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Dissolved Air Flotation (DAF) is a proven and adaptable technology for removing solids, oils and other contaminants from wastewater – and is particularly valued in sectors such as food and beverage for its ability to handle seasonal load variations. To learn more about DAF’s role in modern treatment strategies, FoodBev spoke to Kenda Al Shamas, product manager for wastewater treatment in Iberia at Xylem, about where it fits into today’s water treatment landscape and the key trends shaping its development.

Could you give us a quick overview of what DAF technology is and how it works?

DAF is a physico-chemical water and wastewater treatment process designed to efficiently remove suspended solids, oils, greases and other contaminants from a wide range of wastewater streams. Thanks to its compact footprint and high treatment efficiency, DAF is widely used in both industrial and municipal applications.

The process begins with the addition of coagulants and flocculants, which chemically condition the wastewater and encourage fine particles to aggregate into larger, more easily separable flocs. Pressurised water saturated with dissolved air is then introduced into the flotation tank. As the pressure is released, tiny air bubbles form and attach to the flocs and suspended matter, lifting them to the surface. The resulting floating sludge is removed using a mechanical skimmer.

DAF systems are particularly effective in reducing turbidity and eliminating pollutants – including particulate Biochemical Oxygen Demand (BOD), up to 80%; Chemical Oxygen Demand (COD); Total Suspended Solids (TSS), up to 90%; as well as oils, fats and certain metals. The process ultimately produces two distinct output streams: a high-quality clarified effluent suitable for further treatment or discharge, and a concentrated sludge for disposal or further processing.

What role does DAF play in water and wastewater treatment in the food and beverage sector?

In the food and beverage industry, DAF is a key technology for removing suspended solids, fats, oils and greases from wastewater, significantly reducing organic load (BOD/COD). DAF systems are used either as an effective pre-treatment step to reduce the burden on downstream biological processes, or as a secondary clarifier for final liquid-solid separation. This helps facilities meet discharge limits and minimise surcharge fees associated with high-strength wastewater.

A common challenge in this sector is managing seasonal production peaks, which can lead to sudden increases in flow and contaminant loads. Without proper handling, these spikes can overwhelm treatment systems. While some facilities rely on retention tanks to buffer peak flows, these solutions often require significant capital investment, additional space and may introduce operational issues such as odour control and sludge degradation.

In contrast, DAF units offer a compact, plug-and-play solution that can be quickly deployed and seamlessly integrated into existing infrastructure. This makes DAF an ideal choice for facilities that require immediate, adaptable treatment capacity. Its ability to handle fluctuating loads without compromising effluent quality makes it a reliable and cost-effective technology for ensuring compliance and maintaining performance during peak production periods.

How does DAF compare with other forms of water treatment in terms of cost, efficiency and environmental impact?

DAF is a cost-effective, high-efficiency, plug-and-play solution designed to handle higher solids loading rates than conventional clarifiers. It offers lower capital and operational costs than membrane bioreactor systems, with fast installation and a compact footprint.

DAF also produces more concentrated sludge, which reduces polymer consumption as well as sludge handling and transport costs. Additionally, it supports water reuse strategies, helping to lower overall water consumption and environmental footprint.

Its ability to manage variable loads makes DAF ideal for industries with seasonal fluctuations or space constraints. It ensures consistent effluent quality, helping customers comply with increasingly strict discharge regulations.

What are the most common operational challenges customers face with DAF systems, and how does Xylem help address them?

Common challenges include inconsistent performance, poor sludge removal, high chemical usage and air system issues. Flow and load variations can affect flotation efficiency and lead to operational instability.

Xylem’s strength lies in delivering robust, well-engineered DAF designs that incorporate highly efficient whitewater pumps and skimmers. In addition, our smart controls and automation systems optimise chemical dosing and adapt to changing conditions.

We also offer expert support services to facilitate efficient troubleshooting and performance optimisation. These professional services can be provided either on-site or remotely, depending on customer needs.

How does Xylem’s DAF systems contribute to sustainability goals like water reuse and energy efficiency?

Xylem’s DAF systems contribute to sustainability by enabling the high-efficiency removal of solids, oils and organics, producing cleaner effluent, which leads to easier and more efficient downstream treatment for reuse applications.

By reducing the load on downstream treatment processes, DAF systems also help lower overall energy and chemical consumption. Their compact, high-rate designs reduce space requirements and minimise construction impacts, while the production of more concentrated sludge directly reduces handling, transport and polymer use.

Advanced controls have been developed to optimise sytem performance, helping to minimise waste and operational costs. This makes DAF a key solution for customers looking to reduce their water footprint and environmental impact.

What trends are you seeing in water treatment right now that are influencing how you develop DAF solutions?

Trends such as sustainability and the circular economy are driving innovation in water and wastewater treatment. There is growing emphasis on developing energy-efficient technologies, reducing carbon emissions (CO₂) and maximising water reuse.

These priorities shape how Xylem designs its DAF systems and guide the development of complementary solutions, such as moving bed biofilm reactor (MBBR) systems for biological treatment and sludge dewatering technologies.

Our focus is on delivering solutions that provide high efficiency, low energy and chemical consumption, compact footprints and resource recovery – all while helping customers meet increasingly stringent discharge standards.

Interested in learning how to implement Dissolved Air Flotation technology? Register for our free webinar to explore solutions for wastewater challenges in the food and beverage industry.