An Intro to Urban Wastewater Systems

this video is sponsored by Siemens thanks Siemens when people think of cities they picture glittering skylines busy streets beautiful parks and underfunded mass transit while these are all City things none of it will be possible without the infrastructure under it all particularly the wastewater system sewers basically for every bustling downtown there's one or more of these wastewater treatment plants without them cities would be smaller smellier and sicker this video is an appreciation of the wastewater system I mean how often do we even think about wastewater we just assume that the water going down there or there or there will just be taken care of in this video we'll get into topics like stormwater bioswales water treatment and fatbergs it won't all be gross though we'll also talk about the massive infrastructure projects going on underneath our cities and the infrastructure making our sewers more sustainable let's start with the basics cities have lots of water that people don't want to be there there are two major sources of that water the first is storm water typically rainwater falling on streets roofs parking lots as well as the pervious surfaces like lawns and forests the second is wastewater this is the water that goes down the drain and kitchens and bathrooms all over a city let's start by talking about how stormwater is dealt with how does all this wastewater get swept away from a city there are several types of sewage systems but let's look at the most common for urban areas first we have combined sewers this is a common system in cities it's basically a big old pipe running a couple meters below city streets all of the waste water both wastewater from buildings and stormwater from runoff gets collected into the same pipe the manhole covers you see on city streets lead to these pipes they're big expensive systems that only make economic sense in urban areas combined sewers have been around for a long time Rome's cloaca Maxima is a great example originally built as an open sewer sometime around the 6th century BC it was gradually expanded and covered over time eventually wastewater from aqueducts use flowed into the facility making it a true combined sewer the cloaca Maxima is technically still in continuous use as a small amount of water are still transferred through it to the outfall near the Ponte a bridge over the Tiber River the name combined system provides a clue about the next system a separate system this is where wastewater from buildings gets its own pipes called sanitary sewers and runoff gets another set of pipes called stormwater sewers the sanitary sewer pipes travel to a wastewater treatment plant while the stormwater flows back into the river there are other systems out there but combined in separate systems are the most common in cities you won't find many open sewers these days for example because there are major sources of disease these systems each have their own pros and cons and some of the big ones are related to what happens after the wastewater is collected in a combined system all of the storm water and wastewater reaches a treatment facility here the wastewater is typically removed as solids then the facility removes suspended organic material nitrogen and phosphorus sometimes the remaining liquid is disinfected to kill bacteria then that liquid far cleaner now that when it entered is discharged into waterways this works great normally but during heavy rain events like me too much wastewater for the treatment facility to handle what happens to the excess typically all of that raw sewage gets dumped into a nearby river these are called combined sewer overflow events and they are not great for the environment obviously separate systems don't really have this problem all of the sanitary sewer material goes to the treatment facility while the stormwater is collected and dumped directly into a body of water bypassing any treatment you don't get the black water with the industry turn for toilet waste into the river but stormwater isn't exactly clean either if fix up oil and grease from cars cigarette butts litter and whatever else is on the street it's why you'll sometimes see flows to river painted near storm drains it's to encourage you not to pour anything down that you wouldn't want to be swimming in later the system with the longest history is the combined sewer in big cities like New York Paris and London still use them today most systems installed after about 1950 use a separate approach neither of these systems have stirling environmental records what can be done to make them better for our rivers and lakes one of the most important things we can all do is not put things down drains that don't belong there that means don't wash grease down the sink drain instead drink grease into a can or jar and then throw it away after it hardens in the bathroom don't flush wet wipes tampons condoms or diapers they don't break down and create clogs some of the most infamous clogs in sewer history is a combination of all this stuff I'm talking about the fat birds of London fat birds are giant masses of fat that form into a blockage when combined with diapers wipes and other debris they're also an interesting chemical reaction taking place to waste water often contains a lot of calcium which it picks up when it runs over concrete streets and sidewalks and through concrete pipes when that calcium water mixes with grease and fat it transforms the fat into a dense mass thanks to saponification this is the same chemical process that creates soap the largest fatberg found in the London system was 140 tons and