MASTER'S THESIS - SuSanA

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5 Learning from already implemented CWs (in Albania and the Balkan region) Table 5.1: Design values for constructed wetlands (Nowak 2010,a); (Heise and Nowak 2007) VF Design criteria Albania Germany Specific area demand Total area demand lowland Mountains ≥ 1.5 m²/PE ≥ 3.0 m²/PE ≥ 4 m²/PE ≥16 m² HF Organic load (CSB) Hydraulic load Specific area demand Total area demand Organic load (CSB) Hydraulic load ≤ 16 g/(m²d) ≤ 80 mm/d ≥ 4.0 m²/PE ≥ 8.0 m²/PE ≥ 5 m²/PE ≥ 16 m² ≥ 32 m² ≥ 20 m² ≤ 40 mm/d Planted sludge drying bed Specific area demand ≥ 0.25 m²/PE ≥ 0.4 m²/PE One of the main challenges of CWs is the even distribution of wastewater that is dependent on “the cross sections of the pipes, the distance of pipes, the distance of holes and the feeding quantity per interval”. To be able to guarantee maintenance works, pipes should be installed above the filter bed (Regelsberger 2005). 5.1.4 Advantages and disadvantages of constructed wetlands Advantages and disadvantages of constructed are listed in Table 5.2 (p. 56), compiled from the following sources (Regelsberger 2005), (Heeb and Wafler 2011,b) and (Nowak 2011,a). According to this table, constructed wetlands have many disadvantages but still seem to be a very appropriate solution for rural areas in general and for developing countries. But the actual appropriateness of a CW should be carefully proofed for the concerning site. One of the success factors would be to ensure expertise knowledge for construction, operation and maintenance. Even O&M are kept at a very low level, small mistakes can bring the malfunction of the whole plant. If the plant can work by gravity, no electricity for pumps is needed, what makes it suitable for a country with electricity shortage and power cut-offs like Albania. Dependent on the number of houses connected to a CW and the housing density, CWs can be built for single households as an on-site solution to avoid expensive sewer systems, or as a solutions for a whole village or for community buildings. In general, the smaller the plant is, the easier the equal distribution of the wastewater on the filter bed is. The bigger the plant, the more complicated the distribution gets. According to (Heise and Nowak 2007), CWs are mostly used for settlements with up to 1.000 PE, but the use of the technology is also possible for bigger settlements. 55
5 Learning from already implemented CWs (in Albania and the Balkan region) Table 5.2: Advantages and disadvantages of constructed wetlands Advantages • Very efficient in BOD reduction and pathogen elimination • Simple construction, operation and maintenance • Not sensitive to peaks, high ability to tolerate fluctuations in flow (high process stability) • Constructed with local materials • Construction can provide short-term employment for locals • Fitting well into the environment, aesthetic appearance, creating biotopes • Good solution for few PE • Low O&M costs • Low energy demand • No sludge removal necessary, sludge only from pre-treatment • Re-use of treated wastewater is possible Disadvantages • Large area demand (VF need less area than HF) • Pre-treatment necessary • Requires good knowledge for design and operation. Small mistakes can bring big problems, but only visible after a long time, as plant is quite resistant. According to Jens Nowak, the “plants will work perfect or not at all” • Filter material has to be replaced every eight to 15 years • Need of well working dosing system • Electricity demand if no slope for water transport available • Risk of clogging of the filter material if wrong material used or insufficient pretreatment • Odour can occur, therefore CW should be located with distance to houses 5.2 Assessment of the pilot CW in SOS children’s village Tirana This part deals with the pilot constructed wetland at the SOS children's village in Tirana, the design and implementation, problems with operation and resulting reconstructions, the costs as well as the necessary O&M works. The process of implementation and involved stakeholders will be described in detail in subchapter 7.2.1 Example of implementing a CW at SOS children’s village (p. 86). 5.2.1 Project organisation and location of the pilot plant The constructed wetland for wastewater treatment at the SOS children’s village “Hermann Gmeiner” in Sauk, Tirana, was a project of GIZ (at that time GTZ), Germany, and the General Directorate for Water Supply and Sewerage (GDWSS) of the Ministry of Public Works and Transport (MPWT), Albania. The plant was planned in 2008 by the German Engineer Joachim Niklas from ÖKOTEC GmbH, Germany, and the Albanian Senior Engineer Enkelejda Gjinali. The construction was finished by the end of 2009 and operation started in January 2010. Financing was given by the German Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung (BMZ - German Federal Ministry for Economic cooperation) via GIZ by 80 % and the MPWT Albania by 20 % of the project costs (Gjinali et al. 2011). 56
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MASTER'S THESIS UIM/2011/7
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1 Problem Statement / Background At
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Bauhaus-University Weimar FACULTY O
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List of Abbreviations ADA ADF ALL A
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UNECE VF WB WFD WHO WRA WSP WSS WSS
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Table of content Preface...........
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5.3 Other constructed wetland plant
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1 Introduction 1.3 Milestones After
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