PHYTOREMEDIATION OF KIPEVU WASTE WATER USING VETIVER GRASS (Chrysopogon Zizanioides)
Abstract
Treatment of wastewater worldwide has mainly been done using physical, chemical and
biological wastewater treatment systems such as activated sludge and biological nutrient
removal technologies (Bedewi, 2010).Mombasa City produces large amounts of effluent
water that is collected and primarily treated and discharged to the Indian Ocean. Too
many pollutants in water bodies pose threat to the aquatic species. The main aim of the
study is to come up with an economically and environmentally friendly technology that
will enhance the treatment of Kipevu waste water treatment plant. Field experiments
were conducted in plastic containers of five litres which were set-up simultaneously
with planted vetiver hydroponically and with no vetiver as a control, which was
replicated thrice in four containers. Wastewater was characterized for physicochemical
parameters before and after treatment with vetiver grass. The parameters studied were;
effects of vetiver on reduction of pollutants with time, effect of biomass (number of
Vetiver plants) on treatment efficiency. Wastewater had high levels of Chemical
Oxygen Demand (1440mg/L), Biological Oxygen Demand (75 mg/L) nitrates (775
mg/L), phosphates (25mg/L) and TDS (1432mg/L) were beyond the Maximum
contaminable levels. There was a drastic increase in the pollutants uptake with time.
The levels of nitrates, phosphates, chemical oxygen demand, biological oxygen demand
and total dissolved oxygen reduced by 89.76%, 85.6%, 84.51%, 69.33% and 16.76%
respectively in 28 days. In 28 days, chemical oxygen demand reduced by 91.08%, 92.17
% and 94.92% while nitrates decreased by 85.59%, 87.5% and 92.35% % for 4 plants, 8
plants and 12 plants per 5 litres of wastewater respectively. The potential of vetiver
grass after four weeks hydroponic treatment was found to be efficient in the reduction
of pH, nitrates, phosphates, total nitrogen, total phosphorous, total dissolved solids,
chemical oxygen demand and biological oxygen demand.