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Constructed Wetlands - Sustainable and Cost-Effective Wastewater Treatment in Rural and Peri-Urban Areas Bulgaria

A national conference presenting constructed wetlands as a sustainable and cost-effective wastewater treatment system was held on 29th of April 2011 in Grand Hotel Sofia

08.05.2011 |Claudia Wendland & Bistra Mihaylova

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In the picture: Krasimir Zhivkov

Mr. Krasimir Zhivkov, Governor of the Sofia Oblast, welcomed more than 30 representatives of the Bulgarian ministries of Environment and Agriculture and Health, Basin Directorate, mayors, governors, NGOs, scientists and experts from Germany and Bulgaria who participated at the professional conference “Constructed Wetlands - Sustainable and Cost-Effective Wastewater Treatment in Rural and Sub-Urban Areas Bulgarias”.

Dr. Claudia Wendland, WECF coordinator sanitation projects, introduced in the first presentation into the topic. Constructed wetland is a sustainable and extensive solution to treat efficiently the wastewater from households, communities as well as greywater and even landfill leachate. The constructed wetland comprises a pre-treatment step and a soil filter. The main treatment is a combined physical, biological and chemical process taking place in the filter. Several thousands constructed wetlands for wastewater treatment are in operation since many years in other European countries especially in Germany, Austria and France. Also in the Mediterranean countries it is a more and more applied technology. Constructed wetlands offer a number of advantages compared to conventional technical systems: they maintain a high performance, use less energy, sequester carbon and require less operation and maintenance.



The German expert Dr. Jens Nowak pointed out that although constructed wetlands are a very efficient and low-tech system, their proper design requires the know-how of an experienced expert. Vertical and horizontal flow constructed wetland can be applied as well as hybride systems depending on the effluent standard to be met. If properly designed and constructed, the removal of organic matter, suspended solids, nutrients, pathogens can be achieved. Based on German experiences, the key factor for sustainable success is to avoid clogging of the filter by the following criteria: proper selection of coarse sand for the filter, adequate design of the pre-treatment, sufficient filter area, adequate distribution of wastewater on the whole filter area, intermittent feeding and by a hydraulic bore and regular resting phases without feeding.
Jens Nowak explained a number of different designs in several European countries which can be looked up in his presentation. There are e.g. constructed wetlands predominantly in operation in France which do not require a pre-treatment step but use a two stage process instead.

Dr. Silvia Lavrova, Chemical University Sofia, presented her investigations on wastewater treatment in constructed wetlands in laboratory scale where she applied specific high-strength wastewater streams e.g. coming from farms. She achieved very good results in terms of nutrient removal as well as heavy metal removal, see also her presentation in detail.



Vidrare
The planning, design and construction of the first demonstration plant in Bulgaria was realized in Vidrare, Pravetz municipality. The design and the terms of references were made by the German consultant Andrea Albold, Otterwasser with the support by the Bulgarian consultancy ecoproekt. Ms Albold presented the case study of the wastewater treatment for the Home for Children and Juveniles with Mental Retardation St. Panteleimon in Vidrare in detail.

a constructed wetland

The design was calculated to be 76 population equivalent organic load and 95 population equivalent hydraulic load. A settling tank for pre-treatment of 18 m3 was installed and a soil filter of 266 m2 surface area was implemented in the yard of the home. Ms. Albold explicitly mentioned the excellent cooperation with the companies Ecoproekt and Interstroy group as well as with the municipality and Sofia regional administration that lead to a relatively fast implementation of the project. Please see also the case study in Bulgarian and English language for download.
Irena Petkova, ecological expert from Sofia oblast administration, summarized the benefits of having such a facility in the yard of the home, she emphasized its need and that the new project can serve as an example for replication in other municipalities and institutions. Also the barriers were mentioned which all the organisations involved had to overcome in order to finalize the project.
Thanks to the very good collaboration of the local and regional administration with WECF and EcoWorld2007 and the companies, the first demonstration plant was successfully realized. Together with WECF, Ms. Petkova will take care of a proper operation and maintenance and monitor the performance.


After the conference, many participants accepted the invitation for an excursion to visit the demonstration constructed wetland in Vidrare.
This conference was part of the project “Constructed Wetland in Bulgaria” funded by DBU, WECF and Pravetz municipality.

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DOWNLOADS & LINKS

Programme in English Programma in Bulgarian Case study in Bulgarian Case study in English Presentations: Claudia Wendland Andrea Albold Jens Nowak Silvia Lavrova Irena Petkova

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