Heavy metal levels in analytical laboratories waste: a study for the implementation of a programme for the control and disposal of waste from microbiology and chemical analysis laboratories
Dissertação de mest., Qualidade em Análises, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012Analytical Laboratories daily routine analyses leads to the generation of solid and
liquid waste. Quality assurance and quality control procedures are employed in most of these
laboratories to ensure that accurate results are obtained and the waste generated out of these
analyses are properly stored for collection by waste treatment companies. The cost associated
with waste treatment varies with the type of waste generated. Liquid waste are quantified or
priced according to the volume of waste. Microbiology waste are inactivated and added to
solid waste for collection and treatment but residues from Chemical Analysis Laboratories
cannot be emptied down the drainage systems since it can contain some levels of heavy
metals which can be dangerous to the environment or human. Therefore the objective of this
thesis was to characterize some of these important heavy metals so that they can be treated
and discarded by the laboratory staff leading to reduction in payment for their treatment by
external companies. The research involved the determination of total heavy metal (Pb, Cu
Zn, Cr, Cd, Ni, Fe, As, Hg, Al) levels in Microbiology (M) and Chemical (C ) samples using
the Atomic Absorption Spectroscopy (AAS). Flame technique was used for the analysis of
Cd, Cu, Zn, Fe, Pb, Cr, Ni and Al was analyzed with Furnace technique. However, hydride
generation and cold vapour procedures were used for As and Hg respectively. The mean
concentration of all the Heavy metals analyzed from the chemical (c) and microbiology (M)
samples were all below the Guidelines for Maximum Admissible values for parameter in
industrial water residuals with the exception of Fe, Al, As and Hg levels in the DRAAL and
LAQ chemical samples which showed concentrations values of 5.0, 89.5, 5.93, 0.42 mg/L
and 21.9, 19.0, 3.59, 0.11mg/L respectively, which were higher than the recommended levels
of 2.0, 10, 0.5, 0.05mg/L respectively. The microbiological samples were cultured for
microorganisms by employing the Incorporation Technique with PCA and PDA. No growth
was recorded for both media after 24 and 48 hours of incubation. The results obtained could
be used to implement the WC-D programme (Waste-Control and Disposal programme) for
microbiological and chemical analysis laboratories of the University
