Elimination of methylmercury production potential in excessive sludge in wastewater treatment plants by sulfur addition.

Mercury ions (Hg(II)) in wastewater can accumulate and transform into the highly neurotoxic methylmercury (MeHg) in activated sludge. The release of MeHg can have severe environmental consequences, making the treatment of MeHg-contaminated sludge a pressing concern. In this study, we found that all the collected activated sludge samples, from different wastewater treatment plants in four cities, had the potential for Hg methylation. The Hg-methylating capacity reached a maximum level of 0.70-0.92 µg/g volatile suspended solids after 48 h of exposure to 5 µg/L Hg(II) and showed an average MeHg production rate of 4.8±0.5%. Accordingly, a sludge treatment method involving the addition of elemental sulfur (S0) for a short-term or long-term duration (3 or 180 days, respectively) was proposed. The results demonstrated that this treatment approach effectively mitigated and potentially eliminated MeHg formation by simultaneously reducing Hg bioavailability and Hg-methylating bioactivity. We found that bioavailable Hg(II) ions were converted to a secondary phase similar to insoluble HgS after S0 addition treatment, leading to a decrease in Hg bioavailability in sludge. The enhancement of Hg and extracellular polymeric substances (EPS) complexation via the increasing amount of thiol groups in EPS also reduced the Hg bioavailability after the long-term treatment. Furthermore, the long-term S0 addition significantly reduced the abundance of Hg-methylators with hgcA gene and promoted the growth of Hg-reducers with merA gene, which ensured the complete elimination of MeHg production potential of the excessive activated sludge. Our findings demonstrated that the proposed S0-addition sludge treatment is a promising and safe biotechnology for treating Hg-contaminated sludge. This approach has the potential to contribute significantly to the mitigation of MeHg pollution within environmental contexts.

The exacerbation of mercury methylation by Geobacter sulfurreducens PCA in a freshwater algae-bacteria symbiotic system throughout the lifetime of algae.

Mine-polluted wastewater with mercury (Hg) poses severe environmental pollution since Hg(II) can be converted to highly neurotoxic methylmercury (MeHg) under anaerobic conditions. Previous studies on Hg methylation have focused on aquatic sediments, but few have investigated the MeHg formation in water layers containing algae. In this study, we investigated the dynamic effect of algae on Hg methylation throughout the lifetime of algae. We found that Chlorella pyrenoidosa was a non-methylating alga and exhibited good tolerance to Hg stress (1-20 µg/L); thus Hg(II) could not inhibit the process of eutrophication. However, the presence of C. pyrenoidosa significantly enhanced the Hg methylation by Geobacter sulfurreducens PCA. Compared to the control sample without algae, the MeHg production rate of algae-bacteria samples remarkably exacerbated by 62.3-188.3% with the algal growth period at cell densities of 1.5 × 106-25 × 106 cells/mL. The increase of algal organic matter and thiols with the algal growth period resulted in the exacerbation of MeHg production. The Hg methylation was also enhanced with the presence of dead algae, of which the enhancement was ~62.4% lower than that with the presence of live algae. Accordingly, the potential mechanism of Hg methylation in a freshwater algae-bacteria symbiotic system throughout the algal lifetime was proposed.

In-hospital, short-term and long-term adverse clinical outcomes observed in patients with type 2 diabetes mellitus vs non-diabetes mellitus following percutaneous coronary intervention: A meta-analysis including 139,774 patients.

