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.
A group of 281 men whose wives were not pregnant was used as a control in the study. Researchers found that the majority of the men with pregnant wives displayed a variety of pregnancy-associated symptoms like mood swings and morning sickness. Stomach cramps were the most commonly reported; one man reported his own labor pains that rivaled his wife's while she was delivering their baby. A few of the men who showed signs of sympathetic pregnancy developed pseudocyesis -- a phantom swollen stomach.