ABSTRACT
In this study, ultrasound disruption was employed to enhance the efficiency of microwave disintegration of dairy sludge. Results revealed that ultrasound specific energy input of 1,500 kJ/kg TS was found to be optimum with limited cell lysis at the end of the disruption phase. Biodegradability study suggested an enhancement in suspended solids reduction (16%) and biogas production (180 mL/gVS) in floc disrupted (deflocculated) samples when compared to sole microwave pretreatment (8.3% and 140 mL/gVS, respectively). Energy assessment to attain the 15% optimum solubilization revealed a positive net production of 26 kWh per kg sludge in deflocculated samples compared to 18 kWh in flocculated (sole microwave) samples. Thus, ultrasound disruption prior to microwave disintegration of dairy sludge was considered to be a feasible pretreatment technique.
Subject(s)
Biofuels , Sewage , Anaerobiosis , Flocculation , Methane , Microwaves , Waste Disposal, FluidABSTRACT
In the present work, the surface and filtration properties of TiO2 coated polyacrylonitrile ultrafiltration membranes were investigated. The membranes were coated using the physical deposition method. The appropriate TiO2 coverage proved to be 0.3 mg/cm2, which formed a hydrophilic cake layer on the membrane surface. The cleanability without chemicals and the retention of the coated membranes was compared to the neat membrane after model oily wastewater filtration. The cleaning sustained of rinsing with distilled water and ultraviolet (UV) irradiation of the fouled membranes. The coated membranes have better antifouling properties; higher flux values during oily water filtration and by the mentioned cleaning process a significantly better flux recovery can be achieved. The amount of the catalyst and the irradiation time are limiting factors to the effectiveness of the cleaning process. The UV irradiation increases the wettability of the fouled membrane surface by degrading the oil layer. The coating, the continuous use, and the cleaning process do not significantly affect the membrane retention expressed in chemical oxygen demand.
