CE110 - Technology

*centralized systems

systems that serve a large population with a piped network (can be potable water or wastewater)

*decentralized systems

systems that serve a single household up to a neighborhood (can be potable water or wastewater).

*Unavoidable annual real losses (UARL)

Background leakage

*storm sewer

a sewer that carries only surface runoff, street wash, and snow melt from the land. In a separate sewer system, storm sewers are completely separate from those that carry domestic and commercial wastewater (sanitary sewers).

*combined sewer overflow (CSO)

the discharge of untreated wastewater from a combined sewer, consisting of raw wastewater diluted by stormwater. Combined sewer overflows occur during large storms when the combined flow of wastewater and stormwater is greater than the treatment plant can handle.

*water distribution system

network for distributing potable water to consumers, consisting of pipes and treated water storage reservoirs

*wastewater

water that has been used in homes, industries, and businesses; includes blackwater and greywater.

*blackwater

flush water from toilets (the water, plus the feces and urine)

*Biochemical oxygen demand (BOD)

the concentration of oxygen needed by bacteria to degrade organic matter in wastewater. You can think of BOD as the concentration of biodegradable organic matter.

*fecal sludge

the material removed from latrine chambers and septic tanks (also called septage). Fecal sludges are highly concentrated and thus requires treatment methods different than regular wastewater. Depending on the time of removal, the material can be fresh or have undergone significant decomposition.

*suspended solids

particles that are suspended in water (i.e., they are not dissolved) and can be removed by settling and filtration. Such suspended solids usually contribute directly to turbidity.

*effluent

water that flows from a sewage treatment plant after it has been treated.

*primary wastewater treatment

the first stage of the wastewater-treatment process where mechanical methods, such as filters and scrapers, are used to remove pollutants. Solid material in sewage also settles out in this process.

**secondary wastewater treatment

secondary treatment (following primary wastewater treatment) is usually a biological process for removing dissolved organic matter (or Biochemical Oxygen Demand (BOD)) from primary effluent. Activated sludge is a common means of secondary treatment and has two steps. In the first step, bacteria are provided with oxygen in large aerated basins and the bacteria consume (“eat”) the dissolved BOD, which results in the growth of bacteria. In the second step, the bacteria are removed by settling (secondary clarifier) and most of the bacterial solids (waste activated sludge) is returned to the aeration basin.

*tertiary wastewater treatment

Additional treatment of wastewater beyond that of primary and secondary treatment methods to obtain a higher quality of effluent, typically for non-potable reuse. Tertiary treatment typically consists of coagulation, flocculation, granular media filtration, and disinfection

*advanced treatment

treatment of wastewater beyond secondary treatment (can include nutrient removal, filtration…etc)

*filtration

removal of particles (including suspended solids) from water by passing the water through a bed of granular media (like sand).

*sewer

a system of underground pipes that collect and deliver wastewater to treatment facilities or streams. Sewers can be combined (draining both stormwater and wastewater) or separate (sewer collects only wastewater; a separate storm drain system is used for stormwater)

*septic tank

a tank used to detain domestic wastes to allow the settling of solids prior to distribution to a leach (drain) field for soil absorption. Septic tanks are used when a sewer line is not available to carry them to a treatment plant.

*sedimentation

a treatment process to remove suspended solids by gravitational settling.

*primary energy

energy in the form that it occurs in nature. Natural gas, coal, sunlight, wind are all primary energy sources. Electricity is not because it must be converted from its natural form. The conversion process involves a loss of usable energy.

*energy intensity

energy required to achieve a particular goal; in water systems, energy consumption per unit volume of water supplied, treated, or delivered

*dead pool

the lowest water elevation where water can flow downstream from the dam

*power pool

the lowest water elevation for producing hydropower at a dam

pumped storage

method of storing energy as gravitational potential energy in water by pumping from a lower elevation reservoir to a higher elevation and recovering energy as it flows down again

Resource recovery

producing useful products from wastewater products, especially water, energy, and nutrients (We’ll come back to this one later in the semester!)

Reasons for increases in energy use

• Population/Economic Growth

• Expansion of services (e.g. to provide safe drinking water or extra levels

• Energy intensity which increases due to:

  • Tapping lower quality sources to meet increasing demands 

  • Pumping longer distances or greater elevation change 

  • Falling groundwater elevations

  • More contamination

  • More stringent regulatory requirements

  • Infrastructure deterioration

technology lock-in

A current investment or design decision reduces future options.

stranded asset

Infrastructure that is abandoned before the end of its design lifetime

wastewater-based epidemiology

studying the occurrence and causes of disease in human populations via monitoring targets in wastewater