Sludge Treatment

Sludge TreatmentSludge Treatment

CE 326 Principles of Environmental EngineeringCE 326 Principles of Environmental EngineeringDepartment of Civil, Construction and Environmental Department of Civil, Construction and Environmental

EngineeringEngineeringIowa State UniversityIowa State University

Prof. Tim EllisProf. Tim EllisSpring 2010Spring 2010

AnnouncementsAnnouncements

Monday, April 26Monday, April 26thth Course reviewCourse review Exam reviewExam review

Wednesday, April 28Wednesday, April 28thth 33rdrd Exam during lab period (in lab classroom) Exam during lab period (in lab classroom)

Friday, April 30Friday, April 30thth No classNo class A.S. design lab dueA.S. design lab due

HistoryHistory

Thomas CrapperThomas Crapper Myth or legend?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 Sludge Processes

ThickeningThickening StabilizationStabilization ConditioningConditioning DewateringDewatering Volume ReductionVolume Reduction DisposalDisposal

ThickeningThickening

c___________ sludge using gravity or c___________ sludge using gravity or f________ methods. Primary sludge f________ methods. Primary sludge can be thickened to a maximum of can be thickened to a maximum of about 10% solids and secondary about 10% solids and secondary sludge to a maximum of about 6% sludge to a maximum of about 6% solids.solids.

oncentratinglotation

Gravity thickener

Process flow with recycle:

Dissolved Air Flotation (DAF) Dissolved Air Flotation (DAF) ThickenerThickener

StabilizationStabilization 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

olatileolids

ConditioningConditioning

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

hlorideolymer

DewateringDewatering

V________, pressure, or drying methods for removing w_____ from the solids.

Typically about 25 to 35% solids can be achieved.

acuumater

Volume ReductionVolume Reduction

Drying and p__________ for sale as a fertilizer

C__________ I___________ of sludge with ash

residual for ultimate disposal.

elletization

ompostingncineration

BiosolidsBiosolids

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 appliedapproximately __% of all biosolids are land applied

reated ludge

athogensetals

reated

50

Processes for Class AProcesses for Class A

Processes for generating Class A biosolids: sludge p___________ T____________ treatment (55AC for 24 h) temperature p______ anaerobic digestion

(55AC digester followed by 35AC digester) developed at ISU

asturizationhermophilic

hased

Anaerobic DigestionAnaerobic Digestion

Steps in Anaerobic Steps in Anaerobic DigestionDigestion

Hydrolysis

Acidogenesis

Acetogenesis

Methanogenesis

http://www.water-technology.net/projects/f_waynehill/index.html

Fixed vs. Fixed vs. floating floating covercover

Belt Filter PressBelt Filter Press

Filter Press http://www.metlabsolutions.com/Shriver%20Press%20-%20side.JPG

CentrifugeCentrifuge

Land ApplicationLand Application

CharacteristicsCharacteristics

Blackish in colorBlackish in color

15% - 90% Solids 15% - 90% Solids

Mud-like to granular Mud-like to granular appearanceappearance

Mild to strong odor Mild to strong odor (musty or swamp like)(musty or swamp like)

View of machine used to View of machine used to aerate compost placed in aerate compost placed in

windrows.windrows.

Overview of windrow Overview of windrow composting operationcomposting operation

Plants Grow Better with Plants Grow Better with BiosolidsBiosolids

Tree Rings Before and After Organic Matter Applied

Back River WWTPBack River WWTP

Abu Dhabi WWTPAbu Dhabi WWTP

Budapest WWTPBudapest WWTP

Lake Balaton WWTPLake Balaton WWTP

Wastewater Treatment in Developing Wastewater Treatment in Developing CountriesCountries

Community Biogas Plant in China

Shouguang City WWTP, Shouguang City WWTP, PRCPRC

Shouguang City WWTP, PRC

Settling Problem in Activated Settling Problem in Activated SludgeSludge

Sludge Treatment

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