Microbes in waste water

 

Typical raw sewage has 99.9% water and 0.1% organic and inorganic solids. The following components make the sewage:

·         The organic impurities present in sewage are human faeces, animal wastes (like animal dung), urea (as urine), oil, fruits and vegetable wastes, pesticides, herbicides, etc.

·         The inorganic impurities present in sewage are nitrates, phosphates and metals.

·         The nutrients present in sewage are nitrogen and phosphorus.

·         The microbes present in sewage include bacteria, protozoa which cause water-borne diseases and others

Wastewater contains a diverse community of microorganisms that break down and remove organic pollutants and nutrients from contaminated water. Biological treatment of wastewater is carried out by different microorganisms like bacteria, protozoa, fungi, algae present in wastewater.

Major Groups of Wastewater Microorganisms

• Bacteria are the most abundant and important organisms responsible for the vast majority of organic pollutant degradation. They include aerobic ones Pseudomonas and Bacillus that use oxygen to oxidize waste and anaerobic  ones like Clostridium that function without oxygen.
• Protozoa are single-celled eukaryotic organisms such as amoebas, flagellates, and ciliates which predate on bacteria and degrade suspended particles, thus clarifying the effluent.
• Fungi are multi-cellular decomposers that break down complex organic materials.
• Algae They contribute oxygen to the water through photosynthesis, supporting the aerobic bacteria.

Roles in waste water treatment

• Organic Matter Degradation: Microbes convert complex carbon compounds into carbon dioxide, water, and new microbial biomass and reduce biochemical oxygen demand (BOD).  
• Nutrient Removal: Nitrifying bacteria remove nitrogen through nitrification-denitrification.
• Sludge Stabilization: Anaerobic bacteria digest settled organic solids in digestion tanks to produce methane-rich biogas and stable biosolids.