Fatores litogênicos em pacientes com litíase urinária de Fortaleza, Ceará

Lithiasis is considered a public health issue due to its high prevalence and rates of recurrence. Objective: To identify risk factors for lithiasis in kidney stone patients from Fortaleza, Brazil. In the first stage of the study, the medical records of 197 patients with urinary lithiasis covering the period 1996 2006 were analyzed with regard to clinical and metabolic data. In the second stage, 340 kidney stones were submitted to morphological examination under 10x magnification. According to the external morphology and the cut surface, the stones were classified as pure or mixed, and major and minor components were identified. In addition, the stone fragments of 25 patients treated with lithotripsy were submitted to morphological analysis. In the third stage, a subsample of 50 stones was used in a double-blind comparison of morphological and chemical findings. Results were expressed as concordant, partly concordant (discordant for minor components) or discordant (discordant for major components). The average age of first symptoms was 35.8±13.3 years, with no significant difference between the genders. The male/female ratio was 1:1.7. Recurrence was reported in 53.3% of cases. The main metabolic changes observed were hypernatriuria (80.7%), hypercalciuria (48.7%), low urine volume (43.7%), hyperoxaluria (30.5%) and hyperuricosuria (17.3%). Pure stones represented 34.7% of the total sample of 340 stones. The most common route of elimination was spontaneous for pure stones (49.1%) and surgical for mixed stones (50.5%). Pure stones consisted most frequently of calcium oxalate (OxCa) (59.3%) and uric acid (UA) (23.7%), the former prevalent in women, the latter prevalent in men. The most frequently observed component in mixed stones was OxCa (67.1%), followed by carbapatite (11.2%) and struvite (7.9%). The main components were OxCa and UA for men, and carbapatite and struvite for women. Nearly half (48%) the 25 analyzed fragments were pure, consisting of calcium oxalate dihydrate (COD) (56%), calcium oxalate monohydrate (COM) (48%), phosphate (32%) and UA (20%). Four patients (16%) had infectious stones. In the chemical analysis of the subsample of 50 stones, the most 64 frequently observed major components were calcium (70%), oxalate (66%), ammonium (56%), urate (28%) and carbonate (24%). In the morphological analysis, the main components were calcium and magnesium phosphate (32%), COM (24%), UA (20%), COD (18%) and cystine (6%). Morphological and chemical findings were totally concordant for 38% of the stones, partly concordant in 52% and discordant in 10%. Conclusion: The risk factors for lithiasis in kidney stone patients from Fortaleza (Brazil) were hyperoxaluria, hypercalciuria with or without hypernatriuria, hyperuricosuria and low urine volume

Recuperação de fósforo por cristalização de estruvita

This study investigated the influence of the molar ratio, the phosphorus initial concentration, the mixture gradient, mixing time, pH and the secondary nucleation on struvite s crystallization in synthetic water in batch reactors. The study was divided into two stages. The first investigated struvite s crystallization at different Mg:N:P molar ratios and at different initial concentrations of magnesium, nitrogen and phosphorus. It was also evaluated the importance of secondary nucleation on the struvite s crystallization. In the second, five parameters were tested to evaluate their influence on the struvite s crystallization, which were: Mg:N:P molar ratio, initial concentration of phosphate, mixing time, mixture gradient and pH. The best conditions for struvite s crystallization were: Mg:N:P = 1,3:1:1 molar ratio; mixture gradient = 60 rpm, pH = 10.0, mixing time = 5 minutes and high initial concentrations of the constituent ions of struvite. Furthermore, the use of struvite crystals as seed influenced positively on the struvite s crystallization

Separação de cristais de estruvita de percolado de lodo por flotação por ar dissolvido

The struvite precipitation in wastewater treatments plants offer advantages to obtaining a economically viable product, containing phosphorus, nitrogen and magnesium, in a bioavailable conditions to plants. The precipitation process requires ideal conditions, but all of these aspects are difficult to obtain and may result in resistance to collect crystals during the sedimentation process. Therefore, instead find the best conditions for precipitation, we propose the dissolved air flotation as another method to retrieve the crystals. The application of dissolved air flotation method to promote separation of struvite crystals from sewage supernatant, was evaluated in a precipitation-flotation reactor (flotatest) and were compared with the precipitation-sedimentation assays (jar test). Finally, were observed that the dissolved air flotation process was as feasible as sedimentation to promote struvite crystals separation, and the pH are the most influencer factor for an efficient separation