What is an anaerobic reactor, what is it used for, and in which industries is it useful?

When we talk about sustainable solutions for industrial wastewater treatment, to understand what a anaerobic reactor is fundamental.

In broad terms, this technology It allows the purification of water with a high organic matter load. (common in sectors such as agriculture, food or the chemical industry) through biological processes in the absence of oxygen.

During the process, Anaerobic reactors transform the organic remains in water into biogas, a renewable energy source. In this way, in addition to reducing the environmental impact of industrial waterThe waste generated is valued, improving the energy efficiency of the system.

In this way, in addition to reducing the environmental impact of the dumping, the generated waste is given value, improving the system energy efficiency.

From SITRA, We'll tell you what an anaerobic reactor is, how it works, and why it's a Excellent alternative for wastewater treatment. 

What is an anaerobic reactor and how is it used for water treatment?

An anaerobic reactor is a unit designed to decompose organic matter without using oxygen.

In water treatment, inside this unit there is microorganisms (biomass) that decompose the organic remains present in the flow, transforming them into simpler compounds (such as methane and carbon dioxide) and generating biogas.

The operation of the anaerobic reactor is simple: el Wastewater is introduced into the unit, comes into contact with the active biomass and, as it mixes With it, its organic compounds degrade, generating biogas and reducing the pollutant load of the effluent.

Types of anaerobic reactors 

Depending on how the biomass is organized and behaves within the system, we distinguish three types of anaerobic reactors:

Anaerobic reactors with suspended biomass

The biomass is mixed with the wastewater inside the tank in two ways: 

• All the contents inside the reactor are stirred at once., maintaining a homogeneous mixture (completely mixed or anaerobic contact reactors). 
• The water moves inside the reactor in a single direction., and it gradually mixes with the biomass (plug-flow reactors).
  

Anaerobic reactors with biomass in granular form

In this case, The biomass is organized as compact granules with simple sedimentation.  

We can distinguish between: 

• UASB (Upflow Anaerobic Sludge Blanket). Are the anaerobic reactors most commonly used at an industrial level. Wastewater flows from the bottom up through a sludge bed, and the biomass forms dense, compact granules that break down the organic matter present. ideal for waters with a high organic load, but with few suspended solids.
• EGSB (Expanded Granular Sludge Bed). They are a evolution of the UASB. La The water flow speed is higher, so the mud bed expands more. This type of reactor is recommended all with Treatment plants with limited space or for large flows with many organic remains.

Attached biomass anaerobic reactors (also called film reactors or biofilm)

In this type of anaerobic reactor, The biomass is attached to a solid support.

They may be: 

• Fixed bed or fluidized bed. They use a stationary (fixed bed) or mobile (fluidized bed) support material that facilitates the development of a microbial biofilm. efficient at removing soluble organic compounds and the water retention time inside the reactor is minimal. 
• From a mud blanket. They use support media (plastics, ceramics, etc.) for the biomass to adhere to them. They are suitable for small flow rates and effluents with low solids concentration.

There is a second classification of anaerobic reactors depending on their technological development. 

• 1rd generation anaerobic reactors. They are characterized by retaining biomass without agitation processes or advanced technology (for example, the septic tank or the Imhoff tank).
• 2rd generation anaerobic reactors. They integrate attached biomass or fixing systems to improve contact and degradation of the biological components of the water, increasing the control and efficiency of the process (for example, fixed bed or sludge blanket systems).
• 3rd generation anaerobic reactors. They are the most advanced and are designed to optimize the function of the biomass, allowing shorter water retention times, greater operational stability and more efficient treatment (for example, UASBs and EGSBs).

Choosing one type of anaerobic reactor over another depends on the organic load of the water, the available space, and other technical issues.

In any case, it's best to seek advice from Professionals with extensive experience in wastewater treatment using the most advanced technologies.

What is an anaerobic digester?

An anaerobic digester is a type of reactor designed to stabilize solid or semi-solid organic waste (such as sludge generated during water treatment).  

These types of systems operate under controlled conditions of temperature, pH, and retention time, and They serve to reduce the volume of waste, minimize odors, inactivate potential pathogens, or produce biogas as an energy byproduct. in addition to facilitating the use of digestate for agricultural purposes, with important benefits of composted digestate.

Types of anaerobic digesters for treating sludge

The Types of anaerobic digesters used in wastewater treatment are: 

• Complete mix. They maintain a homogeneous mixture of substrate and microorganisms through mechanical agitation or recirculation. suitable for liquid or semi-liquid waste with low solids concentration
• Batch loading. The system fills completely and It is sealed during the digestion process, which can last for weeks.They are simple and inexpensive, but nor they allow for the continuous production of biogas. 
• Semi-continuous loading. They are fed periodically with new organic matter and, in return, a fraction of the digestate is extracted (i.e., the degrading microorganisms are renewed). This is the most common option for the digestion of sludge and agro-industrial waste.
• Piston flow. The substrate advances linearly, with little or no internal mixing. They are used in waters with solid biological remains.
• High rate. They are integrated with UASB or EGSB reactors to increase treatment efficiency, saving time and resources. They are common in industries with large volumes of organic wastewater.

Difference between an anaerobic reactor and an anaerobic digester

Although Both are based on anaerobic biological processes, The reactors are designed to treat liquid wastewater.While Digesters are used for waste with a higher solids content. such as the mud.

In addition, lReactors are used to treat large volumes in a reduced time, while The digesters need to retain the sludge for a longer time and require very controlled thermal conditions.

In what cases is it recommended to implement an anaerobic reactor?

Anaerobic reactors are recommended in industries whose wastewater has high COD (Chemical Oxygen Demand) loads. 

In these cases, the microorganisms that operate within the reactor They are capable of degrading large amounts of organic matter, producing biogas, while They meet the mandatory quality standards for this type of discharge.

This technology is especially recommended for agri-food and beverage companies (for example, wineries, breweries, juice production plants and fruit processing plants), since their effluents normally contain remains of plant or animal origin. 

However, it should be noted that it is It is common to integrate reactor and anaerobic digester into the same system: The first one treats wastewater and generates secondary sludge, which is then sent to the second one, where it is stabilized, its volume is reduced, and it continues to generate biogas.

Find the appropriate technology y Combining equipment optimally reduces operating costs and improves the sustainability of industrial water treatment systems. 

At SITRA we advise companies to help them manage their waste efficiently. 

We are present throughout the entire water treatment process, and we offer you the best solutions for each case. 

Some of the reasons why We advise our clients to opt for an anaerobic reactor because: 

• • Economic savings and reduction of operating costs.

• Less sludge generation.

• • Better use of space.

• Energy valorization of biogas.

• • Better resistance to variations in concentration and amount of charge.
  • Greater flexibility in biomass treatment.
• High efficacy for the treatment of high COD loads.

It reduces operating costs and improves the sustainability of systems, applying ➡️ water saving measures in industry that do not affect productivity

Do you have more questions about what an anaerobic reactor is or what it is used for? Contact Us for any information you may need. 

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