A Smarter Approach To Biological Treatment - Process Intensification Through Microorganism Selection & Retainment

Are you struggling to meet new or existing ammonia or nutrient discharge limits due to capacity constraints? Unable to expand reactor capacity for higher loads? Facing a costly and disruptive capital upgrade to comply with stricter nutrient standards? There are innovative solutions that could help you overcome these challenges.?

The mantra “doing more with less” has been central to the water industry for over 15 years. As populations grow, regulatory standards tighten, and the focus on resource recovery increases, the pressure to minimize greenhouse gas emissions and reduce capital investment has never been higher. Meeting these challenges requires not just innovation, but efficiency.

One promising approach is process intensification, which aim to increase the bacterial population within reactors, thus improving the removal rate of COD and ammonia per unit volume. These technologies effectively enable existing infrastructure to achieve greater output and usually at lower costs.

The Highs and Lows and Process Intensification

The bacterial population in a reactor is commonly measured by the mass of solids (either suspended or attached to surfaces). For suspended growth systems like the activated sludge process, the concentration of solids is limited by downstream clarifiers. In practical terms, this means a maximum solids concentration of around 5,000 mg/L, with a more typical concentration of 3,500 mg/L to account for wet weather conditions and biological upsets. This limit effectively caps both the reactor’s load (its ability to handle organic matter) and its hydraulic capacity (its ability to treat flow).

Process intensification strategies aim to bypass these limitations by:

• Increasing bacterial populations without raising suspended solid concentrations?through methods like?Integrated Fixed Film Activated Sludge (IFAS)?or?Membrane Aerated Biofilm Reactors (MABR).
• Enhancing settlement characteristics?with techniques like?granule selection?(via substrate and hydrodynamic selection or selective wasting with hydrocyclones) or by seeding with ballasts such as?magnetite (BioMag)?or fine organic particles (Mobile Organic Biofilms or MOB).
• Replacing clarifiers?with physical barriers through?Membrane Bioreactor (MBR)?systems or newer?Dynamic Membrane Systems, allowing for higher suspended solids concentrations.

Each of these technologies and techniques have unique advantages, but they also come with trade-offs. For instance, MABR systems reduce aeration costs but don’t improve settlement, while granulation methods can enhance simultaneous nitrification and denitrification and increase phosphorus-accumulating organisms for bio-P removal. However, techniques like IFAS may raise energy demands due to higher dissolved oxygen (DO) requirements, while others introduce operational complexity, maintenance needs, and higher chemical or resource consumption.

Sludge Age - The Drawbacks of Conventional Methods

All these process intensification techniques rely on the principle of sludge age to cultivate the desired organisms. Sludge age, along with reactor conditions, dictates the microbial community in the reactor, resulting in a diverse and often inefficient mix of organisms. Many of these microorganisms are not directly involved in the desired treatment processes. Moreover, systems with long sludge ages consume significant energy to aerobically digest dead cells and manage higher proportions of inert materials, reducing overall efficiency. This aerobic digestion in the biological reactor significantly reduces our ability to recover biogas from wasted solids, being of a much lower calorific value.

Despite efforts to control factors like redox potential, pH, and dissolved oxygen concentrations to select for more effective organisms, the dynamic nature of influent often makes it difficult to achieve consistent results.

The Future: MicroNiche Engineering for Precise Bacterial Control

A more targeted solution has emerged with?MicroNiche Engineering, pioneered by Microvi Biotechnologies. This approach uses advanced material science and microbiology to create a specialized habitat for desirable bacteria, allowing them to thrive and dominate in treatment reactors. The core of this technology is a polymeric composite material called a biocatalyst, which retains the right bacteria in reactors for years.

The result? A complete separation of sludge age from system design, resulting in:

• Up to?50% reduction in reactor volume
• 30% reduction in aeration energy demand
• 90% increase in potential biogas production?(compared to conventional systems)

Real-World Applications and Benefits

Microvi’s solutions are already making an impact. The biocatalyst technology has been deployed to upgrade existing treatment plants to meet new nitrogen and phosphorus permit limits, as well as for new greenfield sites aiming to deliver high effluent quality at the lowest possible cost. Successful implementations include nitrate treatment for groundwater and high-strength ammonia removal from anaerobic digester liquors.

Looking ahead, we are collaborating with industry leading partners to develop new biocatalysts capable of simultaneously removing phosphorus and producing struvite, as well as solutions that prevent nitrous oxide emissions during nitrification and denitrification. The technology also handles a wide range of flows and loads and able to go dormant followed by rapid start-up, making it particularly well-suited for stormwater treatment, addressing the UK's Combined Sewer Overflow (CSO) challenges.

Conclusion

In an industry where efficiency, compliance, and cost-effectiveness are increasingly critical, bacterial selection and intensification through technologies like MicroNiche Engineering offers a cost-effective path forward. By optimizing bacterial populations and reactor environments, we can meet the water sector’s evolving needs while minimizing environmental impacts and overall costs.

Are you ready to explore how intensification can transform your wastewater treatment operations? If so let’s talk about how you can achieve more with less and for less.