Nicholas P. Cheremisinoff. Handbook of Solid Waste Management and Waste Minimization Technologies
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distribution pipe or tile line embedded in drain field gravel or rock. (6) The effluent
drains out through holes in the pipe or seams between tile sections, then through the
drain field gravel or rock and into the soil. (7) The soil filters remaining minute
solids, some dissolved solids, and pathogens (disease-producing microorganisms).
Water and dissolved substances slowly percolate outward into the soil and down
toward groundwater or restrictive layers. A portion of the water evaporates into the
air, and plants growing over the drain field lines utilize some of the water.
Settleable Solids - Those solids in suspension which will pass through a 2000-
micron sieve and settle in 1 hr under the influence of gravity.
Sewage - The used water and water-carried solids from homes that flow in sewers to
a wastewater treatment plant. The preferred term is wastewater.
Sewage Sludge - A solid, semisolid, or liquid residue generated during the treatment
of domestic sewage in a treatment works.
Sewers - A system of pipes that collect and deliver wastewater to treatment plants or
receiving streams.
Shock Load - The arrival at a plant of a waste which is toxic to organisms in
sufficient quantity or strength to cause operating problems. Possible problems
include odors and sloughing off of the growth or slime on a trickling-filter medium.
Organic or hydraulic overloads also can cause a shock load.
Sieve - A screen with apertures of uniform size used for sizing granular materials.
Single-loop Controllers - A self-contained unit composed of microprocessor-based
sequencers, timers, and programmable logic controllers all dedicated to controlling a
single loop or specific system.
Sink Hole - A naturally occurring basin which has no visible external or surface
drainage, and in which ponding may occur during or following periods of rainfall.
Siphon - A closed conduit that lies above the hydraulic grade line, resulting in a
pressure less than atmospheric and requiring a vacuum within the conduit to start
flow. A siphon utilizes atmospheric pressure to effect or increase flow through the
conduit.
Siting - Choosing a location for a facility.
Skimming - (1) The process of diverting water from the surface of a stream or
conduit by means of a shallow overflow. (2) The process of removing grease or
scum from the surface of waste water in a tank.
Skimmings - Grease, solids, liquids, and scum skimmed from waste water settling
tanks.
Slake - To become mixed with water so that a true chemical combination takes
place, as in the slaking of lime.
Sleeve Bearing - Also known ^journal bearing. A metal jacket fully or partially
enclosing a rotating inner shaft.
Slimes - (1) Substances of a viscous organic nature, typically formed from
microbiological growth, that attach themselves to other objects, forming a coating.
(2) The coating of biomass that accumulates in trickling filters or sand filters and
periodically sloughs away to be collected in clarifiers.
Sloughings - Trickling-filter slimes that have been washed off the filter media. They
are generally quite high in BOD and will lower effluent quality unless removed.
Sludge - (1) Accumulated solids separated from liquids during the treatment process
that have not undergone a stabilization process. (2) Removed material resulting from
chemical treatment, coagulation, flocculation, sedimentation, flotation, or biological
oxidation of water or wastewater. (3) Any solid material containing large amounts of
entrained water collected during water or wastewater treatment.
Sludge Age - Average residence time of suspended solids in a biological treatment
system equal to the total weight of suspended solids in the system divided by the
total weight of suspended solids leaving the systems.
Sludge Blanket - Accumulation of sludge hydrodynamically suspended within an
enclosed body of water or wastewater.
Sludge Blanket Depth - Also referred to as depth of blanket and is a measurement
of the depth of solids in a vessel. The measurement may be performed using a sonic
meter, density meter, or Secchi disc.
Sludge Boil - An upwelling of water and sludge deposits caused by release of
decomposition gases in the sludge deposits.
Sludge Concentration - Any process of reducing the water content of sludge while
leaving the sludge in a fluid condition.
Sludge Collector - A mechanical device for scraping the sludge on the bottom of a
settling tank to a sump from which it can be drawn.
Sludge Density Index - A measure of the degree of compaction of a sludge after
settling in a graduated container, expressed in milliliters per gram (ml/g). The
sludge density index is the reciprocal of the sludge volume index (SVI).
Sludge Holding Tank - A tank, typically constructed of steel or concrete, that is
used for liquid sludge storage.
