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Patented influent control apparatus that allows the system to receive influent on a continuous basis, eliminating the mechanical equipment required to divert influent for multiple basin configurations. |
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Apparatus designed to deliver raw sewage (carbon source) directly to the sludge blanket, facilitating denitrification without the use of costly mechanical mixers. |
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A patented decanter design that is non-mechanical in nature, eliminating frequent overflow and effluent violations due to mechanical failure. |
TECHNICAL OVERVIEW
Primary Treatment
As with any treatment process, the IDEA system works best when inorganic solids are removed from the wastewater stream prior to the reactor. Most smaller IDEA systems will utilize either a preloader or a barscreen.A preloader is a separate tank similar to a septic tank that removes both settleable and floatable solids.Preloaders must be pumped occasionally.As an option to the pre-loader, a cone shaped barscreen may be located within the IVE Collector, and should be cleaned every few days.
The larger systems (Grand IDEA and ENVIROPro) will use an automatic screening device.
Influent Velocity Equalization (IVE) Collector
The patented IVE Collector completely diffuses hydraulic influent flow velocities and turbulence created by splash energy. Furthermore, the IVE Collector diverts downward hydraulic velocities created by influent flows, thereby preventing upset of the biomass in the Omni-Flow Partition during the settle and decant phases of the operation cycle.
Omni-Flow Partition
The patented Omni-Flow Partition (Pre-React Zone) has a cylindrical or rectangular shape, and is elevated from the bottom of the basin. This allows up to a 360 degree opening between the bottom skirt of the Omni-Flow Partition and the basin floor.These design features (shape and elevation) create a very low hydraulic flow (gpm) to hydraulic port area (square feet) ratio, typically less than 3:1.A low transfer rate between the Pre-React Zone and Reactor Basin allows influent to flow through the biomass, preventing wash out and short circuiting during the settle and decant phases of the process.
The Pre-React-Zone created inside the unique Omni-Flow Partition, with its high F:M Ratio, overcomes problems of transient peak flows of both hydraulic and organic loadings. Initial BOD5 absorption into the biomass of 70% to 80% is achieved.Due to the high F:M Ratio, growth of filamentous organisms is discouraged, thereby mitigating sludge bulking conditions.An environment is provided where more desirable rapid-settling zoogleal facultative organisms proliferate.The end result is a superior sludge which settles rapidly.
Aeration System
AES IDEA systems generally use one of four aeration systems, depending on the basin configuration, and strength and volume of wastewater. The four types are built around fixed coarse bubble diffusers, fixed fine bubble diffusers, floating train fine bubble diffusers, and high speed floating aerators.In almost all cases, diffusers are accessible for cleaning without draining the reactor basin.For the first three options, either positive displacement or centrifugal blowers may be used, depending on basin depth, air volume, and customer preference.
Fixed coarse bubble diffuser systems are generally used for low strength, mixing intensive applications. Additionally, projects using deep tankage may be able to use coarse bubble diffusers due to the resulting increased oxygen transfer efficiency.
The most common form of aeration systems use fixed fine bubble diffusers. Today's flexible sheath non-clog fine bubble diffusers result in excellent oxygen transfer efficiency even at shallow depths, while still delivering enough air for mixing purposes.
For large lagoon-based operations (ENVIROPro), AES patented Floating Disk Aeration Chains are generally used. The floating aeration chain uses a flexible air header that extends from one side of the basin to the other.At intervals along the header are disc shaped floats, through which air lines drop to fine bubble diffuser assemblies.Air bubbles rising from the diffusers force the disc shaped float to move in a random pattern around a controlled area of the basin.By installing several such aeration chains throughout the basin, the entire basin can be mixed thoroughly while using only the amount of air needed for biological treatment.
Finally, High-Speed Floating Aerators can be used in conjunction with mechanical mixers for ENVIROPro applications in warmer climates.
Reactor Basin and Decanter
The IDEA Reactor Basin develops an MLSS population that may range in concentration from 1,000 mg/l to over 10,000 mg/l. It is an unsteady-state acclimated population that adapts to alternating anoxic and aerobic conditions which consistently and repeatedly range in DO (dissolved oxygen) concentration from 0 mg/l to 3 mg/l.Consequently, shock organic loads have little effect on the process.As a result, the system achieves nitrogen and/or phosphorus removal and maximizes aeration efficiency.
The patented AES IDEA Floating Decanter may be installed in both pumped effluent and gravity flow effluent configurations. The gravity flow effluent decanter utilizes a ballast tank that can be filled with air or water depending on whether the system is to be decanting.The pumped effluent decanter requires only a simple effluent pump, while the gravity effluent pump requires only a simple air pump.Both systems are extremely reliable and maintenance free.
The unique nature of the AES IDEA decanters in combination with the IVE Collector and Omni-Flow Partition allow the IDEA system to be installed in virtually any basin configuration.
