Investigating the use of dual-stage filtration system for E. coli removal in wastewater

Escherichia coli removal from wastewater used by vegetable farmers for irrigation in developing countries like Ghana is necessary to minimise public health concerns. The ability and efficiency of a two-stage filtration system, which combines coconut biochar and activated carbon, to remove E. coli and total coliforms was investigated. Laboratory and field experiments were conducted under varying hydraulic retention times to assess the system's performance. Using Atomic Absorption Spectrophotometer (ASS) to analyse Cu and Pb and incubation method for total coliform and E. Coli, the results revealed that in the first treatment stage, Pb and Cu removal were 18% and 22%, respectively, improving significantly in the second stage to 92% for Pb and 89% for Cu. For biological contaminants, in the first treatment stage, total coliforms were reduced by 87% and E. coli by 93% while the second stage, saw 99% removal of total coliforms with a comparatively lower removal efficiency (55%) of E. coli after 48 h. These findings highlight the potential scalability of this sustainable, cost-effective filtration system, which uses locally available materials, to improve wastewater quality and promote safer irrigation practices in water-scarce regions.