STUDIES OF DISINFECTION BY-PRODUCTS AND HEAVY METALS IN AHMADU BELLO UNIVERSITY DRINKING WATER SUPPLIES AND OPERATIONS OF SOME TREATMENT PLANTS
STUDIES OF DISINFECTION BY-PRODUCTS AND HEAVY METALS IN AHMADU BELLO UNIVERSITY DRINKING WATER SUPPLIES AND OPERATIONS OF SOME TREATMENT PLANTS
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Date
2011-08
Authors
SHAIBU-IMODAGBE, EGBENYA MUSAH
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Abstract
This study had a broad objective of determining the quality of drinking water produced
by Ahmadu Bello University (ABU) water treatment plant. Its samples were
chemically analysed for general chemical properties, heavy metals and Disinfection
By-Products (DBPs) content in accordance with standard analytical methods and
USEPA methods 551.1 and 552.2 for the DBPs. Structured questionnaire survey was
adopted to evaluate the operating code of practice of the ABU water works and nine
others. 80% of the surveyed water works were found to be of the single train, one
injection point, and one disinfection segment treatment plants. All the water works
have both preliminary and main water treatment processes including screening,
flocculation, sedimentation and disinfection processes. World Health Organization
(WHO) operating code of practice is used by 90% of the treatment plants but in varied
forms. Treatment plants declaring disinfecting water always were 70% though some
reports indicate otherwise while irregular supply prevented those not always
disinfecting. Operators of 60% of treatment plants claimed uninterrupted water
distribution but irregular water distribution was reported. 80% of the treatment plants
had no fully functional service laboratories. Staff were found inadequate, with low
capacity building and have limited professional competence in potable water delivery.
Treated water assessed parameters were pH 7.2, conductivity 96.3μS/cm @ 250C, total
dissolved solids 63.75 mg/l, total organic carbon 2.3 mg/l, nitrate 1.00 mg/l, phosphate
0.12 mg/l, chloride 0.57 mg/l and sulphate 36.17 mg/l. Zinc and lead were the only
heavy metals detected, in concentrations of 0.04 and 0.035 mg/l respectively. Thirtysix
DBPs including nine of the regulated eleven were found in the study. Observed
total regulated Trihalomethanes were 0.0107 and 0.0093 mg/l, total regulated Haloviii
acetic acids 0.52580 and 0.23774 mg/l, total halo-Acetonitriles 0.0269 and 0.0096 mg/l,
total other-DBPs 0.1012 and 0.0409 mg/l and total chlorinated solvents 0.1440 and
0.1306 mg/l (for household and boiled household water respectively) which did not
conform to Nigerian, USEPA, EU and WHO standards because the concentrations of
lead, total THM4, 1,1,2-Trichloroethane and total HAAs exceeded these standards’
maximum permissible levels. Longitudinally, this investigation showed DBP
formation is a consequence of disinfection after which the DBPs were first detected and
in higher concentrations. First morning urine showed higher DBP concentrations than
boiled drinking water triggering public health consequence beginning with increased
excretion by the kidneys to maintain the homeostatic status of the body coupled with
incidences of cancer, diseases of the kidney, liver, the reproductive systems and
damage to the central nervous system. Statistically, observed concentrations were
found to be significantly different between DBP groups (F =3.5115*) or highly
significantly different among the groups (F = 4.8582**) and HAAs (F = 4.93**).
Person’s correlation coefficients (r) ranged from over 0.5 to 0.98 in over 85% of the
analytes indicating a strong combination effects likely varying from additive to
synergistic impacts in the body.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF
DOCTOR OF PHILOSOPHY IN WATER RESOURCES AND ENVIRONMENTAL
ENGINEERING
DEPARTMENT OF WATER RESOURCES AND ENVIRONMENTAL
ENGINEERING, FACULTY OF ENGINEERING,
AHMADU BELLO UNIVERSITY, ZARIA.
Keywords
STUDIES,, DISINFECTION,, BY-PRODUCTS,, HEAVY METALS,, AHMADU BELLO UNIVERSITY,, DRINKING,, WATER,, SUPPLIES,, OPERATIONS,, TREATMENT,, PLANTS