Short answers, pulled from the story.
Joseph Bazalgette designed and oversaw the construction of London's Main Drainage system, comprising 82 miles of underground brick main sewers and 1,100 miles of street sewers. The system intercepted raw sewage that had been flowing into the Thames and diverted it downstream. With only minor modifications, it remains the basis for sewerage design to the present day.
The immediate trigger was the Great Stink of 1858, when the Thames became so foul that Parliament passed an Enabling Act to fund Bazalgette's proposals. The wider context was a series of deadly cholera epidemics: the 1849 outbreak killed 14,137 Londoners and the 1853 epidemic killed 10,738. Although the project was premised on the incorrect miasma theory, the new sewers removed the cholera bacterium from the water supply and effectively ended the epidemics.
Joseph Bazalgette was knighted by Queen Victoria in 1875. He was also elected President of the Institution of Civil Engineers in 1883.
Bazalgette's grandfather was Louis Bazalgette, a tailor and financier who emigrated from Ispagnac in Lozère, France. Louis became principal tailor to the Prince of Wales, the future George IV, and subsequently became wealthy.
Joseph Bazalgette was born on the 28th of March 1819 at Hill Lodge, Clay Hill, Enfield. He died on the 15th of March 1891 at his home on Arthur Road, Wimbledon, and was buried at nearby St Mary's Church.
Bazalgette designed or oversaw numerous London structures, including the Victoria Embankment (1870), Putney Bridge (1886), the current Hammersmith Bridge (1887), and Battersea Bridge (1890). He also laid out Shaftesbury Avenue and Charing Cross Road, made modifications to Albert Bridge, and submitted early plans for the Blackwall Tunnel.