Sludge Lagoon - An earthen basin that receives only sludge that has been removed
from a waste water treatment facility. It does not include a wastewater treatment
lagoon or sludge treatment units that are a part of a mechanical treatment.
Sludge Solids - Dissolved and suspended solids in sludge.
Sludge Thickening - The increase in solids concentration of sludge resulting from
gravitational force in a sedimentation or digestion tank.
Sludge Volume Index (SVI) - The ratio of the volume (in milliliters) of sludge
settled from a 1000-ml sample in 30 minutes to the concentration of mixed liquor (in
milligrams per liter (mg/1)) multiplied by 1000. The SVI is the reciprocal of the
sludge density index.
Slugs - Intermittent releases or discharges of industrial wastes.
Slurry - A watery mixture of insoluble matter, such as lime slurry.
Small Quantity Generator (SQG) - Persons or facilities that produce 220 to 2,200
pounds per month of hazardous waste. SQGs are required to keep more records than
conditionally exempt generators. SQGs may include automotive shops, dry cleaners,
photographic developers, and a host of other small enterprises. SQGs comprise by
far the vast majority of hazardous waste generators.
Smog - Dust, smoke, or chemical fumes that pollute the air and make hazy,
unhealthy conditions (literally, the word is a blend of smoke and fog). Automobile,
truck, bus, and other vehicle exhausts and particulates are usually trapped close to
the ground, obscuring visibility and contributing to a number of respiratory
problems.
Soda Ash - A common name for commercial sodium carbonate (Na
2
CO
3
).
Sodium Bisulfite (NaHSO
3
) - A salt used for reducing chlorine residuals. A strong
reducing agent; typically found in white powder or granular form in strengths up to
44%.
At a strength of 38%, 1.46 parts sodium bisulfite will consume 1 part of
chlorine residual.
Sodium Carbonate (Na
2
CO
3
) - A salt used in water treatment to increase the
alkalinity or pH of water or to neutralize acidity. Also called soda ash.
Sodium Hydroxide (NaOH) - A strong caustic chemical used in treatment processes
to neutralize acidity, increase alkalinity, or raise the pH value. Also known as
caustic soda, sodium hydrate, lye, and white caustic.
Sodium Hypochlorite (NaOCl) - A water solution of sodium hydroxide and
chlorine in which sodium hypochlorite is the essential ingredient.
Sodium Metabisulfite (Na
2
S
2
O
5
) - A cream-colored powder used to consume
chlorine residual. 1.34 parts of sodium metabisulfite will consume 1 part of chlorine
residual.
Soil - A natural body synthesized over time from a mixture of inorganic and organic
parent materials, now supporting living plants. Soils with depth have natural
horizons (layers) that give them their properties. Such properties include texture,
color, structure, and bulk density.
Soil pH - An index of the acidity or alkalinity of a suspension of soil in a liquid such
as distilled water or dilute salt solution. The index is the logarithmic expression of
the activity of H-ions in the liquid surrounding the soil particles. A pH >7.0 is
alkaline and < 7.0 is acid. A soil pH is not a measure of total acidity in a soil. It is a
measure of the acidity or alkalinity of the soil.
Soil Profile - A two-dimensional view of the soil from the earth's surface down to
and including the parent material.
Soil Saturation - The water content of a soil beyond which no more water is
absorbed.
Soil Structure - The arrangement of soil particles into larger particles or clumps.
This arrangement modifies the bulk density and porosity of the soil.
Soil Washing - Water-based volume reduction process in which contaminated soil or
dredgings are separated into a small contaminated fraction, for further treatment or
disposal, and a larger cleaned fraction.
Solid Waste - As defined under RCRA, any solid, semisolid, liquid, or contained
gaseous materials discarded from industrial, commercial, mining, or agricultural
operations, and from community activities. Solid waste includes garbage,
construction debris, commercial refuse, sludge from water supply or waste treatment
plants or air pollution control facilities, and other discarded materials.
Solid Waste Management Facility - Any disposal or resource recovery system; any
system, program, or facility for resource conservation; any facility for the treatment
of solid wastes.
Solidification - Solidification methods result in a solid, low-permeable block of
contaminated soil or sludge. To accomplish this, solidifying admixtures which
mechanically lock contaminants within the solidified matrix are incorporated into the
sludge or contaminated soil. This may or may not involve chemical bonding between
the toxic contaminant and the additive. By decreasing the exposed surface area
and/or encapsulating the waste, contaminant migration can be significantly
decreased.
