As a rule, they consisted of several tanks, the first of which was carried out roughly from large pollution. Then the water was upset to settled small particles. The final dialist was held in special mechanical filters from inorganic compounds. Thus, the septic tank actually imitated the processes occurring with contaminated water when it enters the ground. Naturally, their effectiveness was not high due to the impossibility of biological decomposition of the components of wastewater. As a result, an unpleasant odor appeared, rotting products and pathogenic microbes formed, and the septic tank itself had to be cleaned with the help of asserment about 1 time per month. These technologies are already morally and technologically outdated, I have high cost and very bulky.
