Alkaline Carbon

Powder Activated Carbon for Water Treatment | Technical Specifications

Water is fundamental to life, and in a densely populated, technologically advanced world, ensuring safe and clean drinking water is a top priority. Municipal water treatment plants across the world rely on a range of sophisticated technologies to maintain high standards of water purity, safety, and taste. Among these technologies, one traditional yet highly effective method stands out—powder activated carbon (PAC), particularly wood-based PAC.

This blog explores the science, application, and benefits of wood-based powder activated carbon in municipal water treatment plants, offering insights into why Japan has embraced this material and how it continues to evolve as a solution in modern water purification.

Why Use Powder Activated Carbon (PAC) for Water Treatment


Powder Activated Carbon (PAC) is a fine, porous form of carbon with a large surface area that allows it to adsorb a wide range of organic and inorganic contaminants. The adsorption process is physical (Steam) and chemical, targeting impurities such as:

Dissolved organic matter (DOM)

Chlorine by-products (THMs, HAAs)

Odors and tastes

Pesticides and herbicides

Pharmaceuticals and micro-pollutants

Algae and algal toxins (e.g., geosmin and MIB)

Why Wood-Based Powder Activated Carbon (PAC)?

Activated carbon can be derived from various raw materials like coal, coconut shells, peat, and wood. Among these, wood-based PAC offers several advantages:

  • High porosity and large internal surface area
  • Fast adsorption kinetics (especially for large molecular compounds)
  • Lower ash content and better biodegradability

Water Treatment Challenges and the Role of Wood-Based PAC

Water sources—rivers, lakes, reservoirs, and underground aquifers—are prone to specific contamination due to:

  • Seasonal algal blooms, particularly in summer
  • Industrial and agricultural runoff
  • Natural organic matter, contributing to odor and color
  • Urban pollution

Municipal plants must therefore treat water not just for biological safety (disinfection) but also for aesthetic quality—taste, odor, and clarity

1. Control of Taste and Odor (T&O) Issues

Odor-causing compounds like geosmin and 2-methylisoborneol (MIB), produced by cyanobacteria and actinomycetes, are major problems in surface water during warmer months.

Wood-based PAC, offers ideal porosity particularly effective in removing these compounds.

2. Removal of Organic Micro-Pollutants

Organic micro-pollutants like pesticides, herbicides, and pharmaceutical residues are found in water sources.

Wood-based PAC is favored for its ability to adsorb high-molecular-weight organics due to its porous structure.

3. Algae and Toxin Control

During blooms, some algae release toxins such as microcystins, which are harmful even in trace quantities. While coagulation and filtration remove algal cells, the dissolved toxins require adsorption.

Wood-based PAC is often added prior to sedimentation or directly into rapid mixing basins, providing immediate interaction with toxins.

4. Disinfection By-Product (DBP) Mitigation

Chlorination is widely for disinfection, which can react with natural organic matter (NOM) to form trihalomethanes (THMs) and haloacetic acids (HAAs)—potential carcinogens.

Wood-based PAC pre-treatment reduces NOM concentration, thus limiting DBP formation downstream.

Application Methods of PAC in Municipal Water Treatment Plants

1. Direct PAC Dosing

  • PAC is added as a slurry into the coagulation or rapid mixing tank.
  • Dosage varies from 5 to 30 mg/L, depending on water quality, seasonal changes, and contamination events.
  • Dosing systems are equipped with automated feeders and real-time feedback loops, adjusting based on turbidity, TOC, and algal count.

2. Pre-treatment in Reservoirs

Some municipalities, especially in rural or semi-urban regions, pre-dose PAC in upstream reservoirs or canals feeding into the main plant.

  • This practice gives more contact time, enhancing the removal of slowly adsorbing compounds.
  • It also reduces load on downstream units.

3. Emergency Contamination Response

In the event of sudden chemical spills or algal blooms, plants utilize mobile PAC systems for rapid response.

  • PAC stored in silos is dispersed immediately into the intake basin.
  • This was notably used during the 2004 Mikawa Bay water odor crisis in Japan, where geosmin reached unusually high concentrations.

Case Studies of PAC use for Municipal Water Treatment from Japan

1. Tokyo Metropolitan Waterworks Bureau (TMWB)

  • Serves over 13 million residents.
  • Uses wood-based PAC for seasonal taste and odor control from the Tamagawa River.
  • PAC is dosed at 8–12 mg/L during summer months.
  • Also conducted R&D in partnership with local universities to develop automated PAC feed optimization.

2. Nagoya City Waterworks and Sewerage Bureau

  • Experiences geosmin outbreaks from Kiso River.
  • Implemented wood-based PAC along with high-rate coagulation in their Moriyama plant.
  • The result: 90% geosmin removal efficiency and reduced customer complaints.

3. Osaka City Water Bureau

  • Osaka treats water from Lake Biwa, prone to algal blooms.
  • PAC is added before ozonation to reduce the organic load.
  • Post-treatment monitoring showed significant reduction in THM precursors, improving DBP compliance.

Technical Specification of Wood PAC for Water Treatment