Microbiological degradation of contaminants in reverse osmosis concentrate

In this project, we are investigating the possibility of the microbiological conversion of specific problem substances that are found in reverse osmosis (RO) concentrate during drinking water production. The separable forms of these substances can be selectively removed. The targeted removal of specific problem substances is already used widely in wastewater treatment in other fields such as bioindustry. The primary focus here is on microbiological processes.

Challenges for reverse osmosis

The deterioration of water quality in conventional sources means that drinking water companies and other sectors often turn to treatment techniques involving nanofiltration and/or reverse osmosis (RO). Residual flows from these membrane separation techniques are normally 20-25% of the volume of the input flow. They therefore contain concentrations of dissolved substances that are 4 to 5 times higher. Residual flow management is important to ensure the safe and responsible processing of the concentrate but a suitable method is not always available for this purpose.

When discharged, the concentrate must meet requirements that vary depending on the discharge location. Selectively removing undesirable components from the residual flow makes it possible to comply with specific requirements and therefore to extend the potential range of options for the management of residual flows.

In this project, we are looking at the possibility of the microbiological conversion of specific problem substances in reverse osmosis (RO) concentrate. The separable forms of substances produced in this process can be removed selectively. A trend alert was drafted on this issue in 2020. The aim of this incubator study is to further the development and testing of the most promising techniques.

Priority list of problem substances and techniques

The first step will be a literature study. Data obtained from drinking water companies will result in a priority list of substances to be removed from the RO concentrate. A selection will then be made of the most promising techniques for the residual flow management of RO concentrate. After the most promising substances and techniques for microbiological removal have been selected, laboratory experiments will be carried out.

New microbiological techniques

This incubator study will produce the following deliverables and applications:

  • A reasoned prioritisation of specific problem substances to be removed from RO concentrate. This selection will be based on the recently published trend alert, with an additional literature study and an extra review of priorities set by the drinking water companies.
  • A selection of the most promising techniques for the removal of the problem substances. This selection will also be based on the trend alert published recently and an extra review at the water companies.
  • Experimental results from a laboratory study testing a technique for the microbiological removal of specific problem substances from water with a more complex composition.