Optimization of moving bed biofilm reactors for the treatment of municipal wastewater.

The properties of biocarriers significantly influence the performance of a moving bed-biofilm reactor (MBBR). This study aimed to assess the impact of media type, filling ratio, and hydraulic retention time (HRT) on biofilm formation and MBBR performance in both batch and continuous setups using real municipal wastewater. Two different media, high-density polyethylene (HDPE) and polypropylene (PPE), with varying surface area and properties were used. Biofilm growth and MBBR performance were monitored and optimized using response surface methodology. The effect of different media was investigated for three filling ratios of 20%, 40% and 60% and HRT of 4, 6 and 8 h. Results depicted a better biofilm growth on HDPE media in comparison to PPE carriers due to difference in media structure and surface properties. At all the conditions tested, HDPE media showed comparatively better performance for the removal of organic matter and nutrients than PPE media. The maximum organic matter removal efficiency was found as 77% and 75% at an HRT of 6 h and filling ratio of 40% for HDPE and PPE media, respectively. The ammonia removal was also found better for HDPE media due to its geometry and structure favoring the anoxic conditions with maximum removal of 89% achieved at 6-h HRT and 40% filling ratio. Overall, the system with HDPE media indicated more stability in terms of reactor performance than PPE carriers with variations in the operating conditions.

Sewage sludge management and enhanced energy recovery using anaerobic digestion: an insight.

Sewage sludge (SS) is a potential source of bioenergy, yet its management is a global concern. Anaerobic digestion (AD) is applied to effectively valorize SS by reclaiming energy in the form of methane. However, the complex floc structure of SS hinders hydrolysis during AD process, thus resulting in lower process efficiency. To overcome the rate-limiting hydrolysis, various pre-treatment methods have been developed to enhance AD efficiency. This review aims to provide insights into recent advancements in pre-treatment technologies, including mechanical, chemical, thermal, and biological methods. Each technology was critically evaluated and compared, and its relative worth was summarized based on full-scale applicability, along with economic benefits, AD performance improvements, and impact on digested sludge. The paper illuminates the readers about existing research gaps, and the future research needed for successful implementation of these approaches at full scale.

Life-cycle assessment approach for municipal solid waste management system of Delhi city.

The life-cycle assessment (LCA) approach with route optimization technique was adopted in the present study to evaluate environmental and economic aspects associated with the prevalent waste management system in Delhi city. With an objective of cost minimization and abating environmental hazards from waste transportation systems, ArcGIS was used to identify the most appropriate route for waste transportation. The study was conducted considering four landfills located at Bawana, Bhalswa, Ghazipur and Okhla present in Delhi city. Landfilling, composting, anaerobic digestion, and recycling methods were analyzed for global warming potential (GWP), eutrophication potential (EP), acidification potential, abiotic resource depletion potential and photochemical oxidation potential parameters using LCA software GaBiPro. The results from the LCA studies for the municipal solid waste management system of Delhi city revealed that transportation emissions and landfilling negatively impact the environment. The effect of recycling rate on the landfilling, composting, anaerobic digestion was also studied using sensitivity analysis. Results of sensitivity analysis depicted that recycling of waste is inversely related to the impact categories. Overall, the results exhibited a detrimental effect of landfilling on the environment in terms of GWP and EP. Further, considering the geospatial analysis, two waste recycling stations are proposed in the vicinity of existing waste management plants to reduce the time and cost of waste transport from the landfills to the waste management plants.

Turning Solid Waste into Catalysts: A Path for Environmental Solutions.

Waste, often overlooked, stands out as a prime source of valuable products, meeting the demand for natural resources. In the face of environmental challenges, this study explores the crucial role of waste-derived catalysts in sustainable practices, emphasizing the transformative potential of solid waste materials. Carbon-based catalysts sourced from agricultural, municipal, and industrial waste streams can be transformed into activated carbon, biochar, and hydrochar which are extensively used adsorbents. Furthermore, the paper also highlights the potential of transition metal-based catalysts derived from spent batteries, electronic waste, and industrial byproducts, showcasing their efficacy in environmental remediation processes. Calcium-based catalysts originating from food waste, including seashells, eggshells, bones, as well as industrial and construction waste also find an extensive application in biodiesel production, providing a comprehensive overview of their promising role in sustainable and eco-friendly practices. From mitigating pollutants to recovering valuable resources, waste-derived catalysts exhibit a versatile role in addressing waste management challenges and promoting resource sustainability. By transforming waste into valuable catalysts, this study champions a paradigm shift towards a more sustainable and resource-efficient future.

