Free Water Treatment Class I Exam Flashcards

It destabilizes charged colloids so they can collide and form removable floc. If the particles remain charge-stabilized, they can pass through clarification and burden the filters.

Rapid mixing disperses the chemical through the flow before the initial reactions are lost. Uneven dispersion produces underdosed and overdosed zones instead of consistent destabilization.

Gentle mixing should create collisions that grow settleable floc. Too little mixing limits contact; excessive shear can break formed floc into particles that are harder to settle or filter.

Settling removes much of the particle mass before it reaches the filters. Effective clarification reduces filter loading, slows head-loss development, and supports longer, more stable filter runs.

Direct filtration sends conditioned water to filtration without a separate sedimentation step. Because the filter receives more solids, source-water suitability and coagulation control become especially important.

Particles are passing through the media, seen as rising effluent turbidity or particle counts. The operator should investigate treatment chemistry, hydraulics, media condition, and underdrain integrity rather than merely extending the run.

A newly returned filter can release an initial turbidity spike while the bed ripens. Filter-to-waste keeps that impaired effluent out of the clearwell until the plant's return-to-service criterion is met.

Plant criteria based on performance—such as head loss, effluent quality, flow capacity, or an approved maximum run—should trigger the decision. Waiting for visible failure risks breakthrough and finished-water degradation.

A membrane is a pressure-driven selective barrier. A breach can create a direct passage around that barrier, so integrity indicators and abnormal filtrate quality require prompt investigation.

Oxidize the soluble form into insoluble particles, then separate those particles by clarification or filtration. Oxidation without effective removal can shift the problem downstream instead of eliminating it.

It is the portion of the applied dose consumed by reactions before the measured residual remains: demand = dose − residual. A source-water change that raises demand can lower residual even when the feed setting is unchanged.

CT = disinfectant residual concentration (mg/L) × effective contact time (minutes). Use the approved residual point and effective hydraulic contact time; a tank's nominal volume alone can overstate contact when short-circuiting occurs.

After demand and reactive combined-chlorine compounds are overcome, additional chlorine produces a rising free-chlorine residual. The breakpoint curve—not dose alone—shows the transition.

For U.S. units: lb/day = dose (mg/L) × flow (MGD) × 8.34 ÷ purity as a decimal. Dividing by purity matters because an impure product requires more material to deliver the same active dose.

Detention time = volume ÷ flow, with compatible units. It is a theoretical value; baffling, dead zones, and short-circuiting can make effective contact time shorter.

Calibration adjusts the instrument response against an accepted standard. Verification checks performance without necessarily adjusting it; confusing the two can hide drift or create an undocumented change.

The result must represent the water and compliance period the sample is meant to characterize. An easier but unapproved location can produce a valid measurement of the wrong water.

It records who controlled the sample and when it was transferred from collection through analysis. A complete custody trail supports traceability; it does not replace correct collection or preservation.

Temperature, container, holding time, and chemical treatment are chosen to limit changes in the target analyte. Using the wrong preservation can alter the sample before analysis and make the result unusable.

Total chlorine = free chlorine + combined chlorine, so combined chlorine is the difference between total and free results. A total result alone cannot show how much residual is free.

It is an indicator of particle-removal barrier performance. A rise can warn of breakthrough, but turbidity is not a direct count or identification of pathogens.

pH describes current hydrogen-ion activity, while alkalinity describes acid-neutralizing capacity and resistance to pH change. Two waters can have similar pH but respond very differently to chemical addition.

Verify the sampling point and reference method, then check flow, reagents, cleanliness, calibration, and instrument condition before changing the process. Treating an unverified signal as real can create an actual process upset.

Pressure at the impeller eye falls low enough for vapor bubbles to form and then collapse in higher-pressure regions. The collapse causes noise, vibration, loss of performance, and potentially impeller damage.

Air in the casing prevents the pump from developing the pressure conditions needed to move liquid. Find the air leak or suction problem and restore prime according to the operating procedure; repeated restarts do not correct the cause.

