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Breakthrough analysis of continuous fixed-bed adsorption of sevoflurane using activated carbons

Ang TN, Young BR, Taylor M, Burrell R, Aroua MK, Baroutian S

Chemosphere, 2020 Jan;239:124839.
PMID: 31726519 DOI: 10.1016/j.chemosphere.2019.124839

The inhalational anaesthetic agent - sevoflurane is widely employed for the induction and maintenance of surgical anaesthesia. Sevoflurane possesses a high global warming potential that imposes negative impact to the environment. The only way to resolve the issue is to remove sevoflurane from the medical waste gas before it reaches the atmosphere. A continuous adsorption study with a fixed-bed column was conducted using two commercial granular activated carbons (E-GAC and H-GAC), to selectively remove sevoflurane. The effect of bed depth (Z, 5-15 cm), gas flow rate (Q, 0.5-6.0 L/min) and inlet sevoflurane concentration (C0, ∼55-700 mg/L) was investigated. E-GAC demonstrated ∼60% higher adsorption capacity than H-GAC under the same operating conditions. Varying the levels of Z, Q and C0 showed significant differences in the adsorption capacities of E-GAC, whereas only changing the C0 level had significant differences for H-GAC. Three breakthrough models (Adams-Bohart, Thomas, and Yoon-Nelson) and Bed-depth/service time (BDST) analysis were applied to predict the breakthrough characteristics of the adsorption tests and determine the characteristic parameters of the column. The Yoon-Nelson and Thomas model-predicted breakthrough curves were in good agreement with the experimental values. In the case of the Adams-Bohart model, a low correlation was observed. The predicted breakthrough time (tb) based on kinetic constant (kBDST) in BDST analysis showed satisfactory agreement with the measured values. The results suggest the possibility of designing, scaling up and optimising an adsorption system for removing sevoflurane with the aid of the models and BDST analysis.

Matched MeSH terms: Medical Waste Disposal/methods*
Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology

Hossain MS, Nik Ab Rahman NN, Balakrishnan V, Alkarkhi AF, Ahmad Rajion Z, Ab Kadir MO

Waste Manag, 2015 Apr;38:462-73.
PMID: 25636860 DOI: 10.1016/j.wasman.2015.01.003

Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO2) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO2 sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO2-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO2 exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials.

Matched MeSH terms: Medical Waste Disposal/methods*
Clinical solid waste management practices and its impact on human health and environment--A review

Hossain MS, Santhanam A, Nik Norulaini NA, Omar AK

Waste Manag, 2011 Apr;31(4):754-66.
PMID: 21186116 DOI: 10.1016/j.wasman.2010.11.008

The management of clinical solid waste (CSW) continues to be a major challenge, particularly, in most healthcare facilities of the developing world. Poor conduct and inappropriate disposal methods exercised during handling and disposal of CSW is increasing significant health hazards and environmental pollution due to the infectious nature of the waste. This article summarises a literature review into existing CSW management practices in the healthcare centers. The information gathered in this paper has been derived from the desk study of open literature survey. Numerous researches have been conducted on the management of CSW. Although, significant steps have been taken on matters related to safe handling and disposal of the clinical waste, but improper management practice is evident from the point of initial collection to the final disposal. In most cases, the main reasons of the mismanagement of CSW are the lack of appropriate legislation, lack of specialized clinical staffs, lack of awareness and effective control. Furthermore, most of the healthcare centers of the developing world have faced financial difficulties and therefore looking for cost effective disposal methods of clinical waste. This paper emphasizes to continue the recycle-reuse program of CSW materials after sterilization by using supercritical fluid carbon dioxide (SF-CO2) sterilization technology at the point of initial collection. Emphasis is on the priority to inactivate the infectious micro-organisms in CSW. In that case, waste would not pose any threat to healthcare workers. The recycling-reuse program would be carried out successfully with the non-specialized clinical staffs. Therefore, the adoption of SF-CO2 sterilization technology in management of clinical solid waste can reduce exposure to infectious waste, decrease labor, lower costs, and yield better compliance with regulatory. Thus healthcare facilities can both save money and provide a safe environment for patients, healthcare staffs and clinical staffs.

Matched MeSH terms: Medical Waste Disposal/methods*
Fulltext Factors Contributing to Sharp Waste Disposal at Health Care Facility Among Diabetic Patients in North-East Peninsular Malaysia

Hasan UA, Mohd Hairon S, Yaacob NM, Daud A, Abdul Hamid A, Hassan N, et al.

Int J Environ Res Public Health, 2019 06 26;16(13).
PMID: 31247892 DOI: 10.3390/ijerph16132251

BACKGROUND: Type 2 diabetic patients are major users of medical sharps in the community. Proper sharp disposal practice among them, however, was reported to be low. The current study was aimed to determine the factors contributing to sharp waste disposal at a health care facility among Type 2 diabetic patients.
METHODS: In this cross-sectional study, Type 2 diabetic patients who were on insulin therapy attending health clinics were randomly selected and interviewed using a validated questionnaire. Binary logistic regression analysis was applied.
RESULTS: Out of 304 respondents, only 11.5% of them brought their used sharps to be disposed at health care facilities. Previous advice on sharp disposal from health care providers, knowledge score, and duration of diabetes were significant contributing factors for sharp waste disposal at health care facilities: (Adj. OR 6.31; 95% CI: 2.63, 15.12; p < 0.001), (Adj. OR 1.05; 95% CI: 1.03, 1.08; p < 0.001), and (Adj. OR 2.51; 95% CI: 1.06, 5.93; p = 0.036), respectively.
CONCLUSION: Continuous education and a locally adapted safe sharp disposal option must be available to increase awareness and facilitate diabetic patients adopting proper sharp disposal behavior.

Matched MeSH terms: Medical Waste Disposal/methods*