Rim Werheni

By Rim Werheni Ammeri, Yassine Hidri and Hassen Abdenaceur

In recent years, soil contamination with pesticides has become a crucial news issue with serious short- and long-term effects on human health and its environment. Pesticides play a significant role in the success of modern farming and food production. These compounds have potential for toxicity and adverse effects on human health and ecological soil systems. Pentachlorophenol (PCP) is one of the most recalcitrant chemicals polluting the environment for its stable aromatic ring system and chloride content. Nowadays, many sites are contaminated with this substance. In these areas, concentrations may stay high for a long time because of slow degradation in the soil due to the negative effects that PCP has on soil microbial populations. Bioremediation of PCP contaminated sites can be realized introducing directly, into a contaminated system, microorganisms able to consume selectively the target compound (bioaugmentation) or increasing the microbial indigenous population by addiction of nutrients in form of organic and/or inorganic fertilizers and biosolids (biostimulation). In the present chapter, we present an overview of the effect of PCP pesticide contamination on soil microbial populations (density and diversity), enzymatic activity and physicochemical parameters. Additionally, the bioremediation process will be detailed.

Part of the book: Soil Contamination

By Wafa Hassen, Bilel Hassen, Rim Werhani, Yassine Hidri and Abdennaceur Hassen

The valorization of different organic residues like municipal solid wastes, sewage sludge and olive mill wastewater is becoming more and more worrying in the different modern communities and is becoming relevant and crucial in terms of environmental preservation. The choice of the treatment technique should not be only from the point of view of economic profitability but, above all, must consider the efficiency of the treatment method. Thus, an attempt to remove polyphenols from olive mill wastewater would have a double interest: on the one hand, to solve a major environmental problem and to recover and valorize the olive mill wastewater for advanced applications in food processing and soil amendments. It is also interesting to think of associating two harmful wastes by co-composting such as sewage sludge-vegetable gardens, sewage sludge-municipal solid waste, and green wastes-olive mill wastewater…, to get a mixed compost of good physical–chemical and biological qualities useful for agricultural soil fertilization. Finally, in order to be more practical, we will describe specifically in this chapter a new variant of composting and co-composting technology intended for waste treatment that is very simple, inexpensive and easy to implement.

Part of the book: Humic Substances

By Salma Kloula Ben Ghorbal, Rim Werhani and Abdelwaheb Chatti

A biofilm has been defined as a community of bacteria living in organized structures at a liquid interface. Biofilms can colonize a wide range of domains, including essentially industrial sectors, different natural environments, and also biomedical environments. Bacteria in biofilms are generally well protected against environmental stresses and, as a consequence, are extremely difficult to eradicate. The current study was to investigate the efficacy of different radiations against bacterial biofilms on different surfaces. It was established that the majority of available treatments have proven less effective against pathogenic biofilms, compared to planktonic bacteria. Therefore, new biofilm treatment strategies are needed, including physical treatments such as radiations. UV LEDs offer new solutions to prevent biofilm formation on inaccessible surfaces, such as medical and food equipment and, potentially, sanitary facilities, to limit nosocomial infections, compared to continuous UV irradiation treatment. Moreover, the antimicrobial effectiveness of gamma irradiation is therefore guaranteed in the treatment of bacteria associated with a biofilm, compared to planktonic bacteria. However, limited studies have been conducted to evaluate the inactivation effect of low-energy X-rays on more resistant biofilm pathogens on food-contact surfaces.

Part of the book: Focus on Bacterial Biofilms