<span>Septic tanks rely on
microorganisms to decontaminate the water. These are usually made of concrete
and fiberglass with an in-out pipe system. These septic tanks are important in
the septic system where sewage is treated naturally by holding its contents
long enough for solids and liquids to separate. These things can only be found
in areas that lack connection to main sewage pipes that the government had
provided. They could be found built in suburbs, small towns, and rural areas
and are not suitable for densely built cities. </span>
T cells attack antigens on foreign substances and B cells produce antibodies.
Food is pushed through the digestive tract by muscle contractions called
<span>peristalsis.</span>
Hi !
boys - about 1800 calories
girls - about 1600 calories
