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Tertiary treatment of sewage
effluent via pilot scale slow sand filtration
Farooq,
S.
,
Al-Yousef, A.K.,
Al-Layla, R.I.,
Ishaq, A.M.
Department of Civil Engineering,
King Fahd Univ of Petroleum Minerals,
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Abstract
In view
of limited information available about the performance of actual size slow sand
filtration as a tertiary process in sewage treatment a pilot scale study was
conducted over a period of one year using the secondary treated effluent from
North Aramco Wastewater Treatment Plant, Dhahran, at a flow rate of 0.16 m hr-1
(2L min-1) to determine the process efficiency. Two sizes of local
sand, i.e., effective size (ES) = 0.31, uniformity coefficient (UC) = 2.00; and
ES = 0.56, UC = 1.64, were evaluated in terms of removal of major pollution
parameters such as organic matter, micro-organisms and nutrients. Effective
range of the filter depth was also investigated by conducting the experiments
at three different depths of the sand bed, i.e., 135, 105, and 55 cm for each
size of the sand. It was found that removals of BOD, COD, standard plate
counts, nitrate, phosphate and sulphate vary from 79-92%, 40-60%, 88-93%,
17-30%, 8.3-84%, and 5-10%, respectively, at various sand depths for two
different sizes of the sand.