Anionic and cationic surfactants are very common pollutants which could be biodegraded by microorganisms during the biological step of the Wastewater Treatment Plant (WWTP) process. During the biodegradation step, the microorganisms use the surfactant as as a source of nutrients breaking down their chemical structure into simpler chemical compounds. There have been data showing that certain surfactants can be completely biodegraded to CO2 and H2O, but there have been also data suggesting that some surfactants were extremely low biodegradable. Their low biodegradability could reside on surfactants negative effects on water’s surface, such as reducing air/water oxygen transfer, lowering the water quality by foam introduction and sorption on solid particles which generate a toxic effect on microorganisms. For these reasons it is necessary to determine the individual biodegradability of each surfactant or each class of surfactants. In this study, we investigate de biodegradability potential of cationic and anionic surfactants and subsequently their effect on microorganisms. The cationic surfactants, quaternary ammonium salts are molecules with at least one long hydrophobic alkyl chain attached to a positively charged nitrogen atom. The properties of the cationic surfactants linked to surface activity, adsorption onto negatively charged solids, biocidal activity, and their reaction with anionic surfactants made them desirable for a large number of applications such as fabric softeners, disinfectants, demulsifies, emulsifiers, wetting agents, and processing aids. Unfortunately, quaternary ammonium salts can harm organisms from the aquatic systems. Alkyl sulfate and alkyl benzenesulfonate are two of the main anionic surfactants used and sold in high amounts because of their wide range utility in different fields such as personal care products, petrochemical production and foaming production. The excessively presence of cationic and anionic surfactants in the environment generates concern due the pollution effects on the ecosystems by affecting both aquatic systems (marine ecosystems and freshwater ecosystems). The study of their biodegradation potential was carried out for 28 days and the results showed a partial biodegradation of surfactants induced by the microbiological community from the activated WWTP sludge.

Environmental pollution is an important issue influencing human health and environmental equilibrium. The range of pollutants is very wide due to industrialization and population growth and surfactants are one of the most common organic pollutants due to their extensive use and ubiquitous presence from industry to households. Their massive presence in the domestic and industrial wastewater could affect the Wastewater treatment plants by inhibiting the activated sludge used in pollutants biodegradation treatment step. This paper aimed to study the inhibition effect of three classes of surfactants (nonionic, anionic, and cationic) by measuring the respiratory activity of microorganisms with the application of the Oxygen Uptake Rate (OUR) test. This study established that the surfactants could activate or inhibit microorganisms’ activity, depending on surfactant concentration.

In the last 20 years, moving bed biofilm reactor (MBBR) has been established as a simple yet robust, flexible, and compact technology for wastewater treatment. It is one of the advanced aerobic wastewater treatment processes by taking advantage of both attached and suspended growth systems. The vast majority of bacteria adhere to surfaces and form complex and heterogeneous microbial communities termed biofilms which have tremendous positive potential in biotechnology for biocatalysis and waste treatment. In this work, we studied the Escherichia coli (E. coli) adhesion properties on synthetic artificial materials (SAMs), also known as biofilm carriers, based on High-Density Polyethylene (HDPE). The results showed that E. coli adherence to SAMs is not only preserved but is also enhanced by the presence of 7% cellulose in SAM’s composition.