MASTER'S THESIS - SuSanA
MASTER'S THESIS - SuSanA
MASTER'S THESIS - SuSanA
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4 Presentation of technologies for rural areas<br />
4.3.2.3 Imhoff tank<br />
The Imhoff tank is an improvement of the septic tank, that allows sedimentation and sludge stabilisation.<br />
The tank has two compartments, that are flown through horizontally. The upper compartment serves for<br />
the settling of solids, in the lower compartment the anaerobical stabilisation of the settled solids takes<br />
place. The process produces low amounts of biogas, that leave the reactor through vent channels in order<br />
not to disturb the settling process (Stauffer 2012). Funnel-shaped walls help to collect settled solids at the<br />
bottom. Desludging of the Imhoff tank is possible through water pressure by using a desludging pipe with<br />
an outlet below the water level of the tank.<br />
Figure 4.8: Imhoff tank<br />
(Stauffer 2012)<br />
Figure 4.9: Imhoff tank (Nowak 2010,a)<br />
The effluent from the Imhoff tank requires secondary treatment. Imhoff tanks are used preferably when<br />
further treatment takes place near residential houses, in open ponds or vertical flow constructed wetlands<br />
(Sasse 1998). Imhoff tanks need regular sludge removal to keep effluent quality high. Sludge needs further<br />
treatment and disposal.<br />
Imhoff tanks are a low-cost option suitable for small communities or house clusters. As they can be installed<br />
underground, they do not require much land. To avoid groundworks, the Imhoff tank can be installed on the<br />
ground, but needs to be insulated in colder climates. O&M is simple costs therefore low (Spuhler 2012).<br />
4.3.3 Transport<br />
Transport of wastewater can be realised by sewer system or sucking and transport vehicle and is presented<br />
briefly in sub-chapter 4.1.1 Components of a sanitation system (p.25). Vacuum systems are excluded from<br />
that work as this technology is too sophisticated for the Albanian context.<br />
4.3.4 (Pre-) Treatment<br />
Treatment of wastewater can be distinguished into pre-treatment, primary, secondary and tertiary<br />
treatment. Pre-treatment and primary treatment refer to physical treatment processes while secondary<br />
treatment refers to biological treatment processes, where degradable biological matter is used by<br />
microorganisms. Pre-treatment can be combined with the primary and secondary treatment in one plant,<br />
but most technologies need a separated pre-tretment primary treatment facility where solids can settle<br />
down. Tertiary treatment is a final treatment step to improve the effluent quality if necessary.<br />
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