Wastewater treatment and Biosolids management

Mon, Dec 25, 2017
Treatment wastewater


[][ ]What happens with the water when you’ve used it where does it all go you just push the lever and it’s gone it’s how does it all work can anything go down there are there even any rules and is the sink any different the bathroom sink the kitchen sink actually there is no difference sink toilets same thing behind these walls and under these floors all the drains meet up in a single pipe and head toward the sewers and going about our everyday lives we use a lot of water for drinking washing cooking going to the toilet and much more by using this water it becomes polluted the wastewater we produce is known as sewage everything that leaves the house through the main drain pipe meets up with the sewer right down here in some places to combine sewer both wastewater and storm water in other words everything from inside your house and everything from outside your house brain whatever goes into a single combined sewer offices shops factories and other industries together with rain water that runs off roofs and roads sewage is washed flushed or drained into sewers the underground network of sewers that collect all this wastewater and transports it to the sewage works is known as the sewerage system in the area it drains is the catchment area all of it heads towards the wastewater treatment plant in some places the sewers are separated one for wastewater and the other for storm water in that case only the wastewater heads towards the wastewater treatment plant the storm sewer goes straight to the river untreated because it’s only water right actually no it isn’t all the chemicals that you put on your lawn or the soap with all the phosphates that you wash your car with all head out the storm sewer if you’ve got a separated system straight into the room all the wastewater fins up at moist water treatment plants originally established by the Royal Commission on sewage disposal 1898 1915 objectives of sewerage treatment had as follows to avoid pestilence and nuisance disease and odor the protection of potable water sources from pollution by sewerage discharge and to produce effluence which after dilution with with water a suitable for abstraction as sources of potable supply sewage is a complex mixture of suspended and dissolved materials both categories constitute organic pollution the strength of sewage and the quality of sewage effluent are described in terms of their suspended solids and biochemical oxygen demand these two measures were originally either proposal devised by the Royal Commission the suspended solids are determined by way after the filtration of a known volume of sample through a standard glass fiber filter paper the results being expressed in milligrams per liter dissolved pollutants are determined by the biochemical oxygen demand they exert when incubated for five days at twenty degrees Celsius samples require appropriate dilution with oxygen saturated water and suitable replication the oxygen consumed is determined and the results are get expressed in milligrams per litre the two standards for sewage effluent quality proposed by the Royal Commission or for no more than 30 milligrams per liter of suspended solids and 20 milligrams per litre for biochemical oxygen demand the so-called 30 to 20 standard the Royal Commission in visits that the effluent of this standard would be diluted 8 to 1 with clean river water having biochemical oxygen demand of 2 milligrams per litre or less this standard was considered to be the normal minimum requirement and was not enforced by statute because the character and use of rivers varied so greatly currently most sewage treatment works are required to meet discharge standards set by the urban waste water treatment directive the flow of sanitary sewage alone in the absence of storms in dry season is known as dry weather flow DWF the purpose of these plans is to remove all solids and pathogens you know microorganisms like bacteria and stuff from the wastewater so when it gets reintroduced to the river it’s cleaner than when it arrived at the wastewater treatment plant when it arrives coarse screens remove large solids rags and debris from wastewater and are immediately disposed of it’s here that you see some of the most ridiculous things people have put down their toilets drains and sewers at least this stuff made it this far some things that the water can’t dissolve end up stuck in the sewers leading to sewers being clogged and homes being flooded after those fine screens are used to remove the smaller material in the same way next up is grit removal grit includes sand gravel and other heavy solid materials that are heavier than the organic solids in the wastewater removal of grit happens by getting the wastewater to flow in a spiral pattern heavier particles settle at the bottom of the tank while lighter organic particles are suspended and eventually carried out of the tank from there that water is sent into a settling basin this is where suspended solids settle out and floating scum is removed by skimmers scrapers in the tank moved continuously along the bottom to deposit the raw sludge into hoppers which is sent to a nearby plant where it’s made into pellets for fertilizer after the settling basins the wastewater is sent to the next step by a Archimedes screw pump which forces the liquid upwards the revolutions raise the water thread by thread until it comes out at the top of the cylinder there it is met by the fine curve screen where small items that have made it through the initial screening process are removed things like fruit and vegetable stickers they don’t dissolve and they clog up the system so when you’re pilling them off throw them in the garbage not down the sink now it’s time to get the stuff you can’t see some of this work is done by biological aerated filters essentially what happens here