Short answers, pulled from the story.
The Great Stink forced the British Parliament to halt its sessions in 1858. This event occurred when the River Thames in London became so choked with human waste and industrial runoff that the smell was overpowering. The crisis served as a catalyst for the modern era of sewage treatment.
The activated sludge process arrived in 1912 to revolutionize sewage treatment. This method introduced aeration tanks where microorganisms consumed organic matter in the sewage. Engineers have since refined this technique to create variations such as the Ludzack, Ettinger Process and the Modified Ludzak, Ettinger Process.
A 2021 global estimate revealed that 52% of all sewage is treated. This figure masks a deeper crisis where more than 80% of wastewater generated globally is released into the environment without sufficient treatment. High-income countries treat approximately 74% of their sewage while developing nations treat an average of just 4.2%.
Switzerland became the first country to enshrine the removal of micropollutants in law in 2016. By 2025, the European Union will implement a recast Urban Waste Water Treatment Directive requiring member states to remove at least 80% of six key micropollutants. This fourth stage of treatment often involves activated carbon filters and advanced oxidation processes.
The European Union sets a target for all wastewater treatment plants to be energy neutral by 2045. This goal aims to balance energy consumption with treatment efficiency through processes like anaerobic digestion. The activated sludge process currently accounts for around 30% of annual operating costs in the United States.
The World Health Organization developed guidelines for the safe use of wastewater in agriculture in 2006. These guidelines advocate a multiple-barrier approach to minimize health risks for farmers and consumers. Treated wastewater is increasingly used for irrigation, groundwater recharge, and industrial processes to reduce the strain on freshwater resources.