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Mounira

using an appropriate factor. BOD 5 values (mg/L) are the reading was allowed to stabilize before being
calculated using Equation II. recorded. The instrument was calibrated according

BOD 5 = Reading × Correction factor (II) to the manufacturer’s guidelines before use. DO was
expressed in mg/L and as a percentage of saturation (%).
2.5.5. COD measurement
COD was measured by heating a diluted water sample 2.5.11. Nitrite measurement
with potassium dichromate in a COD reactor at 150°C Nitrite concentration was determined using a DR/2000
for 2 h. A blank sample (reagent + distilled water) was spectrophotometer with a specific program (Program
prepared similarly. After cooling, the absorbance of 345) (Hach DR2000, Germany). After sample preparation
both the sample and the blank was measured at 420 nm and reaction with a NitriVer 3 Nitrite Reagent Powder
using a spectrophotometer (DR2000, Germany). The Pillows, the absorbance of the sample was measured at
COD value was determined based on the difference in 507 nm with a blank used for zeroing calibration. Nitrite
absorbance between the sample and the blank. concentration was expressed in mg/L.

2.5.6. Nitrate concentration measurement 2.6. Statistical analysis
Nitrate concentration was determined using a DR/2000 All statistical analyses were performed using Microsoft
spectrophotometer with a specific program 355 which Excel. Descriptive statistics, including means, standard
was set to 500 nm (DR2000, Germany). After dilution deviations, maximum and minimum values, and 95%
and reaction with a Nitraver 5 capsule, the absorbance CI, were calculated for all measured parameters. To
of the sample was measured at 500 nm, with a blank assess the statistical significance of the reduction in
used for calibration. The final result was adjusted for COD concentrations between the influent and effluent
the dilution factor. wastewater, a paired samples t-test was conducted.
The paired t-test was chosen due to its suitability
2.5.7. Ammonium (NH 4 ) concentration measurement for comparing means from two related groups
NH 4 concentration was measured using a DR/2000 (i.e., measurements taken before and after treatment
spectrophotometer with a specific program (DR2000, from the same source). A p < 0.05 was considered
Germany) at 425 nm. After dilution and the addition of statistically significant.
stabilizing and Nessler reagents, the sample color was
measured against a distilled water blank after a 1-min 3. Results and discussion
reaction period.
3.1. Temperature
2.5.8. PO 4 concentration measurement Temperature was measured using a thermometer for
3−
PO 4 concentration was measured using a DR/2000 the area and both inflow and outflow wastewater. These
3−
spectrophotometer with a specific program (DR2000, measurements are displayed in Figure 3 and Table 3.
Germany) at 890 nm. After dilution and reaction with From Figure 3, we can observe that the temperatures of
a ChromaVer. 3 reagent capsule, the blue color of the the inflow and outflow wastewater are relatively similar,
sample was measured against a distilled water blank with the two curves nearly overlapping. The average
following a 2-min reaction period. temperature of the inflow wastewater is 20.50 ± 3.97°C,
while the average temperature of the outflow wastewater
2.5.9. Temperature measurement is 20.76 ± 4.26°C. The maximum temperatures for
Temperature measurements were performed in situ the inflow and outflow wastewater are 26.75°C and
using a digital thermometer integrated into the portable 27.50°C, respectively. The minimum temperature for
conductivity meter (WTW, Germany). The thermometer the inflow wastewater is 11°C, while the minimum for
probe was immersed directly into the water sample, and the outflow wastewater is 12°C.
the temperature reading was recorded once it stabilized.
Temperature was expressed in degrees Celsius (°C). 3.2. pH
The pH values of the inflow and outflow wastewater
2.5.10. DO measurement were measured, and the results are presented in
DO concentrations were measured in situ using a Figure 4 and Table 4. The results demonstrate that
portable DO meter (WTW, Germany). The DO probe the pH values of both the influent (mean: 7.82,
was immersed directly into the water sample, and 95% CI: 7.74 – 7.90) and effluent (mean: 7.95, 95%

Volume 22 Issue 3 (2025) 170 doi: 10.36922/AJWEP025120085