Solids Inventory - Mass of sludge in the treatment system. Inventory of plant solids
should be tracked through the use of mass balance set of calculations.
Solids Loading - Amount of solids applied to a treatment process per unit time per
unit volume.
Solids Retention Time (SRT) - The average time of retention of suspended solids in
a biological waste water treatment system. Equals the total weight of suspended
solids leaving the system per unit time.
Soluble - Matter or compounds capable of dissolving into a solution.
Soluble BOD - The BOD of water that has been filtered in the standard suspended
solids test.
Solution - A liquid mixture of dissolved substances, displaying no phase separation.
Solvent - Typically a liquid substance capable of dissolving or dispersing one or
more other substances.
Source Reduction - The design, manufacture, purchase, or use of materials (such as
products and packaging) to reduce the amount or toxicity of garbage generated.
Source reduction can help reduce waste disposal and handling charges because the
costs of recycling, municipal composting, landfilling, and combustion are avoided.
Source reduction conserves resources and reduces pollution.
Source Separation - Organizing materials by type (such as paper, metal, plastic,
and glass) so that these items can be recycled instead of thrown away. For example,
many of us separate these items from the rest of our household and office wastes.
Industries also organize materials in this fashion.
Sparger - An air diffuser designed to give large bubbles. Used singly or in
combination with mechanical aeration devices.
Spec. Sheet - Specification Sheet. Detailed information on a product, including
tests,
color, odor, specific gravity, bacterial strains, other major ingredients, etc.
Species - A subdivision of a genus having members differing from other members of
the same genus in minor details.
Specific Gravity - The ratio of the mass of a body to the mass of an equal volume
of water at a specific temperature.
Specific Oxygen Uptake Rate (SOUR) - A measure of the microbial activity in a
biological system expressed in milligrams of oxygen per hour per gram of volatile
suspended solids. Also called respiration rate.
Spiral Air Flow Diffusion - A method of diffusing air in the grit chamber or
aeration tank of the activated-sludge process where, by means of properly designed
baffles and the proper location of diffiisers, a spiral helical movement is given to the
air and the reactor liquor.
Split Bearing Cover - A bearing cover plate that is made up of two halves that can
be easily removed to access the bearing for maintenance or inspection.
Split Case Pump - A pump with a casing that is split parallel to the drive shaft.
Split Rigid Coupling - An inflexible coupling that is split in half parallel to the
pump shaft. This coupling is very useful when the pump impeller needs to be
positioned further away or closer to the motor.
Splitter Box - (1) A division box that splits the incoming flow into two or more
streams. (2) A device for splitting and directing discharge from the head box to two
separate points of application.
Spray Aerator - An aerator consisting of a pressure nozzle through which water is
propelled into the air in a fine spray.
Squirrel Cage Motor - A polyphase motor that is widely used in water and
waste water treatment applications and can be purchased in many configurations.
Enclosures for these motors include open
drip-proof,
totally enclosed non-ventilated,
and totally enclosed fan cooled.
Stabilization - Stabilization techniques limit the solubility or mobility of
contaminants in sludge, even though the physical characteristics of the waste may
not be changed or improved. To accomplish this, reagents are added or other
specialized materials and blended with the sludge or contaminated soil. Stabilization
ensures that the hazardous components are maintained in their least mobile or toxic
form.
Staged Treatment - (1) Any treatment in which similar processes are used in series
or stages. (2) In the activated-sludge process, two or more stages consisting of a
clarifying stage and a biological stage, or two biological stages. (3) In anaerobic
digestion, an operation in which sludge is completely mixed in the first tank and
pumped to a second tank for separation of the supernatant liquor from the solids.
Standard Industrial Classification Code (SIC Code) - A method of grouping
industries with similar products or services and assigning codes to these groups.
Standard Methods - An assembly of analytical techniques and descriptions
commonly accepted in water and waste water treatment (i.e., Standard Methods for
the Examination of Water and Wastewater) published jointly by the American Public
Health Association, the American Water Works Association, and the Water
Environment Federation.
Standard Pressure - Atmospheric pressure at sea level under standard conditions.
