mayor. we also screwed up a few things along the way, from the economy to the environment and social justice. and now, class of 2012, the challenges and the promise of the world are your challenges and promises. your next assignment -- your homework for the rest of your life -- i can do that because i am mayor -- is to run the ball a little further down the field and get us to a better place. i know, many of you are thinking "mayor, i have got to get a job. i have to repay my student loans. i have to prepare for my family." yes, you do. i know going out into the world to fend for yourself in this economy is difficult. it is survival of the fittest,

like something out of "the hunter games." -- "the hunger games." but you are not on your own. is more like -- it is more like "the avengers." while it may not always be evident and while you may face many challenges throughout your life, always remember you are surrounded by a not so secret society of people who want to help you. these are people in business, and governments, sports, entertainment, health care, education. people who have achieved some measure of success or wisdom in there own lives. the greatest gift they can ever give is to pass on a little bit of that wisdom to you and help

you succeed to an even greater degree. don't get me wrong. you and you alone decide what you were going to do with that education and this opportunity and do not waste it. don't ever be afraid to ask for help. whether it is your boss, your family, your mayor. look to your own communities and ask yourself "how can i give back? how can i use my education to help my community and add to the valuable work within my neighborhood or my city?" because if there's one thing i see in this economy that is emerging, clean tech and biotech that are adding some new jobs to our city, is that

success does not come from going it alone. success comes from collaboration. bringing diverse backgrounds together to a common goal. new companies, out incubators in the market. they do not offices. they have a big open tables. they have whiteboards everywhere. the building is built around the notion of collaboration, the idea that success comes from sharing ideas and goals. because that is how we get innovation. that is how you, class of 2012, will lead the world a better place and fix things my generation did not quite get to. that is not just innovation in

technology and our economy, but innovative approaches in the health field, curing diseases, cleaning the air and water, and dealing with social justice. there is no better start than here. we are the gateway to the pacific rim and asia. to the west, the booming economies of latin america and brazil. we are the international destination are rhumba world -- around the world. you, class of 2012, are part of what makes san francisco brand. you represent new ideas, new frontiers, new beginnings. that innovation is perfected in your university's new marketing campaign. "change the world from here."

some of them definitely make you smile. academics covering the world from north beach? funny. the one that struck me the most -- "there is no moral compass app." so, i say to you as well, don't lose yourself and your values. don't forget where you came from, even amid the success you may achieve. some of you know the chinese zodiac for 2012 is the year of the dragon. dragon is the only mythical animal in the chinese zodiac and the most powerful. the year of the dragon is fittingly a time for risk- taking, bold decision, and

innovation. class of 2012, san francisco and the world need your risk-taking. sees the year of the dragon for yourselves, your families, for the rest of us. -- seize the year of the dragon. you are graduating at a time of immense promise. i know i am a little biased, but there is no better place to spend the rest of your lives. we are so proud to you. we are counting on you and we are here to help you realize your greatest objectives. thank you and congratulations, class of 2012. [applause]

because we have a great waste water system here in san francisco, we do about 80 million gallons of waste water here in san francisco, which means we basically fill up 120 olympic sized swimming pools each and every day here in the

city. we protect public health and safety and environment because we are discharging into the bay and into the ocean. this is essentially the first treatment here at our waste water treatment facility. what we do is slow down the water so that things either settle to the bottom or float to the top. you see we have a nice selection of things floating around there, things from bubble gum wrappers, toilet paper, whatever you dump down the toilet, whatever gets into our storm drains, that's what gets into our waste water treatment and we have to clean. >> see these chains here, this keeps scum from building up. >> on this end in the liquid end basically we're just trying to produce a good water product that doesn't negatively impact the receiving water so that we have recreation and no bad

impact on fish and aquatic life. solids is what's happening. . >> by sludge, what exactly do you mean? is that the actual technical term? . >> it's a technical term and it's used in a lot of different ways, but this is organic sewage sludge. basically what it is is, oh, maybe things that come out of your garbage disposal, things that are fecal in nature. it's sludge left in the water after the primary treatment, then we blend those two over and send them over to digestion. this building is built to replace tanks here that were so odoriferous they would curl your hair. we built this as an interim process.

>> is there a coagulant introduced somewhere in the middle of this? . >> this coagulant brings solids together and lets the water run through. that gives us more time in the digestion process, more time to reduce the amount of solids. these are the biggest ones in the world, like we always like to do in san francisco. they are 4 meter, there's none like it in the world. >> really? wow. >> three meters, usually. we got the biggest, if not the best. so here we are. look at that baby hum. river of sludge. >> one of the things is we use bacteria that's common in our own guts to create this reduction. it's like an extra digestion. one of the things we have to do to facilitate that is heat that sludge up and keep it at the temperature our body likes,

98.6 degrees. >> so what we have here is the heat exchanger for digester no. 6. these clog up with debris and we're coming in to -- next wet weather season so we always come through here, clean them out, make sure that we get maximum heat exchange during the colder wet weather. sludge season. >> rubber glove. >> right here. >> rubber glove, excellent. all right, guys. >> thank you. >> good luck. >> this is the full on hazmat. . >> residual liquid. we're taking it time to let it drain. we don't want to get sludge on it necessarily. take your time. stand on the side of it.

. >> should we let it release for a while? . >> let it release. >> is that the technical term? . >> this is the most important bolt on the whole thing. this is the locking bolt. it locks this thing right in place. so now. >> take your hammer and what we want to do, we get rag build up right in here. the hot water recirculates right in here, the sludge recirculates in here. the sludge sometimes has rags in it. all we want to do is go around the clean the rags. let me show you how. take the slide hammer, go all the way through the back, go around. >> got you. >> during the real rainy season, how does that change the way dealing with this job?

is it a lot more stuff in there? . >> what we do, charles, we do this quarterly. every four months we go around and clean all the heat exchangers so we don't have a large build up. . >> go around? . >> yeah. (sound of hammering). >> what i'm trying to do, charles, is always pull it out on the low stroke. >> right. so you are not, like, flying out. now talk about clean up.

. >> then where does this stuff get deposited? . >> we're going to dump it in a debris box and it will go back to the plant. >> if you think back, the romans came up with a system of plumbing that allowed us it use water to transport waste away from the hub of civilization, which enabled cities to grow. . >> you have a large bowl, a drive motor and another motor with a planetary gearbox with differential pressure inside there. the large mass up there spinning separating the solids from the liquid. we have to prevent about once a month, we go in there grease those, change the oil, check the vibration levels.

the operators can tell just by the hum of that machine that it's a harmonic noise emitted that it's out of balance and the machine needs to be cleaned. it will start vibrating and we have vibration analysis machines that will come over here and check the levels. so it's kind of an on-going thing that you have to stay on top of on a daily basis. >> handled properly, you take organic residuals, as we call them, that are leftovers of our society and turn them back into some energy. and we have another ability to take that sludge and get a nutrient value for crops there. we actually are running a kind of composting energy recovery system. >> well, this is a dirty job. we try to do it safely and we try to do it without imposing too much on the public. people want to flush their

toilets and have things go away and not be bothersome again. we do a lot to try to accomplish that. i'd like to invite you to come back any time you want. once you got this in your blood, you are not going to be able to stay away. the raging waters are fun and when we do digester cleaning i really hope you can come back. that's quite a sight. >> yeah, that sounds interesting. >> i really appreciate you coming by and it was a