Identify the metal nanoparticle that acts as a highly effective bacterial disinfectant in the water purification process.

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Silver nanoparticles are widely known for their strong antimicrobial and antibacterial properties. They are extensively used as highly effective bacterial disinfectants in water purification processes to eliminate harmful pathogens. Carbon black is a non-metal, while aluminium and copper are not primarily used as highly effective bacterial disinfectants in this context. Answer: silver