Wastewater sludge represents an important resource for reuse in agriculture. However, potentially harmful pathogens are a main threat in this context. Thus, the aim of this study was to examine the presence of helminth ova and protozoan cysts in dried sewage sludge samples collected from ten wastewater treatment plants (WWTPs) located in eight governorates in Tunisia. Based on morphological criteria, protozoan cysts of Giardia spp., Entamoeba histolytica/dispar/moshkovskii, and Entamoeba coli, were detected in all dried sludge composite samples (N = 116) from the investigated WWTPs. The mean concentration ranged from 1.4 to 10.7 cysts per 100 g dry matter (DM). The identified helminth eggs were Ascaris spp., Strongyles, Taeniid eggs, Hymenolepis nana, Enterobius vermicularis, and hookworm species. Ascaris spp. and Taeniid eggs were detected in 56.9 and 74.1% of analyzed samples, respectively. The presence of Trichuris spp., Hymenolepis diminuta, and Toxocara spp. eggs in dried sewage sludge samples was low (0.9, 1.7, and 2.6%, respectively). The mean concentration of helminth eggs during the three-year study was less than 1 egg/100 g DM. All examined dried sewage sludge sample contents were below the WHO (2006) and US EPA (2003) recommendations, and thus, the sludge can potentially be reused in agriculture.

Microbial characterization of composting is of importance for the optimization of the process and the quality of the end product. The aim of this work was to follow microbial biomass C and N dynamics during the composting process of urban solid waste. Microbial biomass C ( B_C) ranged from 4.06 to 1 μg kg^-1 of dry compost from day 5 to day 62 and decreased to reach 0.44 mg kg^-1 in mature compost. Microbial biomass N ( B_N) showed the same trend as B_C, ranging from 1.472 to 0.443 μg kg^-1 of dry compost from day 5 to day 62. This behaviour is probably related to the decreasing availability of readily decomposable substrates with the ongoing of the process. B_C and B_N showed a strong correlation ( r = 0.78). The dynamics of the B_C/ B_N ratio, index of the chemical composition of the whole microbial population suggested a shift in the composition of microbial populations during the process from prevailing bacteria and actinomycetes to prevailing fungi.

The aim of this study was to evaluate the photobactericidal effect of four photosensitizers (PSs) with different structural and physico-photochemical properties, namely mesotetracationic porphyrin (T4MPyP), dianionic rose Bengal (RB), monocationic methylene blue (MB) and neutral red (NR). Their photokilling activity was tested in vitro on pathogenic bacteria such as Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) suspended in nutrient broth (NB) and in phosphate buffered saline (PBS) through following their influence on the PSs antimicrobial efficacy. Photodynamic inactivation (PDI) experiments were performed using visible light (L) and different PSs concentrations (20–70 μM). The ability of these PSs to mediate bacterial photodynamic inactivation was investigated as a function of type of PS and its concentrations, spectral and physico-chemical properties, bacterial strain, irradiation time and suspending medium. Indeed, they showed antibacterial effects against S. aureus and P. aeruginosa with significant difference in potency. Staphylococcus aureus suspended in NB showed 0.92 log units reduction in viable count in the presence of T4MPyP at 20 μM. Changing the suspending medium from NB to PBS, S. aureus was successfully photoinactivated by T4MPyP (20 μM) when suspended in PBS at least time exposure (10 and 30 min), followed by MB and RB.

Limited access to safe water enhances poverty, hunger and diseases. This study evaluated the drinking water quality stored in home-based systems, located in rural areas of Tunisia. Water management was also documented as an improvement of good practice as most of the water contamination could be related to behavioral patterns. Thirty-nine water samples from five different sources (rainwater, truck cistern, mix, etc.) were screened for enteric parasitic contamination with the modified Bailenger technique. This technique allowed the detection of three protozoa: Giardia spp.; Entamoeba histolytica/dispar/moshkovskii; Entamoeba coli and one helminth specie: Ascaris spp. The overall prevalence of these intestinal parasites was approximately 97% with a relatively high frequency of protozoa over helminths and more specifically E. histolytica/dispar/moshkovskii. This incidence could be correlated to the lack of hygiene practices, sanitation and education. This situation requires the need for frequent monitoring of the water quality and management in these areas.