Table Of ContentEcotoxicological Diagnosis in the Tanning Industry
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Mwinyikione Mwinyihija
Ecotoxicological Diagnosis
in the Tanning Industry
Mwinyikione Mwinyihija, PhD, FCIWEM, HSC, CSci., CBiol., CEnv.
Leather Development Council
P O Box 14480-00800
Nairobi, Kenya
[email protected]
ISBN 978-1-4419-6265-2 e-ISBN 978-1-4419-6266-9
DOI 10.1007/978-1-4419-6266-9
Springer New York Dordrecht Heidelberg London
Library of Congress Control Number: 2010935357
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Preface
The tanning industry is a major source of pollution worldwide, particularly in
developing countries. The major public concern over tanneries has traditionally
been about odours and water pollution from untreated discharges. Important pollut-
ants associated with the tanning industry include chlorides, tannins, chromium,
sulphate and sulphides as well as trace organic chemicals and, increasingly,
synthetic chemicals such as pesticides, dyes and finishing agents, as well as
solvents. These substances are frequently toxic and persistent, and affect both
human and environmental health.
The primary focus in this book was to identify the recently developed ecotoxi-
cological analytical trends (rapid, simple and inexpensive) related to the tanning
industry on terrestrial and aquatic systems. The resultant research data reported,
incorporates both field related and laboratory based techniques to address underly-
ing environmental problems in the tanning sector. The book also includes a chapter
to explore the occupational hazards in a tannery environment caused by contami-
nated dust. It was important to note that an optical set-up involving microscopy and
digital imaging techniques was initially used to determine dust particle numbers
and size distributions as a preamble to ascertaining the dust toxicity levels.
To determine the toxic nature of the dust (in addition to particle size), an ecotoxi-
cological screening of the dust samples (using a solid and liquid assay involving the
response of luminescence (lux)-based bacterial biosensor) was conducted and
which was complemented by chemical analysis to identify possible causative toxic
components. Moreover, a novel technique has been discussed in this book related
to the tannery effluent and associated environmental samples. This included a sec-
tion describing the dissection and manipulation of samples through sparging, treat-
ment with activated charcoal, filtration and pH adjustment.
Finally, the book succeeds in meeting its three main specific objectives at the
end: characterisation of effluents, sediments and riverine samples; assessment of
ecotoxicity; bioremediation potential of primary contaminants and input of envi-
ronmental risk assessment through development of a quantitative and qualitative
risk assessment model. Indeed this book will provide a valuable academic and
referral dimension in environmental management related to the tanning industry.
Nairobi, Kenya Dr. Mwinyikione Mwinyihija
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Acknowledgements
The author expresses his sincere appreciation to Professors Kenneth Killham, Andy
Meharg for their guidance and support in this research, Dr Norval Strachan,
Prof. Graeme I Paton providing critical review and support, Dr. Elizabeth Baggs (for
being most supportive and encouraging all along), Dr. Ovidiu Rotariu, Dr’s. Julian
Dawson, Dominic Standing and the environmental microbiology and soil ecotoxicol-
ogy group in the Institute of Biological and Environmental Sciences, University of
Aberdeen, UK for their direct and indirect contribution to the research work reported
in this book. I would also like to register my appreciation to the staff,academic,
technical and support too. The same is also extended to all cadres of staff at the
Veterinary research laboratories, Kabete, Kenya and other colleagues worldwide
who provided their support in the preparation and publishing of this book.
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Contents
1 Introduction .............................................................................................. 1
1.1 Tanning Industry Perspective ............................................................. 1
1.2 Socio-Economic Importance of the Tanning Industry ....................... 2
1.3 Environmental Threats ....................................................................... 2
1.4 Critical Pollutants Identified .............................................................. 2
1.5 Ecotoxicology and Diagnostic Trends ............................................... 3
1.6 Bioavailability, Bioaccumulation and
Biomagnification ................................................................................ 5
1.7 Biochemical Assays for Diagnostic Purposes .................................... 6
1.7.1 Biosensors .............................................................................. 6
1.8 Measurement of Biomass Activity ..................................................... 9
1.8.1 Dehydrogenase ....................................................................... 9
1.8.2 Mode of Action for DHA ....................................................... 10
1.8.3 Application of the DHA Test ................................................. 11
1.8.4 Limitation in Using DHA Test ............................................... 11
1.8.5 Addressing the Limitations of DHA Test .............................. 11
1.9 Daphnia Test ...................................................................................... 12
1.10 Organisation of the Book ................................................................... 12
2 Main Pollutants and Environmental Impacts of the
Tanning Industry ....................................................................................... 17
2.1 Introduction ........................................................................................ 17
2.2 Soaking .............................................................................................. 19
2.3 Liming ............................................................................................... 20
2.4 De-liming, Bating and Pickling ......................................................... 21
2.5 Chrome Tanning ................................................................................ 21
2.6 NaCl .................................................................................................. 22
2
2.7 Organic Matter ................................................................................... 22
2.8 Hydrogen Sulphide (HS) .................................................................. 22
2
2.9 Chromium Salts ................................................................................. 23
2.9.1 Chemistry of Chromium ........................................................ 23
2.9.2 Trivalent Chromium (Cr3+) ..................................................... 23
2.9.3 Hexavalent Chromium (Cr6+) ................................................ 25
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