Technology Update – April 2023

Welcome to technology update, in which we give you a short update on the latest water treatment process developments, both industrial and from academia.

New PFAS Removal Technology

A press release from the University of British Columbia (Canada) has described the removal of PFAS from water using a new type of adsorbing media, similar to Activated Carbon but many times stronger. The working principle has not been published, although it is expected to be based on polymer beads, similar to ion exchange but with a specific adsorbance for PFAS chains.

In March 2023, the US environmental regulator EPA set legal limits for six strains of PFAS in drinking water, specifically to reduce human exposure. The legal limits were suggested to be set at 4.0 ppt (ng/L) for PFOA and PFOS, the most common types that are mainly found in water. Other PFAS strains are assessed in a combined hazard index. Each PFAS strain’s concentration is divided by the maximum level set for that strain, which adds a score to the index. The sum of these values is the hazard index, and it cannot exceed 1.0. See the EPA publication for the exact calculation.

A month earlier, the EPA announced a plan to use 2 billion USD for the prevention and removal of emerging contaminants, including PFA, from drinking water.

EU Drinking Water Directive

The EU has finally implemented the revision of it’s drinking water Directive. This means that now, all EU countries have tightened regulations on drinking water quality, especially with regards to endocrine disruptors.

Largest Disc Filter Registered

Water and utilities company Veolia has finalised the registration of part of the Bahr El-Baqar wastewater treatment plant as the largest disc filter in the world. The 120 installed disc filters in the plant, now the largest by number of filters and by disc area, treat part of the 5 million cubic meters per day of the wastewater treatement plant. These filters are used specifically to reduce the total suspended solids content of the wastewater so it can be used for irrigation in the Sinai region. This not only reduces the contamination load of the plant into the Nile river, but also reduces the amount of water required to be extracted for irrigation.

Disc Filters work similar to Drum Filters, although their filtration is done by multiple enclosed discs through which the water is sent. The discs rotate and get cleaned at the top, causing the accumulated sludge (cake) to fall into a collection channel for removal.

Norwegian Deep-Sea RO Desalination

Norwegian startup Waterwise has provided proof-of-concept of their Reverse Osmosis (RO) process at a depth of 400 meters under the surface. This avoids common contaminants such as algae and jellyfish, and improves water temperature stability. Addionally, the system only turns 25% of the inlet water into potable water, reducing the brine concentration factor from 2 to 1.3. This means that the outgoing brine, which can cause local high salt concentrations, will have less of an impact on the direct environment. The lower need for pretreatment due to the water quality benefit offsets the lower water recovery, overall changing the energy usage to around 2kWh instead of the current 3.5 kWh averages for modern plants.

The main challenges for the team at Waterwise will be to make the technology resistant to high pressures and the marine environment, as well as choosing suitable locations for the systems to avoid having to pump the produced water long distances to the shore.

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