PETER CHADWICK / SCIENCE PHOTO LIBRARY PETER CHADWICK / SCIENCE PHOTO LIBRARY
Sewage treatment plant. Sewage goes through several stages of treatment. Solid waste (sludge) is removed in settling tanks (round, lower centre). Aeration tanks pump air into the sewage to encourage the growth of micro-organisms that feed on harmful bacteria. Further settlement and filtration removes the final sludge and microbes. This treatment plant is at the edge of the town of Gouritz, South Africa.
Model release not required. Property release not required.