Physicochemical, Heavy Metals Level and Bacteriological Quality of Hand Dug Wells in Awka Anambra State Nigeria
Amos H. Okereke
Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, Nigeria.
Chris O. Anyamene
Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, Nigeria.
Uchechukwu G. Nwankwo
Department of Microbiology, Shanahan University, Onitsha, Anambra State, Nigeria.
Onyekachukwu, I. Udemezue
Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, Nigeria.
Chinenye U. Ezebialu *
Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Good-quality drinking water is essential to human physiology and continued human existence.
Objective: Heavy metal pollution, physicochemical properties, and microbial load of hand-dug wells were evaluated in selected areas of Awka.
Materials and Methods: A total of thirty (30) water samples from hand-dug wells were collected randomly from four communities in Awka using sterile specimen bottles. Fifteen (15) wells were sampled during the rainy season and fifteen (15) during the dry season, yielding thirty (30) hand-dug well samples in total. Physicochemical and chemical properties were determined. Non-metals and heavy metals were analysed using a titrimetric method and an Agilent FS240AA atomic absorption spectrophotometer, respectively. Coliform counts, culture, biochemical tests and molecular characterisation were used to evaluate the bacteriological quality of the samples.
Results: The results showed that turbidity (11.37± - 38.80±5.37 NTU), dissolved oxygen (10.33±1.53 - 17.33±1.53mg/l), biological oxygen demand (6.50±0.30 – 13.87±1.85mg/l), arsenic (0.02±0.00 – 5.14±0.74mg/l), lead (0.42±0.26 – 3.67±1.83mg/l), and phosphate (22.00±1.00 – 160.00±5.57mg/l) exceeded the acceptable WHO limit. Total Dissolved Solids (143.33±3.51 – 688.00±57.19mg/l), Nitrate (54.33±1.15 – 251.67±0.58mg/l), Sulphate (17.67±1.53 – 92.67±2.52mg/l), Fluoride (0.14±0.03 – 5.13±0.40mg/l), and Chloride (0.30±0.26 – 5.80±0.72mg/l), all exceeded the limit only during the dry season, while Nickel, Chromium, and Iron occasionally exceeded the limit only during the rainy season. The limits for cadmium and zinc were exceeded in some samples. Coliform counts were higher during the rainy season (0.7 x 102 – 2.2 x 104), but E. coli (16.7%), an indicator of faecal contamination, was more frequent in the dry season (3; 10%). E. coli and Mesobacillus were the most frequently occurring isolates (5; 16.7%), whereas Micrococcus sp. and Klebsiella sp. were the least frequent (1; 3.3%).
Conclusion: Seasonal variation affects the physicochemical characteristics, heavy-metal concentrations and bacteriological quality of well water. Regular monitoring and treatment of hand-dug well water are needed to improve its quality for domestic use.
Keywords: Hand-dug wells, heavy metals, contamination, coliforms, physicochemical