TURBIDITY REMOVAL EFFICIENCY OF ANTHRACITE

Abstract

In the present dissertation work, a detailed analytical study of anthracite as filter media has been made, taking into account different parameters, viz media size, depth, rate etc. For this, a filter performance index, known as filter coefficient IA I, suggested by Iwasaki, is chosen which is a measure of the efficiency of a filter. the higher value of !I indicates higher turbidity removal. The variation of A, therefore, with respect to time, media size and depth, rate of filtration and alum dose has been studied in order to observe the behaviour of anthracite as filter media. It is observed that,1/4 increases for a few hours and then decreases gradually. Also,,\ is higher for finer size media, lower for higher depths an higher rates. Apart fromAonother performance index termed as filter performance factor is calculated. A filter with higher value of filter per-formance factor is superior in working to filters with lesser values. In addition, a comparative study has also been done between the performance of anthracite and sand as filter media under identical conditions on the basis of above two performance indices. It is observed that anthracite and sand behave alike but the values of and filter performance factor are higher for anthracite, indicating that anthracite media is better in turbi-dity removal than sand. Also in case of anthracite, head loss is lesser and filter run is more. Apart fromt;;sfsize not above 1.3 mm and depth about 15 cm are suitable for anthracite layer.