OFMSW Pretreatment for AD – PROMECO solutions

The combination of  the BIO-EXTRUDER and Promeco Organic Extractor is an ideal solution to the problem of pre-treatment of organic matter sent to anaerobic digestion. 
Goals are removing from the MSW organic fraction heavy and light impurities and pre-treating it to increase the efficiency of anaerobic digestion system. 
Usually OFMSW from separate collection can have impurities and contamination around 15-17% of the weight. This value increases up to 25-28% when the organic fraction is coming from unsorted MSW mechanical treatment.

Both PROMECO machines have been designed taking advantage from a  proven experience in waste management and plastics recycling. Today, after studies and experiments, and thanks to some changes, these machines are also used in the treatment of organic waste.

The PES 600 has a long history of reliability in applications with much more demanding requirements (MSW, mixed plastics, medical waste, etc.). In these applications, PES 600 is already used "continuously", and it is universally recognized and appreciated as a great machine, both for the sturdiness of the structure and for its minimum maintenance requirements.

The entire structure of the centrifuge POS - Promeco Organic Separator - is designed to operate in conditions of heavy stress; every design choice has been made with the goal of giving considerable sturdiness and solidity to all its components, starting from the frame. 
The machine, even if new in this application domain, already has a 10-years life in the field of drying of recycled plastic materials. 
The forces are balanced, and only the static weight of the machine is downloaded on the frame. 
A continuous system ensures the automatic lubrication of the bearings, thus reducing the time for maintenance.

Overall, the PROMECO system for the pre-treatment of MSW organic fraction is an effective, efficient and both capital investment and operations costs are significantly lower in comparison with other solutions offered on the market.

Description of the process

The pre-shredded organic fraction is introduced into the hopper feeding the Promeco Extruder System, and is then conveyed by some screws on a vibrating table, regulating the material flow inside the processing chamber.
In the processing chamber the material is pressed and fractioned, in order to:

• pulperize the organic substance of low cohesion (fruits and vegetables, etc.).
• defiber the organic substance with fiber (meat, wood, bones, etc.)..

The adjustment of the PES front plate, which acts as a matrix to the system, allows to increase the pressure and the mechanical action exerted on the material in the processing chamber. This way a greater defibration of the treated material can be obtained, even if with a relative decrease in production capacity.

The PES600 screws and all the plates (pressure and front), are coated with wear-resistant material to ensure long life and minimize downtime operation.

The pulped/defibered material out of the PES is collected by a screw conveyor, feeding the POS - Promeco Organic Separator. 
On this screw conveyor can be added to a part of the water necessary to obtain the proper degree of dilution, depending on the anaerobic digestion system used.

The input materials are loaded into a feeding bunker; here, a screw conveyor introduces and meters the material inside the drum. 
The drum rotates at a very high speed. Thanks to centrifugal forces exerted on the material, this is pressed on the basket, causing the leakage of the organic substance, which is then extracted to be sent to anaerobic digestion, after removing aggregates of small dimensions with a hydrocyclone.

Inside the basket a screw ensures:

• the turning and the advancement of the material
• the continuous cleaning of the basket
• the discharge of the pulperized organic matter out of the basket

Materials that cannot be  pulperized (such as plastics, metals, textiles and other) are pushed to the end of the drum where they are discharged throught an outlet. These materials are conveyed by a screw and stored, before being sent to their disposal processes.

During processing water is added in the POS, both to clean and dilute the organic substance and to make it more transportable by means of screws, or pumpable. 
The organic matter is released and fall under the machine car. Depending on the quantity of water to be added, dry content ranges from 10 to 25%.

The speed of the main motor and of the two augers are adjustable, allowing rotation speed of the PROMECO ORGANIC EXTRACTOR to be optimized according to the type and quality of the material to be treated.

The system is highly mechanized and controlled by PLC.

Treatment capacity

Treatment capacity depends on the characteristics of the waste and of the desired output; it can reach up to 40 m³/h depending of the incoming bulky density of the input material.