Sustainable Water Management in the Dairy Industry: A case study of milk processing plants in South Africa using water pinch analysis

Visser, Elsa

Sustainable Water Management in the Dairy Industry: A case study of milk processing plants in South Africa using water pinch analysis

Thesis / Dissertation

2026

Publisher

University of Cape Town

Department

Centre for Bioprocess Engineering Research

Faculty

Faculty of Engineering and the Built Environment

Abstract

Water scarcity remains a critical challenge in South Africa, necessitating the adoption of water efficient strategies within water intensive industries, such as dairy processing. In this sector, cleaning operations drive high freshwater demand and contribute to substantial wastewater generation. Considering the environmental and economic impacts of excessive water consumption, this study applies water pinch analysis to identify opportunities for minimising water use and wastewater generation in the South African dairy industry. A comprehensive literature review was conducted to assess the current water consumption patterns and wastewater management strategies in South African dairy facilities. The research methodology involved data collection from industry surveys, site visits, and interviews, enabling the development of a representative base case model of milk processing using SuperPro Designer. The base case simulation established a mass and water balance, forming the foundation for water pinch analysis. This study applied a graphical water pinch analysis approach to develop resource-efficient water network designs. Water pinch analysis was conducted by extracting water flow rates and contaminant concentrations to generate source/sink composite curves, enabling the determination of minimum freshwater requirements. Identifying these requirements provided a basis for designing an optimised water network. Various water network optimisation strategies were explored, including direct reuse, outsourcing of external water, and regenerative treatment. Implementing these optimisations, the minimum freshwater requirement was reduced from 9.12 t/h in the base case to 6.65 t/h through water reuse (Design 1.2). Scenarios incorporating rainwater harvesting and secondary treatments such as anaerobic and aerobic digestion (Design 3.2) further reduced freshwater demand to 5.05 t/h and ultimately to 3.76 t/h with tertiary reverse osmosis treatment (Design 4.1). The findings demonstrate that water pinch analysis can significantly reduce freshwater intake and wastewater discharge, supporting sustainable water management. A techno-economic analysis was conducted to assess the financial feasibility of the proposed water-saving strategies. Four alternative designs were evaluated, ranging from direct water reuse to advanced treatment options incorporating rainwater harvesting, anaerobic digestion, and reverse osmosis. The analysis considered capital and operating expenditures, cost savings, and key financial indicators such as net present value, internal rate of return, and payback period. The analysis revealed that simple designs, such as Design 1.2, provide substantial financial benefits, including a net present value of R4.7 million, an internal rate of return (IRR) of 47.31%, and a short payback period (PBP) of 3.7 years, alongside water savings of 27.07%. These attributes make them particularly suitable for small- to medium-sized dairies. In contrast, advanced designs, such as Design 3.2 and Design 4.1, achieve greater water savings (44.63% and 58.78% respectively) and environmental benefits but require higher investments (CAPEX: R45.00 million and R67.97 million) and have extended payback periods, making them more suitable for larger facilities or regions with high water costs or scarcity. This research advances sustainable water management in the dairy industry by providing a structured approach to optimising water networks. The findings demonstrate that integrating direct reuse with secondary and tertiary treatment not only minimizes freshwater consumption and wastewater discharge but also enhances resource recovery through biogas generation, reducing operational costs and energy dependence. Additionally, the proposed water-saving strategies align with regulatory compliance requirements, support circular economy principles, and contribute to long-term environmental and economic sustainability in water-scarce regions like South Africa.