ד"ר לודמילה מרקוס

~~"ZOOM" SEMINAR
SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Wednesday, March 10, 2021 at 14:00

Fluid structure interaction modeling of the effect of the cerebrospinal fluid on spinal cord traumas

Konstantin Arhiptsov
M.Sc. student of Dr. Gil Marom

With estimated occurrence of 15-50 incidences per million people, acute traumatic spinal cord injury (SCI) is associated with many burdens on patients and their families. Cerebrospinal fluid (CSF) has several important functions, including acting as a shock absorber to protect the central nervous system. While, numerical models can help predicting the SCI mechanics without putting the subjects in danger, previous studies did not focus on alternations in the CSF conditions, such as its pressure, and did not account for the presence of epidural fat. The current study aims to numerically compare the behavior of spine when subjected to several SCI scenarios and under two medical conditions. Specifically, the cord behavior was compared in SCI scenarios that represent burst fracture with and without epidural fat and the CSF pressure was either normal or in a diseased state of intracranial hypertension. To this end, an explicit simulation with a fluid structure interaction (FSI) approach was used. The CSF and the epidural fat were modeled as smoothed-particle hydrodynamics (SPH) and the soft tissues as hyperelastic. This approach, unlike the common previous modeling of CSF as viscoelastic material, allowed us to account for the CSF pressure alteration and its effect on the cord itself. Validation models resulted in good correlation with previous numerical and experimental studies. The results were able to capture the fluid dynamics of the CSF while demonstrating a considerable change in the stresses of the spinal cord, especially in the burst fracture injury. High CSF pressure affected the general shape of the dural sac and caused higher stresses in both the white and gray matters of the spinal cord. Exclusion of the epidural fat from the model significantly increased the calculated stresses in the cord, indicating on the necessity of the fat presence in future models. These results show some important aspects that need to be accounted for in future numerical models of SCI while also demonstrating how the injury might aggravate by preexisting conditions.
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https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09

~~"ZOOM" SEMINAR
SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Wednesday, March 10, 2021 at 14:00
Stripping and Recovery of Ammonia from Centrate Liquid of Anaerobic Digestion Using a Sulfuric Acid By-product: A Case Study
Omer Bar
M.Sc. student of Hadas Maman

The Shafdan plant is the largest Wastewater Treatment Plant (WWTP) in Israel and among the largest and most advanced in the Middle East. On a daily basis, the plant produces: 1. High-quality reclaimed water, which is used for extensive irrigation in the desert area of Israel, 2. Class-A bio-solids (sludge) used as agricultural fertilizer, and 3. Biogas used for renewable energy production. During these processes, two by-products are created: (1) Centrate, which originates from the sludge dewatering system as part of the sludge conversion to commercial fertilizer (bio-solids), and (2) Sulfuric acid (H2SO4), which originates from the process of removing hydrogen sulfide (H2S) from the biogas before using the gas for renewable energy production. Treating the centrate stream is one of the major challenges facing WWTPs, mainly due to its high ammonia and phosphorus concentration. As a result, this stream is currently being discharged into the Mediterranean Sea, a move that violates the Barcelona Convention and may cause problems in the marine ecosystem. Diverse technologies are used for treatment of the centrate, using external additives as acids, bases and minerals or biological solutions which are less stable. The present study offers an integrated solution for treating the centrate using recovered sulfuric acid. The product of this process, "Ammonium Sulfate" (NH4)2SO4, is a fertilizer used in the agricultural industry. The study was carried out in the lab in two stages, repeated between 3 to 6 times. In the first stage, the stripping unit, the ammonia was evaporated by heating the centrate. In the second stage, the scrubbing unit, the ammonia was recovered using sulfuric acid, resulting in agricultural fertilizer. The results showed high efficiency in both stripping and recovery of ammonia (91.5% and 96.2% with a standard deviation of 4.1% and 5.9% respectively). The proposed solution is a good alternative to the treatment of by-products in the Shafdan plant and other WWTPs worldwide. Due to the scarcity of raw materials, technological solutions which recycle existing residual streams are of high importance. In accordance, the illustrated solution utilizes two environmental nuisances created in the WWTP to create one valuable resource. Such a process is a clear example of resource recovery, which is a prominent component in circular and zero-waste economies.
Zoom Meeting
https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09