Abstract:
Water scarcity in developing countries has forced farmers to use sewage as an
alternative source of irrigation water. However, the usage of sewage for vegetable
production has been known to cause excessive and often-unbalanced
addition of nutrients hence posing a threat to food safety. The objective of this
study was to determine the efficacy of slow sand filter and wetland plant in
domestic wastewater treatment. To achieve this objective, samples were collected
from the domestic wastewater collection pond within Jomo Kenyatta
University of Agriculture and Technology (JKUAT). Laboratory tests were
conducted on the collected samples and they revealed the presence of BOD,
DO, pH, TDS, Sulfates, Chloride, Turbidity, Salinity, Conductivity, Alkalinity
and Coliform; whose values varied when compared with that of the parameters
for standard irrigation water. This gave insight to the kind of treatments and filtration
medium that were required to transform domestic wastewater into water
fit for irrigation. A slow sand filter bed was designed and constructed using precisely
six samples materials; sand, sand and wetland plants, gravel, gravel and
wetland plants, mixture of gravel and sand, mixture of gravel and sand with
wetland plants. These materials were used to identify the chemical and biological
changes in domestic wastewater within a seven-day period. The water collected
from the slow sand filter was tested, results showed that, of all six samples,
slow sand filter using the mixture of gravel, sand with wetland plants had
an average percentage efficient of 90% in removing all impurities from domestic
wastewater thereby turning it into water suitable for irrigation. It is hoped that
this study will provide a safe, easy, eco-friendly and cheap method of wastewater
treatment while ensuring the sustainability of wastewater for irrigation and the
expansion of green spaces in urban and peri-urban areas.