How To Select The Right MBBR Media?

MBBR media is a cylindrical suspended plastic carrier made of plastic or other chemically inert materials in the aeration tank. It's often used in the Moving Bed Biofilm Reactor(MBBR)process of sewage treatment, to break down pollutants in water.

However, this media can be made from a variety of materials, and the surface properties of these materials vary greatly. This leads to different growth states and activities of microorganisms, resulting in different treatment efficiencies. Therefore, how to select the appropriate material has become a problem when we design the water treatment projects. In this article, we will compare the characteristics of MBBR media of different materials and the factors to be considered, and provide you with professional selection advice.

 

MBBR media is a cylindrical suspended plastic carrier made of plastic or other chemically inert materials in the aeration tank. It has many small ridges or grooves and has a large surface area ratio, enabling it to attach and grow into a biofilm. In addition, it can float and move freely in the aeration tank, supplying sufficient oxygen to the biofilm to maintain the high activity of microorganisms. Eventually, these microorganisms can actively decompose the organic pollutants in the wastewater in the aeration tank to improve the water quality.

 

MBBR media is available in several material types, and the most common ones include HDPE, PP, and PE. Now let's take a look at what they are respectively.
(1) High-Density Polyethylene (HDPE): High-density polyethylene is a thermoplastic polymer extracted from petroleum. It is used for many purposes, including plastic bottles, milk jugs, and pipes. The density of HDPE MBBR media ranges from 0.941 to 0.965 g/cm³, and the molecular chains are closely arranged. This gives it higher strength to resist the impact of water flow and aeration.
(2) Polyethylene (PE): Polyethylene (PE) is a polymer made from many ethylene molecules linked together, derived from natural gas and crude oil. It has different crystal structures, known as HDPE, LDPE, and LLDPE. It is often used to produce plastic bags, films, bottles, etc. When used as MBBR media, it can resist the erosion of various chemical substances and remain stable in both acidic and alkaline environments.
(3) Polypropylene (PP): Polypropylene (PP) is made by chain-growth polymerization of the monomer propylene. Compared with PE, it has a higher melting point, approximately 160 - 170°C, which allows it to be used in wastewater environments with higher temperatures. At the same time, PP has good chemical resistance and hardly undergoes chemical reactions in common acid, alkali, and salt solutions. If you want to use MBBR media for treating high-concentration organic wastewater (such as wastewater from the papermaking and chemical industries) and applications requiring efficient nitrogen removal, PP material will be a very suitable choice.

1. Sewage Type: Sewage can be classified into various types due to different sources and contains different components such as COD concentration, phosphorus, ammonia, and nitrogen.

Municipal Sewage: Municipal sewage mainly comes from domestic sewage and commercial drainage, etc., and its composition is relatively stable. Its pollutants are mainly organic substances, nitrogen, phosphorus, and other conventional substances. HDPE and PE materials of MBBR media are most commonly used in municipal sewage. They can withstand these components and have a more robust structure, so they can withstand the scouring of large flows of water.

Industrial Sewage: Industrial sewage has a very complex composition, including various strong acids, strong alkalis, heavy metals, and refractory organic compounds, etc. HDPE media not only has chemical corrosion resistance but also has a high mechanical strength structure. It can well withstand the high water flow velocity and aeration intensity of industrial wastewater treatment equipment.

High-Temperature Sewage: PP packing is suitable for high-temperature environments due to its good heat resistance. In some high-temperature wastewater generated during industrial production processes, such as the wastewater from thermal power plants and some chemical production processes, the water temperature may exceed 50°C. The relatively high melting point of PP material (approximately 160 - 170°C) enables it to maintain stable physical and chemical properties at high temperatures without deformation.

2. The Specific Surface Area of the Media: The larger the specific surface area, the more attachment sites there are on the surface of the MBBR media for microorganisms. At this time, a large number of microorganisms can attach, grow, and reproduce, come into contact with and decompose the pollutants in the sewage. Generally, we will choose packing with a specific surface area between 500 - 1000 m²/m³.

3. The Density and Suspension Effect: The degree to which the density of the MBBR media is close to that of water determines whether it can suspend well in the aeration tank. The ideal density of the media for placement is around 0.96 - 1.0 g/cm³. When the density of the packing is close to that of water, under the agitation of the water flow generated by aeration, the packing can be evenly suspended in the sewage. If the media is too light or too heavy, they will float on the water surface or settle at the bottom of the tank.

4. Durability and Service Life: The service life of these media affects your investment cost and maintenance cycle for the aeration tank. Among them, HDPE and PE have a relatively long service life, generally up to 8 - 10 years. Although PP material is heat-resistant, it is relatively more prone to aging. Under the long-term effects of light, temperature changes, and chemical substances, its performance may gradually decline. Therefore, it is more suitable for short-term, cost-effective projects.

5. Economic Cost: Among the common MBBR media, PP material has the lowest cost. It is very attractive in some projects with limited budgets, but due to its poor durability, it needs to be replaced regularly. Although the cost of HDPE material is higher than that of PP, it performs more stably in long-term operation. This will result in a lower replacement frequency and a stable treatment effect.

In sewage treatment, choosing the appropriate media may not be that simple, but we suggest that you can:

• If it is municipal sewage or ordinary industrial wastewater, it is recommended to choose HDPE (high-density polyethylene) media. Because its comprehensive performance is the best and it is very durable.
• If it is a project with a limited budget, PP (polypropylene) media will be more suitable. The price of PP is relatively low, which can help you better control the project cost. However, its durability is slightly inferior to that of HDPE. During long-term use, it needs to be replaced regularly.
• If you want to use these MBBR media for high-temperature and highly corrosive wastewater, we still recommend that you choose HDPE with strong chemical resistance or heat-resistant PP packing.
• No matter what kind of packing is chosen, do not use inferior packing to affect the sewage treatment effect. Regular manufacturers like AquaSust will strictly follow quality standards during the production process. This means that you can obtain MBBR media from them with parameters such as specific surface area and density that meet the requirements.

As a leading manufacturer of MBBR media, AquaSust excels in customizing the materials, dimensions, shapes, and specific surface areas of the media for your water treatment project. And if you still have no idea how to select the appropriate MBBR media, feel free to contact our experts.