Performance of an anaerobic-aerobic reactor and kinetic study of organic matter removal of cattle slaughterhouse effluent

This paper sought to evaluate the behavior of an upflow Anaerobic-Aerobic Fixed Bed Reactor (AAFBR) in the treatment of cattle slaughterhouse effluent and determine apparent kinetic constants of the organic matter removal. The AAFBR was operated with no recirculation (Phase I) and with 50% of effluent recirculation (Phase II), with θ of 11h and 8h. In terms of pH, bicarbonate alkalinity and volatile acids, the results indicated the reactor ability to maintain favorable conditions for the biological processes involved in the organic matter removal in both operational phases. The average removal efficiencies of organic matter along the reactor height, expressed in terms of raw COD, were 49% and 68% in Phase I and 54% and 86% in Phase II for θ of 11h and 8h, respectively. The results of the filtered COD indicated removal efficiency of 52% and k = 0.0857h-1 to θ of 11h and 42% and k = 0.0880h-1 to θ of 8h in the Phase I. In Phase II, the removal efficiencies were 59% and 51% to θ of 11h and 8h, with k = 0.1238h-1 and k = 0.1075 h-1, respectively. The first order kinetic model showed good adjustment and described adequately the kinetics of organic matter removal for θ of 11h, with r² equal to 0.9734 and 0.9591 to the Phases I and II, respectively.

Application of response surface methodology to study the biological removal of nitrogen from effluent of cattle slaughterhouse in a sequencing batch reactor

The aim of this study was to evaluate the efficiency of a sequencing batch reactor (SBR) on biological removal of nitrogen from cattle slaughterhouse wastewater by nitrification/denitrification processes. The effects of initial concentration of ammoniacal nitrogen were investigated at 100; 150 and 200 mg L-1 and air flow rate at 0.125; 0.375 and 0.625 L min¹ Lreactor-1 on the nitrogen compounds removal, by a Central Composite Rotational Design (CCRD) configuration. There were variations from 9.2 to 94.9%, 4.0 to 19.6% and 20.8 to 92.0% in the conversion of ammoniacal nitrogen to nitrate and nitrite concentration and removal of total nitrogen, respectively. The increase of air flow rate and decrease of the initial concentration of ammoniacal nitrogen resulted in higher efficiencies of total nitrogen removal, as well as the conversion of ammoniacal nitrogen to nitrate. During the pre-established intervals of this study, the removal and conversion efficiencies of nitrogen compounds above 85% were achieved in air flow rate variations from 0.375 to 0.725 L min-1 Lreactor-1 and initial concentration of ammoniacal nitrogen from 80 to 200 mg L-1. On denitrification process, we obtained efficiencies from 91.5 to 96.9% on the removal of nitrite/nitrate and from 78.3 to 87.9% on the removal of organic matter.

Effect of cycle time and airflow in biological nitrogen removal from poultry slaughterhouse wastewater using sequencing batch reactor

This study aimed to evaluate the influence of airflow (0.25, 0.50 and 0.75 L.L-1.min-1) and cycle time (10.45 h, 14.25 h and 17.35 h) on a sequencing batch reactor (SBR) performance in promoting nitrification and denitrification of poultry slaughterhouse wastewater. The operational stages included feeding, aerobic and anoxic reactions, sedimentation and discharge. SBR was operated in a laboratory scale with a working volume of 4 L, keeping 25% of biomass retained inside the reactor as inoculum for the next batch. In the anoxic stage, C: N ratio was maintained between 5 and 6 by adding cassava starch wastewater. A factorial design (22) with five repetitions was designed at the central point to evaluate the influence of cycle time and airflow on total inorganic nitrogen removal (N-NH4++N-NO2-+N-NO3-) and in the whole process (nitrification and denitrification). The highest total inorganic nitrogen removal (93.3%) was observed for airflow of 0.25 L.L-1.min‑1 and a cycle time of 14.25 h. At the end of the experiment, the sludge inside the reactor was characterized by fluorescent in situ hybridization (FISH), indicating the presence of ammonia and nitrite oxidizing bacteria.

