Anaerobic fermentation of aerobic granular sludge: Insight into the effect of granule size and sludge structure on hydrolysis and acidification.

Aerobic granular sludge (AGS) has different physicochemical properties and microbial communities compared to conventional activated sludge (CAS), which may result in different behaviors during anaerobic fermentation and require further investigation. This study investigated the effect of granule size and sludge structure on the hydrolysis and acidification of AGS. Experimental results show that AGS exhibited significantly higher soluble chemical oxygen demand (SCOD) dissolution and total volatile fatty acids (TVFA) production (330.6-430.3 mg/gVSS and 231.0-312.5 mgCOD/gVSS) compared to conventional activated sludge (CAS) (167.0 mg/gVSS and 133.3 mgCOD/gVSS). This is because AGS (90.6-96.9 mg/gVSS) had higher extracellular polymeric substances (EPS) content than CAS (81.2 mg/gVSS). EPS can not only serve as substrates but also release the trapped hydrolases. Moreover, the relative abundances of hydrolytic/acidogenic bacteria and genes were higher in AGS (0.46%-3.60% and 3.01 × 10-3%-4.04 × 10-3%) than in CAS (0.30% and 1.23 × 10-3%). The optimal granule size for AGS fermentation was found to be 500-1600 µm. The crushing of granule structure promoted the dissolution of small amounts of EPS and the release of some trapped hydrolases, thereby potentially enhancing the enzyme-substrate contacts and bacteria-substrate interactions. Therefore, the highest SCOD dissolution (510.6 mg/gVSS) and TVFA production (352.1 mgCOD/gVSS) from crushed 500-1600 µm AGS were observed. Overall, the findings of this study provide valuable insights into the recovery of organic carbon from AGS via anaerobic fermentation.

Efficacy and Safety of Pharmacoprophylaxis for Venous Thromboembolism in Patients Undergoing Bariatric Surgery: a Systematic Review and Meta-analysis.

This study aims to assess the efficacy and safety of pharmacoprophylaxis regimens for venous thromboembolism (VTE) in patients undergoing bariatric surgery. A total of 15 studies were included. Low molecular-weight heparins (LMWH) and fondaparinux may be equally effective in reducing VTE risk (OR 1.02, 95% confidence interval [CI] 0.14-7.39). Pooled estimate suggested uncertain effects of augmented LMWH dosing on VTE prophylaxis compared with standard dosing (OR 0.57, 95% CI 0.07-4.39), but may increase major bleeding (OR 3.03, 95% CI 0.38-23.96). Very low-quality evidence showed an inconclusive effect of extended prophylaxis on VTE (OR 0.54, 95% CI 0.15-1.90) and major bleeding (OR 1.24, 95% CI 0.92-1.68) compared with restricted prophylaxis. Standard LMWH dosing may be effective and safe. Current evidences are insufficient to support extended prophylaxis.