Occurrence of aerobic denitrifying bacteria in integrated fixed film activated sludge system.

Denitrification can be enhanced in the Integrated Fixed Film Activated System (IFAS) system by integrating media into the anoxic or aerobic zone. The simultaneous nitrification and denitrification (SND) in the biofilm layers has been reported in the aerobic zone of the IFAS system. In this study, two IFAS systems with Bioweb® media installed in the anoxic or aerobic reactor were operated in parallel to evaluate both anoxic denitrification or aerobic SND in the biofilm layers enhanced by fixed film media at three different nitrite and nitrate recirculation (NR) ratios of 75%, 100%, and 125%.

Evaluation of reusing alum sludge for the coagulation of industrial wastewater containing mixed anionic surfactants.

A coagulation-flocculation process is typically employed to treat the industrial wastewater generated by the consumer products industry manufacturing detergents, soaps, and others. The expenditure of chemicals including coagulants and chemicals for pH adjustment is costly for treating this wastewater. The objective of this study was to evaluate the feasibility of reusing the aluminum sulfate (alum) sludge as a coagulant or as a coagulation aid so that the fresh alum dosage can be minimized or the removal efficiency can be enhanced.

Evaluation of waste activated sludge as a coagulant aid for the treatment of industrial wastewater containing mixed surfactants.

Wastewater generated by the industry manufacturing detergents and various kinds of consumer products normally contains very high contents of mixed surfactants, organic matters expressed as chemical oxygen demand (COD), and phosphates that must be treated prior to discharge to the aquatic environment. In this study, jar-test experiments were conducted to evaluate the waste activated sludge (WAS) as a coagulation aid in the coagulation-flocculation process with ferric chloride or aluminum sulfate as a coagulant for the treatment of wastewater collected from the aforementioned industry. The WAS was selected because of its adsorption capability of anionic surfactants and its availability from the wastage stream of biological wastewater treatment process.