Vorelodos Aerobic Digester

Overview System Components Specifications Solutions Documentation & Tools


Product Features
  • Sanitaire Silver Series II LP fine bubble aeration able to handle wide air flow ranges with minimal pressure loss
  • Sanitaire OSCAR process performance optimizer with DINO nutrient controller
  • Sanitaire decanters with automated control
  • Flygt submersible mixers with integrated variable speed drive
  • Flygt submersible pumps with self-cleaning, non-clog impellers
  • YSI/WTW IQ SensorNet process instrumentation with connection of up to 20 sensors

Rethink your biosolids management strategy 

Often times the biosolids management portion of the treatment plant may not be optimized, resulting in inefficient operation of the entire treatment plant. For instance, did you know that aerobic digestion is the second largest consumer of energy after biological treatment aeration at a wastewater treatment plant? Or, do you realize that up to 50% of the nutrient loading on any given day may be coming from the biosolids process?

Consider a complete solution for your aerobic digester. Vorelodos aerobic digester combines equipment, controls, and service, to offer a solution that ensures wastewater treatment plants meet regulations while reducing operational costs.

Meet regulations while saving money

By focusing on optimizing the operation of the aerobic digester, the Vorelodos solution provides:

  • Up to 90% reduction in nitrogen and phosphorus returned to the main treatment process
  • Wastewater treatment plant process stabilization through reduction of nutrient spikes to the main plant
  • Reuse of biosolids for agricultural purposes
  • Energy consumption in the aerobic digester reduced up to 90%
  • Lower chemical use due to alkalinity recovery and reduction in phosphorus return to main plant
  • Automated decanting to free up operations staffs’ time


System Components

System Components

Sanitaire Silver Series II LP Membrane Aeration

Xylem's Sanitaire Silver Series II LP membrane aeration system is used in aerobic digestion to maximize standard oxygen transfer efficiency (SOTE) and save energy.

The Sanitaire Silver Series II LP, a 9-inch low-pressure version of the Silver Series II membrane, is ideal for aerobic digestion applications. Each diffuser can handle airflow up to 17 Nm(3)/h (10 scfm), with minimal pressure loss. A highly effective, integrated check valve prevents plugging and enables aeration to be easily turned on and off for optimal process control and energy savings.

Sanitaire Decanter

Xylem’s Sanitaire Decanter is used to remove supernatant from aerobic digesters, enabling higher solids concentrations, smaller footprint, and lower capital costs. The automated decanter results in substantial labor savings over time compared to traditional manual digester decanters. Manufactured using rugged, corrosion-resistant, stainless steel construction, it decants from the top down, visibly withdrawing only the uppermost clear water from the basin. The decanter features an integrated floating scum baffle to ensure the supernatant is free from unwanted matter, and includes a variable frequency drive allowing for a range of decant speeds. It also provides ease of access and maintenance as the actuator and drive are mounted outside of the basin at walkway level. Additionally, the decanter acts as an emergency overflow device when not actively decanting as it is parked above top water level when not in operation.

Sanitaire OSCAR Process Performance Optimizer

OSCAR process performance optimizer is included with each aerobic digester solution ensuring smart control, process visibility and optimization. The OSCAR system includes a process control panel (PLC, HMI, Webport, etc.), YSI instrumentation (DO, ORP, NH4, NO3 and/or K), and process controllers (time-based control, DO control, ORP control, and/or DINO nutrient control). 

Flygt Sludge Pumps

Robust submersible Flygt pumps are included to provide reliable, low maintenance pumping of digested biosolids to downstream processes or disposal.

Flygt Mixers

Efficient Flygt submersible mixers (i.e. 4320 mixers) are provided to ensure proper mixing while minimizing maintenance and energy consumption. 


A diverse portfolio of blower technologies are available to suit any aeration need. These reliable, energy-efficient, and easy to maintain blowers optimize diffused aeration systems.



General Information
Biosolids Management, Sludge Treatment, Aerobic Digestion
Sludge Flow Rate
0 to 2,000,000 gpd (7,571 m3/day) typical
Sludge Types
Waste Activated and Primary Sludge
Capable of operation with single tank
Single source of all key equipment
Yes, design and supply of aeration and mixing equipment, pumps, blowers, valves, instruments, and controls into a single optimized package
Shop oxygen transfer test
Mechanical Equipment
Types of Aeration Equipment
Sanitaire Silver Series II LP fine bubble aeration
Types of Submersible Mixers
Flygt submersible mixer with integrated variable speed drive
Types of Pumps
Flygt submersible pump with self-cleaning, non-clog impellers
Types of Blowers
Positive displacement, turbo, or centrifugal with variable flow adjustment
Decanter Material
304 or 316 SS
Type of Decanter
Active, Mechanically Driven
Electro-mechanical screw jack with variable speed motor
Weir visible from basin side wall
Yes, operator can visually observe discharged effluent quality
Parts requiring maintenance accessible from the walkway
Yes, routine maintenance can be performed without draining basin or taking unit out of service
Scum guard to exclude floatable solids
Yes, scum excluded during entire decant cycle
Fail safe overflow protection in case of power outage
Yes, decanter parked above top water level acts as an emergency overflow
Seals and bearings
Maintenance free, synthetic type
Monitoring & Control
Included Hardware
OSCAR Process Performance Optimizer with control cabinet, power equipment, instrumentation and process control modules
Control Cabinet
PLC - Allen Bradley or Siemens, HMI - industrial computer with aspect ratio of 16:9
Power Equipment
Motor starters and variable frequency drives can be provided as panel mount, wall mount and/or housed in motor control center
Standard Ratings
NEMA 12, IP55, UL, CUL, CE
Process Control Modules
Digester Process Control, DO Control, ORP Control, Time-based aeration control, DINO Nutrient Controller
Process Instrumentation
Float and Level Switches
Flygt LTU-40 level transducer and ENM-10 float switch
Dissolved Oxygen (DO) sensor
YSI/WTW model FDO 700 IQ
Total Suspended Solids (TSS) sensor
YSI/WTW model ViSolid 700 IQ
Ammonia/Nitrate/ Potassium Sensors
YSI/WTW model VARiON Plus 700 IQ
Terminal/ Controller
YSI/WTW model 2020 IQ Sensor Net
Oxidation Reduction Potential (ORP) Sensor
YSI/WTW model SensoLyt 700 IQ


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Documentation & Tools

Documentation & Tools