A case of traumatic uterine avulsion in pregnancy

Complete uterine avulsion is an extremely rare complication of trauma sustained during pregnancy. We present the case of a 21-year-old nullipara at 16 weeks' gestation who was involved in a high-speed motor vehicle collision with subsequent fetal demise. Initially she was hemodynamically stable and demonstrated small amounts of intraabdominal free fluid, therefore multidisciplinary conservative measures were undertaken. However, as her condition worsened, she was taken for exploratory laparotomy, revealing complete gravid uterine avulsion at the level of the cervicoisthmic junction. Due to hemodynamic instability and concerns for retroperitoneal bleeding, a supracervical hysterectomy was performed. Although a rare occurrence, our case demonstrates the need for a high level of suspicion for uterine avulsion in certain cases of trauma in pregnancy. This highlights the false reassurance provided by stable vitals in a pregnant patient that may mask ongoing bleeding and development of hemorrhagic shock, the importance of interpreting different imaging modalities together when the cause of instability is unclear, and the utility of a multidisciplinary approach. While our patient underwent hysterectomy due to hemodynamic instability, it is unknown whether earlier investigation with laparoscopy to confirm uterine integrity may have circumvented this and allowed for fertility-sparing management. As such, our case encourages the utilization of early diagnostic laparoscopy if there is concern for uterine avulsion for the consideration of alternative surgical interventions for management.

Simultaneous ammonium and phosphate recovery and stabilization from urban sewage sludge anaerobic digestates using reactive sorbents

The use of low-cost inorganic sorbents as a new sustainable strategy to enhance the valorization of nutrients (N-P-K), from the urban water cycle (e.g., side streams from sewage sludge anaerobic digestion), in agriculture applications is presented. The simultaneous recovery and stabilization of ammonium and phosphate by using a mixture of two reactive sorbents (Na and K zeolites and magnesium oxide) was evaluated. The nutrients stabilization process, favoured at alkaline pH values, is carried out by a) the precipitation of phosphate ions with magnesium and/or ammonium ions and b) the sorption of ammonium by Na- and K-zeolites. MgO(s) promoted the stabilization of phosphate as bobierrite (Mg₃(PO₄)₂(s)) or struvite (MgNH₄PO₄(s)) depending on the applied dose. Doses with the stoichiometric molar ratio of Mg/P promote the formation of bobierrite, while molar ratios higher than 3 favour the formation of struvite. Na zeolites (NaP1-NA, NaP1-IQE) demonstrated efficiency on ammonium stabilization between 60±2 (for 15gZ/L) to 90±3% (for 50gZ/L). The ammonium recovery efficiency is limited by the zeolite sorption capacity. If the target of the fertilizing criteria should include K, then the use of a K-zeolite (e.g., 5AH-IQE) provides a good solution. The optimum pH for the precipitation of struvite and bobierrite is 9.5 and the optimum pH for ammonium removal is between 4 and 8.5. N is present in higher concentrations (up 0.7-1gNH₄⁺/L) when pH is ranged between 8.2 and 8.6. The ammonium recovery ratios were better than those previously reported using only magnesium oxide or even a more expensive reagent as newberrite (MgHPO₄(s)). The recovery mechanisms described generate low-solubility stabilized nutrients forms that potentially can be applied as slow-release fertilizers in agriculture. Thus, the use in agriculture of blends of digested sludge with low-solubility stabilized nutrients forms will improve soils quality properties in terms of organic matter and nutrients availability.

Recovery of ammonia from domestic wastewater effluents as liquid fertilizers by integration of natural zeolites and hollow fibre membrane contactors

The integration of up-concentration processes to increase the efficiency of primary sedimentation, as a solution to achieve energy neutral wastewater treatment plants, requires further post-treatment due to the missing ammonium removal stage. This study evaluated the use of zeolites as a post-treatment step, an alternative to the biological removal process. A natural granular clinoptilolite zeolite was evaluated as a sorbent media to remove low levels (up to 100mg-N/L) of ammonium from treated wastewater using batch and fixed bed columns. After being activated to the Na-form (Z-Na), the granular zeolite shown an ammonium exchange capacity of 29±0.8mgN-NH₄⁺/g in single ammonium solutions and 23±0.8mgN-NH₄⁺/g in treated wastewater simulating up-concentration effluent at pH=8. The equilibrium removal data were well described by the Langmuir isotherm. The ammonium adsorption into zeolites is a very fast process when compared with polymeric materials (zeolite particle diffusion coefficient around 3×10^-12m²/s). Column experiments with solutions containing 100mgN-NH₄⁺/L provide effective sorption and elution rates with concentration factors between 20 and 30 in consecutive operation cycles. The loaded zeolite was regenerated using 2g NaOH/L solution and the rich ammonium/ammonia concentrates 2-3g/L in NaOH were used in a liquid-liquid membrane contactor system in a closed-loop configuration with nitric and phosphoric acid as stripping solutions. The ammonia recovery ratio exceeded 98%. Ammonia nitrate and di-ammonium phosphate concentrated solutions reached up to 2-5% wt. of N.