Effect of Suture Length on the Incidence of Incisional Hernia and Surgical Site Infection in Patients Undergoing Midline Laparotomy: A Systematic Review and Meta-Analysis.

The development of an incisional hernia is a common complication of midline laparotomy. Improper fascial closure techniques have a significant role in its development. It can also lead to poor wound healing and increase the risk of developing surgical site infections (SSI). Upon conducting a thorough literature review, various studies have been conducted on closing abdominal wounds. However, there is a dearth of studies portraying the role of suture length in the prevention of incisional hernia and SSI. The effect of using a greater suture-to-wound length ratio on postoperative outcomes was not clearly analyzed or described. The objective of this study is to assess the effectiveness of using a suture length to wound length ratio ≥4:1 versus a ratio <4:1 in preventing postoperative complications such as incisional hernia and SSI. This study is a systematic review of randomized controlled trials on abdominal wound closure using a suture length to wound length ratio of ≥4:1 and <4:1. published in PubMed, Google Scholar, and Cochrane library. The inclusion and exclusion criteria were defined. The relevant studies identified from 1991 to 2017, were included in the analysis. The primary endpoint was the incidence of incisional hernia, and the secondary outcome was the incidence of SSI. This meta-analysis considered five randomized controlled trials that compared the effects of using different suture length to wound length ratios during abdominal closure on incisional hernia and SSI. Participants ranged in size from 100 to 363. The trial follow-up period ranged from a minimum of 10 months to five years. The outcomes studied in the two groups were incisional hernia and SSI. The relative risk of the occurrence of incisional hernia if the suture length to wound length ratio was ≥4:1 was 0.42 with a p-value of <0.001 which was considered significant. This implied that using a suture length of more than four times that of the wound i.e., 4:1, significantly decreases the risk of developing an incisional hernia by more than half. The relative risk of developing a SSI was 0.98 with a p-value of 0.966. Thus, this method of abdominal closure uing a longer suture length to wound length ratio does not contribute to an increased incidence or significant change in the risk of developing SSI.

The Value of the Sequential Organ Failure Assessment (SOFA) Score and Serum Lactate Level in Sepsis and Its Use in Predicting Mortality.

Background and objective Sepsis is a major health burden that leads to significant morbidity and mortality. Early diagnosis and severity prediction using various scoring systems can reduce the mortality rate, particularly in developing nations. There are two aims of this study. One is to evaluate the prognostic accuracy of the Sequential Organ Failure Assessment (SOFA) score and serum lactate levels in patients with sepsis to predict mortality. The other aim is to evaluate the relationship between the SOFA score and lactate so that we may be able to use lactate as a surrogate predictor of organ dysfunction and mortality in sepsis. Methods An observational prognostic accuracy study was conducted in the Department of General Surgery, Intensive Care Unit (ICU), Rajendra Institute of Medical Sciences (RIMS), Ranchi, Jharkhand, India, between 1 July 2021 and 1 October 2022. We selected 128 patients, calculated their SOFA and lactate levels, and divided them into survivors and non-survivors according to their outcomes after seven days of assessment. The SOFA score and serum lactate levels were assessed as predictors of mortality, and their correlation was studied. Results We observed a significant decreasing trend in the value of the mean SOFA, maximum SOFA, mean lactate, and maximum lactate among survivors, whereas an increasing trend for the same was observed in non-survivors. The receiver operating characteristic (ROC) analysis showed the best diagnostic accuracy of the mean lactate (area under the curve {AUC}=0.996, 95% confidence interval {CI}=0.964-1.00, p≤0.0001). The maximum lactate (AUC=0.987, 95% CI=0.949-0.999, p≤0.0001) and mean SOFA scores (AUC=0.986, 95% CI=0.948-0.999, p≤0.0001) were good at predicting the mortality in sepsis. A slightly lower diagnostic accuracy was found for the maximum SOFA score (AUC=0.969, 95% CI=0.923-0.992, p≤0.0001). There was a strong correlation between the mean lactate and the mean SOFA with a correlation coefficient of 0.883 and p=0.0001. A good correlation was found between maximum lactate and maximum SOFA too (correlation coefficient=0.873, p≤0.0001). Conclusion This study highlights the different predictors of mortality in the patients with sepsis. The maximum lactate was the most accurate in predicting mortality in sepsis. It also demonstrates how serum lactate, due to its strong correlation with the SOFA score, can be used in its place to predict mortality in sepsis and organ dysfunction.