This study aimed to evaluate airborne meso–and–thermophilic actinomycete concentrations and their types at a wastewater treatment plant and a biosolid landfill, in Egypt. Air samples were collected at 200m upwind, and onsite and 300m downwind by using liquid impinger sampler, calibrated to draw 12.5L/min, for 20 minutes. The concentrations ranged between 0.0–7 360CFU/m3 for mesophilic, and 106–586CFU/m3 for thermophilic actinomycetes. Airborne actinomycete concentrations exceeded the suggested occupational exposure limit value of 100CFU/m3. No significant correlations were found between actinomycete concentrations onsite and 300m downwind distance. At the biosolid landfill, upwind thermophilic actinomycetes significantly differed (p<0.05) from onsite and 300m downwind. A total of 40 and 69 airborne actinomycete isolates belonging to 8 genera were identified at the wastewater treatment plant and biosolid landfill. Streptomyces were the dominant actinomycete species. Streptomyces diastaticus, Pseudonocardia compacta and Catellatospora ferruginea were only detected at the biosolid landfill site. Meso–and–thermophilic actinomycetes positively associated with relative humidity, and wind speed positively correlated with onsite thermophilic actinomycetes (r=0.65) at the biosolid landfill. Temperature showed negative effect on survivability of mesophilic actinomycetes (r=-0.8) onsite of the wastewater treatment plant. Waste application facilities increase actinomycete concentrations onsite which may consequently deteriorate air quality in the nearby areas.

The concentrations of 15 priority PAHs were determined in the atmospheric gaseous and particulate phases from nine sites across Assiut City, Egypt. While naphthalene, acenaphthene, and fluorene were the most abundant in the gaseous phase with average concentrations of 377, 184, and 181 ng/m³, benzo[b]fluoranthene, chrysene, and benzo[g,h,i]perylene showed the highest levels in the particulate phase with average concentrations of 76, 6, and 52 ng/m³. The average total atmospheric concentration of target PAHs (1,590 ng/m³) indicates that Assiut is one of the highest PAH-contaminated areas in the world. Statistical analysis revealed a significant difference between the levels of PAHs in the atmosphere of urban and suburban sites (P = 0.029 and 0.043 for gaseous and particulate phases, respectively). Investigation of diagnostic PAH concentration ratios revealed vehicular combustion and traffic exhaust emissions as the major sources of PAHs with a higher contribution of gasoline rather than diesel vehicles in the sampled areas. Benzo[a]pyrene has the highest contribution (average = 32, 4 % for gaseous and particulate phases) to the total carcinogenic activity (TCA) of atmospheric PAHs. While particulate phase PAHs have higher contribution to the TCA, gaseous phase PAHs present at higher concentrations in the atmosphere are more capable of undergoing atmospheric reactions to form more toxic derivatives.

The scarcity of water resources in Egypt has necessitated the use of various types of lower quality water. Agricultural drainage water is considered a strategic reserve for meeting increasing freshwater demands. In this study, a novel model series was applied to a drainage basin in the Nile Delta to optimize integrated water quality management for agriculture and the aquatic environment. The proposed model series includes a waste load allocation model, an export coefficient model, a stream water quality model, and a genetic algorithm. This model series offers an optimized solution for determining the required removal levels of total suspended solids (TSS), the chemical oxygen demand (COD) at point and non-point pollution sources, and the source flows that require treatment to meet a given water quality target. The model series was applied during the summer and winter to the El-Qalaa basin in the western delta of the Nile River. Increased pollutant removal and treated fractions at point and non-point sources reduced violations of the TSS standards from 732.6 to 238.9 mg/L in summer and from 543.1 to 380.9 mg/L in winter. Likewise, violations of the COD standards decreased from 112.4 mg/L to 0 (no violations) in summer and from 91.7 mg/L to no violations in winter. Thus, this model is recommended as a decision support tool for determining a desirable waste load allocation solution from a trade-off curve considering costs and the degree of compliance with water quality standards.