Explain the process of sewage treatment. include primary sewage treatment, secondary treatment, and tertiary treatment. explain how sewage treatment affects biological oxygen demand (bod) and why sewage treatment is important for aquatic health.

8

explanation:

4+4=8

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.

the egg cell forms through 1) meiosis. prophase is a phase in both meiosis and mitosis. fertilization will happen a little later. mitosis happens in my toes while meiosis is for reproduction.