Co-Digestion of the Organic Fraction from Municipal Solid Waste with Manure and Chicken Dung at the Malta North Waste Treatment Facility

The Malta North Waste Treatment Plant (MNWTP) is the second MBT Plant for the treatment of Municipal Solid Waste in Malta.

BTA

Operator: BTA International GmbH
Location of the project: Magthab, Malta

Contact details

Jean Luc Zarb
jean-luke.zarb@wasteservmalta.com

Project goals
 

Process optimisation:
• Digestate
Socio-environmental advantages:
• Renewable electricity/heat supply
• Waste reduction

Project outline
The facility is a key measure under Malta’s Waste Management Plan and contributes significantly to the achievement of national goals by saving a landfill volume of over 58,000 m³/year while recovering material for recycling or RDF production, and producing biogas out of the organic fraction. With a power output of 10 gigawatt hours, the facility became one of the largest renewable energy sources in the country, while the digestate is used to produce landfill coverage substrate, highly valuable for an island such as Malta.
A further objective was to provide a solution for two livestock sector waste streams which have an increasing impact on the island – manure and chicken dung.

Technical data
 
 
 


Performed actions
 
The plant was designed and built by the BEV Consortium, on behalf of WasteServ Malta Ltd. The BEV Consortium comprises:
• BTA International GmbH
• EFACEC Engenharia e Sistemas S.A.
• Vassallo Builders Ltd.
The BEV Consortium was responsible for the design and construction of the MNWTF, which presents the following special features, among others:
• The MNWTF is split across two locations. The organic suspension produced from MSW at the Mechanical Treatment (MT) Plant is pumped over 400 m to the Anaero- bic Digestion (AD) Plant.
• Receipt and co-digestion of residues from the livestock sector at the AD Plant.
• Two step dewatering concept to reduce the demand for flocculants.
• Stabilization of the dewatered digestate in the wet phase in three aeration tanks due to lack of available area for composting.
After the Provisional Approval in 2016, the Consortium has provided WasteServ with two years’ operational support.


Results
The results from the Approval Tests for the Provisional Approval of the MNWTF in 2016 showed that:
• The guarantees for the recovery rates and quality of the recyclable material and RDF were met or even exceeded.
• The requirement of a landfill diversion over 90% for Biodegradable Municipal Waste has been fulfilled.
• The specific biogas production per tonne VS input digester exceeded the design values, hile methane contents were significantly igher than expected.
• The requirements regarding the physical impurities content and the degree of stabilization of he dewatered digestate were met.
The operation of the internal wastewater treatment plant was stable, achieving discharge oads distinctly below the corresponding guarantee values.
Management of the biogas proved to be quite asible with a smaller than usual gas holder and with the installed 1.8MW split between a 1.2MW.