The textile industry is one of the largest globally, producing a wide range of products that are used in a variety of sectors. Because of its size, its environmental impact is important too. In particular, textile production involves significant amounts of wastewater and many environmental problems in general.
Textile wastewater, with a pH often above 10 and called alkaline, poses a critical environmental challenge because of the groundwater contamination it entails. It is therefore essential that industries seeking to pursue a more sustainable business plan pay attention to water recovery systems to curb the industry’s impact.
In this article, I will present what I believe is the most innovative and effective solution to address this problem: the use of carbon dioxide (CO₂) captured directly from smokestack smoke to neutralize the pH of textile wastewater. As we shall see, the transformation of CO₂ into carbonic acid represents an innovative approach to industrial waste management and environmental impact mitigation in the textile industry. Let’s get started.
CONTEXT
Excessive alkalinity in wastewater and its effects
Let’s start with the basics, analyzing what is the concept of alkaline water. In many industrial processes, such as those in the cotton and leather textile industry, the use of alkaline substances, such as caustic soda and hydrated lime, produces wastewater with high pH levels, often above 10 or 11.
Wastewater is extremely harmful to ecosystems if not managed properly. In fact, it can lead to contamination of groundwater and waterways, causing public health problems and irreversible ecosystem damage.
Manufacturing companies must therefore rely on a neutralization system to adjust pH before wastewater can be safely discharged into sewer systems or natural water bodies.
Traditional methods involve the addition of strong mineral acids, such as sulfuric or hydrochloric acid. However, those approaches have some significant disadvantages, including high operational costs and negative environmental impacts due to salinization resulting from the release of salts (sulfates and chlorides) during neutralization processes.
METHODS
Eco-friendly alkaline wastewater pH neutralization with Carbon Dioxide (CO₂)

As mentioned earlier, an innovative solution for alkaline neutralization of textile wastewater comes through an advanced system that uses CO₂ from boiler or generator smokestacks to neutralize alkaline wastewater in the textile industry.
By harnessing the naturally acidic properties of CO₂, it reduces reliance on chemical neutralizers, which are harmful to the environment, but also marks a significant leap toward improving the efficiency and sustainability of treatment plants.
This method can be implemented with a dedicated plant built directly within your own production facility, whether it is textile-related or not. It turns a waste product into a resource, reducing the use of harmful chemicals and operating costs, helping to decrease industry pollution and consequently CO₂ released into the atmosphere.
ANALYSIS
How is CO₂ used to treat water?
The use of CO₂ to treat water involves the dissolution of CO₂ in wastewater, where this chemical component reacts with alkaline components to form carbonic acid, an acid that gently lowers pH without the negative effects associated with mineral acids.
Designed to accommodate varying volumes and pH levels of wastewater, the CO₂ neutralization system promises dynamic control of the neutralization process without the complexities and risks associated with manual handling of chemicals.
The implementation of this neutralization system is flexible and can be integrated into existing infrastructure with minimal adaptations. This operational agility not only increases the safety standards of plant operations but also reduces operating costs, making it an economically attractive option.