is that good microorganisms attached to porous rock eat up the bad microorganisms the waste water is pumped up through the rocks and the bacteria in the water sticks to the rocks bubbles are pumped in to keep the good bacteria alive and working the clean water goes up in the rocks with the bad bacteria attached to them go back down this cleansed water then flows into a channel on its way to be treated by ultraviolet light the water passes high output UV lamps where light disrupts the molecular structure of DNA molecules and the micro organisms this renders the cells unable to replicate before they die the disinfection stage takes seconds eliminates the need for chlorine and makes the final process much safer let’s look now at the sewage treatment process a sewage works such as this treats nearly 40,000 cubic meters of mainly domestic sewage each day at this site trade waste from two local food manufacturers comprises about 8% of the total flow rainwater runoff referred to a surface flow is also treated for simplicity we will refer to all the incoming waste waters as sewage that the sewage treatment works the incoming waste passes through screens which remove large pieces of debris such as plastic paper and cloth the liquid then flows through a number of channels which take out any grit washed in from roads the raw sewage entering the works passes through six millimeter mesh screens the collected solid matter is called screenings and typically comprises rags cotton buds sanitary products and paper the screenings are compacted and sent to landfill the sewage then flows to a grit extractor of the cross-flow type we Road grit and other inorganic matter settle out this material is subsequently washed and also sent to landfill the sewage is then passed forward to large tanks here fine particles sink to the bottom and form a sludge which is regularly removed and further treated on leaving the grit extractor the sewage enters the primary settlement tanks here approximately 70% of the remaining solid matter settles out and forms primary sludge which collects in a sump at the bottom of the tank periodically the sludge is pumped away for disposal or for treatment above this sludge lies the waste water it now has a greatly reduced amount of suspended solids and with it about 30% less biochemical oxygen demand or VOD for short here we use bacteria to clean up the liquid sewage the bacteria help purify the liquid by actively feeding on it and turning most of it into carbon dioxide water and nitrogen in biological filters we encourage bacteria to grow in deep beds of irregularly shaped stones gaps between the stones circulate air which lets the bacteria breathe and thrive that the liquid passes through them an alternative to biological filters is a process called activated sludge where air is bubbled through the sewage to encourage bacteriological growth the air can then be pumped or entrained from the surface by rotating paddles either way once the bacteria have done their work the liquid goes into further settling tanks to remove the remaining particles leaving clean water to flow to the river or if necessary onward to further treatment on this site the wastewater is treated in one of three different types of biological system namely biological filters activated sludge units or oxygen ditches first there were only the biological filters but over the years the activated sludge unit and oxygen ditches were installed here you can see the rectangular biological filters in many works they’re circular but irrespective of their shape biological filters are robust and easy to operate microorganisms growing on the clinker in the bed break down the organic matter in the effluent on leaving the filters the effluent is dosed with ferric sulfate in order to precipitate out the phosphates this prevents eutrophication occurring in the river when the treated effluent is finally discharged at the end of the process the effluent then goes to a humours tank for secondary settlement where microbial solids and precipitated phosphates settle out and are removed a sludge you can see that the water looks much cleaner than it was at the inlet an alternative to the biological filter is the activated sludge unit here the wastewater is aerated and mixed by fine bubbles of air blown through hundreds of ceramic or plastic diffusers such as this the organic matter in the sewage is again broken down by microorganisms but this time they’re suspended in the mixed liquor in a tank the remaining system is the oxygen ditch where almost one-fifth of the sewage at this plant is treated interestingly the oxygen ditch doesn’t require primary settlement the sewage is aerated with the help of large brush raters and the effluent moves around the ditch allowing the organic matter to be degraded by microbes in suspension on exiting it goes to a settlement tank and then to the gravel filter treated effluent from all three systems comes together before discharge into the nearby river you simplistic terms nitrogen in various forms is flushed rinsed or otherwise introduced into the sewer system almost all of this organic nitrogen urea for example is immediately hydrolyzed into ammonia in water gaseous ammonia nh3 is almost entirely converted to ionized ammonia or ammonium nh4 plus specialized autotrophic bacteria or nitrifiers convert the ammonium to nitrite no.2 and then to nitrate no.3 through various biological processes as dissolved oxygen is depleted by the nitrifiers and other organisms in the basin other specialized heterotrophic bacteria d nitrifiers are able to thrive by using the oxygen attached to the nitrate molecules for respiration creating nitrogen gas as a by-product the nitrogen gas then simply bubbles out of the water into the atmosphere pretty slick right well let’s go back to the beginning and take a closer look at each of these important steps in the nitrogen removal process