Biofilm Control: Conventional and Alternative Approaches

Abstract

"Biofouling" is referred to as the unwanted deposition and growth of biofilms. This phenomenon can occur in an extremely wide range of opportunities ranging from colonization of medical devices, during production of ultrapure drinking and process water, and fouling of ship hulls, pipelines and reservoirs. Although biofouling occurs in such different areas, it has a common cause, which is the biofilm. Biofilms are the most successful form of life on earth and tolerate high concentrations of biocidal substances. Conventional anti-fouling approaches usually rely on the efficacy of biocides, aiming for inhibition of biofilm growth. It is important to keep in mind that killing of biofilm organisms usually does not solve biofouling problems as mostly the biomass is the problem and must be removed. Therefore, cleaning is at least equally important. However, for a sustainable antifouling strategy, an advanced approach is suggested, which includes the analysis of the fouling situation, a selection of suitable components of the "anti-fouling menu" and an effective and representative monitoring of biofilm development. One important part of this menu is nutrient limitation, which could be implemented on a much broader scale than is practiced today. Other items on the menu include methods to monitor unwanted biofilm development and assessment of the efficacy of anti-fouling measures. Also, natural anti-fouling strategies are worth exploring and learning from -and nature never relies on only one defence line but on integrated approaches.

The role of cell-surface interactions in bacterial initial adhesion and consequent biofilm formation on nanofiltration/reverse osmosis membranes

“…Besides competition for adhesion sites, an adsorptive layer may provide a metabolically favourable environment for bacterial cells, due for example to enhanced nutrient availability at that surface [103]. However, the presence of this conditioning layer has been overlooked [104], especially in a membrane filtration context. NF and RO membranes are mainly used for the treatment of surface water, groundwater, wastewater effluent and seawater.…”

Assessing biofilm development in drinking water distribution systems by Machine Learning methods

“…For cleaning, cohesion of the biofilm and adhesion to surfaces have to be overcome, which are both aspects of the mechanical stability of biofilms [114]. These help to redistribute the residual disinfectant to all sections of the system and eliminate the existing biofilms and sediments [115].…”

“…Electric fields have also been used for both prevention of microbial adhesion and inhibition of biofilm growth [120]. Practical observation, however, has shown that all kinds of electrodes immersed into water can be colonized by biofilms [114]. Biofilms are present, to a greater or lesser extent, in all DWDSs.…”

“…Knowing how different factors contribute to the growth of biofilms in these systems and ways to control these parameters is devised as the best prevention. Any step towards better understanding biofilm growth and properties will expand the possibilities for a flexible, effective and environmentally suitable response to biofilm development in DWDSs [114].…”

“…Sampling just the flowing water is not an option. It does not give information about the biofilm location, extent or composition and, moreover, it generally underestimates by several orders of magnitude the true microbial (surface) burden of a system [114]. Thus, collecting biofilm samples is necessary for its study.…”