It permits flow in the intended direction and closes against reverse flow. A failed check valve can allow backflow, reverse pump rotation, loss of prime, or damaging transients.

Measure the volume delivered over a known time under representative operating conditions and compare it with the required rate. A stroke or speed setting is only a control position, not proof of delivered dose.

Preventive work is scheduled to reduce the chance of failure; corrective work restores equipment after a fault is found. Relying only on corrective work increases unplanned outages and process risk.

It uses condition trends—such as vibration, temperature, current, or performance—to identify deterioration and schedule work before failure. One abnormal reading should be verified and evaluated in context, not ignored or treated as a diagnosis by itself.

The programmable logic controller executes local control logic from inputs and commands outputs. SCADA supervises, displays, records, and communicates system information; losing the display does not necessarily mean the PLC stopped controlling.

Confirm the field condition and signal quality, then follow the approved response procedure. Silencing an alarm only acknowledges it; it does not remove the process, equipment, or instrument cause.

A documented exercise that proves the generator, fuel and starting systems, transfer equipment, and critical load can function together. An unloaded start may miss failures that appear only during transfer or load.

The comparison detects drift, fouling, or sample-system problems that a plausible display may conceal. Record the result and take corrective action under the calibration and maintenance procedure.

It should connect the asset, observed problem, work performed, parts or settings changed, and return-to-service status. That history supports recurring-fault analysis and prevents incomplete maintenance from disappearing between shifts.

Water hp = flow (gpm) × head (ft) ÷ 3,960. It is the hydraulic power delivered to the water, so required brake or motor power is higher when pump and motor losses are included.

More input power is being used for the same hydraulic output. The trend justifies checking pump condition, operating point, throttling, motor performance, and measurements; it does not identify a single cause by itself.

Surface sources can change rapidly with runoff, storms, temperature, and biological activity. Groundwater is often more stable day to day, although dissolved minerals or contamination can still create serious treatment needs.

It protects the land and recharge area that can contribute water or contaminants to a well. Surface-water protection instead follows the contributing watershed to an intake, river, lake, or reservoir.

It identifies the source, potential contaminant origins, and the source's susceptibility. A protection plan uses that assessment to prioritize preventive actions; the assessment alone does not remove the risk.

It is the water level when the well is not being pumped and has recovered under the defined measurement conditions. Pumping level is measured during withdrawal, so the two values should not be compared without noting operating status.

Drawdown is the difference between static water level and pumping water level under stated conditions. A worsening trend at comparable pumping rates can signal well, aquifer, or equipment changes that need investigation.

Floodwater can carry contaminants to defective seals, casing openings, or other pathways into the well. Protect the site, inspect the sanitary barriers, and follow the authority's response and sampling requirements.

Changes in turbidity, temperature, organics, biology, or chemistry can alter coagulant demand, oxidation, filtration, and disinfection. Early detection allows measured process adjustment before a barrier is stressed.

Preventing contamination reduces risk and can avoid added treatment cost or complexity. It is one barrier in a multi-barrier system, not a substitute for effective treatment and distribution protection.

The Safety Data Sheet identifies hazards, required protective measures, incompatibilities, storage, spill response, and first aid. It must be paired with facility procedures and task-specific training, not used as a substitute for them.

All hazardous energy sources—including stored or residual energy—must be isolated and the isolation verified under the energy-control procedure. A stopped motor or closed control switch is not proof of zero energy.

The atmosphere, engulfment, configuration, or incoming energy can become hazardous without obvious warning. Entry requires the applicable evaluation, isolation, atmospheric testing, controls, communication, and rescue provisions.

Protect people and activate the facility emergency plan: isolate or evacuate, summon trained responders, and notify required parties. An untrained solo response can turn an equipment incident into a life-safety emergency.

Accurate records preserve what occurred, support shift decisions, demonstrate reporting, and allow trend or violation review. Replacing an inconvenient value without documented, authorized correction destroys traceability.

Use unique credentials and grant only the access needed for each role; change defaults and promptly disable obsolete accounts. Shared or excessive privileges weaken accountability and expand the impact of a compromised login.