© 2011 Pearson Education, Inc. AP Environmental Science Mr. Grant Lesson 74 Wastewater and Its Treatment

© 2014 Pearson Education, Inc. Mastery Check Describe and explain the major steps in the process of wastewater treatment. How can artificial wetlands aid such treatment? Wastewater treatment includes primary treatment, which entails the physical removal of grit, sewage solids, and other particulate matter; secondary treatment, which entails the biological removal of other chemical and infectious contamination; and tertiary treatment, which removes residual pollutants and sterilizes the water before returning it to circulation. Artificial wetlands, modeled on natural wetlands, can be constructed to treat a through-flow of wastewater while also providing wildlife habitat and recreational areas.

© 2011 Pearson Education, Inc. Objectives: Define the terms point-source pollution and non-point- source pollution. Assess problems of water quality and propose solutions to address water pollution. Explain how we treat drinking water and wastewater. TED - Too much of the world lacks access to clean drinking water. Engineer Michael Pritchard did something about it -- inventing the portable Lifesaver filter, which can make the most revolting water drinkable in seconds. An amazing demo from TEDGlobal 2009.

© 2011 Pearson Education, Inc. Point-Source Pollution: A source of pollution that involves the discharge of wastes from an identifiable point, such as a smokestack or sewage treatment plant. Non-Point-Source Pollution: A source of pollution that cannot always be traced to an exact point of entry. Define the terms point-source pollution and non-point-source pollution.

© 2011 Pearson Education, Inc. Explain how we treat drinking water and wastewater. Municipalities treat drinking water by filtering and disinfection in a multistep process. Septic systems are used to treat wastewater in rural areas. Wastewater is treated physically, biologically, and chemically in a series of steps at municipal wastewater treatment facilities. Artificial wetlands enhance wastewater treatment while restoring habitat for wildlife.

© 2014 Pearson Education, Inc. We treat our drinking water  Technology and government regulation have improved our pollution control  Treated drinking water is widespread and successful in developed nations  Before water reaches the user, it is chemically treated, filtered, and disinfected  The EPA sets standards for over 90 drinking water contaminants  Local governments and private water suppliers must meet these standards

© 2014 Pearson Education, Inc. We treat our wastewater  Wastewater includes water that carries sewage and that from households, manufacturing, stormwater runoff, etc.  It is treated before being released into the environment  Septic systems  the most popular method of wastewater disposal in rural areas  Underground septic tanks separate solids and oils from wastewater  The water drains into a drain field, where microbes decompose the pollutants  Solid waste is periodically pumped out and landfilled

© 2011 Pearson Education, Inc. We treat our wastewater

© 2014 Pearson Education, Inc. We treat our wastewater  In populated areas, sewer systems carry wastewater to treatment locations  Primary treatment  physically removes contaminants in settling tanks (clarifiers)  Secondary treatment  water is stirred and aerated  Aerobic bacteria degrade organic pollutants  Water is treated with chlorine (and/or ultraviolet light) to kill pathogens  This water, called effluent, is piped into rivers or oceans  Reclaimed water is used for lawns, irrigation, or industry

© 2011 Pearson Education, Inc. Municipal sewer systems

© 2011 Pearson Education, Inc. A typical wastewater treatment facility

© 2014 Pearson Education, Inc. We treat our wastewater  Sludge  solid material resulting from treatment of wastewater  Is decomposed microbially in digesters  Resulting “biosolids” are dried then landfilled, incinerated, or used as fertilizer on cropland  Methane-rich gas created by decomposition can be burned to generate electricity  Six million dry tons of sludge are generated in the United States each year

© 2014 Pearson Education, Inc. Constructed wetlands can aid treatment  Natural wetlands have long filtered and purified water  Human-constructed wetlands can do the same thing  After primary treatment at a conventional facility water is pumped into the wetland  Microbes decompose the remaining pollutants

© 2014 Pearson Education, Inc. Constructed wetlands can aid treatment  Cleansed water is released into waterways or percolates underground  They are havens for wildlife and for human recreation  The United States has over 500 artificially constructed or restored wetlands  Released effluent has helped rebuild coastal wetlands along the Gulf Coast

© 2011 Pearson Education, Inc. Artificial wetlands clean wastewater The U.S. has over 500 artificially constructed or restored wetlands

© 2014 Pearson Education, Inc. TED Video With cutting-edge nanotech, Michael Pritchard's Lifesaver water-purification bottle could revolutionize water- delivery systems in disaster-stricken areas around the globe. "On the outside, it looks like an ordinary sports bottle. On the inside, there's a miracle: an extremely advanced filtration system that makes murky water filled with deadly viruses and bacteria completely clean in just seconds." Allison Barrie, FoxNews.com Michael Pritchard's water filter turns filthy water drinkable (9:29)