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 Wednesday, April 28th 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
Gravity thickener
Process flow with recycle:
Dissolved Air Flotation (DAF) Thickener
Dissolved Air Flotation (DAF) Thickener
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 rganics 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 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
Anaerobic Digestion
Steps in Anaerobic Digestion Hydrolysis Acidogenesis Acetogenesis Photo: Two 3,800m³ anaerobic digesters are used to treat the sludge. Gas collected from the process is used to fire the regenerative thermal oxidizers, as well as the digesters' own heating boilers. F. Wayne Hill Water. Resources Center, Gwinnett County, GA Methanogenesis
Fixed vs. floating cover
Belt Filter Press
Filter Press http://www. metlabsolutions
Centrifuge
Land Application
Characteristics Blackish in color 15% - 90% Solids Mud-like to granular appearance Mild to strong odor (musty or swamp like) Blackish in color Appox. 80% water (slippery) Mud-like to granular appearance Mild to strong odor (musty or swamp like)
View of machine used to aerate compost placed in windrows.
Overview of windrow composting operation
Plants Grow Better with Biosolids
Tree Rings Before and After Organic Matter Applied
Back River WWTP
Back River WWTP
Back River WWTP
Back River WWTP
Abu Dhabi WWTP
Abu Dhabi WWTP
Abu Dhabi WWTP
Abu Dhabi WWTP
Abu Dhabi WWTP
Budapest WWTP
Lake Balaton WWTP
Lake Balaton WWTP
Lake Balaton WWTP
Lake Balaton WWTP
Wastewater Treatment in Developing Countries Community Biogas Plant in China
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Shouguang City WWTP, PRC
Settling Problem in Activated Sludge