Sanitary Engineer Licensure Exam key terms

The branch of civil engineering that plans, designs, and operates systems for safe water supply, sewage and wastewater collection and treatment, refuse disposal, and the control of environmental conditions affecting public health.

The application of engineering principles to prevent disease and protect community health, chiefly through water quality control, excreta and wastewater management, vector control, and safe food and air environments.

The set of measures controlling environmental factors that form links in disease transmission, including water supply, excreta and refuse disposal, insect and rodent control, food hygiene, and housing conditions.

Water that is safe for human consumption and domestic use, meeting physical, chemical, bacteriological, and radiological standards so that it presents no significant health risk when consumed over a lifetime.

The cloudiness of water caused by suspended and colloidal particles that scatter light, expressed in nephelometric turbidity units; it shields microorganisms from disinfection and is a key treatment performance indicator.

The rapid mixing of a chemical such as alum into water to destabilize the electrical charges on fine particles, allowing them to collide and stick together instead of repelling one another.

Gentle, prolonged stirring of chemically treated water so that destabilized particles collide and agglomerate into larger, settleable masses called flocs that can be removed downstream.

A gravity separation process in which suspended solids denser than water settle to the bottom of a basin under quiescent conditions, producing clearer supernatant and a sludge that must be handled.

Passing water through a bed of granular media such as sand or anthracite to remove residual suspended particles, turbidity, and many microorganisms, typically the final physical barrier before disinfection.

Reversing or scouring the flow through a filter bed with treated water and often air to dislodge trapped solids and restore the media's hydraulic and removal capacity after head loss builds up.

The selective destruction or inactivation of pathogenic microorganisms in water, usually by chlorination or another disinfectant, without necessarily sterilizing the water completely.

The concentration of active chlorine remaining in water after treatment and travel through the distribution system; free residual protects against recontamination and indicates whether disinfection was adequate.

The chlorination practice of adding enough chlorine to oxidize ammonia and other reducing substances and leave a free chlorine residual beyond the breakpoint, improving disinfection and controlling tastes and odors.

The product of disinfectant residual concentration and contact time used to judge disinfection efficacy; required CT varies with disinfectant, temperature, pH, and target pathogen log inactivation.

The estimated quantity of water a community requires over a period, comprising domestic, commercial, industrial, public, and fire-fighting uses plus allowance for losses and unaccounted-for water.

The ratio of maximum to average flow used to size pipes, pumps, and treatment units so they can meet the highest hourly or daily demand without excessive head loss or overflow.

The reduction in hydraulic energy of flowing water caused by friction along pipe walls and by fittings, expressed as a length of water column and used to size pumps and gravity systems.

The slope of the energy or piezometric line along a conduit, equal to head loss divided by length; it determines flow direction and drives gravity distribution and sewer design.

The amount of dissolved oxygen consumed by microorganisms while decomposing organic matter in a water sample under specified conditions, commonly measured over five days at 20 degrees Celsius.

A measure of the oxygen equivalent of organic and oxidizable inorganic matter in a sample, determined by chemical oxidation with a strong oxidant; it is faster than BOD and includes non-biodegradable material.

The initial physical stage of wastewater treatment in which screening, grit removal, and sedimentation remove coarse solids, grit, and settleable matter, typically reducing suspended solids and BOD modestly.

The biological stage of wastewater treatment in which microorganisms oxidize dissolved and colloidal organic matter, usually followed by clarification to separate biomass from the treated effluent.

A biological treatment process in which a mixed culture of aerobic microorganisms is kept in suspension and aerated to consume organic matter, then separated in a clarifier and partly returned to the aeration basin.

The average residence time of microorganisms in an activated sludge system, calculated as the mass of solids in the aeration tank divided by the daily solids leaving the system; it controls sludge settleability.

A condition in which activated sludge settles poorly and compacts inadequately, often because of filamentous organisms or an unsuitable food-to-microorganism ratio, causing solids to escape in the effluent.

A fixed-film biological treatment unit in which wastewater trickles over a bed of stone or plastic media coated with a microbial film that absorbs and oxidizes organic matter as air passes through.

An underground settling and digestion chamber that retains household sewage long enough for solids to settle and anaerobically decompose, producing a clarified liquid discharged to a soakaway or drainfield.

A subsurface system of perforated pipes in gravel or soil that distributes septic tank effluent so it can seep into the ground, where soil filtering and biological action provide further treatment.

The safe handling and disposal of human feces and urine to break the fecal-oral transmission route, using latrines, septic systems, or sewers that keep waste away from water sources and contact.

A pipe network that conveys only domestic and industrial wastewater, excluding stormwater, to a treatment facility; the exclusion of storm inflow reduces treatment plant loading and overflow risk.

A single pipe system that carries both sanitary wastewater and stormwater. During heavy rain it may overflow untreated into receiving waters, so interception or storage structures are used to limit pollution.

The minimum average flow velocity in a sewer that keeps solid particles in suspension and prevents deposition; it must be maintained at design flow while avoiding excessive scour at peak flow.

Groundwater entering a sewer through defective joints and cracked pipes (infiltration) plus direct stormwater entry through illegal connections, roof drains, and manholes (inflow), both adding unwanted flow.

The systematic control of generation, storage, collection, transfer, processing, recovery, and final disposal of discarded materials in a manner protecting public health and the environment.

An engineered disposal site where waste is placed in compacted layers and covered daily with soil or other material, with liner, leachate, and gas controls to limit contamination of water and air.

Liquid that has percolated through solid waste and extracted dissolved or suspended contaminants; it is highly polluting and must be collected and treated before release to soil or water.

A priority ordering of waste strategies that favors prevention first, then reuse, recycling, recovery of energy, and disposal last, guiding policy and design toward the least environmental burden.

Measures that reduce or eliminate organisms such as mosquitoes, flies, and rodents that transmit disease, through drainage, sanitation, biological agents, and judicious use of approved pesticides.

The introduction of pollutants into subsurface water by percolation from landfills, septic systems, agricultural chemicals, or spills; once contaminated, an aquifer is slow and costly to restore.