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Sludge Treatment. CE 326 Principles of Environmental Engineering Department of Civil, Construction and Environmental Engineering Iowa State University Prof. Tim Ellis Spring 2010. Announcements. Monday, April 26 th Course review Exam review Wednesday, April 28 th
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Sludge Treatment CE 326 Principles of Environmental Engineering Department of Civil, Construction and Environmental Engineering Iowa State University Prof. Tim Ellis Spring 2010
Announcements • Monday, April 26th • Course review • Exam review • Wednesday, April 28th • 3rd Exam during lab period (in lab classroom) • Friday, April 30th • No class • A.S. design lab due
History • Thomas Crapper • Myth or legend? The World War I doughboys passing through England brought together Crapper's name and the toilet. They saw the words T. Crapper-Chelsea printed on the tanks and coined the slang "crapper" meaning toilet (from : Plumbing and Mechanical, June 1993).
Sludge Processes • Thickening • Stabilization • Conditioning • Dewatering • Volume Reduction • Disposal
Thickening • c___________ sludge using gravity or f________ methods. Primary sludge can be thickened to a maximum of about 10% solids and secondary sludge to a maximum of about 6% solids. oncentrating lotation
Stabilization rganics • Converting the o_______ in the sludge to more stable (inert) forms so they can be handled more easily (more d____________, less potential for odors) and used as soil conditioners. • Typically stabilization involves anaerobic or aerobic digestion. • During digestion considerable v______ s_____ destruction occurs ewaterable olatile olids
Conditioning • Addition of c_________ to allow better separation of the water and the solids. Ferric c_______ and organic and inorganic p_______ are frequently used for sludge conditioning. oagulant hloride olymer
Dewatering • V________, pressure, or drying methods for removing w_____ from the solids. • Typically about 25 to 35% solids can be achieved. acuum ater
Volume Reduction • Drying and p__________ for sale as a fertilizer • C__________ • I___________ of sludge with ash residual for ultimate disposal. elletization omposting ncineration
Biosolids • Biosolids are t_______ s______; • there are two different classes: • Class A: no detectable levels of p___________ and meets m_____ regulations, requires controlled treatment process involving high pH, temperature, or both; no permit required for land application • Class B: have been t_______ but may contain some pathogens and metals, requires permit for land application • approximately __% of all biosolids are land applied reated ludge athogens etals reated 50
Processes for Class A • Processes for generating Class A biosolids: • sludge p___________ • T____________ treatment (55̊C for 24 h) • temperature p______ anaerobic digestion (55̊C digester followed by 35̊C digester) developed at ISU asturization hermophilic hased
Steps in Anaerobic Digestion Hydrolysis Acidogenesis Acetogenesis Methanogenesis
Filter Press http://www.metlabsolutions.com/Shriver%20Press%20-%20side.JPG
Characteristics • Blackish in color • 15% - 90% Solids • Mud-like to granular appearance • Mild to strong odor (musty or swamp like)
Wastewater Treatment in Developing Countries Community Biogas Plant in China