A holistic approach for performance evaluation of wastewater treatment plants: integrating grey water footprint and life cycle impact assessment.

Wastewater treatment plants (WWTPs) have positive and negative impacts on the environment. Therefore, life cycle impact assessment (LCIA) can provide a more holistic framework for performance evaluation than the conventional approach. This study added water footprint (WF) to LCIA and defined ϕ index for accounting for the damage ratio of carbon footprint (CF) to WF. The application of these innovations was verified by comparing the performance of 26 WWTPs. These facilities are located in four different climates in Iran, serve between 1,900 and 980,000 people, and have treatment units like activated sludge, aerated lagoon, and stabilization pond. Here, grey water footprint (GWF) calculated the ecological impacts through typical pollutants. Blue water footprint (BWF) included the productive impacts of wastewater reuse, and CF estimated CO2 emissions from WWTPs. Results showed that GWF was the leading factor. ϕ was 4-7.5% and the average WF of WWTPs was 0.6 m3/ca, which reduced 84%, to 0.1 m³/ca, through wastewater reuse. Here, wastewater treatment and reuse in larger WWTPs, particularly with activated sludge had lower cumulative impacts. Since this method takes more items than the conventional approach, it is recommended for integrated evaluation of WWTPs, mainly in areas where the water-energy nexus is a paradigm for sustainable development.

Iatrogenic L5 Nerve Injury Following Decortication of the Sacral Ala in Posterolateral Lumbosacral Fusion Surgery.

STUDY DESIGN: Cadaver study. OBJECTIVES: To investigate the risk of the L5 nerve injury following sacral ala decortication performed during lumbosacral posterolateral fusion surgery. METHODS: Fourteen fresh cadaver pelvises were dissected through an anterior approach and the L5 nerves on both sides were explored and macroscopically examined by direct observation. Then, the corticotomy of the sacral ala was performed at 0°, 20°, and 30° angles to the sagittal plane through the posterior approach. The site of sacral ala decortication was checked on each side and its distance to the L5 nerve root was measured. RESULTS: The tip of the osteotome was in the danger zone (5 mm medial to 5 mm lateral to the L5 nerve) in all cases (100%) where the osteotome had 0° angle to the sagittal plane. For those with a 20° angle, the osteotome tip laid in the danger zone in 83% and intermediate zone (between 6 to 15 mm lateral to the nerve) in 17% of cases. For those with a 30° angle, the tip was in the safe zone (>15 mm lateral to the nerve) in all cases (100%). CONCLUSION: Osteotomy of the sacral ala with <30° angle to the sagittal plane risks injury to the L5 nerve; whereas osteotomy angle >30° would not cause any injury to the nerve. It should be considered as a possible cause of iatrogenic L5 nerve injury in patients undergoing posterolateral lumbosacral fusion.