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In the aftermath of the First World War the new treatment method spread rapidly, especially to the US, Denmark, Germany and Canada. By the late 1930s, the activated sludge treatment became a well-known biological wastewater treatment process in those countries where sewer systems and sewage treatment plants were common. [106]
The link between water and disease was still not well established and in 1873 the president of the New York board of health declared that "although rivers are great natural sewers, and receive the drainage of towns and cities the natural process of purification, in most cases destroys the offensive bodies derived from sewer and renders them ...
The most common active ingredient of spermicides is nonoxynol-9. Spermicides containing nonoxynol-9 are available in many forms, such as jelly (gel), films, and foams. Used alone, spermicides have a perfect use failure rate of 6% per year when used correctly and consistently, and 16% failure rate per year in typical use. [1]
Medieval contraception is a debated topic among historians, though methods of contraception have been developed not just in modern times. In ancient times, women attempted to protect themselves from unwanted pregnancy with various means and practices, as evidenced by ancient records.
Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on the environment. It is also possible to reuse it. This process is called water reclamation. [1]
The history of water filters can be traced to the earliest civilisations with written records. Water filters have been used throughout history to improve the safety and aesthetics of water intended to be used for drinking or bathing. In modern times, they are also widely used in industry and commerce. The history of water filtration is closely ...
Station for complex water treatment SKO-10K. One of the first steps in most conventional water purification processes is the addition of chemicals to assist in the removal of particles suspended in water. Particles can be inorganic such as clay and silt or organic such as algae, bacteria, viruses, protozoa and natural organic matter.
Sedimentation (water treatment) Septic tank; Septic tank conversion [2] Sequencing batch reactor; Sewage treatment; Skimmer (machine) Slow sand filter; Stabilization pond; Supercritical water oxidation (SCWO) Thermal hydrolysis; Treatment pond; Trickle-bed reactor; Trickling filter; Ultrafiltration; Ultraviolet disinfection; Upflow anaerobic ...