took workers weeks to remove London launched a campaign to encourage people to put fat and wipes into the garbage cans instead London is not the only city battling fatbergs Tokyo had a fatberg wash out to sea in 2000 and since then have been educating their citizens as well London's not just relying on education they're also building a new super sewer to increase capacity and supplement the Victorian era sewers that they rely on now those old sewers were feat of engineering at the time with 1,100 miles constructed out of 300 million bricks the designers had the foresight to build the sewer for 4 million people back when London only had 2 million inhabitants today London's population is approaching 9 million so you can see where the problem is the pipes aren't large enough to flush out those fatbergs like a lot of cities London also experiences make combined sewer overflow events that pollute the river the new sewers will divert this overflow deep underground and send it to another treatment facility London isn't the only city investing in massive combined sewer upgrades Washington DC is spending 2.6 billion dollars to build an additional 18 miles of tunnel to reduce their combined sewer overflows by 96% in the region it's the largest infrastructure project in the area since the Washington metro system opened in the 1970s two titles have already opened and the remaining tunnels will be open early in the next decade Portland Oregon completed its big pipe project in 2011 and reduced its outflows into the lam at River by 94% seriously if you google CSO projects you'll find links to all kinds of city websites that describe their sewer projects to stop dumping raw sewage into their rivers building big expensive pipes often called great infrastructure is one way to solve environmental problems around sewers especially the combined sewers that can trigger outflows but in separate sewers water from the street and parking lot goes directly into nearby waterways without any treatment at all recently green infrastructure has been deployed in cities to improve the quality of storm water before it enters the sewer system one piece of green infrastructure that you've probably noticed in cities already is the bio scale these facilities are essentially rain gardens placed in long narrow spaces between the sidewalk and the curb they take water from the street store it and treat it before the excess water flows into the sewer drain at the far end much of the water that would have ended up in the sewer just gets absorbed into the ground bio swells are planted with vegetation that could absorb excess nutrients like phosphates and nitrates these compounds often cause eutrophication or algae blooms when they are dumped from the sewers directly into a waterway so it's much better to filter them out in a bioswale you'll also see cities with combined sewers building bioswales retention ponds green roofs rain gardens and permeable pavement to reduce the spike in wastewater that occurs when storms bring rain these green facilities hold water is slowly to release them into the sewer system reducing the spike rad for the storm and evening outflows when thinking about wastewater and sustainability it makes sense to think about water but also electricity about three to four percent of US energy consumption is used to move water around electricity is needed to power pumps and water treatment facilities reducing electricity use for wastewater facilities can also reduce carbon emissions and make the whole moving water round thing much more sustainable Anissa pallies will often conduct an energy audit of a water system and find places where energy can be saved sometimes efficiencies can be found by repairing pipe leaks or improving systems to make existing machinery run more efficiently often municipalities looking to improve efficiency and sustainability will opt to replace aging equipment with newer more energy efficient models for example Siemens the sponsor of this video recently worked with a municipality to replace a pumping station run by a steam boiler driven system installed in 1901 not only were these things near the end of their useful life they were inefficient and not sustainable Siemens switched the pumping station from boilers to modern electric pumps that will save the city over four million dollars a year in operating costs more importantly the modern equipment is better for the environment so there you have it sewer systems the engineering marvels that made modern cities possible over a hundred years ago are becoming more efficient in sustainable in the 21st century old sewer pipes and boiler driven pumps are being replaced by new sewer mega-projects bioswales and better electrical infrastructure it's good to know that cities are making these improvements to keep the clean water flowing from our taps and keep our toilets flushing you

Channel: City Beautiful

Views: 360,531

Keywords: city planning, town planning, urban planning, urban design, wastewater, sewers, sewage, sewerage, wastewater treatment plant, sewage treatment plant, bioswales, combined sewer overflow, fatbergs, combined sewers, london, infrastructure, green infrastructure, siemens, stormwater, runoff, drains to river

Id: -HkRkCXPjzw

Length: 9min 39sec (579 seconds)

Published: Thu Aug 29 2019

Reddit Comments

[u/Massive-Gas]

There's a cool water treatment facility that uses the grease from grease traps as a biofuel to run their facility.

[u/Baumbauer1]

restaurants flush a massive amount of grease down their sinks so don't feel bad about flushing a little live oil.

https://www.bbc.com/news/uk-england-london-41577219