用英语解释好吗?
Some STP’s (Sewage Treatment Plants) are rated by “Population Equivalent”.
Population Equivalent (PE) is a term used for estimating the population that will be served by a sewage collection and treatment system. In many cases the estimation is simply the number of people served. For example if a house with four people is served, then the PE is 4. But for other cases, such as hotels, commercial enterprises, or industries, it is more difficult to establish the number of people served. So instead, a population equivalent is estimated from standard tables, or based on the experience of the estimator. The design of the sewage collection and treatment system, is then based on the equivalent population.