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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.