Two-stage sequencing batch reactors with added iron shavings for nutrient removal and aerobic sludge granulation treating real wastewater with low carbon to nitrogen ratios.

In response to the challenges of limited nutrient removal and the difficulty in forming aerobic granular sludge (AGS) with low carbon to nitrogen (C/N) ratios, a novel two-stage sequencing batch reactors (SBRs) (R1 and R2) system with added iron shavings was proposed and established. The results showed that AGS was developed and nitrogen (82.8 %) and phosphorus (94.7 %) were effectively removed under a C/N ratio at 1.7 ± 0.5. The average size of R1 and R2 increased from 45.3 µm to 138.7 µm and 132.8 µm. Under high biological selective pressure, phosphorus accumulating organisms like Comamonadaceae (14.8 %) and Chitinophagales (5.7 %) experienced enrichment in R1. Furthermore, R2 exhibited an increased abundance of nitrifying bacteria (2.3 %) and a higher proportion of nitrogen removal through autotrophic denitrification (＞17.5 %). Overall, this study introduces an innovative two-stage SBRs with added iron shavings, offering a novel approach for the treatment of low C/N ratios wastewater.

Effect of polyethylene terephthalate particles on filamentous bacteria involved in activated sludge bulking and improvement in sludge settleability.

Excessive proliferation of filamentous bacteria within activated sludge leads to sludge structural instability and diminished settling properties, which is a prevalent issue in tannery wastewater treatment. Based on available information, there is a lack of research on the impact of particle addition on filamentous bacteria in activated sludge, specifically with respect to a reduction in sludge bulking. Therefore, polyethylene terephthalate (PET) was selected as the test material to elucidate the effect of particles on sludge bulking. The results illustrate that particles measuring 0.1 mm in diameter have a profound influence on both the quantity and morphological characteristics of filamentous bacteria in activated sludge. In an anaerobic-aoxic-oxic (AAO) reactor, the use of 4000 particles/L led to a significant decrease in the sludge volume index (SVI), reducing it from 358 mg/L to 198 mg/L. The results offer significant insights for resolving sludge bulking problems in tannery wastewaters. Moreover, the results are significant as a reference point for future investigations on the efficacy of incorporating diverse particulate materials to ameliorate issues associated with activated sludge bulking.

A municipal wastewater treatment plant "drinking beer" for reduction of cost and carbon emission.

In wastewater treatment plants (WWTPs), external carbon sources are often required due to low C/N influent. However, the use of external carbon sources can increase treatment costs and cause large carbon emissions. Beer wastewater, which contains a substantial amount of carbon, is often treated separately in China, consuming significant energy and cost. However, most studies using beer wastewater as an external carbon source are still on a laboratory scale. To address this issue, this study proposes using beer wastewater as an external carbon source in an actual WWTP to reduce operating costs and carbon emissions while achieving a win-win situation. The denitrification rate of beer wastewater was found to be higher than that of sodium acetate , resulting in improved treatment efficiency of the WWTP. Specifically, COD, BOD5, TN, NH4+-N and TP increased by 3.4%, 1.6%, 10.8%, 1.1%, and 1.7%, respectively. Additionally, the treatment cost and carbon emission per 10 000 tons of wastewater treated were reduced by 537.31 yuan and 2.27 t CO2, respectively. These results indicate that beer wastewater has significant utilization potential and provide a reference for using different types of production wastewater in WWTPs. This study's findings demonstrate the feasibility of implementing this approach in an actual WWTP setting.

Anesthesia Effect of Remifentanil Combined with Propofol in Laparoscopic Cholecystectomy and Its Impact on Postoperative Cognitive Recovery.

Objective: To investigate the anesthesia effect of remifentanil combined with propofol for laparoscopic cholecystectomy and its impact on postoperative cognitive recovery. Methods: A total of 120 patients who underwent laparoscopic cholecystectomy in our hospital from February 2019 to June 2021 were recruited and assigned into either control group or experimental group at a ratio of 1 : 1 via the random number table method. The patients in the control group were anesthetized with fentanyl combined with propofol, and the patients in the experimental group were anesthetized with remifentanil combined with propofol. The clinical basic indicators (extubation time, recovery time, breathing recovery time, and orientation recovery time), and observer's assessment of awareness/sedation (OAA/S) scores and complications were compared between the two groups. Results: There was no significant difference in extubation time between the two groups (P > 0.05). The postoperative wake-up time, respiratory recovery time, and orientation recovery time of the experimental group were significantly better than those of the control group (P < 0.05). The OAA/S scores of the patients in the experimental group were significantly higher than those in the control group immediately after surgery, 1 h after surgery, and 3 h after surgery (P < 0.05). There was no significant difference in the OAA/S scores between the two groups on the 1st day after operation (P > 0.05). The incidence of complications in the experimental group was significantly lower than that in the control group (P < 0.05). Conclusion: Remifentanil + propofol for laparoscopic cholecystectomy patients has a significant anesthesia effect. This strategy effectively shortens the extubation, awakening, respiratory recovery, orientation recovery time of patients, and OAA/S score, suggest a minor impact on the postoperative cognitive function and state of consciousness. It has a high safety profile and thus is worthy of clinical application.