Challenges of wastewater treatment concerning high construction cost of the wastewater treatment plants and operation and maintenance, also the requirements of highly qualified operators, specially with the mechanical biological treatment systems, made investigation to suit simple systems of low costs and easy operation and maintance of great importance. Slow sand and rough filtration were effective systems when applied in water treatment, due to these filters being easy to construct and operate , with their high filtrate
quality[1,2].
Investigation herein was conducted to study the ability of both the rough and slow sand filters to secondarily treat the sullage wastewater, which primarily treated through interceptor tanks.
The rough filter used in this study mainly was 100 cm gravel of 6-8 mm size operated at filtration rates of 20 and 30 m.d-1. While the slow sand filter used was 60 cm sand of 0.2 mm effective size operated at rates of 4.5 and 8.0 m.d-1. Studies continued for two stages of four and two months for the first stage and second stage, respectively.
BOD5 removal of 35% and 61% was achieved through the rough filter and the slow sand filter, respectively. Also, removal of suspended solids was of 45% and 82% through the rough filter and slow sand filter, respectively. Runs of the rough filter usually extended between 38 and 17 days, while that of the slow sand filter was between 12 - 6 days, according to the filtration rates.