first as a natural reaction in an aqueous solution or in water the vast majority of the organic nitrogen immediately hydrolyzes into ammonia most of this ammonia automatically converts to the ionic form ammonium the equilibrium between the gaseous and ionic forms of ammonia is heavily impacted by the pH of the water a more acidic solution will favour the ionic form ammonium a more basic will favor the gaseous form ammonia since wastewater typically ranges between a pH of 6 and 9 almost all of the ammonia will be in the ionic form since ammonia testing accounts for both forms ionic and gaseous it is not necessary to worry about each form separately no bacteria is necessary for this conversion it just happens the next step in the process consists of converting ammonium to nitrite and then nitrate this two-step process is usually lumped into one term nitrification this step is facilitated by a specialized autotrophic bacteria so what does autotrophic mean there are two broad categories for how organisms obtained carbon required for growth autotrophs and heterotrophs autotrophs are able to obtain their carbon from non-organic sources such as carbon dioxide and the alkaline bicarbonate plants are good examples of how this is done heterotrophs on the other hand require organic sources of carbon essentially heterotrophs get carbon by consuming other organic compounds humans and animals being good examples in contrast to heterotrophic be OD consuming bacteria autotrophic nitrifiers require more time to mature and maintain their population in a biological wastewater treatment system the nitrifiers dictate the srt in nitrogen reducing plants how fast nitrifiers growth depends on the temperature of the wastewater and the amount of dissolved oxygen present if nitrifiers aren’t allowed enough time to thrive you run the risk of accidentally wasting them out of the system entirely and losing nitrification higher temperatures and do concentrations means faster growth colder temperatures and lower do concentrations means slower growth also when no do is present nitrifiers can become completely inactive as a note it is important to remember that nitrifiers are also quite sensitive to pH pinning the function most comfortably in water with the pH between six point eight and seven point five once the healthy population of nitrifiers has developed in your system the first step performed largely by a group of bugs known as ammonia oxidizers will take the ammonium and do and convert it into acid water nitrite and energy if your system doesn’t have adequate alkalinity the acid produced here could create in hospitably acidic conditions for the bacteria resulting in major process hiccups including loss of nitrification the water produced is absorbed in the system the nitrate moves on to the next step and the energy is used by the bacteria to grow and multiply the second step for which a group of bugs known as nitrite oxidizers is largely responsible takes that nitrite and mordio and converts it into nitrate and energy this conversion from ammonia to nitrate is nitrification typically full nitrification is observed when ammonia concentrations are reduced to less than two milligrams per liter and nitride concentrations to less than half a milligram per liter as mentioned nitrification is a very oxygen hungry process as a comparison in order to remove one pound of bo d 1.2 pounds of oxygen are required however to reduce one-pound of ammonia to nitrate 4.6 pounds of oxygen are required since getting dissolved oxygen into wastewater is a very energy intensive process it would benefit every treatment plants electrical bill if they didn’t aerate more than they needed to over aerating does nothing to improve the process it really is flushing money down the toilet after nitrification the nitrogen is still in the system mostly as part of the bugs and in the form of nitrate though not as toxic as ammonia nitrates can still contribute to eutrophication and if released into a source supplying drinking water can endanger human populations specifically infants causing what is known as blue baby syndrome by interfering with blood oxygenation the final step in completely removing nitrogen from the system is called denitrification since nitrification is converting ammonia to nitrate one could think that denitrification is simply the reversal of this process confusingly yet fortunately this is not the case denitrification is performed by a specialized heterotrophic bacteria these guys require some pretty specific conditions to perform this step first of all they need some food or Bo D in order to oxidize that food they need oxygen their easiest and first choice for oxygen is do if there is no deal present however they look to alternative sources such as nitrate these specialists have the ability to strip the oxygen from nitrate molecules to satisfy their needs this critical environment where do is not present yet nitrates are is referred to as anoxic and is absolutely required for denitrification these bugs take the Bo D and nitrate to produce energy base and nitrogen gas the base is actually very useful in buffering the acid produced during nitrification the nitrogen gas then floats in tiny bubbles to the surface and into the atmosphere though great in the biological Basin denitrification in a clarifier can result in undesirable floating sludge there are many alternative strategies for developing anoxic conditions some treatment plants are designed to have dedicated anoxic zone volumes in the flow chart while others strive to develop these anoxic zones within the oxidation ditch or aeration zone by rigidly controlling iteration or by turning off aerators for set periods of time additionally under certain conditions micro anoxic zones can be developed within the bacterial flocks themselves resulting in what is referred to as simultaneous nitrification denitrification various levels