Biological tanks
Biological tanks: the heart of wastewater treatment
Biological tanks, also known as septic tanks or biological treatment systems, are essential components in wastewater treatment processes. These systems play a crucial role in removing organic contaminants from wastewater, allowing for its safe release into the environment or its reuse.
Biological tanks are used in a wide range of applications, from residential homes to industrial plants, significantly contributing to environmental protection and sustainable water resource management.
How biological tanks work
The operating principle of a biological tank is based on the activity of microorganisms that break down and transform the organic matter present in wastewater. These microorganisms, mainly bacteria, use organic matter as a nutrient source, converting it into less polluting substances such as carbon dioxide, water, and biomass. The treatment process takes place inside the tank, where wastewater is retained for a sufficient period to allow microorganisms to act.
Biological tanks can be designed to operate in aerobic mode, where oxygen is present and promotes bacterial activity, or in anaerobic mode, where the absence of oxygen allows specific bacteria to thrive under anoxic conditions. The choice between an aerobic or anaerobic system depends on the plant's specific requirements, the nature of the wastewater, and local wastewater treatment regulations.
Types of biological tanks
There are several types of biological tanks, each designed to meet specific treatment needs. The main categories include:
- Septic tanks: These systems are commonly used in residential areas, especially where a centralized sewer network is unavailable. Septic tanks treat domestic wastewater by separating solids from liquids, allowing bacteria to decompose organic matter. The treated water is then released into the ground through a drainage system, while the remaining solids are periodically removed.
- Continuous flow biological tanks: Primarily used in industrial settings or large residential complexes, these tanks operate with a continuous flow of wastewater, treated in multiple stages. The first stage involves solid sedimentation, followed by biological treatment and clarification. These systems are highly efficient and can handle large volumes of wastewater.
- Moving bed biofilm reactor (MBBR) tanks: In these systems, biomass grows on mobile carriers within the tank, increasing the contact area between microorganisms and wastewater. MBBR tanks are valued for their efficiency and compactness, making them ideal for installations where space is limited.
Activated sludge biological tanks: Mainly used in large wastewater treatment plants, these tanks employ an aerobic process where sludge, composed of bacteria and other microorganisms, is continuously recirculated and mixed with wastewater. This system is highly effective in removing organic contaminants but requires careful management to maintain microbiological balance.
