Degradation of polyacrylamide and possible formation of acrylamide in deep ponds and lakes: a review of the literature
Resume
So-called flocculants are increasingly being used to separate suspended matter and water more quickly and better. The flocculants are used to process dredged material, waste water or washing water from (industrial) production processes. This process produces products such as sludge and filter cake. It may still contain remnants of the flocculants. The products are used, among other things, to raise the bottom of deep puddles. This is necessary to restore the ecosystem in the pond after sand or gravel has been extracted from it.
One of the flocculants used is polyacrylamide. If this substance breaks down, the toxic acrylamide can be formed. This is a Substance of Very High Concern (ZZS (Substances of Very High Concern )). These substances are hazardous to humans and the environment. The Dutch government therefore wants to prevent these substances from entering the environment as much as possible. RIVM has now explored in the scientific literature whether polyacrylamide is broken down into acrylamide in deep puddles. In addition, it has been investigated whether acrylamide can be broken down in a deep pool.
Not enough is known about the formation and release of acrylamide in deep puddles. As a result, it is not clear whether there are any risks for plants and animals that live in the puddles. Or for humans if they eat fish from these puddles. However, it appears that acrylamide is already contained in polyacrylamide and can be released when polyacrylamide is used. It is therefore not excluded that acrylamide can also end up in the urine in this way.
Because of these uncertainties, RIVM recommends conducting more research into the formation of acrylamide in deep puddles. It must also be investigated whether acrylamide contained in polyacrylamide can be released when it ends up in deep puddles. Finally, RIVM advises taking precautions if products treated with polyacrylamide are used in deep puddles. This can be done, for example, by using other flocculants, testing products with flocculants beforehand for acrylamide or determining the quality of the surface water after the product has been used in it.
Abstract
With increasing frequency, substances known as flocculants are being used to separate solid particles from water because it is faster and more effective. Flocculants are used in sand dredging and when purifying wastewater or washings from industrial and other manufacturing processes in order to speed up the process of separation and lower the associated costs. During this process, products such as sludge cake and filter cake are formed. These may contain traces of the flocculants. Such products can be used to raise the bottom of deep ponds and lakes after sand or gravel has been excavated from them. This is done to make the bodies of water suitable for different uses, such as recreation or nature areas.
Polyacrylamide is one of the flocculants used. When polyacrylamide degrades, it can result in a toxic compound called acrylamide. Acrylamide is a Substance of Very High Concern (SVHC). Such substances are hazardous to people and the environment. For this reason, the Dutch government wants to prevent these substances from being released into the environment whenever possible. RIVM has now reviewed the scientific literature to understand whether polyacrylamide is being broken down to acrylamide in deep ponds and lakes. It has also explored whether acrylamide can further degrade in a deep pond or lake.
The results showed that too little is known about the formation and emission of acrylamide in deep bodies of water. As a result, it is unclear whether it poses a risk to the plants and animals that live in the ponds and lakes or to people, when they eat fish that lived in that water. Furthermore, there is evidence that polyacrylamide contains traces of acrylamide that may be emitted when polyacrylamide is used. It is therefore possible that acrylamide may end up in ponds and lakes via this route.
In light of this uncertainty, RIVM recommends further research into the formation of acrylamide in deep ponds and lakes. Another topic that should be studied is whether the acrylamide contained in polyacrylamide can be emitted when a polyacrylamide containing product is deposited in deep bodies of water. Lastly, RIVM recommends that precautions be taken when products that have been treated with polyacrylamide are used in deep ponds and lakes. Examples of precautionary actions are the use of other flocculants, or testing products with flocculants before use to determine whether they contain acrylamide. Another possibility is to monitor the quality of the surface water after the product has been used in a pond or lake.
2023-05-16 20:01:22
#Degradation #polyacrylamide #formation #acrylamide #deep #puddles #literature #survey #RIVM
