Bovine casein as a new soil strengthening binder from diary wastes

Approximately one-third of the edible parts of food is lost or wasted globally. For milk, 18.1% of its annual production is lost or wasted due to insufficient storage, logistics, and freshness (expiration date) issues. Presently, the most common method of managing waste milk is disposing large volumes of waste milk into landfills, which raises concerns on groundwater pollution and local ecosystem disturbance. Casein is a protein-type biopolymer that consists of approximately 24.4 kg from 1 ton of bovine milk. In this study, casein is introduced as a new binder for soil strengthening in geotechnical engineering and dairy waste management purposes. Bovine casein is provided in a solution state for proper mixing with soil. Casein-soil mixtures with different casein contents are prepared to evaluate unconfined compressive strengths at both dried and re-submerged conditions. Experimental results show significant soil strengthening induced by casein treatment even after 24 h of re-wetting, which implies the potential of applying casein-soil mixtures for water-resisting purposes. Feasibility analyses for casein utilization from dairy and milk wastes are provided with socio-, environmental, and engineering aspects, showing both future opportunities and challenges of recycling casein as a soil binder in engineering practices.