Blackburn Meadows is an area of land just inside the Sheffield city border at Tinsley, England. It became the location of the main sewage treatment works for the city in 1884, and is now one of the largest treatment works in Britain. The treatment process was rudimentary, with sludge being removed to ponds and then to drying beds, after which it was used as manure or transferred by rail to a tip at Kilnhurst. The works progressively expanded to improve the quality of effluent discharged to the River Don and was a pioneer in the use of bio-aeration, following experiments by the works manager during the First World War. This process became known as the "Sheffield System", and was demonstrated to visitors from Great Britain and abroad. Despite these improvements, ammonia levels in the river b