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International Journal of Environment and Sustainability, 2016, 5(1): 64-70 65
provide basically primary treatment of waste- water of two add-on treatment systems studied
water. Further, they are inefficient in the by KISR, namely, aerobic- and anaerobic-based
removal of solids and organics due to the add-on post-treatment systems. As shown in
fluctuations in wastewater flow rates and Figure 1, the aerobic-based system consists of
gasification that often lead to the resuspension an aerobic bioreactor, a clarifier, a saturated
of the settled solids. As they do not remove grass bed filter, and a chlorination unit. The
nutrients and pathogens, conventional septic anaerobic-based treatment system is presented
tanks are commonly considered the major in Figure 2. It consists of a sediment tank, a
sources of pathogens and nutrient pollutants in sand-gravel partially anaerobic bioreactor, a
the environment (Richard et al., 2016). saturated grass-bed filter, and a chlorination
Therefore, effluents of the conventional septic unit. These systems were designed in a way that
tanks are not safe for direct reuse (Beavers, oxidation of the organic matter will take place
2002). To utilize such effluents, e.g. for lawn in the (an)aerobic bioreactors, while the
irrigation, a comprehensive post-treatment is removal of the suspended solids will occur in
needed. the sedimentation tanks (clarifiers). The
saturated grass-bed filter unit added for the
Kuwait Institute for Scientific Research (KISR) removal of nutrients and some microorganisms
has studied a number of add-on systems that (Van Buuren et al., 1998). However, all the
can be used in the reclamation of effluents of remaining microorganisms are expected to be
conventional septic tank. This paper compares killed (disinfected) in a chlorination unit.
the irrigation qualities of the final product
Line 1 from Air
Storage tank 2 Clarifier
Chlorination
Saturated grass
filter
Recycle Aerobic Wasted sludge
bioreactor
To storage
Pumping inflow
Figure 1: The aerobic-based post-treatment system (Abusam et al., 2014)
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