Phosphorus is essential for plant growth, but an excess of

Chapter 5, Problem 93

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Phosphorus is essential for plant growth, but an excess of phosphorus can be catastrophic in aqueous ecosystems. Too much phosphorus can cause algae to grow at an explosive rate and this robs the rest of the ecosystem of oxygen. Effluent from sewage treatment plants must be treated before it can be released into lakes or streams because the effluent contains significant amounts of and (Detergents are a major contributor to phosphorus levels in domestic sewage because many detergents contain ) A simple way to remove and from the effluent is to treat it with lime, CaO, which produces and ions in water. The ions convert and ions into ions and, finally, and ions combine to form a precipitate of (a) Write balanced chemical equations for the four reactions described above. [Hint: The reactants are CaO and and and and ] (b) How many kilograms of lime are required to remove the phosphorus from a holding tank filled with contaminated water, if the