Aerobic granular sludge – New application in wastewater treatment

Stellar Tech – Granular sludge was first researched in the 1980s on the UASB anaerobic biological treatment system. Aerobic granular sludge has a higher ability to handle organic matter and phosphorus nutrients than conventional activated sludge.

The process of forming granular sludge is the result of the combination of microbial cells contacting each other relatively stably under physical – chemical – biological conditions. Granular sludge can also be considered as a special case of biofilm development.

However, anaerobic granular sludge has some disadvantages such as long sludge granule formation time, difficulty in controlling operating conditions, having to maintain the reaction tank under high temperature conditions, and not effectively treating wastewater. This type of wastewater has low organic matter content and is especially effective in treating organic matter and nutrients.

Since then, another type of granular sludge has been researched to overcome the disadvantages of anaerobic granular sludge, which is aerobic granular sludge.
1. STRUCTURE AND COMPOSITION OF ANEROOXIC PARTICULATE SLUDGE

Single sludge particles are formed during the first week of the operating period. Sludge particles develop from a characteristic integrated structure with filamentous bacteria as a living axis around which the particles and flocs adhere.

When the sludge particles are stable and solid, inside the particles there exist acidifying, nitrifying, denitrifying and heterotrophic bacteria. Granular sludge has a high ability to remove phosphorus because the innermost layer of sludge particles is anaerobic bacteria, and there are bacteria capable of accumulating poly-phosphate.

In addition, the composition and number of microbial species present in sludge particles depends on the type of substrate, organic matter loading, N/C ratio (Ratio of cell nucleus to cytoplasm) and other conditions. model operating conditions.

Read more: Sludge that is difficult to settle and sludge that floats again – How to handle it
2. FORMATION PROCESS OF AEROBASTIC PARTICULATE SLUDGE
The above stages are presented specifically as follows:
Adaptation phase: This phase starts from the start of model operation until seed mud seeds are formed. Granular sludge germs are mainly composed of filamentous bacteria that stick together.
Granulation stage: This stage is from the formation of seed sludge to the formation of granule sludge. Granular sludge consists of many different types of bacteria coexisting.
Maturity stage: At this stage, granular sludge will grow rapidly and strongly in size and density. After the point when the granular sludge growth will be stable and balanced, to maintain the grain size in the range of 2–5mm, operating conditions must be well controlled.