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.

Filtering cylindrical–conical hydrocyclone

Hydrocyclones have versatile applications in various industrial processes.They functionn on the principle of centrifugal separation to remove a dispersed phase(particles or drops)from a continuous phase(fluid).In unconventional filtering hydrocyclones,the separation efficiency and energy costs have been improved by combining filtration with centrifugal separation.This work investigated experimentally the effect of incorporating a cylinder and a porous cone in a conventional hydrocyclone.It also evaluated the effects of the main geometric dimensions of the separator on the hydrocyclone performance.A differential-evolution algorithm was applied to optimize the hydrocyclone performance,which was represented as the maximum total efficiency and minimum Euler number.The experimental results validated the optimization results and showed that hydrocyclones with optimized geometries exhibited higher total efficiencies(89.59%)and lower Euler numbers(582)than hydrocyclones with other experimental configurations.