A treatment plant is a facility that reduces industrial water consumption and environmental pollution by turning wastewater into purified substances suitable for reuse or discharge to the environment. The plant uses biological, physical, and chemical processes to break down wastes into less harmful substances. Organisms such as bacteria, protozoa, algae, metazoa, fungi, and even animals help break down the chemicals that are a part of a wastewater treatment process. The organisms are maintained in bioreactors that provide the right temperature, pH, and nutrient conditions for their growth and activity.
Bacteria are the primary organisms used in a treatment plant to break down organic compounds in the wastewater. Different species of bacteria have specialized metabolic pathways that degrade specific chemicals. Some bacteria can metabolize heavy metals and nitrogenous compounds. Others are able to digest organics, including proteins, into amino acids, CO2, alcohols, H2S, and methane.
Protozoa are single-celled animals that serve three important functions in the biological treatment process: they crop bacteria, form flocs with them, and remove suspended materials from the wastewater. In addition, these animals are good indicators of biomass health and effluent quality. Fungi are microscopic nonphotosynthetic plants that include yeasts and molds. They are often used in alcoholic beverage production, but they also perform many important functions in biological wastewater treatments. They are good indicators of nutrient availability, adsorb carbon dioxide, and prevent excessive filament bulking in the settling process.
Algae are multicellular plants that use sunlight to photosynthesise dissolved organic carbon in the water they inhabit. They can be grown in separate bioreactors or incorporated into the bacterial processes. They can degrade complex organic compounds and can break down dyes and pesticides into simpler chemical molecules.