MASTER'S THESIS - SuSanA

More documents

Recommendations

Info

4 Presentation of technologies for rural areas 4.3.5.2 Unplanted drying bed An unplanted drying bed (see Figure 4.19) is a man-made drying bed with drainage layer and drainage pipe at the bottom, that collects liquids through the drainage system. The purpose is the dewatering of the sludge. The process reduces the sludge volume by 50 to 80 %. The sludge is not stabilised and needs further treatment (as well as the drained water). For desinfection, co-composting is possible (Tilley et al. 2008). Figure 4.19: Unplanted sludge drying bed (Tilley et al. 2008) Unplanted sludge drying beds are appropriate for small to medium size communes. Large space is required far away from the houses as odours and flies will occur. Advantages are that it is a low-cost treatment with moderate construction cost and no electricity requirements (Tilley et al. 2008). 4.3.5.3 Planted drying bed Planted drying beds are similar to unplanted drying beds, but they are constructed with plants and ventilation pipes (see Figure 4.20). The appearance is therefore similar to vertical flow Cws. Roots facilitate the water to get out of the sludge as roots are growing through the sludge. Sludge is applied into a screening chamber, that is installed next to the drying bed. Purpose is the dewatering and stabilisation of the sludge, but no desinfection. Therefore, planted drying beds should be combined with co-composting. Sludge application can take place every three to seven days, sludge removal is necessary after two to three years (Tilley et al. 2008). Figure 4.20: Planted sludge drying bed (Tilley et al. 2008) 41
4 Presentation of technologies for rural areas Planted sludge drying beds are suitable for small to medium size communities. They are a low-cost solution without electricity requirement, but the accessibility by vehicle has to be given. Disadvantage is that the sludge removal has to be done manually and is work intensive. Odours and flies can appear, effluent needs secondary treatment (Tilley et al. 2008). 4.3.6 Discharge Treated wastewater can be discharged into open water bodies (little rivers or streams, lakes, etc.) or infiltrated into the ground. Infiltration is possible by soak pits or drainage systems. Infiltration uses apsorbtion capacity of the soil and can enrich groundwater sources. The discharge of untreated wastewater bears the risk of pollution of groundwater and surface water bodies. 4.3.6.1 Soak pit A soak pit, also called soakaway pit or leach pit, is a “covered, porous-walled chamber that allows water to slowly soak into the ground” (Tilley et al. 2008) and is used for the discharge of pre-treated wastewater. The pit is lined with porous material to prevent soil collapsing if it is constructed as an empty pit. Unlined pits are filled with rocks and gravel (see Figure 4.21). The bottom should always be lined with sand and fine gravel. The pit should be between 1.5 m and 4 m deep, and located at least 1.5 m above ground water table, far away from the next drinking water source. The cover slab has to be removable for access to maintain the pit. Figure 4.21: Soak pit (Tilley et al. 2008) Discharged wastewater has to be pre-treated, raw wastewater can cause clogging very easily. The appropriateness of the solution for wastewater discharge depends on the characteristics of the soil that should have sufficient absorptive capacity. Soak pits are not appropriate in areas with flooding and/or high ground water table. Advantages are the simple construction and the possibility to use locally available materials. As the pit is implemented underground, it is not visible and no odours occur. Therefore, the acceptance is normally very high. It is possible to use such a soak pit between three to five years without maintenance. Soak pits can be used for discharge of wastewater from single households or neighbourhoods. Disadvantage is the possible pollution of the ground and the groundwater (Tilley et al. 2008). 4.3.6.2 Drainage Different kinds of drainage systems for wastewater discharge to the ground are existing. Wafler already presented the leach field and the forest irrigation (see chapter 4.2, p. 28). 42
Page 1 and 2:
MASTER'S THESIS UIM/2011/7
Page 3 and 4:
1 Problem Statement / Background At
Page 5 and 6: Bauhaus-University Weimar FACULTY O
Page 7 and 8: List of Abbreviations ADA ADF ALL A
Page 9 and 10: UNECE VF WB WFD WHO WRA WSP WSS WSS
Page 11 and 12: Table of content Preface...........
Page 13 and 14: 5.3 Other constructed wetland plant
Page 15 and 16: Figure 5.15: Design of small size C
Page 17 and 18: 1 Introduction 1.3 Milestones After
Page 19 and 20: 2 Methodology • Edvin Pacara from
Page 21 and 22: 2 Methodology interview as the auth
Page 23 and 24: 3 Background information Albania 3.
Page 25 and 26: 3 Background information Albania Th
Page 29 and 30: 3 Background information Albania op
Page 33 and 34: 3 Background information Albania se
Page 35 and 36: 3 Background information Albania Ta
Page 37 and 38: 3 Background information Albania 20
Page 39 and 40: 4 Presentation of technologies for
Page 55: 4 Presentation of technologies for
Page 67 and 68: 5 Learning from already implemented
Page 89 and 90: 6 Site visits and interviews with l
Page 99 and 100: 7 Presentation of the institutional
Page 107 and 108:
7 Presentation of the institutional
Page 109 and 110:
7 Presentation of the institutional
Page 111 and 112:
8 Development of a guideline for th
Page 113 and 114:
9 Conclusion 9 Conclusion At the pr
Page 115 and 116:
List of sources (EG 1991): (Engelma
Page 117 and 118:
List of sources (Nowak 2010,a): (No
Page 119 and 120:
List of sources (WRA 1996): (WRA 20
Page 121 and 122:
Selbständigkeitserklärung Hiermit
Page 123 and 124:
APPENDIX A - Bill of quantities for
Page 125 and 126:
3.1.4 Dam partly surrounding the fi
Page 127 and 128:
4.3.6 4.3.7 4.3.8 PE-pressure pipe
Page 129 and 130:
APPENDIX B - Interview guidelines a
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
APPENDIX C - Site visits 1 Site vis
Page 139 and 140:
APPENDIX C - Site visits 1.3 Wastew
Page 141 and 142:
APPENDIX C - Site visits Only some
Page 143 and 144:
APPENDIX C - Site visits People are
Page 145 and 146:
Page 147 and 148:
APPENDIX C - Site visits persons an
Page 149 and 150:
APPENDIX C - Site visits Figure C.1
Page 151 and 152:
APPENDIX C - Site visits 3.2.2 Wast
Page 153 and 154:
APPENDIX C - Site visits and the wi
Page 155 and 156:
APPENDIX C - Site visits was not al
Page 157 and 158:
APPENDIX C - Site visits 4.3 Result
Page 159 and 160:
APPENDIX C - Site visits The villag
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
APPENDIX C - Site visits The villag
Page 167 and 168:
Page 169 and 170:
APPENDIX C - Site visits whole vill
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
APPENDIX C - Site visits 7.4 Conclu
Page 177 and 178:
APPENDIX C - Site visits speaking t
Page 179 and 180:
APPENDIX C - Site visits The drinki
Page 181 and 182:
APPENDIX C - Site visits If GIZ wil
show all

MASTER'S THESIS - SuSanA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?