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Potential of Adding Constructed Wetland/Fishpond to Waste Stabilization Ponds to Improve Helminths Removal in Morogoro Municipality, Tanzania
OUTWATER, AH; ZACHARIAH, A; NYOMORA, A; FRANCIS, F & KATIMA, JHY
Abstract
A study was conducted to establish the potential of constructed wetlands in Morogoro Urban District,
Tanzania, to remove helminths from wastewater. The standard wastewater treatment regime was failing to effect reliable
removal of helminth eggs and larvae from six wastewater stabilization ponds. An alternative wastewater treatment regime
for the ponds, coupled with a constructed wetland and a fishpond, was devised. Water, soil, and vegetable samples were
tested for the presence of helminth larvae and eggs in a time series design over one growing season. From March to August
2014, experimental plots of carrots and Swiss chard were irrigated with wastewater that had been treated by the alternative
wastewater treatment regime. It was found that the alternative wastewater treatment regime coupled with the constructed
wetland and fishpond appeared to remove helminths completely. No helminths were found in the wastewater after it passed
through the alternative system, and none were found in the market-ready carrots and chard. Numbers of helminth larvae
and eggs showed evidence of seasonality, which is potentially useful knowledge for farmers in order to avoid helminth
infection: almost all larvae were found at the end of the hot dry season. Monsoon rains followed and washed the helminth
larvae and eggs away and none were found at the end of the season.
Keywords
wastewater stabilization ponds; constructed wetlands; helminth removal; hookworm; sewage treatment
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