How to Manage Surface Area Loading Rate in Wastewater Treatment

By: Tom Frankel
Post Date: December 22nd 2023

Table Of Contents

1. What Is a Surface Area Loading Rate?
2. What Is a Solid Loading Rate?
3. MBBRs and Surface Area Loading Rates
4. Why Choose SSI Aeration MBBR Systems?
5. Contact SSI for Surface Area Loading Rate Solutions

Wastewater treatment is crucial for both human health and the environment. Finding effective and timely ways to remove toxic or harmful waste from wastewater should be a top priority for wastewater treatment plants. As technology advances and improves, some wastewater treatment facilities may not even realize more efficient processes and systems are available.

So, how can these facilities improve? One way is by understanding surface area loading rates. Additionally, implementing certain treatment systems, such as moving bed biofilm reactors (MBBR), can help streamline and speed up wastewater treatment processes.

What Is a Surface Area Loading Rate?

In wastewater treatment, the surface area loading rate refers to the amount of water that goes through 1 square foot of a wastewater treatment tank per day. Surface area loading is also known as the hydraulic loading rate in wastewater treatment.

The surface area loading per tank tells us how much water each tank can handle. A typical rate for wastewater plants is 300 to 1,200 gallons per day (GPD) per square foot.

How to Calculate Surface Area Loading Rate

Since the surface area loading rate is the number of gallons of wastewater that pass over one square foot of tank per day, you can calculate surface area loading rates by dividing the system’s total GPD by the tank’s surface area in square feet:

• Surface Area Loading Rate in GPD/ft²= total GPD/total surface area in ft²

What Is a Solid Loading Rate?

The solid loading rate (SLR) is the weight of solids removed daily per square foot of a clarifier’s surface area. These solids are typically extracted from wastewater by a secondary clarifier. To determine a system’s SLR, divide the total pounds of solids entering the system by the surface area of the clarifier. SLRs are written as pounds per square foot.

• SLR in pounds/ft² = total solids in pounds/total surface area in ft²

MBBRs and Surface Area Loading Rates

Moving bed biofilm reactors (MBBR) are an effective solution for companies and industrial plants that produce wastewater. With many benefits and excellent results, MBBR systems are a top option for plants looking to improve surface area loading rates.

What Is MBBR?

MBBR is a natural wastewater treatment process that uses biofilm to extract waste. During this treatment process, microorganisms clean the water by consuming waste. These microorganisms are added to wastewater via media systems or media carriers.

Media come in various shapes like coin-shaped discs, squares and hexagonal wheels. These carriers provide a large surface area, perfect for microorganism growth. Media and water also have similar density levels, which allows them to mix well and makes it easier for the microorganisms to remove waste consistently.

During this treatment, oxygen is added to the tank to help promote microorganism growth. As wastewater flows through the tank, mesh screens prevent the microorganism carriers from being swept away with the moving water.

While MBBR can be a standalone treatment, it is often used as a step in a much more extensive treatment process. Other accompanying treatments typically include disinfection and grit removal.

How MBBR Can Impact Surface Area Loading Rates

MBBRs have a high hydraulic capacity, meaning they can handle more water, which increases surface area loading rates and the overall efficiency of wastewater treatment.

Since the carriers and microorganisms used in MBBR are so small, they take up minimal space, allowing for more water and more effective and efficient waste removal. With so much surface area, MBBR systems can also handle shock loads.

Additionally, MBBR systems have a relatively low hydraulic retention time (HRT), averaging about a few hours or less. HRT is the time needed for a water treatment system to treat wastewater. The faster the treatment process, the more water can be treated — so low HRT is ideal.

As media continuously move and consume waste, MBBR systems process and treat wastewater more quickly than other systems.

Benefits of MBBR

Treatment plants using MBBR systems will see better surface area loading rates and other benefits. Some of these benefits include:

• Extended system life span
• Lower space requirements
• Better treatment efficiency
• Increased hydraulic capacity
• Lower energy, operating and maintenance costs
• Simpler operation compared to more traditional systems

Various media options are available, and SSI Aeration’s MBBR systems automatically and naturally adjust to any changes in the surface area loading rate.

Why Choose SSI Aeration MBBR Systems?

Through innovative and advanced designs, SSI Aeration has created the best MBBR system in the industry. Plants and treatment centers that use SSI Aeration products get efficient and effective systems and receive the following benefits:

• In-house media creation: The engineers at SSI Aeration create superior quality media that meet the requested specifications for an even more efficient system.
• Industry-specific experience: SSI has extensive experience working with various industries to meet their MBBR needs. These industries include textile, food, pulp-and-paper manufacturing, chemical manufacturing and petroleum-processing industries.
• Robust R&D program: The SSI research and design program is always looking for ways to improve and enhance MBBR media and systems, so MBBR systems from SSI will always include the newest technology and methods.
• In-house diffuser creation: SSI engineers create their own diffusers to provide plants with the highest quality and performance. These diffusers are also specifically designed for complete compatibility with SSI media.
• SOTE testing: SSI Aeration offers standard oxygen transfer efficiency (SOTE) testing year-round. We also have a library of existing test reports that may be able to approximate your system’s efficiency.

Contact SSI for Surface Area Loading Rate Solutions

SSI engineers have the expertise and experience to help optimize your facility’s surface area loading rate and overall productivity. SSI Aeration can improve your wastewater treatment efficiency, whether it’s a complete system replacement or a supplemental product. With various advanced products and services, SSI has the solution for even the most unique facility needs.

From cutting-edge MBBR technology to installation and staff training services, SSI Aeration has positioned itself as a global leader in the wastewater treatment industry. See why so many facilities trust SSI technology, and contact a representative today to learn more about what these products and services can do for you.

Tom Frankel

Mr. Frankel co-founded SSI in 1995 with experience in design and distribution of engineered systems. He is in charge of sales, marketing and operations in the company. Mr. Frankel holds multiple US patents related to diffusers. He is a graduate of Washington University in St. Louis.