Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Crude biodiesel refining using membrane ultra-filtration process: An environmentally benign process

Ceramic membrane separation system was developed to simultaneously remove free glycerol and soap from crude biodiesel. Crude biodiesel produced was ultra-filtered by multi-channel tubular membrane of the pore size of 0.05 μm. The effects of process parameters: transmembrane pressure (TMP, bar), temperature (°C) and flow rate (L/min) on the membrane system were evaluated. The process parameters were then optimized using Central Composite Design (CCD) coupled with Response Surface Methodology (RSM). The best retention coefficients (%R) for free glycerol and soap were 97.5% and 96.6% respectively. Further, the physical properties measured were comparable to those obtained in ASTMD6751-03 and EN14214 standards

Removal of residual palm oil-based biodiesel catalyst using membrane ultra-filtration technique: An optimization study

In this research work, residual potassium hydroxide catalyst was removed from palm oil-based alkyl esters (biodiesel) using membrane separative technique, with the aim of achieving high-quality biodiesel that meets international standard specifications. Further, Central Composite Design (CCD) coupled with Response Surface Methodology (RSM) was employed to study the effects of the system variables such as flow rate, temperature and transmembrane pressure (TMP) on the retention of potassium. At the optimum conditions, the coefficient of retention (%R) of the catalyst was 93.642, and the content of the potassium was reduced from 8.328 mg/L to 0.312 mg/L; a value well below the one specified by both EN 14214 and ASTM D6751 standards. In addition, the comparison between predicted and experimental values for the catalyst retention offers a reasonable percentage error of 0.081%. Therefore, this study has proven that membrane technique can be used to post treat crude biodiesel; in order to achieve high-quality biodiesel fuel that can be efficiently used on diesel engines

High quality biodiesel obtained through membrane technology

In this study, a ceramic membrane with a pore size of 0.02μm was used to purify crude biodiesel to achieve biodiesel product that meet both ASTM D6751 and EN 14241 standards specifications. The membrane system was successfully developed and used for the purification process. Process operating parameters such as transmembrane pressure, flow rate and temperature were investigated. Application of central composite design (CCD) coupled with Response Surface Methodology (RSM) was found to provide clear understanding of the interaction between various process parameters. Thus, the process operating parameters were then optimized. The optimum conditions obtained were transmembrane pressure, 2bar, temperature, 40°C and flow rate, 150L/min with corresponding permeate flux of 9.08 (kg/m 2h). At these optimum conditions, the values of free glycerol (0.007wt) and potassium (0.297mg/L) were all below ASTM standard specifications for biodiesel fuel. In addition the physical properties of biodiesel at the optimum conditions met both ASTM D6751 and EN 14214. This work showed that with ceramic membrane of pore size 0.02μm, biodiesel with high qualities that meet the stringent standards specifications more than those currently in application can be achieved. © 2012 Elsevier B.V

Dual-wavelength passively Q-switched erbium ytterbium codoped fiber laser based on a nonlinear polarization rotation technique

We report a room temperature all-fiber dual-wavelength Erbium Ytterbium codoped fiber laser (EYDFL) operating at 1543.3 and 1545.4 nm using a nonlinear polarization rotation (NPR) technique. An isolator is used in conjunction with a multilobed double-clad Erbium Ytterbium codoped fiber to induce intensity-dependent loss in a sufficiently high loss ring cavity to achieve dual-wavelength and Q-switching simultaneous operations. At the threshold pump power of 0.27 W, the EYDFL generates a sequence of pulses with repetition rate of 12.06 kHz and pulse width of 11.56 mu s. When the multimode pump is increased to 0.60 W, the repetition rate can be tuned to 57.94 kHz. The lowest pulse width of 5.04 mu s and the maximum pulse energy of 72.01 nJ are obtained at the pump power of 0.55 W. The simple and inexpensive dual-wavelength Q-switched NPR-based laser has a big potential for applications in metrology, environmental sensing, and biomedical diagnostics. (C) 2015 Wiley Periodicals, Inc

Refining technologies for the purification of crude biodiesel

In biodiesel production, downstream purification is an important step in the overall process. This article is a critical review of the most recent research findings pertaining to biodiesel refining technologies. Both conventional refining technologies and the most recent biodiesel membrane refining technology are reviewed. The results obtained through membrane purification showed some promise in term of biodiesel yield and quality. Also, membranes presented low water consumption and less wastewater discharges. Therefore, exploration and exploitation of membrane technology to purify crude biodiesel is necessary. Furthermore, the success of membrane technology in the purification of crude biodiesel could serve as a boost to both researchers and industries in an effort to achieve high purity and quality biodiesel fuel capable of replacing non-renewable fossil fuel, for wide range of applications. (C) 2011 Elsevier Ltd. All rights reserved

The effects of water on biodiesel production and refining technologies: A review

Presence of water during biodiesel production and purification processes, storage and use in compression ignition (diesel) engines causes problems that cannot be ignored. These problems include: difficulties in biodiesel processing especially during alkali-catalyzed transesterification process, deterioration of biodiesel quality, decrease in heat of combustion, corrosion of fuel system components, and acceleration of hydrolytic reaction. Beside use of water during biodiesel purification results in wastewater discharges which causes environmental effects, due to high contents of chemical oxygen demand, biological oxygen demand, and higher pH values. Thus, this study critically analyzed and examined the effects of water on biodiesel production and the refining of crude biodiesel. Furthermore the effects of water on the quality of biodiesel were also examined. © 2012 Elsevier Ltd. All rights reserved

Production of biodiesel using high free fatty acid feedstocks

The enormous challenges faced in the search for suitable and profitable feedstocks to produce biodiesel cannot be over-emphasis. This paper has provided an overview of different catalysts used in processing different kinds of feedstocks for the production of biodiesel. Although the process of biodiesel production from refined feedstocks is less cumbersome and could provide biodiesel yield of more than 98, but its product cost is high. Thus, the recent biodiesel production from low-quality feedstocks, though presents challenges but has equally provided biodiesel yield comparable to that obtained from refined feedstocks. Furthermore the physicochemical properties of biodiesel derived from low-quality feedstocks are discussed. Additionally economic evaluation of biodiesel from low-quality feedstocks is examined. The result showed that if less expensive feedstocks are used to produce biodiesel, a 25 reduction in cost production is possible. Thus making biodiesel price reasonably closed to the price of petro-diesel. (C) 2012 Elsevier Ltd. All rights reserved