Aerobic Granular Wastewater Treatment - A New Technology

With new permits requiring the removal of more nitrate/nitrite and phosphorus, wastewater treatment systems are becoming more complex with anaerobic/ass erobic/anoxic zones that frequently require separate reactors. The footprint and operational challenges have become larger than seen with conventional activated sludge treatment of 30 years ago.

Among the new trends in advanced wastewater treatment, Aerobic Granule Sequencing Batch Reactors claim to simultaneously oxidize organics, oxidize ammonia, reduce nitrate/nitrite, and remove soluble phosphate. All while not requiring secondary clarifiers to settling biological solids. What is this new technology? What are its advantages? What are the disadvantages?

First the technology

• Use a  modified SBR technology with short settling times
• Aerobic granules are microbial structures which are larger and more dense than regular floc - are the desired biomass
• Aerobic granules are targeted at 15 - 20 g/L vs 3 - 5 g/L for activated sludge units
• The granules are built with short settling times and feast/famine feeding

Advantages

• 20% less surface area required for treatment plant
• 30% lower power (energy) requirements
• Reduced operator activity as all treatment phases occur in one tank
• Less solids for dewatering/disposal
• Does not require expensive media to support bacteria or membranes for solids seperation

Disadvantages

• Relatively new technology 
• We don't know impact rapid changes in influent makeup or toxic shocks/spills
• First units have been in domestic/light industrial and food processing industries - we don't have real world data on industrial wastewater treatment systems.