The chemical steps of CO₂ use in textile wastewater treatment
The process with CO₂ takes place in two key phases:
1st PHASE:
2 NaOH + CO₂ = Na₂HCO₃ + H₂O
2nd PHASE:
Na₂CO₃ + CO₂ = 2 NaHCO₃
Okay, seen like this, the formula may not be clear to everyone, but I’ll try to explain it. What does it mean in essence?
Dissolution of CO₂ reacts with alkali components to form carbonic acid, an acid that lowers pH without the negative effects associated with mineral acids.
In the first step, hydroxide molecules (OH⁻) react with carbon dioxide (CO₂) to form carbonate (CO₃²⁻) and water (H₂O). In this way, an acidification reaction takes place in which CO₂ acts as an acid and reduces the alkalinity of the water.
In the second step, carbonate (CO₃²⁻) reacts further with CO₂ and water (H₂O) to form hydrogen bicarbonate (HCO₃⁻). This is an equilibrium reaction that contributes to the further reduction of the pH of the water, making it even less alkaline.
THE FURNITURE OF CARBONIC ANHYDRIDE
Carbonic anhydride, or carbon dioxide (CO₂), is obtained from smokestacks or industrial flue gases and subjected to a cleaning process. Depending on the type of fuel used and the amount of excess oxygen supplied during combustion in the boiler, the concentration of CO₂ can vary.
It is supplied in cylinders or racks in situations where less gas is required.
How to convert CO₂ into carbonic acid in simple terms
This water treatment process basically harnesses CO₂, a significant greenhouse gas, by converting it into a more stable and less “harmful” form, such as carbonic acid, which can then be used to treat and neutralize wastewater.
The process is based on four key steps, each with its own benefits for the environment:
- CO₂ capture: CO₂ is captured from the exhaust fumes of industrial smokestacks through processes which include physical, cooling and cleaning methods. This step is crucial for reducing greenhouse gas emissions into the atmosphere;
- conversion to carbonic acid: captured CO₂ is then converted to carbonic acid (H₂CO₃) through special diffusers that create a reaction with water. Carbonic acid is a weak acid and is a less “harmful” form of carbon than gaseous CO₂;
- bases neutralization: in textile wastewater, carbonic acid can be used to neutralize bases, adjusting the pH and facilitating the removal of pollutants. This step improves the efficiency of wastewater treatment processes, making them more sustainable and less harmful to the environment;
- wastewater purification: in addition to reducing CO₂ emissions, this process contributes to the purification of waste water, reducing the environmental impact of the textile industry. The conversion of CO₂ into a useful product reduces the need for greenhouse gas disposal and supports a more sustainable management of industrial resources.
This approach is an example of a circular economy, where waste from one process is used as a resource in another, helping to reduce the environmental impact of industrial activities. Research and development in this area is key to implementing innovative technologies that can address the environmental challenges associated with the textile and other industries.

ADVANTAGES
A global sustainable solution: the benefits of neutralizing alkaline wastewater with CO₂
As the textile industry continues to seek new solutions, the use of CO₂ is a winner from at least 4 perspectives.
1) Economic savings: adopting neutralization with CO₂ in the textile industry allows strong mineral acids, such as sulfuric acid, to be eliminated at significant economic savings.
Companies can completely eliminate their purchase by reducing the operational costs associated with wastewater treatment, contributing to the company’s bottom line and environmental sustainability goal.
2) Emission reduction: implementing advanced technologies to capture CO₂ directly from industrial smokestacks is an effective strategy to minimize the environmental impact of greenhouse gas emissions. Not only does this approach help to significantly reduce the amount of carbon dioxide released into the atmosphere, but it also aligns with the climate change mitigation goals defined in the Kyoto Protocol. Through the adoption of this method, companies can obtain green credits, which are internationally recognized certifications attesting to the reduction of greenhouse gas emissions. Incorporating such practices not only promotes the transition to a low-carbon economy but also supports the development of an environmentally responsible business model in line with global efforts to combat climate change.
3) Operational efficiency: a significant advantage of CO₂ neutralization is its ability to prevent the risk of overdosing, a common problem with strong acids. Overuse of acids can lead to an excessive lowering of the pH in the water, causing corrosion and efficiency problems in subsequent processes. With CO₂ neutralization, this risk is completely eliminated, allowing precise control of the neutralization process without compromising the quality of wastewater treatment.
4) Improved water quality: this method does not increase the levels of sulfates and chlorides in the discharged water, which can allow a higher water recovery rate in treatment processes.
Let’s recap the advantages of wastewater neutralization by CO₂:

Significantly reduces costs associated with neutralization

Qualifying for carbon credits and green certifications

Making it a cost-effective and environmentally responsible choice

Reducing the reliance on hazardous chemicals

Ensuring pH levels remain within safe limits

Allowing for increased water recovery downstream in the biological treatment plant

Minimizing risks associated with overdosing, as organic acid overdose

Contributes significantly to reducing CO₂ emissions into the atmosphere
CONCLUSIONS
Wastewater treatment with CO₂: opportunities for companies
The CO₂-based approach can help companies recover wastewater while complying with environmental regulations and improving their sustainability image.
The way and pace of production in the textile industry causes significant negative environmental, climate and social impacts, particularly in terms of resource, land and water consumption and the release of chemical pollutants.
To embrace circular economy principles, my experience suggests that the best way to do so is to surround yourself with partners and suppliers who have embarked on the same journey toward sustainability. Entering this view means welcoming important strategic benefits, for example:
- attracting SRI capital and new talent;
- acquisition of a target audience of green consumers;
- early adaptation to regulations and increasing regulation on the various areas of sustainability management and communication, as outlined for example in the EU Sustainable Textiles Strategy.
There are a number of companies around the world at the forefront of wastewater treatment using CO₂. All you have to do is explore to find the right partners.