Introducing Process Intensification

Globally, the water sector is facing a perfect storm of challenges: rapid urbanization, aging infrastructure, extreme weather events, and stricter discharge regulations. The reality of this? Municipalities are under increasing pressure to do more with less space, reduced energy, and fewer operational costs. These combined pressures are fueling interest in process intensification (PI) as a means to enhance wastewater treatment. To learn more, we spoke to Andrea Maggio, product manager at Xylem about how PI is shaking up the industry.

What is process intensification?

The conventional solution to upgrade a water resource recovery facility (WRRF) is to build additional biological and settlement tanks. This is a well-understood approach across the water sector. However, when building and hydraulically connecting new structures to an existing facility, WRRFs face challenges associated with construction and operational scheduling, particularly when space is limited.

PI is an alternative that avoids, or at least minimizes, additional construction. It reuses existing structures to increase the capacity of the facility, allowing the same tank volumes to treat additional flow and load to meet new effluent requirements.

Why is process intensification important for municipalities?

PI represents a complete rethink of how treatment processes are designed, integrated, and operated. At its core, PI aims to compress and enhance treatment operations to deliver greater performance in a smaller footprint. For municipalities facing land constraints, aging infrastructure, and budget limitations, the promise of compact, high-efficiency systems could not come at a better time.

PI is opening new doors for municipalities, which – with the right strategies – can upgrade their WRRFs to be smarter and more resilient, meet regulatory demands, and turn their treatment challenges into sustainable opportunities.

What treatment factors should be considered when upgrading a WRRF?

When upgrading an existing WRRF via PI, municipalities can implement several improvements to enhance biological performance. Additional load typically requires more biomass, and this can be supported by addressing a mix of nutrient removal needs, oxygen demand, and hydraulic factors. For example, tighter ammonia and nitrogen limits often call for longer solids retention times, resulting in greater biomass. Total nitrogen limits may require facilities to add or increase anoxic volume. Stricter phosphorus limits may require chemical addition, which increases solids handling. Tighter nutrients limits further drive the need for greater total solids removal performance. These adjustments in turn raise oxygen demand and may require aeration upgrades. Finally, clarifiers and other hydraulic factors must be evaluated to ensure reliable performance under higher flows and solids loading.

Among the many technologies enabling PI, two stand out for their ability to combine performance, compactness, and adaptability: ballasted clarification and activated sludge dynamic filtration.

What is ballasted clarification?

Ballasted clarification uses magnetite - fully inert iron ore particles - to ballast biological floc or conventional chemical floc, enhancing settling rates.  This allows treatment plants to expand capacity and improve performance at a relatively low cost – ideal for process intensification.  The BioMag® system from Xylem can be applied to activated sludge systems, providing up to 300% more treatment capacity within existing tankage and delivers faster and more reliable clarification than alternative systems.

^{Ballasted clarification provides a cost-effective solution for activated sludge systems, providing as much as 300% more treatment capacity in existing tanks.}

BioMag systems can also achieve total phosphorus in the effluent as low as 0.2mg/L and can handle variations in flow and solids. With up to 95% of the magnetite recovered and reused, the BioMag system offers a simple, reliable, and cost-effective solution for intensifying the activated sludge process and meeting stringent effluent limits.

How does activated sludge dynamic filtration work?

Activated sludge dynamic filters (ASDF) are an innovative membrane technology that provides small-footprint MLSS filtration for activated sludge applications. The Taron™ activated sludge filter from Xylem’s Sanitaire brand is a unique technology that relieves solids and hydraulic loading on secondary clarifiers, significantly expanding treatment plant capacity. Its specialized design uses micro-mesh discs partially submerged within the activated sludge. As these discs rotate, a dynamic ‘sludge cake’ layer forms, filtering biological floc to achieve a high-quality effluent with typical filtrate total suspended solids (TSS) of less than 10 mg/L.

^{Activated sludge dynamic filtration is an efficient, space-saving wastewater treatment solution for biological systems that replaces traditional secondary clarification followed by tertiary filtration systems.}

With a footprint up to 60% smaller than traditional clarifiers, the Taron™ activated sludge dynamic filter integrates easily with existing infrastructure. The system boasts low power consumption, operational simplicity, and resilience to varying hydraulic loads. Its modular ‘plug-and-play’ design arrives fully configured for simple installation with minimal civil works, making it ideal for PI retrofits.

If it’s time to rethink biological treatment and solids separation at your plant to meet future water quality demands, within tight operating parameters, shine the spotlight on process intensification.