Effect of alum treatment and Ph adjustment on turbidity and levels of seleccted ions in grey water from Githurai, Kenya
Skudi, Joseph Bwire
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Increase in population results to an increase in the volume of grey water generated, thus decreasing the availability of fresh water. In Kenya and developing countries acute water shortages are extremely experienced consequently resulting to water rationing and increase in water prices by water vendors. Therefore treatment of the grey water generated, for reuse in toilet flushing and laundry work could reduce fresh water demands. This study therefore proposed to determine the effect of alum treatment and pH adjustment in lowering turbidity and the levels of ions contaminants such that treated grey water could be reused for laundry and toilet flushing. The study was conducted in Githurai, peri urban settlement of Nairobi, densely populated and associated with unsafe disposal of grey water on to the ground. The inorganic contaminants of grey water occurs mainly in form of cations of lead, mercury, calcium, magnesium, manganese, ferrous and anions of nitrates, sulphates, chlorides, phosphates and fluorides. Therefore the levels of inorganic cations. were determined in the raw greywater and after treatment with alum and pH adjusted. It was found out that, turbidity in raw grey water was above the prescribed limits for potable water by Kenya Bureau of Standard (KEBS). Cations of Fe in all types of grey water were found to be above O.3mg/L, Mn were found to be slightly above OAmg/L in bathroom and laundry, Ca and Mg were found to be above 60mg/L, Pb was found to be lower than O.Olmg/L in almost all types of grey water and Hg ions were found to be lower than O.Olmg/L in almost all types of grey water. Upon filtration and pH adjustment in the range of 6.5 to 8.5 units, turbidity and levels of ions were within the prescribed limits by KEBS. At these levels the water could be used for toilet flushing and laundry without staining clothes and toilet fixtures thus meeting the objectives for treating raw grey water. This implied fresh water used for flushing toilets and laundry could be spared for cooking and drinking and this could significantly lower fresh water demands. The results of this study could go a long way in achieving Millennium Development Goal and consequently Kenyan vision 2030 if the community is sensitized and policies put in place.