THE MBT PLANT
The plant receives non separated Municipal Solid Wastes. Its capacity is 450 t/day. The waste is weighed at the entrance of the plant on an electronic weighbridge. The software of the weighbridge automatically registers each event and puts the data into the archive.
DESCRIPTION OF THE MECHANICAL TREATMENT
The wastes are delivered into a Reception hall, which allows the storage and the pretreatment of the wastes for an interval of 48 hours. After presorting of non-specific and/or oversized waste the rest of the waste is fed by a wheeled loader into the pre-shredder for size reduction and opening of bags.
With an incined conveyor the waste is transported into a sieve drum with three sections and a capacity of 50 t/hour. The sieve drum sections separate the incoming waste stream into three different in size fractions:
- - residual organic fraction – for composting
- - lightweight 3D fraction – NIR separation
- - lightweight 2D fraction – hand sorting and baling
PRODUCTION OF RDF (REFUSE DERIVED FUEL)
The residual waste from the middle and oversized fraction is transported to a shredding line as raw material for production of RDF (fuel from waste). The shredding line for RDF has a maximum capacity of 224 t/day or 82 000 t/year. It is located in 3 halls – reception hall with pit conveyors and a preliminary shredder, main treatment hall for shredding and separation and a storage hall for the produced RDF.
The shredding plant consists of two identical lines which work separately. The bigger fraction goes into the preliminary shredder which capacity is 14 t/hour and then through a magnetic separator for ferrous metals, after which it enters one of the lines through a pit conveyor. The pit conveyor of the other line is directly fed with the smaller size material.
In the next stage material goes through a wind sifter which separates the light combustible material from the heavy noncombustible material. The heavy fraction is directly transported into containers and the light fraction is fed into the fine shredders, each with capacity from 6 to 8 t/hour where it is reduced in size up to 30mm. After the fine shredding through chain conveyors the material is transported to the storage hall forming two separate piles – one out of each line.
DUST REMOVAL – AIR FILTER
As dust is released in the air by separation and shredding processes there was installed a de-dusting system to clean the outgoing air streams from the dust particles. This filter equipment provides cleaning which complies with the EU emission norms for harmful substances released into the atmosphere from sites and activities which are potential sources of emissions.
COMPOSTING / AEROBIC BIOLOGICAL STABILIZATION
The 0-60 mm fraction goes into the composting tunnels. The process of aerobic stabilization is conducted in closed type bio-tunnels 10 pcs, each with capacity of 480 t. The material is treated there in a close forced environment. All key parameters of the process are controlled automatically: Oxygen content Temperature Moisture content
PROCESS PARAMETERS
The organic material stays into the tunnels about 18 days, as for this time undergoes different phases/stages of stabilization:
Preparation – day one (30°С)
Hygienization – days two and three (>60°С)
Composting/aerobic digestion – about 14 days (55°С)
Cooling – last day (down to 35-40°С)
The produced stabilized organic fraction is used for covering of contaminated sites.