For the last four decades, viability of photocatalytic degradation of organic compounds in water streams has been demonstrated. Different configurations for solar TiO₂ photocatalytic reactors have been used, however pilot and demonstration plants are still countable. Degradation efficiency reported as a function of treatment time does not answer the question: which of these reactor configurations is the most suitable for photocatalytic process and optimum for scale-up and commercialization? Degradation efficiency expressed as a function of the reactor throughput and ease of catalyst removal from treated effluent are used for comparing performance of different reactor configurations to select the optimum for scale-up. Comparison included parabolic trough, flat plate, double skin sheet, shallow ponds, shallow tanks, thin-film fixed-bed, thin film cascade, step, compound parabolic concentrators, fountain, slurry bubble column, pebble bed and packed bed reactors. Degradation efficiency as a function of system throughput is a powerful indicator for comparing the performance of photocatalytic reactors of different types and geometries, at different development scales. Shallow ponds, shallow tanks and fountain reactors have the potential of meeting all the process requirements and a relatively high throughput are suitable for developing into continuous industrial-scale treatment units given that an efficient immobilized or supported photocatalyst is used.

Integrated aquaculture–agriculture systems (IAASs) offer a sustainable approach to mitigating soil salinity by utilizing aquaculture effluents for irrigation. This study evaluates the growth performance of Nile tilapia (Oreochromis niloticus) and red tilapia (Oreochromis spp.) under varying salinity conditions and investigates their effluents on intercropped wheat and sugar beet. A field experiment was conducted using a randomized block design with seven treatments: control (chemical fertilizers dissolved in freshwater) and brackish water effluents from Nile tilapia and red tilapia at salinities of 5 ppt and 10 ppt as monocultures or mixed polycultures. Fish growth parameters were assessed, while wheat and sugar beet morphological and yield traits were monitored. Statistical analyses, including correlation and principal component analysis, were performed. Red tilapia outperformed Nile tilapia at 10 ppt salinity, achieving the highest final weight (174.52 ± 0.01 g/fish) and weight gain (165.78 ± 0.01 g/fish), while the mixed polyculture at 10 ppt exhibited optimal feed conversion (FCR: 1.32 ± 0.01). Wheat growth and yield traits (plant height, stalk diameter, and panicle weight) declined significantly under salinity stress, with 10 ppt treatments reducing plant height by ~57% compared to the control. Conversely, sugar beet demonstrated resilience, with total soluble solids (TSS) increasing by 20–30% under salinity. The mixed effluent partially mitigated salinity effects on wheat at 5 ppt but not at 10 ppt. This study highlights the potential of IAAS in saline environments, demonstrating red tilapia’s adaptability and sugar beet’s resilience to salinity stress. In contrast, wheat suffered significant reductions in growth and yield.

Microbial communities perform important roles in nutrient cycling, degradation of environmental pollutants, and support of various life forms on Earth. Mangroves live in very harsh environments, and if not for the existence of several microbial species in their ecosystems, they would not survive. The Egyptian Red Sea coast is dominated by two mangrove species, Avicennia marina and Rhizophora mucronata , which serve as breeding grounds for marine organisms and aid in carbon sequestration. Despite their ecological significance, comparative studies examining the physiochemical properties and heavy metal concentration of mangrove sediments of two dominant species along the Egyptian Red Sea coast (Hamata, Mangrove Bay, and Saffaga) and their relationship to microbial and functional diversity are scarce. Our findings revealed significant differences in sodium ions, potassium ions, organic carbon, and bulk density at 30–50 cm depth across the locations. Heavy metal analysis revealed significantly lower concentrations of zinc and manganese and high concentrations of copper in sediment samples collected from Mangrove Bay at all sampling depths. Metagenomics analysis revealed that the dominant phyla across the three sites were Pseudomonadota , Bacillota , and Bacteroidota , along with Actenomycetota , and Chloroflexota , and unclassified bacteria. Within the phylum Bacillota , several major classes were identified, including Bacillota_A_368345 , Bacillota_I , and Bacillota_C . Functional prediction revealed a higher abundance of microbes involved in energy metabolism and carbon cycle, whereas a lower abundance of microbes involved in sulfur and nitrogen cycles was noted across the sites. In conclusion, the identification of different microbial communities in sediments collected along the Egyptian Red Sea coastal areas suggests the role of different mangrove species and human activities in recruiting unique microbial species involved in promoting their survival under different environmental factors.