Anaerobic Digestion in Wastewater Treatment

Anaerobic digestion is a valuable treatment solution for organic wet waste and sewage sludge that generates renewable energy. It is a sustainable way to turn waste into resources, reduce greenhouse gas emissions, and promote circular economy principles. The technique has become increasingly relevant to industry as the latest applications are not only more energy efficient than older aerated processes, but they can also produce useful amounts of sustainable biogas that can directly replace natural gas in many applications.

What is anaerobic digestion?

Anaerobic digestion (AD) is a natural process that breaks down organic material in the absence of oxygen, using microorganisms to convert it into biogas and digestate. The process normally takes place in a gas-tight vessel, known as a digester or AD reactor, that allows the ideal conditions for bacteria to carry out the process explained below.

The anaerobic digestion process

We’ve set out the process below which explains how anaerobic digestion turns waste into renewable energy and food for the earth in 5 simple steps.

  1. Organic material, such as food waste or animal manure, is loaded into a sealed tank called a digester.
  2. Bacteria inside the digester break down the organic material into smaller molecules, such as sugars and fatty acids.
  3. Other microorganisms, called archaea, then convert these molecules into a gas called biogas, which is made up mostly of methane.
  4. The biogas is collected and can be used as a renewable energy source.
  5. The remaining solid material, called digestate, can be used as a fertiliser or processed further to recover valuable components.

Anaerobic Digestion Advantages

There are four distinct advantages of anaerobic digestion as part of the wastewater treatment process:

Renewable energy: Biogas produced by the digester is a renewable energy source that can be used to generate electricity and heat.

Waste reduction: Using the Anaerobic Digestion process can help reduce the amount of organic waste going to landfills, which can reduce greenhouse gas emissions and mitigate climate change.

Cost savings: Companies who invest in this technology can reduce operating costs by using the energy produced to power their plant operations.

Nutrient-rich fertiliser: The solids remaining after the digestion process can be used as a nutrient-rich fertiliser for crops and can help reduce the use of costly chemical fertilisers.

What industries would benefit from Anaerobic Digestion at their wastewater treatment plant

Anaerobic digestion is most beneficial where there is a large volume of organic wet waste, hence its heavy adoption in the agricultural and Food and Beverage sectors. That being said, the opportunities are not limited to these sectors as it can also be used to treat sewage waste – which could apply to any large site that processes organic matter or sewage. However, it is not well suited to the treatment of hazardous waste or waste streams containing high levels of certain contaminants.

Anaerobic Digestion Solutions

Contact us today to find out more about how Anaerobic Digestion could help you to recover energy from waste at your wastewater treatment plant

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Anaerobic digestion process in wastewater treatment‍

As companies work hard towards Net Zero targets, and deal with the rising cost of resources, more focus is being put on long term solutions for sustainable operations and for meeting environmental targets in a cost effective way. Anaerobic digestion is an effective way of processing organic wet waste in order to produce energy and by-products that can be sold on.

When combined with aerobic water treatment technologies it can also be part of the process to recycle water for use on site, thus reducing the requirement for potable water on site. In this way, over the long term it could be a wise investment that could more than pay for itself in terms of neutralising the cost of running the wastewater treatment plant.

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Anaerobic Digestion Plant Management

Managing an Anaerobic Digestion plant requires specialist skills and knowledge in order to ensure the highest standards of safety and maximise the production of valuable biogas for energy and heat.

Operational and Process Safety

High standards of operational safety are important on any site, but as the process creates methane which is highly combustible, additional measures must be in place to prevent a major accident such as an explosion, that would post a threat to life, health and the environment. By implementing additional process safety practices, Alpheus provides protection and reassurance. Find out more in our guide to process safety in wastewater treatment.

Maximising biogas production

As anaerobic digestion is an organic process, with microorganisms working to breakdown organic material to produce biogas, the production of gas is very dependent on optimal conditions in the reactor. Even small changes to the wastewater being processed, can have a big impact on biogas production.

Alpheus closely monitors reactor health and the effluent being processed in order to optimise biogas production at all times.

Read our case study on how we helped The Glenmorangie Company increase biogas production at their distillery in Tain.

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