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An organic approach to water treatment

Coagulants form an essential part of the water treatment process, helping to optimise the entire water cycle. Inorganic coagulants are typically metal-based products and are the conventional ‘tried and tested’ choice for many companies.

While these inorganic coagulants are still being utilised and have a role to play in wastewater treatment, there are increasing environmental concerns associated with their use.

As a result, there has been rising interest in exploring more environmentally friendly alternatives, such as organic or green coagulants that are natural and sustainable.

The Function of Inorganic Coagulants

Most inorganic coagulants function in the same way. One common example is poly-aluminium chloride (PAC), which is routinely used across industrial applications.

The coagulant destabilises impurities in the water through a process known as sweep flocculation.

While this process removes impurities from the water, it also adds to the overall sludge volume due the strongly acidic nature of the coagulant that requires pH adjustment using sodium hydroxide. The result is an additional sludge called aluminium hydroxide.

The quantity of sludge that needs to be treated and removed is potentially 50 per cent higher compared to when inorganic coagulants are used.

Removing the sludge can be a time-consuming endeavour, and it normally requires an off-site disposal involving large vacuum tankers to safely remove the sludge from site.

Consequently, firms are required to spend money on transport, and this will add to the site’s overall carbon footprint. With environmental concerns being prioritised now more than before, many site managers are considering alternatives to mitigate such situations.

Poor Quality Effluent

PAC is an effective coagulant and still has a place in effluent treatment, especially in the removal of phosphates in drinking water and industrial applications.

However, in industrial applications, particularly when dealing with wastewater from the food and beverage industry, PAC exhibits a significant weakness — it is sensitive to any change in an effluent’s pH level.

Maintaining the effluent stream’s pH within the range of pH 7-8 is crucial for ensuring effective treatment. But poor pH control and inconsistencies in the treatment processes can jeopardise this pH balance and compromise the effectiveness of treatment.

The result is poor quality discharge and potential penalties or fines associated with non-compliance to discharge requirements.

On the other hand, organic coagulants work effectively at a wider pH range (4-8) and there is improved control over a broader span of pH in the system. As a result, there is a reduced need for the handling of hazardous pH correction chemicals and less input from site engineers are required to monitor the process conditions.

Organic coagulants are also very effective at removing fats, oils, and grease (FOGs) from wastewater. Notably, the use of organic coagulants has delivered extremely positive results in ready-made meals and oil processing factories.

Environmental concerns around certain inorganic coagulants extend far beyond additional CO2 emissions. For example, waste produced as a by-product of some inorganic coagulants can be highly corrosive and hazardous.  Apart from its potential harm to operators, these substances can also pose an environmental threat, especially when introduced into wildlife habitats.

This concern is particularly relevant to inorganic coagulants that contain large quantities of heavy metals.

Reduced Pollution

“In recent years, people have become more aware about the risks surrounding heavy metal pollution and how these metals can wreak havoc on natural environments, as well as on human and animal health,” shared Inshan Sheriff, National Hydrex Manager for Australia at Veolia Water Technologies.

“Organisations that use inorganic coagulants in its processes can be contributing to the cycle of pollution. As such, there is a strong environmental case to opt for organic alternatives.”

Indeed, organic coagulants can be applied at a far lower dosage while remaining effective across a wide range of applications. These solutions naturally produce far lower quantities of sludge. Furthermore, organic coagulants do not consume any alkalinity from the liquid they are added to, therefore minimising any pH or conductivity changes.

Organic coagulants, due to their composition, do not cause a rise in salt or metal presence when employed to treat an effluent stream. As such, concerns about pollution can be significantly diminished. These alternatives effectively tackle many challenges and enable organisations to implement safer and more sustainable wastewater treatment processes.

Veolia Water Technologies offers a wide range of Hydrex water treatment chemicals and dosing equipment and services.

These Hydrex chemicals have been specially formulated to optimise operations at water treatment facilities, including organic solutions that enable less toxic and more sustainable practices. Manufacturers can rely on Veolia’s comprehensive range of Hydrex solutions that are backed by their team of skilled sales and chemical service engineers, who are trained in water treatment processes, equipment, and chemistry.

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