of denitrification may be required depending on the local discharge permit however full biological denitrification typically results in only one to three milligrams of nitrate in the effluent stream to meet increasingly stringent standards the clean water is often put through a further filtration process sometimes shallow gravel beds are used to filter out any fine particles alternatively beds of reeds can also be used to give a final polish to the cleaned water before it’s returned to the environment this method is particularly useful in rural locations to improve the water quality further the effluent is filtered through gravel filters sometimes referred to as deep sand filters once these filters are full of solids they’re back washed and the washings go to the inlet of the works the treated effluent is now suitable for discharge to a river water quality is constantly measured using remote automatic sensors and double-checked periodically by technicians the final output from this works is well inside the statutory requirements the works can fully treat three times dry weather flow if the incoming flow is greater then after passing through the grit extractor the excess cascades over this we’re into the channel on the left and flows into storm tanks here just under fourteen and a half thousand cubic meters of sewage can be stored and treated later this is the equivalent to three times dry weather flow for two hours in the unlikely event that the flow to the works is greater than six times the dry weather flow the storm tanks are designed to overflow and discharge direct to the river only an exceptionally heavy rainfall with this occur typically about twelve to fifteen times a year this isn’t as bad as it sounds firstly the effluent is highly diluted with rain and secondly the river will be in spate and hence further dilution of the effluent takes place thus minimizing its impact on the environment so let’s recap wastewater leaves your house gets treated at the wastewater treatment plant and returns here the same place your drinking water comes from why it’s important to pay attention to what you put down sinks toilets and sewers number two and teepee that’s it that’s all that goes down there oh and teepee it means toilet paper oh yeah and this soap and water that’s it the purpose of a wastewater treatment to remove all solids and pathogens you know microorganisms like bacteria and stuff is to accelerate nature specifically to develop specific conditions to grow some special bugs so what are these bugs all of the bugs being grown in the wastewater treatment plant are natural and perform the same tasks albeit in a little less dense populations in water and soil around the world the vast majority consists of various populations of bacteria to perform the bulk of the wastewater treatment process such as VOD removal nitrification denitrification phosphorus uptake and so on generally these bacteria are pretty boring to look at under the microscope but not all the bugs are boring looking at a sample under the microscope will in fact reveal some other more exciting guys they don’t really contribute much to the overall process but can play an important role in process control so who are these guys let me make a note here that some of these guys will vary from process to process so you’ll have to get to know your own population let’s take a look at a family called stock ciliates first here we have a couple varieties that we’re gonna talk about first is bored of selling these guys attached onto a flock of bacteria and have a retractable tail they can be pretty quick then there’s Epis stylus similar before does sell Epis tieless also uses his tail to latch on to bacterial flock formations however this guy’s a little bit more passive and does not have the retractable feature so he doesn’t move around as much now to the family of the free-swimming ciliates these guys also come in a few different varieties here’s NASPA Disko these little critters are easily identified by their mini crawling likes say hello to light on itis i don’t know if i pronounced that correctly and here is trickled filament look at this guy go ah yes and rotifers these are a higher life form with cool hairy mammals and are much larger than many of the other bugs we see here some forms are much more mobile and move around constantly others a little bit less active on our worm friends the nematodes these tiny worms who can be active or just swimming lazily around the neighborhood can also be an indicator of some certain conditions both nematodes and rotifers can be indicative of an older bacterial biomass and in wastewater are indicative of a higher degree of purification or seeding from an attached growth system another important bacteria to note are called filamentous bacteria these include micro tricks parvis Ella nocardia theöthe ryx and a whole bunch of other characters with no names but are classified as type like length length length like type zero nine one four as you would expect filaments can also be used to identify conditions of sludge there is a whole suite of indicator tests available to identify which kind of present in your sludge so do we care who’s in our process and how many of them there are great question the answer is yes here’s why researchers in England several years ago evaluate the presence of ciliated organisms and treatment plants what they did was compare the effluent quality to the organisms that were present and they developed cable which correlated which organisms were present based upon what the effluent quality was like by identifying the filaments and by quantifying and tracking their presence one can use that information to understand and identify the potential effluent quality you would see for example vorticella and Epis tieless are seen normally with high quality effluent swear as a peculiar is seen more often in a lower quality effluent