on 26 january 1847. he made a careful and exact survey of liverpool and its surroundings, involving approximately 3,000 geodetical observations, and resulting in the construction of a contour map of the town and its neighbourhood, on a scale of one inch to 20 feet (6.1 m). from this elaborate survey newlands proceeded to lay down a comprehensive system of outlet and contributory sewers, and main and subsidiary drains, to an aggregate extent of nearly 300 miles (480 km). the details of this projected system he presented to the corporation in april 1848. in july 1848 james newlands' sewer construction programme began, and over the next 11 years 86 miles (138 km) of new sewers were built. between 1856 and 1862 another 58 miles (93 km) were added. this programme was completed in 1869. before the sewers were built, life expectancy in liverpool was 19 years, and by the time newlands retired it had more than doubled. london joseph bazalgette, a civil engineer and chief engineer of the metropolitan board of works, was given responsibility for similar work in london. he designed an extensive underground sewerage system that diverted waste to the thames estuary, downstream of the main center of population. six main interceptor sewers, totaling almost 100 miles (160 km) in length, were constructed, some incorporating stretches of london's 'lost' rivers. three of these sewers were north of the river, the southernmost, low-level one being incorporated in the thames embankment. the embankment also allowed new roads, new public gardens, and the circle line of the london underground. the intercepting sewers, constructed between 1859 and 1865, were fed by 450 miles (720 km) of main sewers that, in turn, conveyed the contents of some 13,000 miles (21,000 km) of smaller local sewers. construction of the interceptor system required 318 million bricks, 2.7 million cubic metres of excavated earth and 670,000 cubic metres of concrete. gravity allowed the sewage to flow eastwards, but in places such as chelsea, deptford and abbey mills, pumping stations were built to raise the water and provide sufficient flow. sewers north of the thames feed into the northern outfall sewer, which fed into a major treatment works at beckton. south of the river, the southern outfall sewer extended to a similar facility at crossness. with only minor modifications, bazalgette's engineering achievement remains the basis for sewerage design up into the present day. other cities in the uk in merthyr tydfil, a large town in south wales, most houses discharged their sewage to individual cess-pits which persistently overflowed causing the pavements to be awash with foul sewage. paris, france in 1802, napoleon built the ourcq canal which brought 70,000 cubic meters of water a day to paris, while the seine river received up to 100,000 cubic meters (3,500,000 cu ft) of wastewater per day. the paris cholera epidemic of 1832 sharpened the public awareness of the necessity for some sort of drainage system to deal with sewage and wastewater in a better and healthier way. between 1865 and 1920 eugene belgrand lead the development of a large scale system for water supply and wastewater management. between these years approximately 600 kilometers of aqueducts were built to bring in potable spring water, which freed the poor quality water to be used for flushing streets and sewers. by 1894 laws were passed which made drainage mandatory. the treatment of paris sewage, though, was left to natural devices as 5,000 hectares of land were used to spread the waste out to be naturally purified. further, the lack of sewage treatment left parisian sewage pollution to become concentrated downstream in the town of clichy, effectively forcing residents to pack up and move elsewhere. the 19th century brick-vaulted paris sewers serve as a tourist attraction nowadays. hamburg and frankfurt, germany the first comprehensive sewer system in a german city was built in hamburg, germany, in the mid-19th century.: 2 : 43 : 8 in 1863, work began on the construction of a modern sewerage system for the rapidly growing city of frankfurt am main, based on design work by william lindley. 20 years after the system's completion, the death rate from typhoid had fallen from 80 to 10 per 100,000 inhabitants.: 43 the sewer system of memphis, tennessee in 1880 united states the first sewer systems in the united states were built in the late 1850s in chicago and brooklyn.: 43 in the united states, the first sewage treatment plant using chemical precipitation was built in worcester, massachusetts, in 1890.: 29 sewage treatment initially the gravity sewer systems discharged sewage directly to surface waters without treatment.: 12 later, cities attempted to treat the sewage before discharge in order to prevent water pollution and waterborne diseases. during the half-century around 1900, these public health interventions succeeded in drastically reducing the incidence of water-borne diseases among the urban population, and were an important cause in the increases of life expectancy experienced at the time. application on agricultural land early techniques for sewage treatment involved land application of sewage on agricultural land.: 12 one of the first attempts at diverting sewage for use as a fertilizer in the farm was made by the cotton mill owner james smith in the 1840s. he experimented with a piped distribution system initially proposed by james vetch that collected sewage from his factory and pumped it into the outlying farms, and his success was enthusiastically followed by edwin chadwick and supported by organic chemist justus von liebig. the idea was officially adopted by the health of towns commission, and various schemes (known as sewage farms) were trialled by different municipalities over the next 50 years. at first, the heavier solids were channeled into ditches on the side of the farm and were covered over when full, but soon flat-bottomed tanks were employed as reservoirs for the sewage; the earliest patent was taken out by william higgs in 1846 for "tanks or reservoirs in which the contents of sewers and drains from cities, towns and villages are to be collected and the solid animal or vegetable matters therein contained, solidified and dried..." improvements to the design of the tanks included the introduction of the horizontal-flow tank in the 1850s and the radial-flow tank in 1905. these tanks had to be manually