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Technology

2.1.07 Clean and effective – decentralised disposal systems for hotel complexes

Many tourist resorts in southern countries do not have any environmentally friendly means of waste and wastewater disposal or energy supply. The MODULAARE research and demonstration project used a Turkish hotel complex to test a sustainable solution to these problems: the procedure developed combines the fermentation of organic waste with membrane technology for wastewater cleaning. The resulting products: process water, fertiliser and biogas.

Tourist resorts cannot enjoy stable economic development if their environment is not intact. Heavily visited regions, rapidly growing new resorts and ecologically sensitive areas in particular need to orient their tourism toward the guiding principle of sustainability – and ensure that their energy and water supplies and waste and wastewater disposal facilities are environmentally compatible.

Spot checks have determined a daily water consumption of up to 1,200 litres per guest in international holiday hotels (including apportioned consumption for green facilities and swimming pools). By way of comparison: households in Germany currently consume about a tenth of this, an average of 123 litres per resident per day. Wastewater often flows – poorly cleaned – into rivers or directly into the sea because sewage facilities in the hotel complexes are either poorly maintained or lacking altogether; it is often not possible to be connected to the central wastewater disposal system as tourism resorts are often outside built-up areas. Waste disposal causes just as many problems: large hotels produce up to 2.5 kilograms per guest every day, which is often disposed of at unauthorised dumps.

Integrated concept for tourism regions

One answer to these problems, particularly in ecologically sensitive regions, are “Integrated modules for high-efficient wastewater treatment, solid waste disposal and regenerative energy production in touristic resorts” (MODULAARE). This is the title of the project combining membrane technology in wastewater treatment and anaerobic fermentation in the treatment of bio-waste to enable targeted nutrient flow management for wastewater and organic waste. This results in a virtually closed nutrient cycle in an almost wastewater-free hotel – and also produces valuable by-products such as process water, fertiliser and energy.

The “Sarigerme Park” hotel complex in Turkey

The “Sarigerme Park” hotel complex in Turkey
The “Sarigerme Park” hotel complex in Turkey
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To put this procedure to the test in a practical setting, the international project team set up a test facility at the “Hotel Sarigerme Park” on the Turkish Aegean coast in 2005. Concluded in 2008, the project was managed by the Verband zur Förderung angepasster, sozial- und umweltverträglicher Technologien e.V. (AT-Verband, association for the promotion of adapted, social and environmentally compatible technologies, Stuttgart); the Institute for Sanitary Engineering, Water Quality and Solid Waste Management at the University of Stuttgart was in charge of scientific management, MEMOS Membranes Modules Systems (Pfullingen) produced the membrane technology and Bio-System Selecta GmbH (Konstanz) produced the anaerobic system. The administrative authorities for the island of Mainau on Lake Constance supplied basic data and supported the project’s public relations.

Membranes cleaning the wastewater

A MODULAARE biogas module

A MODULAARE biogas module
A MODULAARE biogas module
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The procedure used recovers biomasses from the wastewater via membranes – not through final clarification (sedimentation) as usual. Membranes not only remove all solids, but also large amounts of germs and viruses. The membrane bioreactor upstream is a mechanical cleaning process that removes the solids. The membrane filtration enables increased concentrations of biomasses (experts refer to a higher space-time yield): bio-membrane reactors operate with biomass contents of 10 to 15 grams per litre. This value is about three times higher than conventional activated sludge reactors (approx. 4 g/l) because the biomass concentration in the activation no longer depends on the sedimentation behaviour in the secondary settler. The MODULAARE process provides further treatment of excess sludge together with kitchen and garden waste in the fermentation module.

MODULAARE membrane module

MODULAARE membrane module
MODULAARE membrane module
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The membrane system offers a number of technical ways to eliminate nutrients. Carbon, nitrogen and/or phosphorus can also be reused to some extent – depending on the intended use of the cleaned wastewater. Phosphorus can be used within garden irrigation as a fertiliser; the process can also provide soil protection, especially in areas with a negative humus balance like the Mediterranean area. The modular nature of the system allows it to adapt to seasonal fluctuations in guest numbers, be it through a different solids content or activated/deactivated membrane modules.

Biogas covers energy requirements

Hotel waste can consist of more than 70% organic material. Due to the nature of the waste, only around a third of it can be treated aerobically (compost) without major technical efforts. The high water content and the structure of the material means there can be sufficient anaerobic areas to result in considerable odour; compost can also easily dry out in Mediterranean and arid zones due to the high air temperatures. Fermentation on the other hand can treat up to 90% of the organic waste, and the fermentation residue can be used in agriculture.

The MODULAARE project has developed a practicable concept that permits optimum use of biogas: used either to provide heat or – converted into electricity – to cover the high amounts of energy required by the membrane bioreactor. Any wastewater (e.g. from drainage) is fed directly back into the membrane bioreactor.

Project website www.modulaare.de

Verband zur Förderung angepasster, sozial- und
umweltverträglicher Technologien e.V. (AT-Verband)

Dr. Udo Theilen (Coordinator)
Dieter Steinbach, Andrea Schultheis (MODULAARE overall concept)
Waldburgstraße 96
70563 Stuttgart, Germany
Tel.: +49(0)7 11/7 35 52 79
Fax: +49(0)7 11/7 35 52 80
E-mail: atverband@aol.com
Internet: www.at-verband.de
Funding reference: 02WD0440

University of Stuttgart
Institute for Sanitary Engineering, Water Quality and Solid Waste Management
Departments of Wastewater Technology and Siedlungsabfall (municipal waste)

Prof. Dr.-Ing. Martin Kranert
(scientific management)
Bandtäle 2
70569 Stuttgart, Germany
Tel.: +49(0)7 11/68 56 55 00
Fax: +49(0)7 11/68 56 54 60
E-mail: martin.kranert@iswa.uni-stuttgart.de
Internet: www.iswa.uni-stuttgart.de
Funding reference: 02WD0441
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Project website

www.modulaare.de