Wastewater Design CE Spring, 2009

Outline Introductions Syllabus Course overview A “brief history of wastewater” Overview of wastewater treatment

Personal/Professional Background Civil Engineering (UBA) Ann Arbor wastewater treatment plant (0.5 years) ALN&M consulting in Ann Arbor (2.5 years) Montgomery Watson Harza (5 years)

4 Lake of Guadalupe, Mexico Chicago Water Supply Master Plan Some projects… Sanitary Infrastructure, Venezuela Oil Refinery WW Venezuela

Course Overview Modeling of microbial growth –Thermodynamics –Kinetics Wastewater characterization Biological processes –Suspended growth –Attached growth Physical/chemical processes –Settling –Aeration –Disinfection Process Modeling

Potential Design Topics Metcalf & Eddy Design Competition Mishawaka Wastewater Treatment Plant –Modeling South Bend Treatment Plant –Waste heat to digesters Metcalf & Eddy Design Competition –Nutrient removal –Carbon footprint

Guest speakers Karl Kopec (Mishawaka WWTP) Joshua Boltz, Ph.D. (CH2MHill) Art Umble, Ph.D. (Greeley and Hansen) Joe Cantwell (SAIC - Wisconsin Focus on Energy) Prakasam Tata, Ph.D. (formerly MWRDGC) Stephen Fralish (Wightman Petrie)

Modeling - BioWin

A Brief History of Wastewater Treatment (by Prof. Ketchum)

Manhole Sewer River 00 oo Civil Engineer

Air

What is Wastewater? Used potable water Domestic sources Commercial and industrial sources Stormwater, groundwater May contain –Pathogens –Degradable/non-degradable organics –Nutrients (P, N, C) –Inorganic contaminants (heavy metals, NO 3 - ) –Solids

Impacts on Environment Pathogens (drinking water, bathing) Oxygen depletion Turbidity, silt buildup in receiving waters Eutrophication Toxicity to ecosystems, humans Lake of Guadalupe, Mexico

Wastewater Treatment Objectives 1900 to early 1970s –Suspended and floatable material –Biodegradable organics –Pathogens 1970s to 1980 –Aesthetic, environmental concerns –Nutrient removal –Widespread treatment of wastewater Since 1980 –Toxic compounds

“Hot” Issues Wastewater as an energy sink/source Wastewater as a water source (reuse) Nutrient removal Priority pollutants, heavy metals Unregulated contaminants (endocrine- disrupting compounds, PPCPs) Combined sewer overflow

Treatment Processes Large solids  strainer Settleable solids  short settling Particulate organics  longer settling Dissolved organics  biodegradation Dissolved nutrients  chemical, biological removal Large solids Settleable solids Particulate organics Dissolved organics (blue)

Wastewater Treatment Process PRIMARY Primary clarifier Grit Influent Bar screen Grit chamber Screenings PRELIMINARY Supernatant return Belt thickener Anaerobic digester Belt press Dewatered sludge Pump (typical) Effluent O2O2 Secondary clarifier Cl 2 Chlorine contact tank Return sludge Aeration tank SECONDARY Waste sludge Removes settleable organics Removes dissolved organics Removes large and settleable inorganic solids

Screens

Grit Removal

Primary Settling

Activated Sludge

Secondary Settliing

Solids Digestion

Treatment Levels Preliminary – large objects, grit Primary – settleable solids Secondary – biodegradable organics Tertiary – nutrients, suspended solids Advanced – additional dissolved and suspended materials - reuse applications

Nutrients cause eutrophication

Examples of nitrogen-induced uutrophication Long Island Sound Chesapeake Bay Gulf of Mexico

NH 3 -N, TN, mg/L Year Nitrogen Standards for Wastewater Source: Art Umble, Ph.D., Greeley and Hansen TN = total nitrogen = NH NO NO org N

Conventional N removal Biological Nitrogen Removal NO 2 - NO 3 - AOB NOB NH 4 + 6e - 2e - Nitrification N2N2 3e - 2e - DB NO 2 - Denitrification

Nitrogen Removal in Activated Sludge BOD, NH 4 + O2O2 Settling tank Aeration basin Anoxic basin NO 3 - NH 4 + Aerobic nitrification (AOB/NOB) Anoxic denitrification NO 3 -