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Gerson, et al.

Table 7. Cumulative removal efficiencies across the
Kalobe waste stabilization pond treatment stages

Parameter Influent Final effluent Overall
(anaerobic (maturation removal
inlet) outlet) efficiency (%)
BOD 5 93.00 39.00 58.06
COD 612.00 78.00 87.25
TSS 320.00 41.00 87.19
Ammonia 15.40 3.00 80.52
(NH )
3
Nitrite 0.46 0.38 17.39
(NO )
2
Figure 6. Maturation pond – stage-wise concentration TDS 1,034.00 892.00 13.74
and reduction Abbreviations: BOD : Biochemical oxygen demand, 5-day;
5
COD: Chemical oxygen demand; TDS: Total dissolved solids;
TSS: Total suspended solids.
Table 8. Daily industrial discharge flow data for
April 2025
Industry Total Daily average
flow (m ) (m /d)
3
3
Pepsi 20,108 670.3
Tanzania Breweries Limited 12,307 410.2
Coca-Cola Kwanza 4,298 143.3

treatment under mixed municipal and industrial
loading conditions. Organic matter removal was strong,
Figure 7. Overall treatment performance: Influent with COD and TSS reduced to levels typical of well-
versus final effluent functioning tropical WSPs, confirming that anaerobic
and facultative processes remain effective in high-
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These variations highlight that Pepsi was the largest temperature environments. These results align with
contributor in terms of volume. Peak discharges from findings from similar systems in Ghana, Ethiopia, and
TBL and Pepsi were observed midweek, with certain Kenya, where COD reductions of 80–90% and TSS
days (e.g., April 30: TBL – 700 m ; Pepsi – 812 m ) reductions of 70–90% have been reported. 13,23
3
3
showing substantial hydraulic load spikes. In contrast, BOD removal was modest and did not
Such fluctuations may lead to intermittent consistently achieve Tanzanian discharge standards.
overloading of the treatment system, particularly This partial non-compliance can be attributed to
affecting sedimentation and biological processes in intermittent hydraulic shock loads originating from
21
the anaerobic and facultative stages. This pattern of industries, particularly during peak discharge days.
21
unregulated peak flows suggests the need to: (i) Install Comparable challenges have been noted in Ethiopia,
pre-discharge flow equalization tanks at industrial sites, where breweries and beverage industries periodically
(ii) coordinate discharge scheduling with the utility, and overwhelm pond systems, depressing performance. 13,23
(iii) strengthen flow monitoring and regulation policies The link observed in this study between peak flows
to minimize system shock-loading. and efficiency declines highlights the need for flow
equalization at the industrial source.
4. Discussion Nutrient and salt removal were especially weak.
Nitrite removal was negligible, reflecting incomplete
The performance of the Kalobe WSPs demonstrates nitrification–denitrification pathways, often inhibited
both the potential and the constraints of pond-based by fluctuating organic loads, short retention times, and

Volume 22 Issue 6 (2025) 206 doi: 10.36922/AJWEP025320249