How to limit eutrophication of watercourses?

The eutrophication of rivers is a real environmental plague. This process of excessive enrichment of aquatic ecosystems with nutrients leads to the proliferation of invasive plant species. The immediate consequence is a reduction in the diversity and richness of fauna and flora. One way to limit this phenomenon is to replace the cleaning formulations based on nitric or phosphoric acid, resulting in nitrates and phosphate rich effluents which are the cause of eutrophication, with formulations based on methane sulfonic acid. This is what Arkema offers with its SCALEVA^® MSA solution.

What is eutrophication?

Derived from the Greek word "eutrophe", meaning "well-nourished", eutrophication is a natural aging process of watercourses due to the accumulation of nutrients. However, human activities greatly accelerate this process.

What are the causes of eutrophication?

Eutrophication mainly occurs in fresh waters. Its main cause is an abundance of nutrients, such as phosphorus and nitrogen derivatives.

These nutrients come from various sources, such as the application of synthetic fertilizers or the spreading of manure used in agriculture. The leaching* of nitrogen (nitrates, nitrites) and phosphorus (phosphates) from these activities and the discharge of industrial wastewater rich in nitrates and phosphates (very present in laundry detergents and other household and industrial cleaning products) contribute to the enrichment of surface waters and to the phenomenon of eutrophication.

What are the consequences of eutrophication?

The eutrophication of watercourses is characterized by hypoxia, i.e. a decrease in the concentration of oxygen in the water. The proliferation of algae on the surface creates a barrier preventing sunlight from penetrating the water and reducing exchanges between the upper and lower layers.

This directly affects the plants, fish, and other animal or plant species at the bottom of the water body that are less oxygenated. When these species die, they become a source of food for bacteria, which consume a significant amount of oxygen during digestion. The undigested residues of plants, algae, and animals accumulate at the bottom of the watercourse, eventually creating an anaerobic (oxygen-free) environment and the generation of dangerous reduced species (methane, hydrogen sulfide, ammonia).

Eutrophication, when it occurs, has a direct impact on the biodiversity of watercourses and affects the entire food chain in the vicinity of these ecosystems.

What strategies to limit eutrophication?

Palliative solutions, aimed at removing organic matter from watercourses, can be deployed, but they are costly and tedious to implement. Starting by limiting the actions that cause the accumulation of nutrients in watercourses is therefore a much more effective approach.

Thus, some agricultural practices are evolving towards a more environmentally friendly approach. The soil regeneration, for example, enables to maximize the water absorption capacity, thus limiting lixiviation and maintaining nutrient availability in the soil. This results in a more efficient use of nutrients, (synthetic fertilizers or manure), minimizing the amount of nutrients lost in the environment and thus limiting the phenomenon of eutrophication. The restoration of ecosystems improves their ability to act as natural sinks and buffers for these nutrients. A more virtuous circle is then set in motion.

On the industrial wastewater side, regulatory bodies also play a crucial role in the development of sustainable practices with the establishment of thresholds for nitrate and phosphate levels in discharges.

These regulations encourage industrialists to act on two levers:

Implementing more specific wastewater treatment processes for nitrates and phosphates,
Adopting or developing technical alternatives to the use of nitric or phosphoric acid widely used in the cleaning industry.

One of the increasingly widespread alternatives is Arkema's SCALEVA^® MSA (Methane Sulfonic Acid) solution, which can replace nitric or phosphoric acid in cleaning formulations used in many industrial sectors, including for the cleaning of rust and lime deposits in the food industry.

Today, entire sectors where large quantities of nitric or phosphoric acids are used have chosen to replace them with methane sulfonic acid to benefit from the very high solubility of its Calcium and Iron salts (mesylates).

Why is methane sulfonic acid a solution for the future?

Eutrophication is a critical environmental problem that requires immediate attention and action to mitigate its impacts on aquatic ecosystems. Understanding this phenomenon allows to implement measures to prevent it.

One of the actions that industry can easily undertake is to replace phosphoric and nitric acids with SCALEVA® Methane Sulfonic Acid in their cleaning formulations, to benefit from the same properties while avoiding nitrate or phosphate discharges.

Readily Biodegradable**, methane sulfonic acid is part of the natural sulfur cycle and has an extremely low chemical oxygen demand. It can be easily treated by wastewater treatment plants.

*Leaching or lixiviation is the treatment of a substance or mixture with a liquid to extract its soluble constituents.

** According to the OECD test 301 A and as mentioned on the SCALEVA® Safety Data Sheet.

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