On the other hand, current research suggested that biofilms can be useful for constructive purposes such as a template of new materials[1][2] that may find applications in the industry.
Biofilms can consist of a multitude of bacteria, fungi, and algae which are able to absorb, immobilize, and degrade many common pollutants found in wastewater.
[4] Biofilms contain a high amount of extracellular polymeric substance (EPS) which is made up of polysaccharides, proteins, DNA, and phospholipids.
[7] Heavy metals— such as lead, copper, manganese, magnesium, zinc, cadmium, iron, and nickel—form complexes with negatively charged functional groups in the EPS and become trapped.
[8] Recent studies also employ biofilms to trap and aggregate difficult-to-remove microplastics for convenient removal from the polluted environment.
This includes suspended solids, pathogens, and organic compounds increasingly found in agricultural, industrial, hospital, and household wastewater.
[12] Producing dairy products is a water-intensive process and generates large amounts of wastewater from washing equipment and from by-products.
[14][15] This technology in particular has been used in industry as an alternative to conventional activated sludge processes in order to remove organic matter and nutrients, such as carbon, nitrogen, and phosphorus.
[17][18] Current bioelectrochemical systems for treatment of complex wastewater (e.g. contains dye, antibiotics, heavy metals) by inducing redox reactions can be time-intensive and have limited mass transfer.
It is still unclear the cost of this technology and how it can handle varying conditions of wastewater (e.g. electrical conductivity, concentration of salt, pH).
These factors can make it challenging to use immobilized biocatalysts to produce bulk chemicals and fuels that often have a low market price.
[21] Due to the structure of biofilms, there are mass transfer limitations that lead to gradients in nutrient and product concentrations, pH, and temperature.
Thus, bacterial subpopulations develop which can reduce the amount of bacteria actively producing the chemical of interest thereby decreasing product yield.
For some low-value bulk chemicals that do not require sterile conditions, this feature can be taken advantage of by using a mix of microbes which may improve the overall yield.
It has been considered as an alternative to conventional wastewater treatment methods, or as a step before the membrane reactor, or to reduce the amount of solid sludge produced.
Researchers have looked at treating dairy, animal carcass, brewery, winery, and domestic wastewater, to name a few, with microbial fuel cells.
This technology, however, has yet to be fully successful on a large scale due to low power density and the fluctuating temperature and composition of real wastewater.