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Removal of nutrients like nitrogen and phosphorus from wastewater can be accomplished by precipitating these as the mineral struvite (NH 4 MgPO 4 . 6H 2 O). Predicting struvite precipitation potential, yield, and purity is important for designers and operators of reactors for struvite precipitation. In this paper, a mathematical model of this precipitation process is developed using physicochemical equilibrium expressions, mass balance equations for nitrogen, phosphorous and magnesium, and charge balance. The model was simulated to explicitly solve for equilibrium concentrations of eighteen species that included dissolved (three), ionic (ten), and solid (five) species for a given set of initial concentrations of ammonium-nitrogen, magnesium and phosphate-phosphorus, and pH. The model simulations were validated against literature experimental data, which used synthetic as well as actual wastewater, and data from our experiments. The model satisfactorily predicted most data. Struvite fraction in the precipitate ranged from 27% to 100%. The purity of struvite in the precipitate and the pH that maximizes struvite fraction was dependent on the initial concentrations of ammonium, magnesium, and phosphate. Optimum pH and struvite fraction was, respectively, 8.5 and 29.3% for an equimolar mixture of ammonia, magnesium, and phosphate and 9.8 and 98.3% for 10:1.7:3.4 mM ratio. Struvite fraction in the precipitate increased as magnesium became limiting or as ammonia to phosphate ratio increased and magnesium to phosphate ratio decreased. Since the struvite component is only a fraction of the total solids, it is erroneous to report the total precipitate produced as being struvite as is conventionally done.

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Objective: Postpartum haemorrhage (PPH) is one of the important obstetrical emergencies and a leading cause of maternal morbidity and mortality. According to the World Health Organization, postpartum haemorrhage constitutes 25% of all maternal deaths worldwide. In situations where medical line of management fails to control postpartum haemorrhage, anterior division of internal iliac artery ligation can play an important role as a lifesaving and fertility preserving surgical procedure. Keeping this in mind, our study aimed to analyze indications and efficacy of anterior division of Internal Iliac artery ligation in the form of uterine salvage and saving maternal life. Study design: This was a retrospective study carried out in the Department of Obstetrics and Gynaecology, Government Medical College, Aurangabad during the period of July 2014-January 2016. A total of 57 cases that had undergone ligation of anterior division of internal iliac artery were included in the study and different indications and efficacy were studied. Results: Atonic PPH (52.63%) leads the list of indications for ligation anterior division of internal iliac artery ligation followed by traumatic (19.29%), adherent placenta (12.2%), mixed variety (10.52%) and coagulopathy (5.26). Maximum efficacy in terms of preserving fertility and saving maternal life was 73.33% and 93.3% respectively in atonic PPH. Overall efficacy of this procedure in terms of uterine salvage was 54.38% and in terms of saving maternal life was 87.71%. Conclusion: Anterior division of IIAL was effective method in controlling refractory PPH, reducing morbidity and preserving uterus and future fertility. It is safe life saving procedure at experienced hands.