Tricobezoar gástrico

Bezoar is a foreign body in the digestive tract originated from ingestion of varied substances, mainly vegetal hair or coats, staple fibers among others. We present a case of a 16-year-old female with trichotillomania history of approximately 5 months, diagnosed through clinical evidence of traumatic alopecia made by her dermatologist. Though asymptomatic the presence of tricobezoar was suspected and confirmed through digestive seriography and high digestive endoscopy. The patient was operated on for gastrotomy and removal of bezoar, with good postoperative follow-up, except for surgical wound infection.

Úlcera gástrica terebrante e pancreatite aguda provocadas por tricobezoar

Bezoar is a foreing body whitin the digestive tract originated from ingestion of varied substances, mainly vegetal fiber or hair. We present a case of a 14-year-old girl with trichotillomania, gastric trichobezoar, gastric ulcer and acute pancreatitis. The patient was operated on for anterior gastrotomy and removal of trichobezoar, with good postoperative follow-up. We illustrate this case to emphasize the need for recognition of gastric ulcer with acute pancreatitis and surgical management.

Variability in the fecal egg count and the parasitic burden of hair sheep after grazing in nematode infected paddocks

This study aimed to evaluate the variability in the fecal egg count (FEC) and the parasitic burden of naive hair sheep after grazing in nematode infected paddocks. The research was carried out in Tabasco, Mexico, during two periods (August and December). In each period 32 lambs were grazed for one month on African star grass (Cynodon plectostachyus) contaminated with gastrointestinal parasitic nematodes. FEC, packed cell volume (PCV) and body weight (BW) were recorded. Gastrointestinal worms were recovered at necropsy. Data were analyzed with the MIXED procedure of SAS using a model of repeated measurements over time. A higher number of Haemonchus contortus worms was found in December (2814±838) than in August (1166±305). The opposite occurred with Cooperia curticei (2167±393 and 3638±441, respectively). The FEC and correlation coefficient in respect to the worm burden were higher in December (6516 ± 1599, r=0.83, respectively) than in August (4364±771, r=0.44, respectively). A high variability in resistance-susceptibility to gastrointestinal nematodes (GIN) occurred in Katahdin × Pelibuey lambs after grazing.

Advanced ceramics: evaluation of the mechanism of stock removal and ground surface quality

The aim of this work is to evaluate the mechanism of stock removal and the ground surface quality of advanced ceramics machined by a surface grinding process using diamond grinding wheels. The analysis of the grinding performance was done regarding the cutting surface wear behavior of the grinding wheel for ceramic workpieces. The ground surface was evaluated using Scanning Electron Microscopy (SEM). As a result it can be said that the mechanism of material removal in the grinding of ceramic is largely one of brittle fracture. The increase of the h max can reduce the tangential force required by the process. Although, it results in an increase in the surface damage, reducing the mechanical properties of the ground component.

The selective and non-selective cyclooxygenase inhibitors valdecoxib and piroxicam induce the same postoperative analgesia and control of trismus and swelling after lower third molar removal

We compared the clinical efficacy of orally administered valdecoxib and piroxicam for the prevention of pain, trismus and swelling after removal of horizontally and totally intrabony impacted lower third molars. Twenty-five patients were scheduled to undergo removal of symmetrically positioned lower third molars in two separate appointments. Valdecoxib (40 mg) or piroxicam (20 mg) was administered in a double-blind, randomized and crossed manner for 4 days after the surgical procedures. Objective and subjective parameters were recorded for comparison of postoperative courses. Both agents were effective for postoperative pain relief (N = 19). There was a similar mouth opening at suture removal compared with the preoperative values (86.14 ± 4.36 and 93.12 ± 3.70% of the initial measure for valdecoxib and piroxicam, respectively; ANOVA). There was no significant difference regarding the total amount of rescue medication taken by the patients treated with valdecoxib or piroxicam (173.08 ± 91.21 and 461.54 ± 199.85 mg, respectively; Wilcoxon test). There were no significant differences concerning the swelling observed on the second postoperative day compared to baseline measures (6.15 ± 1.84 and 8.46 ± 2.04 mm for valdecoxib and piroxicam, respectively; ANOVA) or on the seventh postoperative day (1.69 ± 1.61 and 2.23 ± 2.09 mm for valdecoxib and piroxicam, respectively; ANOVA). The cyclooxygenase-2 selective inhibitor valdecoxib is as effective as the non-selective cyclooxygenase inhibitor piroxicam for pain, trismus and swelling control after removal of horizontally and totally intrabony impacted lower third molars.