Industrial Wastewater Loads and Pretreatment Performance of Beverage Industries Discharging to Mbeya Municipal Waste Stabilisation Ponds beya Municipal Waste Stabilization Ponds

Abstract

Industrial wastewater is a growing threat to municipal Waste 
Stabilisation Ponds (WSPs) in rapidly urbanising Sub-Saharan cities. 
This study evaluated the pretreatment efficiency and quantified 
pollutant loads from three major beverage industries—Tanzania 
Breweries Limited (TBL), Coca-Cola Kwanza, and Pepsi—that 
discharge into the Kalobe WSP in Mbeya, Tanzania. Weekly grab 
samples were collected over a one-month period (n = 12 per 
industry), and physicochemical parameters, including BOD₅, COD, 
TSS, nutrients, and pH, were analysed following Standard Methods. 
Daily pollution loads (kg/day) were calculated from measured flows 
and concentrations, and statistical differences were tested using 
one-way ANOVA and Pearson correlation at a 95% confidence 
level. Results showed significant variation in wastewater quality 
among the industries (p < 0.05). In terms of treatment efficiency, 
Coca-Cola consistently maintained the lowest pollutant 
concentrations, demonstrating effective pretreatment and 
compliance with national standards. TBL recorded elevated 
suspended solids due to brewing by-products, while Pepsi 
exhibited the poorest pretreatment performance, discharging the 
highest organic loads (BOD: 124.81 kg/day; COD: 245.46 kg/day) 
despite moderate flow. Collectively, Pepsi accounted for 71% of 
BOD and 76% of COD loads entering the WSP, underscoring that 
industries with insufficient pretreatment disproportionately stress 
municipal systems. The findings underscore the urgent need for 
targeted upgrades to Pepsi’s pretreatment facility, stricter 
enforcement of load-based discharge permits, and improved 
industry–utility collaboration. This study is the first in Tanzania to 
apply a mass-based load assessment framework for industrial 
discharges, providing a replicable model for regulatory action. The 
results 
support implementation of Tanzania’s Industrial 
Wastewater Regulations (2020) and contribute to achieving SDG 
6.3 on reducing untreated wastewater.