Characterization of bottom ash from two hospital waste incinerators in Rabat, Morocco

Abstract

The uncontrolled disposal of bottom ash generated by the incineration units of hazardous and infected wastes in developed countries are the main cause of significant damage, such as contamination of the soil, as well as surface and underground waters, which may put both the environment and public health at risk. In Morocco, little information is available on the chemical properties of the resulting ashes. In this study, 16 hospital waste ash samples were collected from the incinerators of the two main hospitals in Rabat: Ibn Sina and Cheikh Zayd. A series of tests was conducted, including particle size distribution, mineralogical and chemical composition, and heavy metal leaching behaviour. The results showed that the samples were composed mainly of P2O5 (18%), SiO2 (17%), Na2O (16%), CaO (14%) and SO3 (10%). Moreover, chemical analysis clearly demonstrated that medical waste (MW) contains large amounts of waste generated by domestic activities in the hospital, with a lack of sorting system in the monitoring of MW. Furthermore, the ashes contained high concentrations of heavy metals such as zinc, lead, chromium and nickel with a vast range of 0.5-25071 mg/kg. Leaching tests showed that the extracted amounts of all the heavy metals were lower, with concentrations < 2.85 mg/kg. Comparison of the corresponding heavy metal concentrations with the limit values set by the Council Decision 2003/33/EC allowed us to conclude that bottom ashes meet the waste acceptance criteria regarding these heavy metals.

Heavy Metal Contamination of Soils around a Hospital Waste Incinerator Bottom Ash Dumps Site

“…In a descending order of concentration Zn > Pb > Cr > Ag > Cd > Hg were all found to be above USEPA allowable limits for safe disposal to a landfill site. Our findings were similar to studies conducted in Morocco and Kenya [ 18 , 19 ]. The heavy metals found in the bottom ash are usually associated with the waste feed stock (thermometers, blood pressure cuffs, laboratory chemicals, plastics, syringes, etc.)…”

Characterization and evaluation of the leachability of bottom ash from a mobile emergency incinerator of COVID-19 medical waste: A case study in Huoshenshan Hospital, Wuhan, China

“…According to the XRF, ICP, and XRD results, Ca compounds were the main components in MBA, and their contents were much higher than those of bottom ash in a previous study ( Bakkali et al, 2013 ; Gidarakos et al, 2009 ; Kougemitrou et al, 2011 ). The results indicated that MBA could easily form a geopolymer paste and have good mechanical properties during landfill disposal ( Abdullah et al, 2017 ).…”

“…These variations could be attributed to the large number of medical products, such as protective suits, face masks, glasses needles, scalpels, and knives. The presence of Na and K in MBAs probably originates from medicine, physiological saline, blood-stained cotton, wound-dressing materials and body fluid in medical waste, which has been previously reported ( Bakkali et al, 2013 ; Shen et al, 2019 ). Some products in medical waste could increase the content of metals in MBAs.…”

“…The bulk densities of MBAs ranged from 1.3678 to 1.4308 g cm −3 , which are comparable to those of bottom ashes in previous reports ( Huber et al, 2020 ). MBAs are highly alkaline with a pH level of approximately 13, which might be attributed to the presence of alkali metals and metallic compounds such as Na 2 O, K 2 O, CaCO 3 , CaO, MgCO 3, and Al 2 O 3 ( Adotey et al, 2018 ; Bakkali et al, 2013 ). The moisture contents of MBAs range from 1.07% to 1.87%, indicating that the incineration almost dried these MBAs.…”

Healthcare waste management research: A structured analysis and review (2005–2014)

“…Bo et al (2009) treated MW incinerator fly ashes with supercritical water and H 2 O 2 and found this experiment as effective treatment for hazardous elements detoxification in MW fly ash. Bakkali et al (2013) collected samples of fly ash from 16 hospitals to conduct a series of tests and showed that the samples were composed mainly of P 2 O 5 (18%), SiO 2 (17%), Na 2 O (16%), CaO (14%) and SO 3 (10%). Further, the ashes contained high concentrations of heavy metals, such as zinc, lead, chromium and nickel with a range of 0.5-25,071 mg kg -1 .…”