Particle composition and biological stability

Treatment processes can influence the biological stability of water in different ways. In the Netherlands and Flanders, the biological stability in drinking water treatment is being improved as much as possible. Extensive research into biological stability has shown that both particles and dissolved organic matter influence the biological stability of drinking water.

Better understanding of role of particles and dissolved organic matter in biological stability

The key question concerns the extent to which dissolved organic matter needs to be removed to obtain biologically stable water.

  1. A proper answer to this question requires a better understanding of the composition of particles and dissolved matter. Which nutrients are bound to particles and how can these be determined (which measurement methods/analyses)? Consideration is given, among others, to particle-bound extracellular polymeric substances (EPS), polysaccharides, iron, carbon and phosphate. A supplementary question is which (of these) nutrients play an important part in biological stability problems?
  2. Along with better insight into the composition of particles and dissolved matter, it is also important to understand how they can be most efficiently removed. Among other things, this will depend on their size. It is assumed that they are colloids and suspended particles. Rapid filtration plays an important role in utilities that use groundwater, and the question concerns the degree to which these particles need to be removed to prevent the above-mentioned problems from occurring in the distribution network. Water utilities using surface water also apply other techniques – as, for example, in Evides’s research into terminal ultrafiltration (and capillary nanofiltration) for the extensive removal of particles and dissolved matter and the improvement of biological stability in the distribution network.

The goal is to acquire deeper knowledge about the composition and removal of particles and dissolved matter from the pumping station, so that problems in the distribution network can be better controlled. The focus will be on the relation with the biological stability, and specifically through the removal of these particles using rapid filtration or membranes. These are subjects to be discussed in the workshop, which constitutes the first activity in this research project (see activities).

Sharing knowledge and experience in workshop to formulate research questions

Knowledge from previous research and water sector experience in biological stability in connection with drinking water treatment – focussed, among others, on particles (including measurement methods) – will be bundled and presented in a workshop.

Based on the information acquired, a decision will be taken after the workshop with the project supervision group on the follow-up. In particular, this will involve the choice of one specific subject that has the greatest support among the parties concerned, from both groundwater and surface water treatment utilities.

The right treatment set-up to control biological stability

In the first instance, the research project will provide knowledge about the composition of particles that is pertinent to biological stability problems. This knowledge will allow for a better grasp of the operation of relevant treatment processes (e.g., rapid filtration and ultrafiltration), and perhaps lead to their improved set-up. This developed knowledge provides an important basis for the proper appraisal and set-up of suitable treatment processes with regard to biological stability.