BACKGROUND: Several studies have shown that patients with type 2 diabetes mellitus (T2DM) have worse clinical outcomes in comparison to patients without diabetes mellitus (DM) following Percutaneous Coronary Intervention (PCI). However, the adverse clinical outcomes were not similarly reported in all the studies. Therefore, in order to standardize this issue, a meta-analysis including 139,774 patients was carried out to compare the in-hospital, short-term (<1 year) and long-term (≥1 year) adverse clinical outcomes in patients with and without T2DM following PCI. METHODS: Electronic databases including MEDLINE, EMBASE, and the Cochrane Library were searched for Randomized Controlled Trials (RCTs) and observational studies. The adverse clinical outcomes which were analyzed included mortality, myocardial infarction (MI), major adverse cardiac events (MACEs), stroke, bleeding, target vessel revascularization (TVR), target lesion revascularization (TLR), and stent thrombosis. Risk Ratios (RR) with 95% confidence intervals (CI) were used to express the pooled effect on discontinuous variables and the analysis was carried out by RevMan 5.3 software. RESULTS: A total number of 139,774 participants were assessed. Results of this analysis showed that in-hospital mortality and MACEs were significantly higher in patients with T2DM (RR 2.57; 95% CI: 1.95-3.38; P = .00001) and (RR: 1.38; 95% CI: 1.10-1.73; P = .005) respectively. In addition, majority of the short and long-term adverse clinical outcomes were also significantly higher in the DM group as compared to the non-DM group. Stent thrombosis was significantly higher in the DM compared to the non-DM group during the short term follow-up period (RR 1.59; 95% CI: 1.16-2.18;P = .004). However, long-term stent thrombosis was similarly manifested. CONCLUSION: According to this meta-analysis including a total number of 139,774 patients, following PCI, those patients with T2DM suffered more in-hospital, short as well as long-term adverse outcomes as reported by most of the Randomized Controlled Trials and Observational studies, compared to those patients without diabetes mellitus.

Adverse clinical outcomes associated with double dose clopidogrel compared to the other antiplatelet regimens in patients with coronary artery disease: a systematic review and meta-analysis.

BACKGROUND: Recently, several newer antiplatelet treatment strategies have been used in patients with coronary artery disease (CAD). Apart from the dual antiplatelet therapy (DAPT) consisting of aspirin and clopidogrel, double dose clopidogrel (DDC), triple antiplatelet therapy (TAPT) consisting of aspirin, clopidogrel and cilostazol and other newer antiplatelet agents have shown to be effective in different ways. In this analysis, we aimed to systematically compare the adverse clinical outcomes and the bleeding events which were observed when DDC was compared to the other antiplatelet regimens in patients with CAD. METHODS: English publications comparing DDC with other antiplatelet regimens were searched from MEDLARS/MEDLINE, EMBASE, www.ClinicalTrials.gov and Google Scholar. Adverse cardiovascular outcomes and bleeding events were the study endpoints. Statistical analysis was carried out by the RevMan 5.3 software whereby odds ratios (OR) with 95% confidence intervals (CIs) were calculated. RESULTS: A total number of 23,065 participants were included. Results of this analysis showed major adverse cardiac events (MACEs), all-cause mortality, cardiac death, stroke, stent thrombosis, revascularization and myocardial infarction (MI) to have been similarly manifested in patients who were treated with DDC versus the control group with OR: 0.98, 95% CI: 0.78-1.22; p = 0.83, OR: 0.95, 95% CI: 0.77-1.17; p = 0.62, OR: 0.97, 95% CI: 0.79-1.20; p = 0.81, OR: 0.98, 95% CI: 0.65-1.48; p = 0.94, OR: 0.84, 95% CI: 0.40-1.75; p = 0.64, OR: 0.88, 95% CI: 0.52-1.49; p = 0.63, and OR: 0.89, 95% CI: 0.65-1.21; p = 0.45 respectively. Any minor and major bleedings were also similarly manifested. When DDC was compared to DAPT, no significant difference was observed in any bleeding event with OR: 1.58, 95% CI: 0.86-2.91; p = 0.14. Even when DDC was compared with either ticagrelor or prasugrel or TAPT, still no significant difference was observed in terms of bleeding outcomes. CONCLUSIONS: In patients with CAD, adverse clinical outcomes were not significantly different when DDC was compared to the other antiplatelet regimens. In addition, bleeding events were also similarly manifested when DDC was compared to DAPT, TAPT or ticagrelor/prasugrel.