Impurities and colloidal substances are two of many fouling conditions that reduce the membrane filtration performance used in wastewater treatment. This study investigates the potential of fluidic-oscillation-generated microbubbles (MBs) to defoul the filtration membrane. Cartridge filters for microfiltration (MF) of 1 μm pore size were fouled using surface seawater collected from the Hull coastal area. The seawater was circulated at 5.8 L/min to actuate colloidal substance deposition on the membrane surface. The recorded feed channel pressure drop (ΔP) across the membrane filters showed rapid fouling occurred in the first 8 hrs of the circulation. Fluctuations of ΔP during the next 8 hrs were observed showing the colloids filling the pores of the membrane, and remaining steady for 2 hrs showing the membrane was completely fouled. The filtration membrane was cleaned and defouled using fluidic-oscillator-generated MBs. The fouled membranes were sparged with 1 L/min of air scouring for ∼1 to ∼2 hrs to remove the deposited colloids and impurities on the surface of the membrane. The membrane, analysed by Scanning Electron Microscopy (SEM), UV254 and Electrical Conductivity (EC) meter, showed the extent of MBs-mediated removal of the deposited colloidal particle from the membrane surfaces. This study found that the highest defouling rate occurs with MBs generated by fluidic oscillator (closed vent), followed by MBs generated by fluidic oscillator (opened vent) and MBs generated without fluidic oscillator at 9.53, 6.22, and 3.41 mbar/min, respectively.

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Iron (Fe) and manganese (Mn) are two of many substances that are causing harm to human health and various environmental contamination. This study investigates the performance of rapid sand filter as an improvement to the existing commercial filter media. Rapid sand filters were tested using groundwater collected from Kg Budi Kelantan. Groundwater collected were tested using seven velocities ranging from 0.89 to 5.04 m/hr. The concentration of Mn, Fe and turbidity of the treated groundwater were compared. It is found that the highest Mn, Fe and turbidity removal were recorded by using velocity of 4.38 m/hr followed by 2.95 m/hr and 2.4 m/hr. These three velocities represent more than 95% removal of final treated groundwater, where final Fe, Mn and turbidity ranging from 0.06 mg/L to 0.09 mg/L, 0 to 0.4 mg/L and 0.9 to 3.0 NTU, respectively. A positive trend also recorded where the initial head loss of the sand filter is directly proportional to the flow velocity. This means the filter media was still under a clean condition and no accumulation of sediment deposit occurs. The significance of this study to treat groundwater by removing the iron and manganese especially in rural areas were achieved successfully.