Glossary
| A | B | C | D | E | F | G | H | I | K | L | M | N | O | P | R | S | T | U | V | W |
A
Ad hoc management: A management approach in which no comprehensive effort is made to promote water efficiency: Efficiency actions that are implemented are likely to have been made without considering the effect on efficiencies in other parts of the system.
Adjustable speed drive (ASD): Devices that allow pumps and motors to adjust speeds to match varying load requirements.
Aeration control systems: Control systems that help optimize water treatment performance by controlling and adjusting the amount of air put into wastewater basins.
Air drying: The final stage in the primary treatment process of sludge in which digested sludge is placed on sand beds for air drying. Air drying requires dry, relatively warm weather for greatest efficiency; some plants have a greenhouse-like structure to shelter the sand beds.
Anaerobic digestion: An option of sludge processing that produces methane that can be burned as a fuel.
Aquifers: One or more geologic formations containing sufficient saturated porous and permeable material to transmit water at a rate sufficient to feed a spring or for economic extraction by a well.
B
Baseline: An analysis of the efficiency of a water utilities operation at a given point of time that can be used to compare with future efficiency.
Benchmark: Something that serves as a standard by which others may be measured or judged.
Bubble diffusers: In wastewater treatment, devices used to provide oxygen and agitation in biological treatment.
Bundling: Inclusion of many smaller projects together in a larger project.
Buyback: Offering industries money if they succeed in reducing certain levels of water everyday.
Bypass valve: Valve that allows flow to go around a system component by increasing or decreasing the flow resistance in a bypass line.
C
C-value: A factor of value used to indicate the smoothness of the interior of a pipe: The higher the c-value, the smoother the pipe, the greater the carrying capacity, and the smaller the friction or energy losses from water flowing in the pipe: To calculate the c-value, measure the flow, pipe diameter, distance between two pressure gauges, and the friction or energy loss of the water between them.
Capacitors: Devices that store electrical energy and are used to correct low power factor: Capacitors improve power factor and reduce the total power (kVA) that equipment consumes by supplying magnetic needs and locally reducing the reactive power (kVAR).
Centrifuge: A type of equipment used for dewatering: Centrifuges use rapid rotation of a fluid mixture inside a rigid vessel: The many designs of centrifuges include solid bowl, basket, and disc-stack.
Champion: A strong advocate for water efficiency in a water utility.
Chlorination: A major disinfection process for wastewater.
Climate change: A phenomenon caused by increased concentrations of CO2, methane, and other greenhouse gases that has begun to affect municipalities adversely around the world through more extreme weather events, such as droughts, heat waves, floods, and storms.
Cogeneration: The production of electricity using waste heat (as in steam) from an industrial process or the use of steam from electric power generation as a source of heat.
Comminutor: Equipment that grinds up debris into finer particles.
Computerized control systems: Managing energy use by controlling pump operation, monitoring pump efficiencies, shifting loads to off-peak times, and controlling variable speed drives or pumps.
Cross-fertilization: In this report, the exchange of ideas and information among departments and people of different backgrounds.
D
Demand-side: Actions that reduce the amount of water consumed: This creates more system capacity, possibly avoiding investments in new facilities and equipment.
Dewatering: Sludge typically has a water content of greater than 90 percent, causing expensive recycling or disposal of pretreated sludge: Dewatering separates the liquids from the solids, thereby reducing recycling or disposal costs.
Digester gas: In anaerobic digestion, the sludge is fed into an air-free vessel: The digestion produces a gas, which is mostly a mixture of methane and carbon dioxide: The gas has a fuel value and can be burned to provide heat to the digester tank and even to run electric generators: This gas is called digester gas.
Digestion: A method of biological sludge treatment: Digestion can be either aerobic or anaerobic.
Disinfection: Destroying harmful microorganisms, thereby freeing from infection.
E
Efficiency kits: These contain inexpensive water-saving devices; supplied by municipalities to induce customers to conserve water.
