MASTER'S THESIS - SuSanA

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5 Learning from already implemented CWs (in Albania and the Balkan region) Distribution of wastewater to horizontal filter occurred only in the first meters of the distribution pipe (but can be considered as sufficient for the plant in SOS children’s village as it is the second biological stage). The distribution pipe lay on the filter bed, but should normally be dug into the filter material. The water level in the shaft between horizontal filter and storage tank was below the effluent pipe what showed leakages in the shaft. During re-construction, the shaft between the horizontal filter and the effluent storage tank was equipped with a new effluent pipe deeper in the tank that had a knee fitting and a connected pipe for determining water level by turning it around. Because the walls had holes the water never reached the planned level in the shaft and therefore also not in the horizontal filter. The soil behind the liner of the HF bed was slipped down because the scarp was constructed too steep (normally it should be ≤ 1:1). 5.2.6 Review of reconstruction in 2011 One year after his first visit and recommendations for reconstruction, Jens Nowak visited the plant again in November 2011. His observations at the constructed wetland plant concerning the functionality were overall positive and most problems that were observed in 2010 had been corrected in the meantime. But still, some problems were existent. The findings of Jens Nowak are recorded in the document “Success of Reconstruction of Constructed Wetland SOS children’s village Tirana – 14.11 and 16.11.2011” (Nowak 2011,c) and will be shortly presented in this section. The sludge removal takes place twice a week, therefore no problems with clogging occurred after reconstruction. Sludge level in the Imhoff tank and the third chamber is measured with electronic device four times a year. As there is no sludge in the pumping chamber any longer, it shows that pre-treatment is working very well now. Due to the better settling of the sludge, valves for wastewater discharge on the two vertical filter beds can be closed completely and no clogging of the vertical filter beds occurs any longer. Reed plants on the vertical filter beds grow very well and there is no need to remove them. Some trees are growing in vertical filter bed Ia which have to be removed as soon as possible. The aquatic plantation on the horizontal filter bed is not growing very well and a leakage is visible at the influent area. The leakage should be closed and the water level increased until the plants are growing better. The pipe in the effluent shaft of the horizontal filter is too short and must be made longer to determine the water level (by rotating it). The effluent shaft seems to have leakages because the water level is below the effluent pipe what means that water is not leaving through the pipe as foreseen. It seems like the liner at the horizontal filter bed was cut off to remove some of the soil behind and is not replaced. Therefore, soil will be washed into the filter bed during rain and it is recommended to repair it. Some rainwater interceptions are still missing above the sludge filter bed and the horizontal filter bed to prevent rainwater running down the hill into the filter beds. Covers of manholes and shafts are still the same concrete ones, too heavy for one person to move them and already destroyed at some corners. Therefore, manholes are (partly) opened on purpose what can bring mosquito plagues. Lids should be replaced, e.g. by lids out of plastic, metal or wood. Same problems were mentioned by Martina Winker after her visit in October 2011. Mosquitoes occurred due to open water on the filter beds and in the collection tank and caused problems for the children. According to the SOS children'S village technician, the children get regularly ill because of mosquito bites (this information was given by the SOS children’s village technician to Martina Winker). Ianother option to improve the CW plant at the village is to use the treated wastewater for irrigation as it was originally planned. The sludge drying bed is working very well, a secondary filter layer of sludge can be observed. During the site visit in November 2011, Jens Nowak stated that one of the vertical filter beds was 63
5 Learning from already implemented CWs (in Albania and the Balkan region) clogged in 2010 but is now working very well again. It seems that it could recover without any problems when it was not in use for the time of reconstruction. 5.2.7 Effluent control and results of sampling The “Water quality control report, June – December 2011” of Zamira Rada and Enkelejda Gjinali (Gjinali and Rada 2011) is still under preparation. First results are given in the report for the period from June until December 2011. Samples were taken on a regular basis every month, starting in June 2011. According to (Gjinali and Rada 2011), the several sampling points are: 1) Influent (S1) 2) Imhoff tank, in (S2) 3) Imhoff tank, out (S2) 4) VF, in (both VF, so in total two samples) (S3 and S4) 5) VF, out (both VF, so in total two samples) (S3 and S4) 6) HF, in (S5) 7) HF, out (S5) 8) Storage tank, in The sampling point numbers are not as precise as it would be necessary. The influent must be the same as “Imhoff tank, in” and not an own sampling. Sampling point numbers of the filter beds are as well not precise, as the same numbers are used for influent and effluent. But the report gives only one value per sampling point. Therefor it can only be assumend that the value is the one of the effluent of the filter beds. According to (Gjinali and Rada 2011), the monthly tests show that the plant is working well and reaches the treatment requirement for TSS, COD and BOD 5 given by Albanian and EU law. Further tests have been done by Jens Nowak. Samples were taken in November 2011 from the effluent of the the pre-treatment, the vertical and the horizontal filter beds and tested in a German laboratory in December 2011. The results were very satisfying and show again that plant is working very well at the end of 2011. Results of the sampling are given in Table 5.5 (p. 64). Table 5.5: Sampling results November 2011 (Nowak 2011,c) Effluent pretreatment Effluent vertical filters Effluent horizontal filter Point pH COD [mg/l] N total [mg/l] NH 4 -N [mg/l] NO 3 -N [mg/l] NO 2 -N [mg/l] S2 6.8 254 49.1 39.3 - - 5.2 S3, S4 7.1 < 15 41.9 1.76 36.9 0.33 3.5 S5 7.4 < 15 29.7 0.66 28.3 0.042 3.4 P total [mg/l] 64
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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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Figure 5.15: Design of small size C
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1 Introduction 1.3 Milestones After
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2 Methodology • Edvin Pacara from
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2 Methodology interview as the auth
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3 Background information Albania 3.
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APPENDIX C - Site visits 4.3 Result
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MASTER'S THESIS - SuSanA

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