Abstract—The high rate activated sludge stage of the multiple-stage sludge treatment plant is characterized by high efficiencies of treatment, cost, and size, compared to conventional activated sludge treatment plants. A pilot plant with an industrial discharge flow of 135L/h was designed according to the highly loaded activated sludge stage (A-stage). The plant simulated the biological and chemical treatment of sludge by adding alum to the aeration tank in dosages of 100, 150, 200 and 250 mg/L. The results clearly indicate that the highly-loaded activated sludge, the A-stage of the absorption/bio-oxidation system, has a high efficiency for the elimination of organic and inorganic matters. Without adding aluminum salt, the chemical oxygen demand, the total phosphate and the total nitrate were approximately 52.43%, 47.82%, and 40.09% respectively. The chemical-biological process with a dosage of 200mg/L alum resulted in 76.07% reduced chemical oxygen demand and improved efficiency of phosphate and nitrate removal to 73.5% and 66.98% respectively compared with the biological process in the A-stage. Index Terms—Alum, COD, industrial wastewater, nitrate, phosphate. I. INTRODUCTION Industrial activities represent an important pollutant source contributing to a significant increase in ion concentrations and contaminating bodies of water, especially considering that such ions can be disseminated through the food chain [1]. In 1910, researchers began investigations on the treatment of wastewater simply by aeration. In Manchester, similar experiments were conducted, but after a certain aeration period they stopped aeration, let the flocs settle, decanted the supernatant, and added more wastewater, repeating this cycle several times. After the buildup of a certain amount of biomass, they obtained a fully nitrified effluent at an aeration period of 6 hours. They called the settled sludge "activated sludge" [2]. Activated sludge is obtained through a biological process used to remove organics from wastewater like the trickling filter. Activated sludge processes are used to grow a biomass of aerobic organisms that will breakdown the waste and convert it into more bugs. This is accomplished in large Manuscript received February 12, 2014; revised April 30, 2014. Mamdouh Y. Saleh, Medhat H. Elzahar, and Mohamed Z. Elshikhipy are with the Civil Engineering Department, Faculty of Engineering, Port Said University, 42523 Port Said, Egypt (e-mail: mamsaleh29@yahoo.com, melzahar@yahoo.com, eng-moh-zak@hotmail.com). Gaber El Enany is with the Physical Chemistry, Physical and Mathematical Engineering Department, Faculty of Engineering, Port Said University, 42523 Port Said, Egypt (e-mail: gaber71@hotmail.com). aerated tanks, called aeration basins, instead of the trickling filter's fixed media. Activated sludge processes return settled sludge to the aeration basins in order to maintain the right amount of bugs to handle the incoming "food". Activated sludge processes have higher removal efficiencies at 95-98% than trickling filters at 80-85% [3]. The conventional process of obtaining activated sludge consists of passing wastewater through an aeration tank, a secondary clarifier and a sludge recycling line. The flow model is plug flow with cellular recycle. Both influent sewage and recycled sludge enter the tank at the head end and are aerated for a period of 6 hours. The conventional sludge load (F/M) ranges from approximately 0.2 to 0.4kgBOD 5 / kgMLSS/day [4]. In Germany, researchers developed the first two-stage activated sludge plant, or AB system, which consists of a series of two independent activated sludge plants. The first stage is characterized by a high sludge loading rate (F/M), while the second stage has a rather low F/M. The excess sludge of the second stage is usually transferred to the first stage [2]. The absorption/bio-oxidation technique (AB-system) was invented and patented as a two-stage activated sludge plant without primary sedimentation. In this process the excess sludge of the second stage is not transferred to the first stage [2]. The sludge load (F/M) in the high-load stage (A-stage) approximately ranges from 0.6 to 1.5kg BOD 5 / kgMLSS/day, and for the low-load stage (B-stage) F/M ranges from 0.1 to 0.2 kg BOD 5 / kg MLSS/day [4]. The COD elimination efficiency in the A-stage is variable and easy to control. The degree of efficiency obtained can vary between 42-50% depending on the sludge load and the method of operation [4]. In the activated sludge process, a bacterial biomass suspension (the activated sludge) is responsible for the removal of pollutants. Depending on the design and the specific application, an activated sludge wastewater treatment plant (WWTP) can achieve biological nitrogen (N) removal and biological phosphorus (P) removal, besides removal of organic carbon substances [5]. Nitrogen is present in several forms, for example as ammonia (NH 3 ), ammonium (NH 4 + ), nitrate (NO - 3 ), nitrite (NO - 2 ) and as organic compounds. In untreated wastewater, nitrogen is mostly present in the form of NH 4 + and organic nitrogen. Nitrogen is an essential nutrient for biological growth. It is one of the main components in all living organisms. However, when nitrogen is present in influent wastewater, problems may arise [6]-[8]. Ammonia is toxic to aquatic organisms, especially for higher life forms such as fishes. When ammonium is oxidized to nitrate, a significant oxygen demand in the receiving water may give rise to a severe depletion of the dissolved oxygen concentration. Industrial Wastewater Treatment Using High Rate Activated Sludge and Alum Additive Mamdouh Y. Saleh, Gaber El Enany, Medhat H. Elzahar, and Mohamed Z. Elshikhipy International Journal of Environmental Science and Development, Vol. 5, No. 6, December 2014 551 DOI: 10.7763/IJESD.2014.V5.544