Food Waste Composting in Catering Unit

In one of the largest Catering units in the country, an integrated waste management facility was set up to prevent them from ending up in the landfill. The management has innovated creating an integrated Green Point within the company’s facilities.

A large amount of waste generated is recyclables (mainly cartons) and organics from the preparation of meals. Material pre-conditioning was already in place in the company, so the staff training program was not considered necessary.
The chosen solution consists of 3 stages.

The first stage concerned the reduction of the volume of recyclable materials and their exploitation as products for sale. For this purpose, the vertical press PEL B1500 was used with which the recyclable waste is compressed and bundled in packages of approximately 150-200 kg.

Recyclable parcels are collected from a private company at a price determined by the price of the materials in the Greek market.

The compression system has provided less space for collecting recyclables but also cleanroom and order.

The second stage concerned the reduction of the volume and weight of organic waste. This was accomplished by installing the SUPER COMPACT dewatering unit. The dewatering unit consists of a powerful waste bin which slurries all organic waste which is then led to a centrifugal unit to make the solids separate from the liquids. The fluids are removed through the drainage system while the solid residue is concentrated in special containers. In this way the volume and weight of organic waste is reduced from 50% to 70%. The process is shown below.

In the third and final stage of the waste management, the produced material is led to a closed-loop mechanical composting unit, the ROCKET in vessel composter, where after 14 days, immature compost is produced.

Dehydration is a prerequisite for the composting process because micro-slicing increases the contact surface of micro-organisms while reducing the moisture content of waste to 50%, which is ideal for proper composting. When adding organic wastes, the corresponding amount of wood (chopped branches, wood chips or any other form of wood) should always be added, due to the need of a carbon source for the composting micro-organisms.

Once the material enters the ROCKET chamber, the composting process is undertaken by aerobic microorganisms. The process is aerobic and occurs in 4 stages with different temperatures. The 4-channel recorder is connected to a computer and produces the temperature graphs from where the information is received for the course of the process. Temperatures reach up to 80 degrees ensuring the hygienic state of the produced compost by potentially dangerous pathogens.

The final product is transferred in special bags and needs to stay for another 2 weeks outdoors to mature and be ready for use.