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Performance of Kalobe waste ponds, Mbeya

limited oxygen transfer in facultative zones. Ammonia Despite these limitations, the findings provide
removal was moderate but fell short of benchmarks valuable baseline information on the functioning
reported for tropical WSPs (60–80%), suggesting that of Kalobe WSPs and highlight critical areas for
algal–bacterial interactions were constrained by organic intervention. Future research should incorporate multi-
overload. TDS reduction was minimal, consistent seasonal monitoring, automated flow measurement,
24
with evidence that conventional ponds are not designed and expanded parameter analysis to provide a more
for salt removal, which requires specific polishing comprehensive assessment of treatment dynamics.
processes such as wetlands or ion-exchange media. 8,25
Ecologically, the persistence of ammonia, nitrite, 6. Conclusion and recommendations
and TDS in the effluent presents risks for aquatic life
in receiving waters. Ammonia concentrations above The Kalobe WSPs demonstrated that, even under high-
3 mg/L are toxic to sensitive fish species, while elevated strength mixed municipal and industrial wastewater
nitrite interferes with oxygen transport in aquatic conditions, stabilization ponds can achieve meaningful
organisms. Dissolved solids above 1000 mg/L alter reductions in organic matter and suspended solids.
ionic balances and reduce freshwater biodiversity. The Nevertheless, the system did not consistently meet
observed effluent levels at Kalobe WSPs, therefore, Tanzanian effluent discharge standards, particularly for
raise concerns about downstream ecological stress. BOD, nitrite, and TDS.
This study makes a novel contribution by This study provides novel evidence from Tanzania,
documenting the performance of a Tanzanian where little quantitative data exists on WSPs receiving
WSP receiving combined domestic and industrial industrial inputs. By documenting system performance
wastewater. Unlike most regional studies that evaluate under mixed loadings, the study highlights the persistence
purely municipal systems, this case illustrates the of nutrients and dissolved solids, pollutants that are not
compounded challenges of mixed loading, where adequately treated by conventional pond configurations.
brewery and beverage effluents exacerbate nutrient These findings are important for regulators and utilities
persistence and destabilize biological processes. These in Tanzania and across the region, as they demonstrate
findings emphasize that, while WSPs remain a viable both the strengths of WSPs in tropical climates and the
low-cost technology in resource-constrained settings, critical gaps in nutrient and salt removal.
they require complementary interventions—including Policy interventions are therefore needed to address
industrial pre-treatment, flow regulation, and post- these gaps. Industrial flow regulation and equalization,
treatment polishing—to ensure regulatory compliance stricter enforcement of pre-treatment requirements,
and environmental protection. and the introduction of cost-effective polishing steps
(such as constructed wetlands or sand filtration)
5. Limitations of the study would improve system reliability. If integrated into
existing management strategies, these measures would
This study was limited in several respects that should be strengthen the capacity of WSPs to meet national
acknowledged. First, sampling was conducted during standards and safeguard downstream ecosystems.
the dry season only; therefore, seasonal variability,
particularly the influence of wet-season inflows and Acknowledgments
dilution, was not captured. Second, while composite
grab sampling was applied, daily and diurnal variations The authors gratefully acknowledge the technical and
in industrial discharges may not have been fully logistical support provided by Mbeya Urban Water
represented. Third, the analysis focused on conventional Supply and Sanitation Authority (Mbeya UWSA) and
water quality indicators (BOD , COD, TSS, ammonia, the participating beverage industries. Special thanks are
5
nitrite, and TDS) but did not extend to heavy metals extended to the staff of Mbeya Zonal Laboratory for their
or emerging contaminants, which are often present assistance during sampling and analysis. The authors
in industrial effluents and may affect long-term pond also wish to thank their colleagues and friends who
performance and ecological safety. Finally, the study contributed during the design and writing of this article by
relied on reported flow data from industries for load offering insightful and practical suggestions. Their help
calculations, which may contain uncertainties due to in reviewing the manuscript and providing constructive
irregular monitoring practices. critique greatly improved the quality of the work.

Volume 22 Issue 6 (2025) 207 doi: 10.36922/AJWEP025320249