VALORISATION OF BIOWASTE OF SNAIL SHELL AND WATER HYACINTH INTO FUNCTIONAL BIOPOLYMERS AND BIOPLASTICS: A REVIEW

Abstract

The growing accumulation of biowaste in the environment, coupled with rising concerns about plastic pollution, has intensified interest in sustainable materials derived from renewable resources. Among such wastes, snail shell residues and water hyacinth biomass occupy a unique position as both environmental liabilities and valuable feedstocks for biopolymer production. This review synthesizes current literature on (i) contamination of snail shells and water hyacinth by heavy metals and persistent organic pollutants (POPs), (ii) extraction and characterisation of chitosan from snail shells and carboxymethyl cellulose (CMC) from water hyacinth, (iii) microbial load considerations affecting material safety and performance, and (iv) development of biodegradable bioplastics based on chitosan–CMC systems reinforced with oil-palm fibre. Emphasis is placed on understanding contaminant binding mechanisms, process optimisation strategies, physicochemical and functional properties of the derived polymers, and their suitability for high-value applications. Key challenges related to contamination risks, microbial safety, scalability, and market competitiveness of bioplastics are critically discussed. The review highlights research gaps and future directions required to enable safe, standardised, and economically viable valorisation pathways for these abundant bioresources within a circular bioeconomy framework.