Energy management system: A management structure designed to identify, implement, and verify savings from energy efficiency opportunities.
Energy performance contract (EPC): A way to finance and implement a capital improvement project by using a client’s cost savings to cover project costs: An energy services company (ESCO) provides this service.
Energy services company (ESCO): A company that offers to reduce a client’s energy costs, often splitting the cost savings with the client through an energy performance contract (EPC) or a shared savings agreement.
F
Facility assessment: A review of all equipment and devices involved with the processing, delivery, and treatment of water to identify efficiency opportunities: Also referred to as facility energy audits.
Filter press: A method of sludge dewatering.
Financial hurdle rate: A rate of return on investment that a proposed project must reach to be implemented.
Friction: The force that resists relative motion between two bodies in contact.
Frictional head: The head component attributable to friction.
G
Gray water: Processed wastewater not fit for drinking, but that can be used effectively in the industrial sector and for toilets or certain agricultural uses.
Grit removal: A wastewater treatment process to remove solids from wastewater.
H
Head: The measure of pressure indicating the height of a column of system fluid that has an equivalent amount of potential energy.
Headworks: A device or structure at the front or diversion point of a waterway to control the amount of water flowing.
Horizontal axis washing machine: A type of washing machine that spins clothes along a horizontal axis. They typically use less water than vertical axis machines.
I
Impeller: The spinning component in a centrifugal-type pump that pushes fluid through the system.
Incineration: A method of sludge treatment involving burning of the solid portion of the waste.
Infiltration: When water or other liquid permeates into a sealed pipe.
K
Kilovolt-ampere (kVA): A measurement of total power—active power, which does work (watts), and reactive power, which creates an electromagnetic field (VAR) (kVA2 = kW2 + kVAR2). Capacitors can help reduce the total power required by supplying magnetic requirements (kVAR) on site.
Kilovolt-ampere reactive power (kVAR): One VAR is equal to a volt-ampere of reactive power; a kVAR is one thousand VARs: Reactive power does not do work like active power (kilowatts), but instead produces an electromagnetic field. Installing a capacitor can generate the required magnetic field on-site, reducing the total power (kilovolt-amperes) required to run a piece of equipment.
L
Load profile: A set of data often in graphic form portraying the significant features of energy consumption and demand of customers.
M
Metering: Measurement of water and electricity flow and consumption.
Methane: A colorless odorless flammable gaseous hydrocarbon (CH4) produced by decomposition of organic matter and carbonization of coal and is used as a fuel and starting material in chemical synthesis.
Metrics: Measures of water efficiency. By creating a set of metrics to gauge improvements and identify inefficiencies, water efficiency management teams will be better able to prioritize opportunities and assess their progress.
Monitoring: Tracking water efficiency programs: By developing comprehensive monitoring systems, many potential supply-side and demand-side savings opportunities can be identified, implemented, and verified.
N
Nomograph: A graph consisting of three coplanar curves, each graduated for a different variable, so that a straight line cutting all three curves intersects the related values of each variable.
O
Organochlorine: A by-product of the chlorine disinfection process for wastewater.
Outsourcing: The practice of subcontracting a function or most functions to outside companies. See also “energy service contracts:”
Overdesign: Systems designers occasionally overestimate the needed capacity to meet highest flow conditions. This can lead to operational problems and increases in costs.
Overharvesting: Removing more water from the ground, lakes, and rivers than is naturally replaced. This is an environmentally threatening endeavor.
Oxidation ditch: A ditch that holds partially treated wastewater to allow algae, aquatic plants, and microorganisms in decomposition process of the organic waste.
Ozonation: A disinfection process for wastewater using ozone.
P
Payback: The rate at which the savings from the project covers the initial costs of the project.
Pilot project: A small-scale version of a large project: Many utilities like to test ideas and potential actions on a small pilot level before they commit to a large investment.
Pipe relining: Recoating the interior of pipes with a low friction material to reduce friction losses.
