Wastewater Treatment Quiz

Domestic wastewater is also called ______ wastewater

The water that enters the sewer system through leaking joints, cracks, and breaks is called ______

Inflow is storm water that enters the sewer system from storm drain connections, roof leaders, and foundation and basement drain, or through ______ covers

Runoff resulting from rainfall and snowmelt is called ______ water

Over-aeration, resulting in DO levels of 5-6, can lead to undesirable microorganisms and filamentous bulking in the sludge.

Operational causes of non-filamentous organisms include over-aeration and the presence of toxic substances.

Aeration techniques include the use of air diffusers and ______, each with its unique advantages and limitations.

Wastewater ponds and lagoons are used for natural purification processes, with aerobic ponds often referred to as polishing or tertiary ponds.

The success of an ______ is often dependent on the performance of the final clarifier.

Trickling filters utilize randomly packed solid medium and are simple with low operating costs but may have odor and clogging problems.

The presence of oxygen in ______ is primarily provided by photosynthesis, and lagoons are distinguished from ______ by artificial aeration to provide oxygen.

Various cures and techniques can be employed to address issues such as adjusting F/M ratio and DO levels, ______, and pre-treating wastewater.

Attached growth systems, such as trickling filters and ______, are populated by a variety of organisms and are effective in treating wastewater.

Filamentous bulking in ______ can be caused by operational and wastewater characteristic factors.

Biotowers use ______ in a vertical arrangement and are suitable for higher porosity and low weight.

Dissolved oxygen (DO) levels are crucial for the aerobic processes, with the ______ being 1.5 – 2.5 mg/L.

Biological wastewater treatment involves the use of microorganisms to convert organics in wastewater into ______ or biomass.

In biological treatment, the rate of biomass production and food utilization is affected by factors such as temperature, pH, toxins, salt concentration, oxidants, and ______.

Microorganisms in biological treatment may be irreparably damaged by sudden changes in environmental factors, requiring a gradual adjustment to a wide range of ______.

The design of biological systems for wastewater treatment requires knowledge of biological principles, kinetics of metabolism, mass balance principles, and ______ operations.

Two types of biological growth/culture used in wastewater treatment are suspended cultures/growth and attached ______.

Design parameters/operational parameters in the activated sludge process include F/M ratio, MLSS, MCRT/SRT, and ______, which affect treatment efficiency and waste activated sludge production.

F/M ratio measures organic loading and affects aeration period and treatment efficiency, with low ratios resulting in high treatment efficiency and little waste activated ______.

MLSS represents the suspended solids in the reactor and is useful in the determination of F/M, sometimes expressed in terms of suspended ______.

MCRT/SRT represents the average time in which microorganisms or solids stay in the reactor, and HRT represents the average time in which the liquid remains in the ______.

Wastewater contains a wide variety of organics and requires a wide variety of organisms or a mixed culture for complete ______.

The microorganisms involved in biological treatment are the same as those in natural freshwater systems but are carefully controlled in engineered reactors to optimize organic ______.

Suspended cultures/growth in wastewater treatment include activated sludge, ponds, and lagoons, with variations such as step aeration, tapered aeration, contact stabilization, pure oxygen activated sludge, oxidation ditch, high rate, and extended ______.

Fine ______ consist of woven wire or cloth perforated plates and should be mechanically cleaned on a continuous basis.

Mechanically-cleaned bar ______ have bar racks 3 to 4 inches apart, while manually-cleaned bar ______ require good flow distribution and velocity control.

Disposal methods for ______ include hauling to disposal areas, burial on the plant site, incineration, disposal with municipal solid wastes, and grinding and returning to the wastewater flow.

Comminution involves shredding ______ to approximately 8 mm in size using devices like a hammermill or a barminutor.

Grit ______ is essential to separate non-biodegradable solids from organic suspended solids, and it includes channel-type horizontal-flow grit chambers, aerated grit chambers, and vortex-type grit chambers.

Grit ______ protect mechanical equipment, reduce heavy deposits, and minimize the frequency of digester cleaning.

Parshall ______ and Palmer-Bowlus ______ are commonly used for flow measurement in wastewater treatment.

Primary ______ involves sedimentation, which separates suspended particles from water through gravitational settling in sedimentation basins or tanks.

Factors affecting ______ tank efficiency include the type of solids, age of wastewater, rate of solids flow, cleanliness, and mechanical condition of the tank.

Sedimentation achieves removal efficiency for settleable solids (90-95%), suspended solids (50-65%), BOD (20-35%), and colloidal solids (not removed unless coagulants are added).

Flow distribution in sedimentation ______ is managed by inlet structures to evenly distribute the flow and prevent short circuiting.

Secondary ______ involves the biological conversion of dissolved and colloidal organics into biomass, which can be subsequently removed by sedimentation.

Types of sewer systems: sanitary sewer system, storm sewer system, and collection water system.

Contaminants of concern in wastewater treatment include suspended solids, biodegradable organics, pathogens, nutrients, priority pollutants, refractory organics, heavy metals, and dissolved oxygen.

The treatment objectives for wastewater treatment are the removal of suspended and floatable material, treatment of biodegradable organics, elimination of pathogenic organisms, removal of toxic compounds, and removal of nitrogen.

Wastewater treatment systems are divided into preliminary, primary, secondary, tertiary, and solids treatment and ______.

Preliminary wastewater treatment involves the removal of large solids to prevent damage to the remainder of the unit operations through screening, comminution, grit removal, and ______.

Primary wastewater treatment aims to remove a portion of suspended solids and organic matter by settling or sedimentation, typically removing about 60% of solids and 30% of ______.

Secondary wastewater treatment is directed principally at the removal of biodegradable organics and suspended solids, including biological treatment by activated sludge, fixed-film reactors, lagoons, and ______ systems.

Tertiary wastewater treatment involves the polishing of secondary effluent, primarily removing nutrients, toxic compounds, increased amounts of organic material, and suspended ______.

Solids treatment and disposal includes the collection, stabilization, and subsequent disposal of the solids removed by other ______.

Wastewater treatment methods are classified into physical unit operations, chemical unit processes, and ______ unit processes.

Preliminary ______ includes screening, the first operation performed on incoming wastewater for the purpose of removing materials that might damage equipment or hinder further ______.

Screening devices are used to remove coarse solids from wastewater, which consist of sticks, rags, boards, and other large objects that find their way to the wastewater collection ______