Innovative approaches to treating wastewater
In this blog, infrastructure engineer Ari Hammerschlag explores the pressure on legacy wastewater systems caused by increasing urban population and a global drive to minimise potable water consumption. And, how this has led the water industry to develop new and more innovative ways to treat wastewater and sustainably reuse the output.
At Buro Happold our specialist wastewater engineers are constantly reviewing the market and the technologies being developed, and are excited by how quickly this area of the industry is changing. In this blog, we explore emerging technologies for wastewater treatment which have advanced from two of the more traditional approaches to wastewater treatment.
The first traditional approach ‘Constructed Wetland’ consists of a shallow basin filled with a type of filter material. Vegetation in the wetland provides a surface (roots, stems, and leaves) upon which microorganisms can grow as they break down organic materials. The second, ‘Conventional Activated Sludge’ or CAS, is a traditional process for wastewater treatment that uses the supply and restriction of oxygen to treat water.
The schematic below sets out the stages that would typically be undertaken in a large CAS wastewater treatment plant.
While both of these traditional techniques for treating wastewater are reliable and low maintenance, they require large land takes, pose issues with odour and mosquitos, and can be difficult to upgrade or adjust in size. This is particularly significant in an urban development and industrial context where space is often at a premium.
These issues have resulted in the development of a number of new alternatives to traditional CAS systems that also offer additional benefits to an asset owner such as reductions in the following factors:
- Land take
- Odour and visual impacts
- Energy use
- Water losses
- CAPEX
- OPEX
- Ownership considerations
- Maintenance
Some of these new technology alternatives are set out in the following infographic.
Four of these innovative new technology types are briefly summarised below:
1. Sequence Batch Reactor (SBR) – Similar processes as CAS however carried out sequentially in the same tank. Find out more in this Case Study.
2. Integrated Fixed Film Activated Sludge systems (IFAS) – An IFAS is similar to a CAS treatment plant with the addition of a growth media (film) which increases the ‘real estate’ for bio-reaction in the tank. This results in a smaller reactor footprint and shorter wastewater retention times in the reactors. Types of IFAS include:
- Membrane Aerated Biofilm Reactor (MABR). Find out more in this Case Study.
- Food Chain Reactor (FCR). Find out more in this Case Study.
3. Moving Bed Biofilm Reactor (MBBR) – This technology is very similar to an IFAS system with the main difference being that the film is not fixed, but suspended in the aerobic and/or anoxic tanks. Find out more in this Case Study.
4. Membrane bioreactor (MBR) – A membrane bioreactor combines a biological treatment step, typically the activated sludge described above, with a membrane process, usually a low-pressure ultrafiltration or microfiltration membrane for wastewater treatment. Find out more in this Case Study.
This blog has highlighted how choosing the right technology mix for a project requires careful consideration. If you are facing wastewater challenges, contact our specialist engineers to discuss how we can help you select the most appropriate and efficient, wastewater treatment technology for your project.
