There are many different kinds of sewage treatment plants which vary in the process by which they treat wastewater. Generally, they can be classified into the following types of system: 1  Activated sludge plant (ASP). 2  Rotating disc system. 3  Submerged aerated filter (SAF). 4  Suspended Media Filters (SMF).
In certain species of sea life, male pregnancy is common. The male incubates and births live young instead of the female. Human males are not able to do so, and medical risks of a male pregnancy are extreme. Transgender individuals can become pregnant if reproductive organs are left intact. A common phenomenon is a sympathetic pregnancy, where a man exhibits all the symptoms of pregnancy along with his expectant partner.
In rare cases, a woman (or even a man) believes she is pregnant, only to find out that her symptoms were caused not by pregnancy, but by something else entirely. False pregnancy, clinically termed pseudocyesis, is the belief that you are expecting a baby when you are not really carrying a child. People with pseudocyesis have many, if not all, symptoms of pregnancy -- with the exception of an actual fetus.