Standby Motor - An identical motor that is maintained in case of breakdown or
malfunction of a pump's prime driver.
State Emergency Response Commission (SERC) - The agency appointed by the
governor of a state to oversee the administration of EPCRA at the state level. This
commission designates and appoints members to LEPCs and reviews emergency
response plans for cities and counties.
Static Head - Vertical distance between the free level of the source of supply and
the point of free discharge or the level of the free surface.
Static Level - (1) The elevation of the water table or pressure surface when it is not
influenced by pumping or other forms of extraction. (2) The level of elevation to
which the top of a column of water would rise, if afforded the opportunity to do so,
from an artesian aquifer, basin, or conduit under pressure. Also called hydrostatic
level.
Static Suction Head - The vertical distance from the source of supply when its level
is above the pump to the center line of the pump.
Static Suction Lift - The vertical distance between the center of the suction end of a
pump and the free surface of the liquid being pumped. Static lift does not include
friction losses in the suction pipes. Static suction head includes lift and friction
losses.
Static Tubular Aerator - A system in which air is blown into vertical tubes
submerged in a liquid, promoting mixing and oxygen transfer.
Stator - The stationary member of an electric motor or generator.
Steady Flow -(I)A flow in which the rate or quantity of water passing a given
point per unit of time, remains constant. (2) Flow in which the velocity vector does
not change in either magnitude or direction with respect to time at any point or
section.
Steady Nonuniform Flow - A flow in which the quantity of water flowing per unit
of time remains constant at every point along the conduit but the velocity varies
along the conduit because of a change in the hydraulic characteristics.
Step Aeration - A procedure for adding increments of settled wastewater along the
line of flow in the aeration tanks of an activated-sludge plant.
Step-feed Process - A procedure for adding increments of settled wastewater along
the line of flow in biological reactors of an activated-sludge process.
Sterilization - The destruction of all living organisms. In contrast, disinfection is the
destruction of most of the living organisms.
Stiff White Foam - A collection of minute bubbles that are formed on the surface of
biological reactors when incomplete digestion of surfactants occurs.
Stoichiometric - Pertaining to or involving substances that are in the exact
proportions required for a given reaction.
Storm Sewers - A separate system of pipes that carry only runoffs from buildings
and land during a storm.
Stormwater - That portion of rainfall that does not infiltrate into the soil.
Stormwater Management - The management of runoff to provide controlled release
rates to receiving systems, typically through the use of detention/retention facilities
such as lakes.
Straggler Floe - Large (6 mm or larger) floe particles that have poor settling
characteristics.
Strain Gauge - A device that converts a movement, such as a coil of wire as it is
loaded, into a change in electrical properties. This results in a very sensitive
measurement of the strain. Strain gauges are often used in pressure sensors and
weight scales.
Submerged Aerated Filter - A device in which highly aerated effluent flows
through inert medium that is completely submerged; fixed microbial film reduces the
BOD and ammoniacal content of the effluent.
Submerged Biological Contactor - An aerobic treatment system in which plastic
medium that is largely submerged in effluent is rotated by rising air, the fixed
microbial film on the medium reducing the BOD value.
Submersible Pump - A motor and pump combination designed to be placed entirely
below the liquid surface. Submersible pumps are typically constructed as pumps
vertically closed-coupled to a submersible motor. They are used for domestic and
industrial treatment applications and for pumping ground water from wells.
Submicron Particles - Particles of less than ljum in size, present in smoke and
fumes.
Subsoil - The part of the soil profile beneath the surface soil that has been altered
from its original geologic characteristics. In many instances, it is called a "B
horizon."
Substrate - (1) Substances used by organisms in liquid suspension. (2) The liquor in
which activated sludge or other matter is kept in suspension.
Suction Gauge - A pressure gauge placed on suction piping near the point where the
pump connection is made. The gauge reading gives a good approximation of the
suction head conditions.
Suction Head - (1) The head at the inlet to a pump. (2) The head below atmospheric
pressure in a piping system.
Suction Lift - The vertical distance from the liquid surface in an open tank or
reservoir to the center line of a pump drawing from the tank or reservoir and set
higher than the liquid surface.
Suction Valve - A valve that is located on the suction piping of a pump.
Suctoreans - Ciliates that are stalked in the adult stage and have rigid tentacles to
catch prey.