this English study was updated to reflect the condition for nitrification in a wastewater treatment plant and what they did was compare what particular ciliated organisms were present when nitrification was occurring and what organisms were present when it was no longer nitrifying in this second study a table was prepared and it showed the abundance of organisms that are more likely to reflect nitrifying conditions versus those that are present when might non nitrifying conditions accrue in all of these studies it was stressed by the researchers and should be understood by anyone using this identification technique that the relative abundance will probably change based upon the specific operating conditions and the wastewater stream characteristics for each and every wastewater treatment plant as such the tables provide a good starting point but should only be used as a starting point and if one wants to be certain what’s going on they develop the table for their own facility using these studies one can see that when you see critters such as Florida sella when you see the shelled amoebas when you see some types of rotifers you see those only when there is low Bo D present in the waste it’s not always the case but it’s usually an indication that those conditions are present the best solution for any wastewater treatment plan is to do their own analysis prepare their own table and if you do that you’ll be able to use the stock ciliates the rotifers and the amoebas to indicate what is happening and possibly predict the future of what it’s going to change as previously touched upon filming tracking can be another powerful tool to monitor conditions in a wastewater treatment plant the abundance and type of filaments present can indicate various process conditions such as low dissolved oxygen low f2m ratio sept isset e excessive grease and oil nutrient deficiency and low pH checking filaments requires the use of staining tests tests for sulfur granules cell size and presence of septa as well as identification of attached growth on the filament Jenkins Richards and diagur developed the chart to use in the evaluation process with sufficient testing the exact filament can be identified the dominance of a filament indicates the operating conditions if you want to change the biomass change the underlying condition which supports that filament for example type 1701 indicates a low do wear type of 1851 indicates a low f2m ratio so what physical parameters could very well correlate with your microorganism populations well the following list is a good beginning spi and settling rates temperature bodt SS and nutrient removal rates dissolved oxygen levels f2m ratios wasting rates and sr t mix liquor concentration pH and the presence of pollutants once you identify and track indicator organisms you can change the conditions you have control over such as the mixed liquor concentration aeration Braslow pH adjustments and nutrient deficiencies this is Becton sewage works in East London the largest sewage plant in Europe over 300 acres fenced off from curious eyes a sheer scale only comprehensible from the air this one plant has to deal with the sewage and waste of all of North London over three and a half million people producing more than 12 million gallons of waste every hour these bubbling tanks of raw effluent are being slowly purified through a complex series of tanks and filters and after this water is so clear it can be pumped straight out into the Thames this is Becton sewage treatment works in the east of London and it’s Europe’s biggest it was originally part of Joseph Bazalgette scheme in the 19th century sewage was simply stored here in tanks then pumped out to the river at high tide so you’ll be pleased to know today’s process is a lot more refined and takes just four hours for raw sewage to be clean enough to return to the river every day this treatment works handles the sewage from 3.4 million Londoners and that’s an astonishing volume it equates to 34 Olympic swimming pools every hour the first process happens here at the inlet works using these screens large lumps like bricks wood rags a raked out once collected these large objects will all be washed and sent to a landfill sites nearby they’ve even had half a car here meanwhile the remaining sewage passes on to the next part of the process into these primary settlement tanks now very basically it enters at that end and flows relatively slowly this way over the top of each tank is a moving bridge which has two blades to remove a solid organic material from the sewage the top blade skims scum from the surface while a second submerged blade dredges the heavier settled sludge from the bottom of the tank all this solid sludge is then sent for further processing the remaining sewage then flows down this way towards the secondary biological treatment process and here it is in these tanks the sewage is mixed in with billions upon billions of bacteria so all the dissolved materials that still remain can be by degraded and pumping air from below at very high pressures causes the sewage to be saturated with dissolved oxygen and this accelerates the biological breakdown is brilliant finally the treated effluent is tested to ensure it’s clean enough to go back into the Thames remember all of the solids which was skimmed off earlier they’re taken to a processing plant these sludges are bought to this filter press where it’s the waters and the resulting sludge cake is incinerated and that provides 75% of this entire works power needs bio solids are the nutrient-rich byproduct of modern municipal wastewater treatment since the 1980s the management of these organic solids has been increasingly focused on recycling efforts to control pollution at its source have dramatically improved the quality of wastewater coming in to treatment plant and the quality bio solids now produced by these plants the sludge