PFAS Treatment and Remediation Services for Water

SAFF – Surface Active Foam Fractionation

Envytech offers the SAFF – Surface Active Foam Fractionation technology, created by OPEC systems. The first sustainable treatment method for PFAS- contaminated water. SAFF does not use filter materials, only air and electricity, and is completely unaffected by other pollutants such as metals or organic substances, particles, pH, nutrients or other water chemistry.

STEP 1

The SAFF process utilizes the physio-chemical properties of PFAS compounds to attach to fine air bubbles as a result of its hydrophobic and hydrophilic properties. When accurately controlled bubbles are introduced and allowed to rise in a narrow column of water, the bubbles become exceptionally effective in collecting PFAS compounds that are loosely bound to the water molecules. Once at the surface, PFAS can easily be removed by separation and concentration through a passive ”spill over weir” system, and an active vacuum system. Treated (aerated) water can then be released to the recipient. The collected PFAS concentrate is passed on to further fractionation steps to become a high concentration liquid of relatively small volume suitable for destruction via permanent destruction techniques such as high temperature thermal combustion, Super Critical Water Oxidation (SCWO) or Electrochemical Oxidation (EO).

The system has significant advantages compared to all other technologies on the market as the process is very robust. SAFF works without reduced effect, regardless if the water contains large amounts of suspended solids and contaminants of various kinds, including oil and biological substances. The system is not sensitive to high concentrations and is not pH sensitive. The system is not in need of any pre-treatment systems, but to minimize service work, water comprising larger suspended particles can advantageously pass via some form of separation e.g. a lamella separator.

The SAFF system works by accumulating the PFAS compounds at the top of the first treatment column where the first fractionation step takes place. When air is injected at the bottom of the column and rises in a created vortex, the PFASs attach to the bubbles and flow with them to the surface. Foam and water flow over a “weir design” at the top of the column (see figure 2) and therefore called ”the wet cut”, as both the created foam and the underlying water are removed. This underlying water is removed as PFAS stratifies at the top of the column as the shorter chain PFAS do not have the same foam potential as the longer chains.

Before the end of the first fractionation step, the water level in the column is raised, forcing the water in the top of the column to be collected, so that as much of the stratified PFAS substances as possible are included in step two. The first fractionation step increases the PFAS concentrations by about 10-fold.

STEP 2

In the second fractionation step, the same process takes place as in step 1, but as concentrations of PFAS are now around 10 times higher, a drier foam is obtained which is removed with vacuum. The vessel where the second fractionation step is performed is equipped with carefully calibrated sensors that control a vacuum pump and its distance to actual process foam levels. The hyperconcentrate generated by this process is led to a collection container where it is stored pending step 3. In this second fractionation step, the concentration is further increased by up to 1,500 times, which means that the total concentration increase is now around 10,000 times initial levels.

STEP 3

In the third fractionation step, which is performed in the same way as step 2, further concentration increases are obtained. The total increase in concentration obtained over the three steps is between 50,000 – 2,000,000 times initial concentrations in the untreated water. The hyperconcentrate waste volumes are therefore this same factor less than the processed feed water volume. Expected amounts of waste depend on the type of water that is treated, but from projects carried out we see that the expected amount of waste for landfill leachate are less than 1m³ per 40,000m³ of treated water, and for groundwater about 10 liters per 40,000m³ of treated water.

EXPECTED RESULTS

To date (Oct 2021), 3 full-scale projects comprising PFAS have been carried out with SAFF. OPEC Systems has treated PFAS-contaminated groundwater using a SAFF system for over 2,5 years at an active military air base in Australia where extensive fire drills have been carried out. In total, more than 60,000m³ of water has been treated during this period, which has included drought times. Outgoing water has never exceeded the levels of Australia’s drinking water guidelines. In Södertälje, Envytech is treating leachate from the Telge Landfill, and since February 2021, more than 90,000 m³ of water has been treated down below treatment targets. Envytech is also treating leachate at the NSR landfill in Helsingborg where approx. 10,000 m³ of water has been treated since August 2021.

All projects have been carried out without pre-treatment systems or filter materials. Treatment results using SAFF are similar regardless of which water is put through the system.