The Effect of Wastewater Cations on Activated Sludge Characteristics: Effects of Aluminum and Iron in Floc

• Published in: Water environment research Vol. 78; no. 1; pp. 31 - 40
• Main Authors: Park, Chul, Muller, Christopher D., Abu-Orf, Mohammad M., Novak, John T.
• Format: Journal Article
• Language: English
• Published: Alexandria, VA Water Environment Federation 01.01.2006; Blackwell Publishing Ltd
• Subjects: Activated sludge; Aluminum; Aluminum Compounds - metabolism; Applied sciences; biopolymer; Biopolymers; cations; Cations - metabolism; Chromatography, Ion Exchange; conditioning; Dewatering; Divalent cations; Effects; effluent; Effluents; Exact sciences and technology; floc; Flocculation; General purification processes; General treatment and storage processes; Industrial Waste; Ions; Iron; Iron Compounds - metabolism; Other industrial wastes. Sewage sludge; Pollution; Polysaccharides; protein; Research Papers; Sewerage works: sewers, sewage treatment plants, outfalls; Sludge; Sludge dewatering; Waste Disposal, Fluid - methods; Wastes; Wastewater; Wastewaters; Water treatment and pollution; Water treatment plants; Activated sludge; Ammonium; Waste treatment; Scavenging; Dehydration; Sewage sludge; Sewage treatment plant; Waste water; Biological purification; Offset; Chemical oxygen demand; Biopolymer; Water quality; Conditioning; Waste water purification
• ISSN: 1061-4303; 1554-7531
• DOI: 10.2175/106143005x84495

Wastewater samples collected from seven wastewater treatment plants (WWTPs) were characterized to assess the impacts of wastewater cations on the activated sludge process. The cations included in this study were sodium $({\rm Na}^{+})$ , potassium, ammonium, calcium, magnesium, aluminum (Al), and iron (Fe). Among the selected cations, Al and Fe were of most interest to this study because their role in bioflocculation has not been extensively studied and remains largely unknown. The data showed that WWTPs contained highly varying concentrations of ${\rm Na}^{+}$ , Al, and Fe in the wastewater and that these cations were responsible for differences between WWTPs as to sludge dewatering rates and effluent quality. In general, a high influent ${\rm Na}^{+}$ concentration caused poor sludge dewatering and effluent characteristics. However, when sufficient Al and Fe were present in floc, the deleterious effects of ${\rm Na}^{+}$ were offset. The data associated with Al further revealed that waste activated sludge with low Al contained high concentrations of soluble and colloidal biopolymer (protein + polysaccharide), resulting in a high effluent chemical oxygen demand, high conditioning chemical requirements, and poor sludge dewatering properties. These results suggest that Al will improve activated sludge effluent quality by scavenging organic compounds from solution and binding them to floc.