A by-product of sewage treatment is usually a semi-solid waste or slurry, called sewage sludge, that has to undergo further treatment before being suitable for disposal or land application.
Life expectancy is defined statistically as the average number of years remaining for an individual or a group of people at a given age.Longevity refers to the characteristics of the relatively long life span of some members of a population.athematically, life expectancy is the mean number of years of life remaining at a given age, assuming constant mortality rates. It is denoted by, which means the average number of subsequent years of life for someone now aged, according to a particular mortality experience.
The statistic shows the average life expectancy at birth by continent in 2014. The average life expectancy at birth worldwide was 71 years in 2014.Life Expectancy. Life expectancy is defined as a statistical measure of how long a person may live, based on demographic factors such as gender, current age, and most importantly the year of their birth.he statistic shows the average life expectancy at birth by continent in 2014. The average life expectancy at birth worldwide was 71 years in 2014. Life Expectancy.