from the primary and secondary settling tanks is thickened in a picket fence thickener then centrifuged and finally line is added to stabilize it sewage sludge can be anaerobically digested to produce a combustible gas buried in landfill sites composted or incinerated but most of its transported to farms for use as a soil conditioner in our main wastewater treatment process we took the contaminants out of the waste water and concentrated them in the sludge now we’ve got to treat the sludge in order to make it less toxic to destroy the pathogens and have less of an impact on the environment we also want to make it where it’s easier to handle and the processes that we’re gonna look at they include thickening digestion and dewatering these processes will take the sludge recover some of the energy from it that we can use to power our wastewater treatment plant and also turn out a beneficial product that can be used for soil conditioning this is the sludge thickening process it’s the first step and the solids handling processes and it’s very similar to clarifiers that we looked at before where we slow the water down and allow the solids to settle out but the special feature of thickening is that we’re taking our solids concentrations from about a half a percent all the way up to six percent solids the freezin we do that is so that we have less energy to pump the solids and so that we have a better treatment and the remainder of the solids handling processes in the gravity thick nor we use gravity to settle the sludge out and make it thicker so is easier to treat and the rest of the solids handling facilities in this facility it’s a dissolved air flotation thickener or adapt and in it we take and dissolve air in the sludge under pressure then we release that pressure and the sludge floats to the top we end up with about a five percent solids blanket on the top which we scrape off and send to our solids handling facilities for digestion we’re in the pump gallery for the sludge digesters we thicken the sludge in the sludge thickeners and we send it over here to the digesters in the digesters we heat the sludge up and the microorganisms start to break it down get rid of some of the volatile compounds make it to where it won’t degrade any further in that process it also destroys some of the pathogens when we’re finished the sludge is turned into a useful product but during that process we also generate some methane that methane gas we can use to run generators and those generators power part of our wastewater treatment plant they also generate waste heat which we use to heat up the digestion process so it’s a nice circle we use a whole lot of the energy that’s stored inside that sludge to make our process cheaper to operate you this is the digested sludge after we’ve used microorganisms and heat to destroy the pathogens and reduce the material that might degrade further and cause odour problems but there’s still a lot of water left in this sludge so we’re gonna have to do some dewatering process to get rid of the water make it easier to handle cheaper to transport and so that we can land apply it as a soil conditioner the use of bio solids has come under considerable public and regulatory scrutiny regulations for wastewater solids highly protective of human health and the environment in 2009 wastewater sludge production in UK amounted to around 1.2 millions a dry solids of which 77 percent was recycled to agricultural land and for EU as a whole there are about 6.5 megatons of dry solids produced annually in the next decade sludge disposal to all the established outlets could become increasingly difficult the challenges faced have been how to maintain cost-effective and secure methods of sludge disposal and engender public confidence in all disposal and recycling options of increased importance is a potential of renewable energy from the anaerobic digestion of sewage sludge sludge treatment and disposal may account for 40% of the operating cost of a wastewater treatment facility treatment process begins with the separation of sewage into solid and liquid material the solid waste or sludge is broken down by bacteria in digestion tanks one of the byproducts of sludge digestion is biogas containing a high proportion of methane in the past at most sites the gas had only been used to fuel a hot water boiler which then heated the digestion tanks but this far more gas produced than is actually needed for heating the only way of disposing of the excess gas was to burn it off using a flare stack environmentally that’s not a great solution by far the best option is to take all of the potential energy and methane gas produced by the digestion process and use it in a combined heat and power plant here methane gas from the digestion process is used to fuel modern highly efficient engines driving alternators to produce electricity at the same time heat produced by the engines is transferred by a hot water system to the digestion tanks it’s a very efficient and self fueling process and the fuel is free the remaining sludge can then be used as a fertilizer on local farms by rethinking how we manage and use our water we can begin to solve many of the problems we’ve all learned about reducing reusing and recycling our trash we need to learn to apply these 3 R’s to all of our resources especially water the water supply guys use the term integrated water management but like we said they’re only concerned with water supply and not the big picture true integrated water management needs holistic reform that integrates multiple agencies and members of the public and solves multiple problems beyond just meeting our ever-increasing water demands if we take a closer look at how we use water at home there are many opportunities to conserve and minimize our own water footprint first of all we can reduce our water consumption with low-flow showerheads laden clothes washers and