The present invention intends to disclose a process for in situ flocculation followed by solidification of biomedical waste that is capable of simultaneously treating and disinfecting solid and fluid samples. The process comprises of the addition of the waste samples to an alkaline aqueous solution of metal silicates followed by the addition of an organic or inorganic acid for flocculation and a solid metal oxide or phosphate at a defined volumetric and/or weighted composition leading to instantaneous solidification with >99.9% microbial disinfection and an all-in-one disinfecting device for treatment of biomedical waste. The present disclosure also provides a disinfection-flocculation-solidification and disposal device comprising the disinfection composition.