Power factor: The ratio of active power (kW) to total power (kVA): A low power factor indicates a high level of reactive power (kVAR) that can waste electricity. Many utilities charge a penalty for low-power factors. Installing capacitors can correct low-power factors.
Pressure gauges: Instruments to measure pressure within a water system.
Price structure: A system that charges different prices for different customers and levels of consumption. To determine an appropriate price structure, utilities usually ascertain the price elasticity of water demand.
Primary treatment: The key method for pollutant removal from sewage by means of sedimentation.
Programmable logic controls: Computerized control systems applied to electrically controlled equipment, such as pump variable frequency drives.
Proportional, integral, and derivative control (PID): Used to moderate wastewater flows rather than allow wastewater to surge and then stop.
Pump efficiency: A measure of the ability of a pump to transfer energy efficiently into pumping action.
R
Real-time rate pricing: The cost of buying or selling power based on the actual rates at specific times during the day.
Recalibration: Reformulating the set of graduations to indicate values or positions on a meter gauge.
Reclaimed water use: Water that has been used and would normally be disposed of, but is instead reused.
Renewable water: The amount of water that a watershed can replenish during a given timeframe: This is the amount of water that can safely be extracted without the danger of overharvesting.
Return on investment (ROI): A financial metric used to assess projects (ROI = profit/average capita * 100).
S
Screening: A primary wastewater treatment process to remove solids.
Secondary treatment: Also known as biological treatment, this process further reduces the amount of solids by helping bacteria and other microorganisms consume the organic material in the sewage.
Sludge treatment: Stabilization or removal of hazardous waste constituents from a waste that is a mixture of both liquids and solids.
Stabilization: A sludge treatment process that chemically or physically immobilizes the hazardous constituents in the waste by binding them into a solid mass: The resulting product has a low permeability that resists leaching.
Static head: The head component attributable to the static pressure of the fluid.
T
Thickening: A sludge treatment process that removes as much water as possible before final dewatering of the sludge.
Throttle valves: A valve that regulates the supply of a fluid by increasing or decreasing the flow resistance across it.
Trickling filters: Used to reduce biological oxygen demand, pathogens, and nitrogen levels, trickling filters are composed of a bed of porous material (rocks, slag, plastic media, or any other medium with a high surface area and high permeability). Wastewater is first distributed over the surface of the media, where it flows downward as a thin film over the media surface for aerobic treatment and is then collected at the bottom through drain systems.
Trihalomethanes: Chlorinated by-products of wastewater disinfection processes.
U
Ultraviolet disinfection: A process using an ultraviolet (UV) light source, which is enclosed in a transparent protective sleeve. It is mounted so that water can pass through a flow chamber, and UV rays are admitted and absorbed into the stream. These rays destroy bacteria and deactivate many viruses.
Ultraviolet irradiation: UV irradiation is a physical disinfection process and, thus, different from a chemical disinfection process, such as chlorination. It has become the most common alternative to chlorination for wastewater disinfection in North America.
Unaccounted-for water: Loss in water supply and treatment due to leaks, unauthorized water usage, and poor water distribution and system maintenance.
V
Vacuum filter: A system of sludge dewatering.
Variable frequency drives: Drives used to match motors and pumps to varying load requirements.
W
Water accounting: A system to account for water brought in from a source and delivered to end users, the customers. It should identify unmetered water, unauthorized water usage, leaks, losses, and so on.
Water audit: A methodical examination and review of a customer’s water consumption. Water audits can point out savings opportunities to the end user and, thus, act as a catalyst to induce implementation of efficiency measures.
Water subsidy: Charging a low water rate to consumers, even though the true cost of using water may be much higher. This has a distortionary effect and also encourages wasteful behavior.
Water-saving equipment: Equipment that helps conserve water, for example, low-flow faucets, ultralow flush toilets, efficient washing machines, and so on.
Water-use categories: Different categories used to identify different types of water users, that is, residential, commercial, and so on: Targeting relevant efficiency programs at each category will be much more effective than having one generic program for all.