Green chemistry, an effective and sustainable alternative for water treatment in industry

The regulations governing the use of chemicals in industry are changing fast, particularly when it comes to water treatment, a crucial issue in a context of water stress and deterioration in the quality of water resources. Between progressive bans and a precautionary principle applied a priori manufacturers need to find alternative solutions that are safe, equivalent and capable of supporting their ecological transition, while ensuring regulatory certainty. The aim is to to reduce or even eliminate the use of conventional chemicals. This is the role of green chemistry, the first applications of which are already available.

Although many innovative and alternative solutions are emerging to limit the use of chemicals, controlling microbial load and COD often involves the use of biocides. Sodium bromide was one of the biocides frequently used by industry, but it was classified as a category 2 CMR (carcinogenic, mutagenic and reprotoxic) in 2022. Its use must now be the subject of a documented assessment with a view to its replacement, in order to limit the risks, within the meaning of the Labour Code.

Widely used since the 1970s, sodium bromide is designed to increase the effectiveness of chlorinated biocides in water that is too alkaline (pH>8). However, in addition to its CMR classification (which could eventually be described as “proven”, category 1), its environmental footprint means that its use should be limited or even eliminated; in particular, polluting extraction, concentration and transport processes (NaBr is imported from Asia, the Middle East and America) raise questions about bromine discharges into ecosystems where it is not naturally present, etc.

Sodium bromide is an emblematic example. Other molecules, such as azoles (copper corrosion inhibitors), morpholine (volatile amines) and many other compounds are already subject to CMR classification. More generally, it is now imperative for manufacturers to seek alternative solutions that are just as effective, but also safer for employees, environmentally friendly, compliant with regulations and in line with manufacturers' commitments to reducing their environmental footprint.

To meet the need for water disinfection in industrial processes, various alternatives can be envisaged to replace the use of certain biocides in water treatment strategies, combining physical treatment devices and the principle of green chemistry.

The concept of green chemistry emerged in the United States in the 1990s, with the aim of designing chemicals and processes that would reduce or even eliminate the use and synthesis of hazardous substances.

The growing need for eco-responsible water treatment means that a scientific approach based on the search for a green and sustainable alternative must be initiated. The stakes are high, since the aim is to replace some of the conventional chemical treatments, which may be effective but which carry human, environmental and economic risks.

This challenge can only be resolved as part of a genuine long-term development strategy for products formulated using green chemistry, based on both a scientific and industrial approach: applied research, laboratory tests and then tests under real conditions, before marketing. In the meantime, there are complete ranges of products formulated from renewable or recycled active ingredients that are non-toxic, biodegradable, have a reduced carbon footprint and are at least as effective as conventional chemicals.

BWT's biodegradable products (antiscalants, copper corrosion inhibitors and biodispersants) are currently being deployed at Fraîcheur de Paris sites, with positive results after a year's deployment. For the operator of the urban cooling network for the City of Paris, developing a cooling network with high environmental efficiency means deploying innovations on production plants and networks to avoid the use of conventional chemicals.

With a view to reducing the use of conventional chemicals in industry and other sectors, green chemistry complements a range of existing alternatives. These include, for example, the in situ generation ofa fresh disinfectant solution by electrolysis using only water, salt and electricity. In a similar way, the combined UV-C treatment with the addition of hydrogen peroxide, which can also be produced in situ, can also be an excellent alternative to the use of conventional chemicals, depending on the circumstances.

These alternatives are highly effective in preventing bacterial growth and produce fewer, if any, by-products in the waste stream, making them a viable option when evaluating the replacement of certain traditional biocides in chemical treatment strategies for industrial water. These alternative processes bring eco-responsible chemical manufacturing into the plant, enabling control of water treatment and management of the value chain, costs and monitoring.

These are strategies that respond to the challenges of ecological transition and anticipation of regulatory changes in the industry, driven by the social and environmental responsibility of manufacturers, but also by their customers, partners and public authorities. In this context, it is the role of service providers to innovate and to make these innovations accessible in order to support their industries in this transition.