other smart appliances although our sewer systems are designed to process human waste we put many other things down our sewer lines like kitchen scraps cleaners drugs and other chemicals which can get into our rivers and ocean harming fish and other aquatic life we should think before we use our drains for waste disposal in many homes more than half the water used goes to maintain a big green lawn wasting water that we could drink or leave in place for fish and other wildlife plants adapted to our region’s climate and soil require a lot less water and maintenance replacing a part of our lawn with native plants can save up to half of our household water use an ocean friendly garden conserves water and reduces polluted runoff helping to reduce flooding and keep pollution out of our creeks and coastal waters while giving you a beautiful garden full of new wildlife a really fun alternative to boring grass by contouring the land adding dry creeks or seasonal ponds and using permeable solutions for our walkways and driveways runoff can soak into the soil to recharge local aquifers we can also capture rain from our gutter with a simple rain barrel and keep it for reuse later much of the water that we used inside our homes can also be reused on our Gardens called great water this is slowly being accepted as a great way to reuse the water from your clothes washer or bathtub to water the plants in your garden reusing our slightly used water in this way not only helps reduce our water demand but it also reduces the amount of water we send to the wastewater treatment plant every day these basic ideas can be applied on a larger scale within our neighborhood or our entire city think of the benefits read by entire neighborhoods that reduce water use capture rainwater and eliminate water pollution we can redesign our communities to capture rain close to the source to filter back into the ground like the natural water cycle or to store it for reuse during dry times the streets in our neighborhood can be landscaped with contoured ditches known as bioswales these capture Street runoff so trees and plants can use and filter the water where space is limited large underground cisterns can collect storm water for later use pervious pavement can filter rainwater through parking lots reducing runoff known as low-impact development it’s rapidly catching up knowing that development can transform the landscape from one that sheds water causing flooding and water pollution back to a more natural state that captures and absorbs water many treatment plants can generate energy from solid waste and new technologies may make it possible to generate enough to operate the plant as well as provide a local source of biofuel if we rethink how we transport and process wastewater new opportunities arise many cities are now reclaiming waste water that’s right sewage for reuse in our homes and businesses or for direct recharge of aquifers one of the best opportunities for waste water is recycling it to drinking standards potable reuse is the process of purifying our wastewater to make it drinkable waste water from homes and businesses is forced to very fine filters allowing water molecules through while trapping dissolved salts and other impurities potable reuse is an efficient source of water because it makes use of water that is already in our local water system and it is also good for the environment because it takes impurities out of the system eliminating the need to discharge polluted wastewater into the ocean communities around the country are already drinking it as part of their normal water supply turning raw sewage into drinking water doesn’t sound terribly appetizing but that’s what’s happening in Orange County in Southern California Orange County faces chronic water shortages to meet the needs of its growing population the county spent five hundred million dollars on a state-of-the-art water treatment plant it’s the first of its kind in the United States there’s few new sources of water and this is going to be one that’s going to be key environmentally friendly cost competitive and if recycles the facility treats the sewage with advanced filtration technique such as reverse osmosis where high-pressure sends water molecules through ultrafine membranes ultraviolet light is also used to remove contaminants but the biggest challenges are not technological one of the problems these type of projects has to overcome is separating the toilet from the tap the process is state-of-the-art technology but unless the people are willing to accept the water all the engineering goes for not it’s the idea of drinking water from a toilet that’s not easy for everyone to swallow to win over the public the plant opens its doors daily for tours visits which end of course with a tasting session this is a basically an example to the world on how you can recycle sewage we have to do this I mean it’s we’re running out of water we’ve got to do this for the time being the water is pumped into underground aquifers where it will stay for several months before joining the drinking waters now is the time for a water management system that integrates the 3 R’s reduce reuse recycle to address our water crisis and help reverse the damage caused by our current mismanaged system this truly integrated water management program creates a holistic solution that incorporates ocean friendly gardens and low-impact development to reduce our impact on the water supply ray water systems encourage the reuse of our precious water resources and potable reuse recycles the water we’ve already paid for and transported we have the unique opportunity to transform water management and meet our current and future needs with science and technology that is proven to work residents businesses and government agencies must all work together to seize this opportunity and chanter water happiness before it’s too late you.[/][/]