| dc.description.abstract | Abstract: The prominent drinking water
treatment process practised to eliminate
turbidity from surface water, especially during
high turbidity occurrence in the surface water,
is coagulation, sedimentation and rapid sand
filtration for many years. However, the
possibility of turbidity removal using a slow
sand filter (SSF) was not extensively studied in
the case of high turbidity occurrence in the
surface water. This study aimed to evaluate the
performance of SSF in terms of turbidity
removal in surface water, when pre-adding
poly-aluminium chloride (PACl) as a coagulant
chemical along with the pre-treatment by
roughing filter. One per cent of PACl is prepared
and dosed at the rate of 20 mg/L with raw water
into the water intake chamber before it reaches
the SSF. The raw and treated water samples
were collected every six-hour intervals. The raw
water samples whose turbidity level more than
50 NTU were considered and analysed from 174
nos of trails. Turbidity level of raw water and
filtered water was observed in the range of 50-
313 NTU and 0.31-5.5 NTU respectively. The
turbidity of treated water by SSF was observed
to be well below the SLS 614;2013 acceptable
limit of 2 NTU in 98.8% of the treated samples.
It is observed the turbidity removal efficiency
increases when the raw water turbidity level
increases. The result shows turbidity of treated
water from SSF was complying with the
requirement in 98.5% of the trails, which enable
the proper function of treatment plant during
the high raw water turbidity by complying with
SLS 614-2013 when adopting this methodology | en_US |
