Biofilm is a multilayer and multicellular biological membrane complex in terms of structure and composition, composed of different types of bacteria and other microorganisms, surrounded by a layer of organic and inorganic substances. Homogeneous biofilms (single-species biofilms) do not occur in the natural environment. As they are heterogeneous, they are so resistant to various measures aiming to get rid of them. The biofilm matrix is also very dense and therefore difficult to remove.
Another problem related to the presence of biofilm is biofouling. Biofouling, or biological fouling is the proliferation of biological material on the surface of various devices (which is highly dangerous for all types of systems).
Biofilm is a serious threat not only to the proper and efficient operation of a plant and equipment, but can also cause dangerous chronic diseases and infections. It is one of the biggest hazards in hospital facilities. In these places, it is particularly dangerous and poses a serious challenge to sanitation services. For example, there may be biofilm formations on catheters, drains and other equipment used in hospitals. Biofilm is resistant to numerous substances, including antibiotics or biocides.
This protective structure for bacteria and for other pathogens is also resistant to factors such as high temperature, mechanical extraction or bactericidal chemicals. Where does this uniquely effective protection exhibited by biofilm come from?
It is not only related to the density of a multilayer and structurally diverse matrix, but also to the ability of the biofilm to produce substances referred to as EPSs, i.e. polymeric secretions that further bind and strengthen the architecture of the biofilm. In such favourable conditions, hazardous and health-threatening microorganisms develop really fast, they include: Legionella, Listeria or E.Coli bacteria.
Effective biofilm control - preventing biofilm formation
Without a doubt, getting rid of biofilm is not a simple task, but it is a must. The best way to deal with biofilm, however, is basically preventing biofilm from developing. Maintaining high standards of hygiene and cleanliness as well as using appropriate disinfection methods, can completely prevent the phenomena of massive proliferation of microorganisms, which then form the biofilm.
The following measures thoroughly solve the problem of biofilm formation:
- as early as a plant design phase: creating simple forms so that they do not promote the proliferation of microorganisms in inaccessible spots,
- using the right materials for the production of systems and equipment as it is the smoothness of a surface that is critical (acid-resistant steel with highest coefficients is the best),
- frequent and precise washing of the equipment,
- monitoring the condition of the system and equipment, replacing faulty elements,
- disinfection measures compatible with systems and equipment.
If biofilm is detected, proceed to remove its layers as quickly as possible. It is important to act quickly because biofilm can split, spread and infect other parts of the system. Biofilm removal works must be comprehensive. Usually several methods must be used simultaneously.
These methods are grouped into: mechanical, chemical, thermal and enzymatic.
- mechanical: physical removal of biofilm (cleaning off the formation). These works include: scraping or brushing aiming to get rid of the basic structure of the biofilm layer, which in turn facilitates its removal by chemicals.
- chemical: these methods aim to remove the structures of biofilm completely and to get rid of microorganisms that have the ability to form biofilms. These techniques are selected according to the material of the installation. For this purpose, agents such as ozone, chlorine and its compounds (e.g. chlorine dioxide - particularly effective in removing biofilms from water systems), peroxyacids (e.g. very effective peracetic acid with hydrogen peroxide) or biguanides are used.
- thermal: less effective than the above, but used in systems that "respond" well to sterilization by steam.
- enzymatic: additional method used to enhance mechanical and chemical removal. Enzyme-based formulations can be used to decompose biofilm and, last but not least, to enhance disinfection procedures.