jurnal moicrobilogi

1. Evaluation of Microbiological and
Physicochemical Parameters of
Alternative Source of Drinking
Water: A Case Study of Nzhelele
River, South Africa

2. Abstract
Background
Access to clean and safe drinking water is still a problem in developing countries and more pronounced in
rural areas. Due to erratic supply of potable, rural dwellers often seek for an alternative source of water to
meet their basic water needs. The objective of this study is to monitor the microbiological and
physicochemical water quality parameters of Nzhelele River which is a major alternative source of drinking
water to villages along its course in Limpopo province of South Africa.

3. Methods
Membrane filtration method was employed in
evaluating the levels of E. coli and
Enterococci in the river water from
January-June, 2014. Specialized multimeter
was used to measure the pH, electrical
conductivity and turbidity of the river
water. Ion Chromatograph was used to
measure major anions such as fluoride,
chloride, nitrate and sulphate in the
water.

4. Result
High levels of E. coli (1 x 102 - 8 x 104
cfu/100 mL) and enterococci (1 x 102 – 5.7
x 103 cfu/100 mL) were found in the river
water and exceeded their permissible limits
of 0 cfu/100 mL for drinking water.
Turbidity values ranged from 1.12-739.9
NTU. The pH, electrical conductivity,
chloride, fluoride, nitrate and sulphate
levels were below their permissible limits
for drinking water.

5. Conclusio
n
The river water is contaminated with faecal
organisms and is unfit for drinking
purposes. However, the levels of the major
anions accessed were within the permissible
limits of drinking water.

6. Clean and safe water is an important natural
resource for the sustainability of life and a
healthy economy. Freshwater availability is one
of the major problems facing the world and
approximately one third of drinking water
requirement of the world is obtained from
surface sources like rivers, dams, lakes and
canals . These sources of water also serve as
best sinks for the discharge of domestic and
industrial wastes. The biggest threat to
sustainable water supply in South Africa is the
contamination of available water resources
through pollution
INTRODUCTION

7. MATERIALS AND METHODS
•Sampling
All sample bottles used were soaked in a livid detergent, followed by rinsing with
tap water until they were free of detergent. Six samples were collected monthly
from 30th January to 10th June, 2014, making a total of 36 samples. The samples
were collected randomly along different sampling locations in Nzhelele River using
sterile sampling bottles. Each sample was collected by submerging the sample
container into the river at about 100–300 mm below the surface with an open end
facing against the current flow direction . Field measurements of pH and Electrical
conductivity (EC) were performed using a 340i Multimeter (WTW, Weilheim,
Germany) while Turbidity was measured with a Tobcon turbidimeter (TB200,
Orbeco Hellige, Sarasota, FL, USA). The samples were transported on ice chest to
microbiology laboratory of the University of Venda.

8. •Analysis of Faecal
Indicator Organisms
All samples were analysed within 6 hours of collection as recommended by the
American Public Health Association (APHA) except for January samples which were
analysed within 16 hours of collection this was because of difficulties to reach the
sampling sites due to heavy rainfall encountered on the way before reaching them.
Each water sample was analysed for E. coli and Enterococci levels. Samples (100
mL) were diluted (1:10) in accordance with level of pollution, and analysis was
performed using the membrane filtration culture method in accordance with the
standard methods described by APHA

9. •Analysis of Anions
The method reported by Edokpayi et al. was employed in this study: The samples
were filtered through 0.45-micron syringe filter and placed in an autosampler
connected to Metrohm 850 Ion Chromatograph (IC) supplied by Metrohm,
Switzerland. Calibration standards for fluoride, chloride, nitrate and sulphate were
prepared from two multi element standards. 1 mg/L, 5 mg/L, 10 mg/L and 20 mg/L
were prepared by serial dilution from a stock solution of 100 mg/L. The eluent used
was a combination of Na2CO3 and NaHCO3; prepared by weighing accurately 0.168
g and 0.6784 g into 2 L volumetric flask and filled to the mark using ultrapure water.
0.5M sulfuric acid was used as a regenerant solution. Prior to analysis, the eluent
was degassed using an ultrasonic bath for 15 minutes. The IC has a flow rate of 0.7
mL/min, maximum and minimum pressure of 15.0 mPa and 0.1 mPa respectively.

10. •Validation of Analytical
Methodology
In order to validate the analytical methodology, recovery studies were performed.
Known concentrations of the test analyte were added to the sample. The
concentrations of both the spiked and unspiked samples were determined and
percentage recovery was obtained.

11. •Statistical Analysis
Delta Graph 7 was used for drawing the graphs. SPSS version 20.0 was used for
evaluating the average values obtained from each sampling month. The student t-
test of SPSS was employed in the comparing of the means with probability set at
p<0.05.

12. Result
• Faecal Indicator
Organisms
Total E. coli and enterococci counts in the
samples from six different sites along the
river are presented in The box-and-whisker
plots which indicate the mean (diamond) of
the levels of E. coli and enterococci in each
site, the first, second, and third quartiles
(box), and minimum and maximum
(whiskers) are also presented in

13. • Faecal Indicator Organisms
The percentage recovery obtained for fluoride,
chloride, nitrate and sulphate concentrations
were 93%, 96%, 95% and 97%, respectively.
The average pH values ranged between 7.21-
7.76 Table . The average EC values varied from
83.47 -136.07 µS/cm, during the sampling
period. shows the turbidity values measured
during the sampling periods.

14. • Physicochemical parameters
The percentage recovery obtained for fluoride,
chloride, nitrate and sulphate concentrations were
93%, 96%, 95% and 97%, respectively.. The average
EC values varied from 83.47 -136.07 µS/cm, during
the sampling period. Fig. shows the turbidity
values measured during the sampling periods. Low
levels of anions were found in the water samples
collected from the various sampling sites. All the
anions investigated complied with the SANS
permissible limit of drinking water.

15. • DISCUSSION
High levels of E. coli and enterococci were found in the river
water which could pose a health risk to the consumers of
this water resource.
The concentrations of the anions determined did not present
any health risk to the health of the consumers of this resource.
Although high concentration of fluoride exceeding 1.5 mg/L
can affect the bones and teeth of humans, the average levels
observed in this study was lower than 1 mg/L for each sampling
month. Nitrogen is an important plant nutrient and often
applied to agricultural lands to enhance plants productivity.
Although various forms of agriculture are practiced in the study
area, the concentrations of nitrates determined complied to
SANS guidelines for safe drinking water

16. • CONCLUSION
Surface water should be protected against undue
anthropogenic influence. The river examined in this study
and many others which are used by rural dwellers around
the world are increasingly loaded with various classes of
pollutants from both point and non-point sources. Although
the physicochemical water quality parameters investigated
in this study complied with the benchmark values, the water
is polluted with faecal matter with potential risk of
waterborne diseases to the users of this resource. In order
to prevent negative episode of waterborne diseases, it is
recommended that water abstraction of water from
Nzhelele River for domestic purposes without proper
treatment should be discouraged. Cheap and efficient point
of use water treatment devices should be developed.

17. Thank You!