de-sludged periodically, until the introduction of automatic mechanical de-sludgers in the early 1900s. chemical treatment and sedimentation as pollution of water bodies became a concern, cities attempted to treat the sewage before discharge.: 12–13 in the late 19th century some cities began to add chemical treatment and sedimentation systems to their sewers.: 28 in the united states, the first sewage treatment plant using chemical precipitation was built in worcester, massachusetts in 1890.: 29 during the half-century around 1900, these public health interventions succeeded in drastically reducing the incidence of water-borne diseases among the urban population, and were an important cause in the increases of life expectancy experienced at the time. odor was considered the big problem in waste disposal and to address it, sewage could be drained to a lagoon, or "settled" and the solids removed, to be disposed of separately. this process is now called "primary treatment" and the settled solids are called "sludge." at the end of the 19th century, since primary treatment still left odor problems, it was discovered that bad odors could be prevented by introducing oxygen into the decomposing sewage. this was the beginning of the biological aerobic and anaerobic treatments which are fundamental to wastewater processes. the precursor to the modern septic tank was the cesspool in which the water was sealed off to prevent contamination and the solid waste was slowly liquified due to anaerobic action; it was invented by l.h mouras in france in the 1860s. donald cameron, as city surveyor for exeter patented an improved version in 1895, which he called a 'septic tank'; septic having the meaning of 'bacterial'. these are still in worldwide use, especially in rural areas unconnected to large-scale sewage systems. biological treatment it was not until the late 19th century that it became possible to treat the sewage by biologically decomposing the organic components through the use of microorganisms and removing the pollutants. land treatment was also steadily becoming less feasible, as cities grew and the volume of sewage produced could no longer be absorbed by the farmland on the outskirts. edward frankland conducted experiments at the sewage farm in croydon, england, during the 1870s and was able to demonstrate that filtration of sewage through porous gravel produced a nitrified effluent (the ammonia was converted into nitrate) and that the filter remained unclogged over long periods of time. this established the then revolutionary possibility of biological treatment of sewage using a contact bed to oxidize the waste. this concept was taken up by the chief chemist for the london metropolitan board of works, william libdin, in 1887: ...in all probability the true way of purifying sewage...will be first to separate the sludge, and then turn into neutral effluent... retain it for a sufficient period, during which time it should be fully aerated, and finally discharge it into the stream in a purified condition. this is indeed what is aimed at and imperfectly accomplished on a sewage farm. from 1885 to 1891 filters working on this principle were constructed throughout the uk and the idea was also taken up in the us at the lawrence experiment station in massachusetts, where frankland's work was confirmed. in 1890 the les developed a 'trickling filter' that gave a much more reliable performance. contact beds were developed in salford, lancashire and by scientists working for the london city council in the early 1890s. according to christopher hamlin, this was part of a conceptual revolution that replaced the philosophy that saw "sewage purification as the prevention of decomposition with one that tried to facilitate the biological process that destroy sewage naturally." contact beds were tanks containing an inert substance, such as stones or slate, that maximized the surface area available for the microbial growth to break down the sewage. the sewage was held in the tank until it was fully decomposed and it was then filtered out into the ground. this method quickly became widespread, especially in the uk, where it was used in leicester, sheffield, manchester and leeds. the bacterial bed was simultaneously developed by joseph corbett as borough engineer in salford and experiments in 1905 showed that his method was superior in that greater volumes of sewage could be purified better for longer periods of time than could be achieved by the contact bed. the royal commission on sewage disposal published its eighth report in 1912 that set what became the international standard for sewage discharge into rivers; the '20:30 standard', which allowed "2 parts per hundred thousand" of biochemical oxygen demand and "3 parts per hundred thousand" of suspended solid. activated sludge process most cities in the western world added more effective systems for sewage treatment in the early 20th century, after scientists at the university of manchester discovered the sewage treatment process of activated sludge in 1912.this section is an excerpt from activated sludge § history. the davyhulme sewage works laboratory, where the activated sludge process was developed in the early 20th century the activated sludge process was discovered in 1913 in the united kingdom by two engineers, edward ardern and w.t. lockett, who were conducting research for the manchester corporation rivers department at davyhulme sewage works. in 1912, gilbert fowler, a scientist at the university of manchester, observed experiments being conducted at the lawrence experiment station at massachusetts involving the aeration of sewage in a bottle that had been coated with algae. fowler's engineering colleagues, ardern and lockett, experimented on treating sewage in a draw-and-fill reactor, which produced a highly treated effluent. they aerated the waste-water continuously for about a month and were able to achieve a complete nitrification of the sample material. believing that the sludge had been activated (in a similar manner to activated carbon) the process was named activated sludge. not until much later was it realized that what had actually occurred was a means to concentrate biological organisms, decoupling the liquid retention time (ideally, low, for a compact treatment system) from the solids retention time (ideally, fairly high, for an effluent low in bod5 and ammonia.) their results were published