Database of Waste Management Technologies Life

Case Study 13 – Mechanical Biological Treatment (MBT)

 

General Information Photo Gallery
Name: Solid Mechanical Recycling and Composting Plant-Landfill (EMAK) of Chania case study 13

The MBT unit and Landfill in Korakia, Acrotiriou, Chania

case study 13

The Composting tank

Owner: Chania Prefecture
Operator: Trans Municipal Enterprise of Solid Waste Management (DEDISA) of Chania
Technology: MBT, Composting enriched organic
Designed Capacity: 70,000 tpa MSW & 105,000 tpa (branches and pruning) – Projection year 2015
Cost: 30,000,000 € (total investment cost for the year 2001)
Location: Chania, Crete, Greece
Served Area: Chania Prefecture
Commercial Start Up: 2005
Contact Details
Address: Korakia Akrotiriou, 73100
Chania, Crete,
Greece
Phone Number: +30 28210-88262
Fax: +30 28210-88766
Email: info@dedisa.gr
Website: www.dedisa.gr

 

Short Description

The MBT Unit of Chania was implemented by the Prefecture of Chania and its budget amounted to 25.8 million euro (75% financed by the Cohesion Fund II).

The facility occupies an area of 110,000 m2 and has a total installed capacity of 2.3 MW. Operator of the facility is Trans Municipal Enterprise of Solid Waste Management (DEDISA) of Chania, who is responsible for the management of MSW of the Prefecture of Chania.

The Unit has been designed to treat MSW and recover 65% of recyclable materials and compost. The provision of the rest material (35%) has been to end up to the adjacent landfill.

The main parts of the facility are the following:

  • Reception
  • Mechanical Shorting (2 lines)
  • Composting Unit
  • Refinery-maturation
  • Environmental Pollution Control Unit

Although the Facility has been initially designed to process MSW, nowadays the operation of the facility has been altered to receive MSW as well recyclable materials of the recycling scheme that has been established the last years in Chania.

Currently the facility processes two different waste streams; the MSW stream which amounts 270 tn/day (2009) and the stream of the collected recyclable material which amounts 46 tn/day (2009).

About 110 tn of MSW and the whole amount of the recyclable material stream enter the Mechanical Shorting Unit in daily basis. The Mechanical Shorting unit operates in two lines. The first line receives MSW and the second line receives recyclable materials. The line of the recyclable materials is used to short the different types of recyclables. The line of the MSW is used to recover recyclables and the organic matter of MSW that enters the composting unit. A percentage of 30% of residues is lead to the landfill.

In 2009, about 10,000 tn of recyclable materials were reclaimed and sold at Recycling Companies of Athens and Heraklio with a profit of 1,100,000 € (including the aid of the Hellenic Recycling Company-E.E.A.A). Furthermore, about 60 tons/day of organic matter entered the composting unit along with pruning and shredded branches.

The compost produced at the composting unit is tested at the chemical laboratory of the Unit and the Mediterranean Agronomic Institute of Chania (MAICh).

Until recently the compost has been mainly used for land restoration. Furthermore, the potential of using the produced compost as a fertilizer has been introduced in a pilot scale at local plant nurseries.

More detailed information on the MBT and composting operations is provided in the “Extra Information” section.

 

Key Facts

Treatment Capacity: 94,441.5 tpa (mean values per annum)
Input Material: MSW 79,122 tpa
Recyclables 13,158 tpa
Green Waste 960 tpa
Bulky Waste 1,201.5 tpa
Output Products: Compost 1,745.38 tpa (2490 tpa wet compost for storage with 30% humidity)
Total Recyclables 9,651 tpa
Cardboard 38.18%
Mixed Paper 32.94%
PE (white film) 3.00%
PE (mixed film) 9.06%
Ferrous metals 13.60%
Aluminum 0.19%
PET 1.41%
PE 0.96%
PP 0.54%
Tetrapak 0.1%
Coloured glass 0.07%
Residual to landfilling 24,983 tpa

 

Extra Information

Description of the MBT operations

The Solid Mechanical Recycling and Composting Plant- Landfill of Chania was established in 2005. A pilot scale system started to operate and manage the MSW decreasing the organic biodegradable fragment of waste leaded to the landfill. Analytically, the tracks after weighting, discharged the MSW and a grapple transferred the materials in a bag opener where the waste bags were torn and lead through the belt for mechanical process. Two rotary sieves, the first with 250 mm and the second with 70 mm holes, sorted the waste mechanically by size. The >250 mm fraction was sent to manual removing of bulky e.g. paper, plastic, the fraction between 250 mm and 70 mm was hand-sorted for composting and the residual fraction was sent to landfilling, and last the <70 mm fraction was send for recycling, passing through a magnet for metal removal. During this process, the compost was stirred by screw turners and water was added to keep compost moisture between 45-55% and temperature between 50-65oC. The compost in the bioreactor was monitored and the following characteristics were measured: pH, water content, organic carbon, ash and EC. About 10.5 tn of compost produced per day while flip-flop sieves and gravimetric cyclones removed non biodegradable materials. Finally, the refined compost was placed in open air rows for further maturation.

MBT process data
Number of Trommels 2
Total recovery capacity of trommels 125 kg/h
Number of magnets 3
Total recovery capacity of magnets 147 kg/h
Number of eddy current separators 1
Total recovery capacity of eddy current separators 13 kg/h
Number of handpickers 15 per shift
Total recovery capacity of handpickers 220 kg/h
Total storage area for recyclables 800 m2

Description of the Composting Operations

The biological unit consists of an intensive aerobic process, a refinement step and a maturation state before storage. A closed Fast Composting Tank (FCT) receives the mixture of Organic fragment of MSW and Green Waste. Forced aeration is provided, using drains deposed at the bottom of the tank, with the same piping system excess water. Four retractable screw turners attached in a moving bridge above the tank turn, mix and move the active material to the other side of the tank. Water sprinklers build in the top of the turners for the addition of water to the process. The material reaches to the other side of the tank after 4 weeks, where a fifth screw turner set in a conveyer belt, retrieves the composted mixture to the refine unit. The conveyed compost leaded through a 100mm holes vibrant flip flop screen where uncomposted bulky material is collected. The composted below 100 mm fragment leaded to a combined air separation and ballistic separation system that retreats the heavy substrate like dull and glass. The not composted bulky and heavy substrate is sent for landfilling. Finally, the refined compost (RC) is placed in open air rows for further maturation, for several weeks. Every 15 days a new row was created from the daily RC production. During this state, temperature of the rows was measured daily and adjusted by water addition while aerobic conditions were provided to the rows by turning with fork trucks.

Composting process data
Fast Composting Tank 1
Dimensions (LxWxH, m) 67.20x22x1.70
Retention time (days) 30-40
Capacity (m3) 837.76
Aeration via perforated floor Yes
Air flow (m3/h) 20,000
Total area occupied (m2) 2,500
Water used for wetting of the material (m3/day) 4.53
At the time the Plant uses only 1/3 of the Fast Composting Tank