Investigation into citrus packhouse raw wastewater quality in the Cape Winelands, South Africa

Abstract

Untreated wastewater from citrus packhouses in the Cape Winelands region of South Africa was assessed as a first step towards identifying suitable treatment options for fungicide reduction and potential wastewater reuse. Global literature on citrus processing wastewater is limited, and this research aimed to contribute to filling that gap. This study was not conducted to identify pollution sources or culprits but rather to establish a baseline understanding of citrus packhouse wastewater. Raw effluent samples collected from 3 packhouses were analysed for key physical, chemical and microbiological parameters, including Escherichia coli. (E.coli), total suspended solids (TSS), total dissolved solids (TDS), chemical oxygen demand (COD), pH, electrical conductivity (EC), and the postharvest fungicides imazalil (IMZ) and fludioxonil (FLU). The results indicate high variability in wastewater characteristics both within and between packhouses, particularly for E. coli (coefficient of variation (CV) = 4.67); TSS solids (CV = 1.49) and IMZ (CV = 1.8). Notably, mean values for total suspended solids and chemical oxygen demand exceeded established South African wastewater discharge limits. This, along with the presence of imazalil fungicide residues, emphasises the importance of responsible wastewater management for mitigating risks and exploring reuse opportunities in packhouse operations. This study informs the global development of cost-effective, practical wastewater treatment solutions that help packhouses meet regulatory environmental safety requirements while maintaining operational efficiency. By addressing wastewater management challenges proactively, packhouses can enhance sustainability, regulatory compliance, and resource efficiency, ultimately aligning with global trends toward more responsible water use and effluent treatment practices. Recommendations for further research include: the investigation of wastewater treatment technologies suited to citrus packhouse effluent, the testing of additional postharvest fungicides, distinguishing between soluble and insoluble chemical oxygen demand, expanding the study across multiple seasons and a wider range of packhouses and a detailed risk analysis for long-term sustainability of citrus wastewater management.