Biosand Filtration as A Green Approach to Septic Tank Effluent Management in Accra Technical University
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Date
2017-07
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University of Ghana
Abstract
Introduction: Sewage and household effluents at Accra Technical University (ATU), Ghana
have been discharged into the ocean for years. This degrades environmental media and is
detrimental to ecological systems. The institution also lacks adequate water for non-edible
purposes. The Biosand Filter (BSF) is an innovation on the slow sand filter which has found
use in preventing the discharge of raw sewage into the environment. The study aimed to test
the performance of a BSF on sewage tank effluent and assess the suitability of the filtrate for
non-drinking purposes.
Method: Three modified interconnected BSF were constructed on-site, with last filter
connected to a storage tank. The modification was the provision of an additional media
(charcoal) in the second barrel. Samples were collected of raw STE (pre-filtrate) and after
passing through the BSF (post-filtrate). Samples were analysed for physical and
microbiological parameters at designated laboratories. Measured values of the parameters in
pre- and post-filtration samples were compared with EPA (Ghana) reference values. The
removal efficiency was determined as the difference between pre- and post-filtrate parameters
and expressed as a percentage of the pre-filtrate.
Results: Most of the effluent parameters from the PBSF were within the EPA standards, while
others were unacceptable. However, the ability of the BSF to effectively improve effluent
quality was demonstrated by removing excess quantity of nutrients and coliforrns varied
significantly (P<O.05). Nitrogen (83.3%), Phosphorus (89.5%), TSS (71.3%), TDS (66.2%),
Total coliform (99.9%), Faecal coliform (99.7%) and E. coli (97.6%).
Conclusion: BSF is effective for upgrading physical and microbial quality of sewage at
household and institutional level, prior to discharge in the environment. It produced a filtrate
that meets EPA standards for irrigation of non-edible crops.
Keywords: wastewater, sewage, effluent, biosand filter, Ghana, liquid waste.
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Keywords
Biosand Filtration, Green Approach, Septic Tank Effluent Management, Accra Technical University, Ghana