All over the world, environmental engineers, environmental biologists, biochemists, and other scientists are concerned about environmental pollution. In particular, different treatment technologies and applications in terms of water and soil health have been investigated for years. Studies show that the bioprocess (biosorption, bioremediation, bioaccumulation, etc.) approach is more advantageous (economical, easy to design, and environmentally friendly, etc.) than many treatment methods. Thanks to these advantages, bioprocesses have been preferred for the removal of different pollutants in the receiving environment. Effective microorganisms (EMO) are defined as mixed cultures of advantageous and naturally occurring microorganisms that can be used as vaccine material. EMO is a natural fermentation product that is not chemically or genetically modified in the form of a concentrated solution. An EMO consists of 10 species, including photosynthetic (Rhodopseudomonas palustrus and Rhodobacter spheroids, etc.), lactic acid (Lactobacillus plantarum, Lactobacillus casei, and Streptococcus lactis, etc.) bacterial groups, yeasts (Saccharomyces cerevisiae and Candida utilis, etc.), actinomycetes, and fermenting fungi is coming. The main components of EMO are lactic acid bacteria, yeasts, and photosynthetic bacteria. In liquid solution, they are in harmony. This article aims to review the literature on 'EMO' from different scientific databases and discuss the effectiveness of using EMO for bioprocess.