Sludge Storage
Because the IDEA process operates at extended sludge ages, significantly less sludge is produced compared to conventional systems. This low sludge production, combined with the ability to operate at high MLSS values, results in the ability to actually store sludge within the reactor basin, eliminating the need for a sludge holding tank.However, the sludge produced will have a lower solids content.Therefore, AES recommends either an aerated sludge holding tank or gravity thickener be installed on larger systems.
Disinfection
Any standard disinfection process may be used in conjunction with the IDEA process. Typical processes are tablet, liquid, or gas chlorination, and ultraviolet radiation.
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PROCESS CONTROL
System Options
The AES IDEA systems are flexible enough to be designed with a Programmable Logic Controller (PLC), solid state, or Supervisory Control And Data Acquisition (SCADA) based control system. In all cases, the same high quality effluent standards and reliability are maintained.
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most cost effective system |
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occupies the least amount of space |
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most economically serviceable |
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operating personnel may be more familiar with solid state based control systems |
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can be programmed to automatically adjust process cycles to feedback from ancillary equipment such as flow meters, pH probes, and remote pump stations |
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facilitates the feedback and accumulation of operating data |
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facilitates monitoring of all equipment in the plant |
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the process can be easily adjusted |
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will ease the transition to a SCADA system at a later date |
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all advantages of the PLC system |
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allows continuous, real-time, monitoring of all equipment operation and processes |
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allows continuous, real-time, monitoring of remote locations such as pump stations |
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allows operators to monitor and review past feedback from when the plant was unattended |
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allows access to the above information from remote terminals (including laptops) |
Solid State Control System AdvantagesPLC System AdvantagesSCADA AdvantagesControl Logic: Four Hour Cycle
The AES IDEA process normally operates on a three phase cycle, repeated every four hours. The cycle may occasionally be changed to facilitate the treatment of higher strength wastewater.
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aeration phase length = 2 hours |
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settle phase length = 1 hour |
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decant phase length = 1 hour |
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feed = continuous |
The settle phase is typically set at 1 hour in length. No aeration will take place during the settle cycle.
The decant phase follows the settle phase. The decant phase is typically set at 1 hour in length.No aeration will take place during the decant phase.The decanter will run until the basin water level reaches FLS1 or until 1 hour has passed, whichever occurs first.
The system is equipped with an alarm water level float (FLS4) that will indicate either extremely high flow conditions or equipment failure. The alarms will be both audio and visual.
In some cases, control of the sludge wasting pump will be automatic. This may be required in large systems or by systems requiring high levels of nutrient removal (nitrogen and phosphorus).In such cases, wasting will occur every cycle at the end of the decant phase.
BIOLOGICAL PROCESSES
Biochemical Oxygen Demand (BOD) Removal
In the IDEA process, as with all aerobic treatment processes, unwanted organic pollutants in wastewater are consumed by aerobic (requiring oxygen) microorganisms.The most widely used indicator of the relative strength of organic wastewater is Five Day Biochemical Oxygen Demand (BOD5).BOD5 is defined as the amount of dissolved oxygen the aerobic microorganisms require to biologically oxidize the organic matter.
During the Aeration Phase of the IDEA process, naturally occurring microorganisms grow and reproduce by consuming organic pollutants and oxygen.The by-products of this process are carbon dioxide, water, and the continued life cycle of the microorganisms.The process may be summarized in the following equation:
In general, 1.5 pounds of oxygen are required for every pound of BOD5 to be removed.
Nitrification
Nitrogen exists in wastewater in two principal forms, organic nitrogen and ammonia nitrogen. Ammonia exerts high levels of oxygen demand that are harmful if discharged to the environment. This problem can be eliminated by converting the ammonia and organic nitrogen to nitrate.
In the IDEA process, ammonia and organic nitrogen are converted to nitrate by a two-step process facilitated by naturally occurring aerobic microorganisms. In the first step, nitrosomonas bacteria convert ammonia (NH4) and oxygen to nitrite (NO2), water, and hydrogen ions:
In the second step, nitrobacter bacteria convert nitrite and oxygen to nitrate (NO3):
For these reactions to occur, 4.57 pounds of oxygen are required for every 1 pound of ammonia to be removed. Additionally, it should be noted that 7.1 pounds of alkalinity (as CaCO3) will be required per pound of ammonia.
Denitrification
High levels of nitrate are also polluting in many areas, thus necessitating their removal also. In the IDEA process, naturally occurring bacteria use organic carbon (incoming sewage) to convert nitrate to nitrogen gas, water, and carbon dioxide.This process occurs in an anoxic (very low dissolved oxygen) environment where the denitrifying bacteria get theoxygen they require from the nitrate molecule, causing the nitrogen to dissipate as nitrogen gas.The following equation illustrates the process:
Phosphorus is a nutrient for algae growth that often must be removed.Under the ideal conditions created by the IDEA process, phosphorus removal is accomplished by biological means.The microorganisms in the mixed liquor are able to remove an amount of phosphorus from the wastewater over and above the amount that is required for growth.This is termed "luxury uptake."
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