Wastewater renovation using constructed soil filter (CSF): A novel approach

Constructed soil filter (CSF) also known as Soil Biotechnology (SBT) is a process for water renovation which makes use of formulated media with culture of soil macro- and microorganisms. CSF combines sedimentation, infiltration and biodegradation processes to remove oxidizable organics and inorganics of wastewater in a single facility. Operating experience shows hydraulic loading in the range of 0.05-0.25 m3/m2 h and organic loading up to 200-680 g/m2 d. The results show increase in dissolved oxygen levels, COD removal (from 352 mg/l to 20 mg/l); BOD removal (from 211 mg/l to 7.0 mg/l); suspended solids removal (from 293 mg/l to 16 mg/l); turbidity reduction (from 145 NTU to 5.3 NTU); iron (from 5 mg/l to 0.3 mg/l); arsenic (from 500 μg/l to 10 μg/l); total coliform and fecal coliform removal (from 145 × 105 to 55 CFU/100 mL and 150 × 108 to 110 CFU/100 mL respectively), with desired pathogen levels as per WHO standards, i.e. ≤103 CFU/100 mL. CSF reveals advantages such as low HRT (0.5-2.0 h), low energy requirement (0.04 kW h/m3), no pre-treatment, high dissolved oxygen levels in the effluent, no biosludge production, no mechanical aeration and no odor, fish compatible water quality and evergreen ambience.