An overview of wastewater  
Collection of wastewater
      The “Shambles” is a street or area in many medieval English cities, like London and York. During the eighteenth and nineteenth centuries, Shambles were commercialized areas, with meat packing as a major industry. The butchers of the Shambles would throw all of their waste into the street, where is was washed away by rainwater into drainage ditches. The condition of the street was so bad that it contributed its name to the English language originally as a synonym for butchery or a bloody battlefield.
In old cities, drainage ditches like those at the Shambles were constructed for the sole purpose of moving storm water out of the cities. In fact, discarding human excrement into these ditches was illegal in London. Eventually, the ditches were covered over and became what we now know as storm sewers. As water supplies developed and the use of the indoor water closet increased, the need for transporting domestic wastewater, called sanitary waste, became obvious. In the United States, sanitary wastes were first discharged into the storm sewers, which then carried both sanitary waste and storm water and were known as combined sewers. Eventually a new system of underground pipes, known as sanitary sewers, was a constructed for removing the sanitary wastes. Cities and parts of cities built in the twentieth century almost all built separate sewers for sanitary waste and storm water.

Estimation Wastewater Quantities
Domestic wastewater (sewage) comes from various sources within the home, including the washing machine, dishwasher, shower, sinks, and of course the toilet. The toilet or water closet (WC), as it is still known in Europe, has become a standard fixture of modern urban society. As important as this invention is, however, there is some dispute as to its inventor. Some authors credit John Bramah with its invention in 1778; others recognize it as the brainchild of Sir John Harrington in 1596. The latter argument is strengthened by Sir John’s original descri ption of the device, although there is no record of his donation his name to the invention. The first recorded use of that euphemism is found in a 1735 regulation at Harvard University that decreed, “No Freshman shall go to the Fellows’ John.”
The term sewage is used here to mean only domestic wastewater. Domestic wastewater flows vary with the season, the day of the week, and the hour of the day. Note the wide variation in flow and strength. Typically, average sewage flows are in the range of 100 gallons per day per person, but especially in smaller communities that average can range widely.
      Sewers also commonly carry industrial wastewater. The quantity of industrial wastes may usually be established by water use records, or the flows may be measured in manholes that serve only a specific industry, using a small flow meter. Industrial flows also often vary considerably throughout the day, the day of the week, and the season.
In addition to sewage and industrial wastewater, sewers carry groundwater and surface water that seeps into the pipes. Since sewer pipes can and often do have holes in them (due to faulty construction, cracking by roots, or other causes), groundwater can seep into the sewer pipe if the pipe is lower than the top of the groundwater table. This flow into sewers is called infiltration. Infiltration is least for new, well-constructed sewers, but can be as high as 500m3/(km.day)(200000gal/mi.day).For older systems, 700 m3/(km.day)(300000gal/mi.day)) is the commonly estimated infiltration. Infiltration flow is detrimental since the extra volume of water must go through the sewers and the wastewater treatment plant. It should be reduced as much as possible by maintaining and repairing sewers and keeping sewerage easements clear of large trees whose roots can severely damage the sewers.
Inflow is storm-water collected unintentionally by the sanitary sewers. A common source of inflow is a perforated manhole cover placed in a depression, so that storm-water flows into the manhole. Sewers laid next to creeks and drainage ways that rise up higher than the manhole elevation, or where the manhole is broken, are also a major source. Illegal connections to sanitary sewers, such as roof drains, can substantially increase the wet weather flow over the dry weather flow. The ratio of dry weather flow to wet weather flow is usually between 1:2 and 1:4.
      For these reasons, the sizing of sewers is often difficult, since not all of the expected flows can be estimated and their variability is unknown. The more important the sewer and the more difficult is to replace it）, the more important it is to make sure that it is sufficiently large to be able to handle all the expected flows for the foreseeable future.

System Layout
     Sewers collect wastewater from residences and industrial establishments. A system of sewers installed for the purpose of collecting wastewater is known as a sewerage system (not a sewage system ). Sewers almost always operate as open channels or gravity flow conduits. Pressure sewers are used in a few places, but these are expensive to maintain and are useful only when there are severe restrictions on water use or when the terrain is such that gravity flow conduits cannot be efficiently maintained.
A typical system for a residential area is shown in Figure 1. Building connections are usually made with clay or plastic pipe, 6 inches in diameter, to the collecting sewers that run under the street. Collecting sewers are sized to carry the maximum anticipated peak flows without surcharging (filling up) and are ordinarily made of plastic, clay, cement, concrete or cast iron pipe. They discharge into intercepting sewers, or interceptors, that collect from large areas and discharge finally into the wastewater treatment plant.
Collecting and intercepting sewers must e constructed with adequate slope for adequate flow velocity during periods of low flow, but not so steep a slope as to promote excessively high velocities when flows are at their maximum. In addition, sewers must have manholes, usually every 120 to 180 m(400 to 600 ft) to facilitate cleaning and repair. Manholes are necessary whenever the sewer changes slope, size, or direction. Typical manholes are shown in Figure  

Conclusion
     Sewers have been a part of civilized settlements for thousands of year, and in the modern United States we have become accustomed to and even complacent about the sewers that serve our communities. They never seem to fail, and there never seems to be a problem with them. Most important, we can dump whatever we want to down the drain, and it just disappears.
     Of course, it doesn’t just disappear. It flows through the sewer and ends up in a wastewater treatment plant. The stuff we often thoughtlessly dump down the drain can in fact cause serious problems in wastewater treatment and may even cause health problems in future drinking water supplies. Therefore, we must be cognizant of what we flush down the drain and recognize that it does not just disappear.

需要的人下吧。。。。不是有人要么？呵呵

怎么全是英文的啊
没有几个能看的懂的
还是我英语学的不够啊

废水   的概观;
废水的收集
    "蹒跚" 是许多中古的英文城市的一个街道或区域 , 像伦敦和约克。在十八的和第十九世纪期间，蹒跚被开放买卖区域,藉由如一种主要的工业包装的肉。 蹒跚的屠夫会将他们的全部废物丢进街道, 哪里是进入排水沟渠之内被雨水冲走了。 街道的情况是如此的坏以致于它为 butchery 或一个血腥的战场本来有助于了对英文的语言它名字如一个同义字。
在旧的城市中，在蹒跚像那些的排水沟渠为从城市移动暴风雨水的唯一目的被构造。 事实上, 丢弃人类的排泄物进这些沟渠之内是违法的在伦敦。 最后，沟渠被复盖在而且之上变成我们现在如暴风雨下水道的。 如水补给发展和户内的洗手间的使用,被叫做卫生的废物对传送国内的废水需要,变成明显。在美国，卫生的废物进入暴风雨下水道之内被首先卸货, 然后被运的卫生废物和暴风雨都浇水和是即是组合的下水道。最后地下的一个新的系统以管输送,即是卫生的下水道, 是一为除去卫生的废物构造。在二十的世纪内被建造的城市城市和部份为卫生的废物几乎全部建造分开的下水道而且起风水。

楼主是想拿工份吧：）））