Page 76 - {PDF Title}

Hossain, et al.

overhead storage tanks, which serve as the primary Instruments were routinely calibrated using standard
distribution points for the municipality’s pipeline solutions to maintain precision. Blank tests were
network, broadly representing the overall water quality. conducted to account for background interference,
At present, Kushtia Municipality supplies water whereas control tests with known reference values
through two primary modes. The first mode includes ensured measurement consistency. Before use,
10,158 private pipeline connections, covering reagents were tested for expiration dates and
approximately 33% of the total municipal area. The compliance with analytical requirements. To assess
24
second mode consists of 56 PWPs, of which 39 are measurement repeatability and accuracy, triplicate
currently operational. These PWPs provide free access measurements (n = 3) were conducted for each
to drinking water, primarily serving marginalized sample, and results were compared for consistency.
communities. The locations of these PWPs are detailed Equipment was regularly maintained and inspected
in Table S1. to prevent systematic errors. Calibration records,
QA/QC documentation, and maintenance logs were
2.4. Sampling, sample collection, and analysis systematically maintained to verify the performance
Water samples were collected from Kushtia and reliability of analytical techniques.
Municipality’s four WTPs and key points within the
municipal pipeline network to assess water quality 2.6. Treatment efficiency
trends across the distribution system. At each WTP, The removal efficiency of a WTP is defined as the
one sample was collected from the inlet (untreated percentage reduction of a pollutant or a set of pollutants
water) and one from the outlet (treated water exiting the from influent (untreated) to effluent (treated) water.
31
overhead storage tanks). In addition, four samples were A higher removal efficiency indicates that the WTP
purposively selected from a 500 m buffer zone based effectively removes contaminants and improves water
on consultations with local authorities, preliminary quality. This study used Equations I – II to calculate
assessments, and geographic and usage considerations individual treatment efficiency and mean cumulative
within the network. While the sample size was limited, efficiency for all measured parameters. The individual
4
the study aimed to capture general water quality trends efficiency ( ) for the -th water parameter at time
across the distribution system, balancing practicality t (at the time of analysis) was calculated using:

and cost-effectiveness with analytical feasibility.
) ] ×100
In total, 12 water samples were collected from = [1− ( , ) /( , (I)

March 1 to March 7, 2024, covering different stages where C and C represent treated and untreated
o
in
of treatment. The samples were categorized into three water, respectively.
sources: (i) four untreated samples from WTP inlets, The mean cumulated efficiency ( ) for n water

(ii) four treated samples from overhead storage tanks, parameters at the time t was determined using:
and (iii) four samples from PWPs. The sampling n
1
locations are illustrated in Figure 1. Polypropylene = � ef (II)
plastic bottles were used for sample collection. Before n j 1 jt
sampling, bottles were thoroughly washed, rinsed with
deionized water, autoclaved, and dried completely in a 2.7. WQI calculation
laminar flow hood. Dissolved oxygen (DO), electrical A total of 13 parameters (Table S2) were utilized to
conductivity (EC), total dissolved solids (TDS), pH, determine the WQI using the weighted average method,
temperature, and oxidation-reduction potential (ORP) initially developed by Horton and later refined by
32
were measured on-site, while all other parameters Brown et al. The mathematical calculation of WQI
33
were measured in the laboratory. Samples were kept was carried out in three stages: (i) determining the unit
at 4°C until analysis. The analytical instruments and weight (Wn) of water quality parameters, (ii) calculating
30
methodologies used for sample analysis are summarized the subindex or quality rating of the water quality
in Table 1. parameters, and (iii) aggregating these values to obtain
the final WQI.
2.5. Quality assurance (QA) and quality control
(QC) procedures 2.7.1. Calculation of Wn
Multiple QA/QC techniques were implemented The Wn of each water quality parameter was calculated
to ensure measurement accuracy and reliability. using Equation III, which divides the constant of

Volume 22 Issue 1 (2025) 70 doi: 10.36922/ajwep.8163