The Potential of Subsurface Infiltration for the Treatment of Biofil Toilet Technology Effluent

Generally discharges from on-site sanitation （OSS） system could be a source of pollution to the environment if not well managed. This work illustrates the potential of subsurface infiltration to treat secondary effluent from a novel on-site vermi-biofiltration system called the Biofil Toilet Technology （BTT）. In practice, the BTT effluent is discharged via sub-surface infiltration. The focus of the research was to determine possible contaminant removal within the first 1.5 m depth of soil column. To achieve this objective, laboratory scale soil columns were designed and constructed for the treatment of secondary domestic wastewater from the BTT. Four different soil columns, each with 1.5 m depth of soil （sandy soil--SS, loamy soil--LS, clayey soil----CS, and red laterite soil--RLS） and fifth column with 0.45 m multi-layer sand filter were constructed and characterized. The columns were fed with the BTT effluent and sampled at ports spaced at 0.3 m, 0.8 m, and 1.5 m depths. Using the samples, parameters like COD, BODs, TSS, T-N, NO3-N, NO2-N, PO4-P, and pathogenic indicator microbes were monitored. RLS and SS columns efficiently removed COD, BODs, and TSS from the BTT effluent below the Ghana Environmental Protection Agency （GH EPA） guideline values. Up to 99% COD removal were observed in RLS column. A two to five log pathogen removal was recorded for the soil columns. The RLS and SS were found to have a high efficacy for contaminant removal with up to 80% of all contaminants being removed at a depth of 0.3 m along the soil columns. Thus the subsurface infiltration system can serve as a promising technology for the BTT effluent treatment. The study recommends the incorporation of infiltration systems to the BTT especially for areas with high water table or clayey soils.

Nutrient and Microbial Reduction Properties in Pervious Composites for Blackwater Treatment

The focus of this experiment was to compare the treatment performance of nutrient and microbial reduction in granite （GR）, shredded polyethylene terephthalate （SP） and palm kernel shell （PKS） composites after solid/liquid separation of blackwater. Laboratory tests were conducted on replicated specimens of the GR, SP, and PKS pervious composites and the mechanisms of microbial reductions and nutrient transformation in blackwater treatment investigated after filtration. Six cylindrical specimens measuring 1 l0 mm x 100 mm and made from the GR, SP, and PKS were used to determine the physical and hydrologic properties （density and permeability） of the specimens. Additional six pervious specimens measuring 0.3 m x 0.3 m ~ 0.05 mm were used for the solid/liquid separation of blackwater. Blackwater was first infiltrated through a layer of coir fibre and net lining and then run through each pervious composite specimen. Nutrient （ammonium, nitrate, nitrite, total nitrogen, and total phosphorus） and microbial （Escherichia coli and coliforms） analyses were conducted on the effluent from the specimens and compared. The GR, SP, and PKS particle sizes were seen to be uniformly graded and similar. The composite specimens did not have significant effects on the nutrient transformations and removal of organic matter but for total phosphorus. However, escherichia coli and other coliforms＇s growth were limited in the SP. Hydrophobic interactions between the SP composite and microbial cells of the microbes could have promoted attachment and limited their growth. It was observed that the mean pH in the effluent filtered through the composites was higher than in the influent partly due to the availability of calcium carbonate in the cement. The study suggests that the SP composite is a promising alternative to the GR composite for the reduction of microbial constituents in blackwater vis-a-vis its light-weight compared to the other pervious composites.