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Organic fraction waste sorting:

This is the first step of the anaerobic digestion or aerobic digestion of the household waste to get the organic fraction.

Valorga acquired an experience without any precedent on the choice of its sorting equipment the sorting unit is adapted to the composition of the waste to be treated. Valorga International can join forces with other industrial partner and sorting unit equipment suppliers in order to meet the requirements of waste sorting.

Sorting equipment is based on the following principles:

 Granulometric sorting,

 Magnetic sorting,

 Densimetric sorting.

This step allows to reach :

 Recycled fractions (iron metals and non-iron metals),

 Organic Fraction which is send to anaerobic digestion unit or aerobic digestion unit,

 The remaining fraction with high calorific power can undergo a specific treatment, i.e. plastics incineration.


Valorga® methanization Process

Principle
The Valorga process is an anaerobic biological treatment process for waste organic fraction with source sorted collection or not.

Description

Valorga digesters are vertical cylinders with a specific design in order to obtain a horizontal plug-flow type process. They contain a vertical median inner-wall on approximately 2/3 of their diameter. The orifices for introducing and extracting the matter are located on either side of the wall. The wall forces the fermenting matter to follow a circular pathway in order to go around it and to cover the whole surface of the reactor. Together with the vertical mixing, this particular design can guarantee a controlled retention time inside the reactor which is of particular importance for sanitary purposes.

Advantages of Valorga digester

1
Because of its process: a dry, continuous and plug flow system Valorga technology is specifically adapted to the treatment of organic municipal solid waste, such as the biodegradable part of household waste, catering waste, solid sewage sludge. The process operates under anaerobic conditions with a high dry solid content of 25 - 35 %, owing to a specific process design. As a consequence, the requirement for only minimal water additions makes the overall water and heat balances very favourable.

 Anaerobic digestion leads to the production of a high methane content gas: the biogas. This technique allows a net energy production with several ways of valorisation (steam, methane gas, electricity, fuel),

 Oxygen-free fermentation takes place in closed fermentation tanks called digesters, avoiding any smell nuisances. It is noticeable that during the fermentation process, the volatile organic smelly acids, which are intermediate components of anaerobic digestion, are naturally transformed in biogas inside the digesters. In aerobic composting, volatile fatty acids can be emitted into the air and must be recovered and treated in a bio-filter.

 This technique does not require a large land area.

The anaerobic digestion of the organic material is usually followed by a short aerobic phase (about two weeks) which completes the stabilisation of the digested matter. After this phase, the compost is fully stabilised (degree 5 of the German norm LAGA M10) and can be stored and commercialised.

2The flexibility of the process Valorga towards a variable quality of the household refuse and thus towards various types of collection, explains by the fact that the process Valorga is the first process of methanization applied as the same time for the treatment of the household refuse sorted out mechanically from bulk collection and for the organic fraction from source sorted collection.


Speeded up composting

 The aerobic digestion occurs in two successive steps :

 
Fermentation step,

 Refining step.

Dynamic aerobic process

The dynamic aerobic digestion process is a stage of fermentation while the organic matter is returned with or without ventilation.

Valorga develops several technologies :

 Aerated boxes composting process 

This process needs a wheeled loader which will charge and discharge boxes. The aeration of the matter is insured by a bored floor where the air circulated thanks to fans. The advantage is simplicity and reliability of this technology

 Aerated windrow composting process 

This process is apply with a turning machine which returns windrows two times a week. The windrow aeration is insured by a bored floor where the air circulated thanks to fans.

 Aerated corridors composting process 

This process uses a automatic turning machine on rail. The windrow aeration is insure by a bored floor where the air circulated thanks to fans.

Static aerobic digestion

The static composting is a step of fermentation while the matter is aerated but it is not return.

Valorga develops several technologies :

 Aerated tunnels composting systems

This process is based on a fermentation in concrete tunnels without . La fermentation se déroule dans un tunnel en béton fermé. The windrow aeration is insure by a bored floor where the air circulated thanks to fans.

 Thermic biodrying


Biological air treatment

The polluted air is sucked from all the buildings and sent to an acid scrubber and a biofilter. The treated air is then rejected in the atmosphere without any odour emission.


Excess water treatment

The possible excess process water, related to the incoming waste moisture, can be discharged into the sewage network, after an additional purification step if necessary, depending on local regulations.


Biogas valorisation unit:

The produced biogas can be upgraded as follows:

 Heat and/or electricity production,

 Fuel for vehicles,

 Steam production,

 After a purification step, injection in the city gas network.