Anaerobic Advance Digesters (AAD)

Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in the absence of oxygen which bring several benefits:

High COD Load
High COD / BOD Reduction
No Chemical Consumption
Low Opersating Cost
Biogas Generation

One of the end products is biogas, which is combusted to generate electricity and heat, or can be processed into renewable natural gas and transportation fuels.

Inside the digester. Anaerobic digestion is the simple, natural breakdown of organic matter into carbon dioxide, methane and water, by two groups of microorganisms, bacteria and archaea. Since many of these are intolerant to oxygen, this process is known as anaerobic

Advantage of Anaerobic Digester

Higher BOD / COD reduction
More biogas storage at the top of the digester & no need of separate biogas holder
Can operate over a wide temperature (25 °C – 40 °C)
Better Process Stability to Handle Shock Loads due to Long HRT & Large Biomass Inventory
Ability to Handle High Strength
Wastewater without Pre-dilution
Lower Sludge Generation and thereby Reduced Sludge Disposal Problem
Minimal Energy requirements
Greater and uniform gas production
No Running Chemicals Or Dilution Water Required
In-built clarifier in the digester & therefore low suspended solids at the digester outlet
Simple operation & minimum instrumentation
Ability to remain dormant for weeks at a time but ready for quick start-ups

Anaerobic Advance Reactor vs UASB

Perfect Design for operation philosophy and convenient
Efficient Reactor solids separation
Capacity to Resist Shock Loading
Smaller Foot Print and save lot of space
Floating roof with Geo Membrane with all safety
Higher BOD, COD reduction compare to all other processes

More Biogas Generation to generate electricity
Work well with 25- 38 C temp
Low operating cost compare to all other processes
Less Execution time and quick installation
Unique design for flushing arrangement

COD Reduction and Biogas Generation

Managed Alkalinity

Anaerobic Digesters generate alkalinity via the decomposition of Organic Nitrogen and hence there is no need for Caustic addition or Alkalinity Control. The pH neutral effluent after our anaerobic treatment can be discharged safely for further treatment or be used in agricultural fields for its fertiliser value. It will not require any further pH adjustment. Other technologies with a lower HRT or otherwise will require pH adjustment and daily continuous addition of chemicals which will add maintenance cost for daily operations, since the conversion of Organic Nitrogen to Ammonia and Bicarbonate will not be complete.

Flexible Digester Cover

World Technologies digesters have a polymeric reinforced membrane cover which is good for tough Anaerobic and corrosive environments. The polymeric membrane floats on the liquid surface and is attached to the side walls of the digester tank. Thus, the load of the membrane cover is taken up by the water and not the side walls of the tank. The polymeric membranes are resistant to corrosion and can be easily fixed during operation if required. Other digesters use steel covers and the weight of steel is transferred to the digester walls and hence the walls are thicker and incur a higher cost. Further, the steel will corrode due to the H2S in the biogas.

No Chemicals for Operation

Our digesters during initial start up will require some seed sludge either from local domestic sewage plant or animal waste for the anaerobic bacteria to be added to the digesters. Some alkalinity addition may be required. This is only one time during start up and commissioning. Other technologies require routine and continuous addition of chemicals such as lime dosing because of the smaller HRT of the digesters. This results in annual increase in O&M costs. Their technology requires a lime solution tank and feed equipment capital investment.

Consistency of Operation

Due to the high HRT, our digesters provide consistent performance and can take peak loadings without any problems. Other technologies have lower HRTs and higher loading rates. This may lead to sludge washouts and the operation of the overall digester system becomes very delicate which results in partial treatment, and hence will be difficult to control. Once out of control, and if the Anaerobic Bacteria is washed out, it will take another few months for it to destabilise, which would require experienced manpower.

Unique Mixing Technology

We uses a slow speed lamella mixing technology which is a submerged mixer with a mast to lift the mixer for service and repair. This high volume low power mixer is designed to provide complete mixing of digester contents. Other technologies require multiple mixers and use top entry mixers. With multiple mixers connected power is high and hence yearly Operation & Maintenance cost will be high.

Seed Sludge/ Wastewater out

Our designs do not have this problem, other technologies such as UASB and low HRT digesters require and rely on the development of dense sludge particles which settle at the bottom part of the digester. With increased 100% feed loading, these sludge washes out from the digester and hence this technology requires dilution of the waste and cannot feed 100% of the waste

Clarifiers to Prevent Sludge Washout

Our technology does not require any clarifiers on top of the digesters to hold off the washout of sludge. Some other technologies require their special patented such clarifiers at the top of the digesters that would prevent the sludge to washout from the digesters.

COD Reduction and Biogas Generation

World Technologies can offer COD reductions in the range of 75% – 80% our technology typically is seen to provide around 44% more biogas than competing technologies.