Which microorganisms are used in sewage water treatment and what is their role?
The microorganisms used in sewage water treatment include bacteria, fungi, protozoa, algae, nematodes, amoebae and viruses. The bacteria commonly found are mainly intestinal and soil inhabiting types such as Coliforms, Streptococci, Clostridia, Micrococci, Pseudomonas, and Lactobacilli.
The role of these microorganisms is to carry out microbiological degradation activities including hydrolysis, oxidation, and reduction on decomposable nutrients present in sewage. They help in decomposition and stabilisation of wastes through both anaerobic and aerobic processes.
In the anaerobic process, microorganisms break down organic matter into CH₄, CO₂, H₂, and N₂. In the aerobic process, they break down organic matter into CO₂ and H₂O, thereby removing suspended organic material from the effluent.
Explanation
The textbook context clearly lists the variety of microorganisms present in sewage (bacteria, fungi, protozoa, algae, nematodes, amoebae and viruses) along with specific bacterial types. The role is described under secondary/biological treatment where microorganisms perform degradation activities (hydrolysis, oxidation, reduction) to decompose and stabilize wastes. The context also provides the end products of both anaerobic and aerobic decomposition processes.