tools available for addressing that contamination quickly and within your existing infrastructure. But the carbon you choose matters. 

Hyera produces sustainable, high-performing activated carbon purpose-built for the drinking water treatment and PFAS remediation challenges municipalities face today. 

If your municipality is working through compliance timelines or evaluating treatment options, reach out to Hyera for solutions.

Frequently Asked Questions

What is powdered activated carbon used for in water treatment?

PAC removes taste and odor-causing compounds, synthetic organic chemicals, disinfection byproduct precursors, PFAS, and suspended contaminants including microplastics. 

What is the difference between PAC and granular activated carbon?

PAC particles fall between 0.180 mm and 0.025 mm. GAC has larger particles between 0.2 and 5 mm, runs in continuous fixed-bed filter systems, and can be thermally reactivated and reused after exhaustion.

Can activated charcoal remove microplastics from water?

Emerging research indicates that activated carbon can contribute to microplastics removal through adsorption of associated organic pollutants and physical capture during coagulation and sedimentation processes. Standardized testing protocols for PAC-specific microplastics removal are still under development.

Does the EPA recommend powdered activated carbon for water treatment?

Yes. The EPA recognizes activated carbon adsorption, including PAC, as one of the most studied and effective technologies for removing PFAS and other organic contaminants from drinking water.