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International Conference on

Recent Trends in Environmental Sustainability

ESCON22/ETERM/03
Effect of mixing conditions and floc characteristics on filtration efficiency in drinking
water treatment system

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Affifa Aqdas , Hira Amjad , Imran Hashmi
1 Institute of Environmental Sciences and Engineering (IESE), School of Civil and
Environmental Engineering (SCEE), National University of Sciences and Technology
(NUST), H-12, Islamabad, Pakistan
Correspondence: hamjad@iese.nust.edu.pk

Abstract
Humic substances are major part of NOM (Natural Organic Matter) contamination in surface
water. Many advance technologies are available for removing humic acid from drinking water,
but they are costly and posing severe environmental effects. Conventional water treatment
process includes coagulation-flocculation using alum as chemical coagulant due to its cost
effectiveness and easy availability. To enhance efficiency of coagulation-flocculation for
humic acid removal, it is necessary to study flocs properties in detail. This research article is
highlighting the connection between different mixing conditions of flocculation and floc
properties i.e., floc size and fractal dimensions (Df). It is very crucial to study floc sizes and
their Df in detail go achieve the settling of them in less time. Floc size and Df are studied on
three different mixing conditions i.e., 25 rpm, 30 rpm and 35 rpm. Maximum floc size was
achieved at 35 rpm that is 415.7µm at 20 minutes and maximum Df was achieved at 35 rpm
that is 2.53 Df at 18.5 minutes. This study can help in minimizing membrane flux towards the
membrane surface for filtration and eventually reducing its fouling and frequent replacement.
Hence, ultimately beneficial for improving water quality in treatment plants that plays a main
role in achieving SDG 6 ‘clean water and sanitation’ target 6.1 ‘safe and affordable drinking
water for all’.

Keywords: Coagulation – flocculation; Drinking water; Floc Size; Fractal dimensions; Humic
acid

Department of Environmental Sciences, COMSATS University Islamabad, Vehari Campus

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