Since January 2020 various tests and pilots for the removal of different Per-and Polyfluorinated Substances (PFAS) using CERAFILTEC’s Active Cake Layer Filtration (ACLF) process have been successfully executed. The removal of C6-C8 chains including PFOS, PFOA, PFHxA, and HFPO-DA (GenX) as well as C3-C5 short-chain molecules, i.e. PFBA and PFBS are in focus. The tests confirm highly effective removal of PFAS chemicals with substantial cost savings over Granular Activated Carbon (GAC), Ion Exchange (IX) resin, and Reverse Osmosis (RO) processes. The benchmark results are outlined below.
The ACLF process has been established by CERAFILTEC team members over the last decade for the selective removal of dissolved ions. Large plants with over 400,000 m³/d (~100 MGD) total capacity are operating successfully where the ACLF operation has become the go-to solution due to substantial cost savings. The same process also works for the removal of PFAS molecules as well as Dissolved Organic Carbon (DOC), Volatile Organic Compounds (VOC), Trihalomethane (THM), humic acids, drug residues, odor, taste, and color. Just the adsorbent changes to Powdered Activated Carbon (PAC).
Activated carbon is already known to be an effective adsorbent for the removal of PFAS chemicals. CERAFILTEC’s ACLF process now optimizes how the adsorbent is utilized: Maximizing specific surface areas and shortening adsorption pathways. This is done by covering the ceramic flat sheet membrane with a very thin and loose coating of PAC. All water must pass through this coating. This process is only possible with ceramic flat sheet membranes.
The highly effective and efficient adsorption capabilities are based on two facts:
- The smaller the particle size, the larger the specific surface area, the better the adsorption capacity – PAC is about 25 times smaller than GAC particles
- The closer the particles (adsorbent) are to each other, the thinner the boundary layer between the particles, the shorter the pathways of the contaminants (adsorbates) to the adsorbent – up to 45 faster and most effective adsorption
Both conditions are perfectly combined in CERAFILTEC’s ACLF process for the first time.