Water and Wastewater Engineering

This set of vocabulary flashcards covers the fundamentals of water and wastewater engineering, including water sources, quality parameters, supply systems, sewer design, and biological treatment kinetics.

Potable water

Water that is fit for drinking, safe, and agreeable.

Wholesome water

Water which contains minerals in small quantities at a requisite level and is free from harmful impurities.

Surface sources

Water sources including ponds, lakes, streams, rivers, and storage reservoirs.

Sub-surface sources

Underground water sources including springs, infiltration wells, wells, and tube-wells.

Average water need

An estimated average of $6517355000000000000\,liters/capita/day$.

Continuous Water Supply System

A system where water is available $24\,hours$ a day and seven days a week.

Intermittent Water Supply System

A system where water is supplied for a few hours every day or on alternate days.

Per capita demand formula

Calculated as $Q/P$, representing the quantity of water supplied during the year divided by the number of days in the year and the number of persons served.

Arithmetical increase method formula

$P_n = P + nI$, where $P$ is the population of the base year, $n$ is the number of decades, and $I$ is the average increase per decade.

Geometric increase method formula

$P_n = P (1 + \frac{i}{100})^n$, where $i$ is the percentage increase per decade.

Colloidal Particles

Electrically charged particles in constant motion with sizes ranging from $1\,\mu m$ to $1\,mili\,micron$, which cannot be removed by filtration but require coagulation.

Dissolved Particles

Impurities with sizes less than $10^{-3}\,\mu m$ obtained by weighing the residue after evaporation from a filtered sample.

Turbidity

A measure of the extent to which light is absorbed or scattered by suspended material, measured in Nephlometric Turbidity Units (NTU).

Alkalinity

The quantity of ions in water that will react to neutralize hydrogen ions; a measure of buffering capacity.

Total hardness

Caused by multivalent metallic cations, primarily calcium and magnesium; considered very hard if in excess of $300\,mg/L$.

Fluorosis

Mottling of teeth caused by excessive levels of fluoride in drinking water supplies.

Toxic heavy metals

A group of harmful metals including arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver.

Biodegradable organics

Organic materials like starches, fats, proteins, alcohols, and acids that can be utilized as food by microorganisms.

Biological Parameters

Indicators of pathogens including bacteria, viruses, protozoa, and helminths; specifically $Escherichia\,coli$ and Total coliform.

Aeration

A unit operation of gas transfer used to remove taste and odor, decrease $CO_2$, and increase dissolved oxygen ($DO$).

Sedimentation

The removal of suspended particles through gravitational settling by reducing the velocity of flow.

Black water

Wastewater originating from toilets, kitchens, and sinks, containing human waste and potentially macro-plastics.

Grey Water

Wastewater source from bathroom sinks and washing machines without urine, feces, or food waste; suitable for reuse.

Night Soil

A historical term for human excreta (feces and urine), now more commonly called fecal sludge.

Sullage

Wastewater originating from bathrooms, kitchens, and wash basins that lacks organic matter from human waste.

Sewerage

The network of sewers used in the collection, conveyance, and disposal of waste.

Dry weather flow (DWF)

The flow through sewers available during non-rainfall or dry periods.

Lateral sewer

A pipe that receives discharge from one or more houses and carries it to a branch sewer.

Outfall sewer

The component that receives flow from the trunk sewer and conducts it to a treatment plant or final disposal.

Drop man-hole

A manhole used when the difference in elevation between incoming and outgoing sewers is more than $60\,cm$.

Combined system

A sewerage system where only one sewer is installed to transfer both sanitary sewage and storm sewage.

Wastewater return factor

The ratio of wastewater to water supply, generally ranging from $70\%$ to $90\%$, practically calculated as $Q_{ww} = 0.8Q_{ws}$.

Peak factor for population < 20,000

A factor of $3$ used to estimate maximum flow; the peak factor decreases as the contributory population increases.

Rational Method Formula for storm water

$Q = \frac{CIA}{360}$, where $C$ is the runoff coefficient, $I$ is rainfall intensity ($mm/hr$), and $A$ is the catchment area in hectares.

Primary treatment

Wastewater processes using physical unit operations like screening, grit chambers, and skimming tanks to remove large floating and settleable solids.

Secondary treatment

Biological processes such as trickling filters or activated sludge used to remove soluble and colloidal organic matter.

Aerobic process

A metabolic activity of microorganisms that essentially requires the presence of molecular oxygen.

Anaerobic process

A process that operates in the absence of molecular oxygen, such as an anaerobic sludge digester.

Monod Equation

$\mu = \mu_m \frac{S}{S+K_s}$, where $\mu_m$ is the maximum growth rate constant and $K_s$ is the half velocity constant.

Half velocity constant ($K_s$)

The concentration of the limiting substrate when the growth rate constant ($\mu$) is half of the maximum growth rate constant ($\mu_m$).