Sewage Treatment - AP Environmental Science
- What process is used to settle solids in primary treatment?
- Sedimentation. Gravity allows solids to settle to the bottom of tanks.
- Which treatment stage typically involves aeration tanks?
- Secondary treatment. Aeration provides oxygen for biological waste breakdown.
- Identify a method used for odor control in sewage treatment.
- Carbon filters. Activated carbon absorbs odorous compounds from air.
- What does a high BOD indicate about water quality?
- High levels of organic pollution. More organic matter requires more oxygen for decomposition.
- What is removed during the screening process?
- Large debris. Prevents clogging and damage to treatment equipment.
- Name a biological process used in secondary treatment.
- Trickling filters or activated sludge. Both use microorganisms to consume organic pollutants.
- Which nutrient is often removed during tertiary treatment?
- Phosphorus. Prevents eutrophication in receiving water bodies.
- What is the purpose of using coagulants in sewage treatment?
- To clump fine particles for easier removal. Chemicals bind small particles into larger, settleable flocs.
- What is the first step in primary sewage treatment?
- Screening. Bars or mesh remove large objects from wastewater.
- Which treatment process uses microorganisms to degrade waste?
- Biological treatment. Living organisms consume and break down pollutants naturally.
- Identify a common by-product of sewage treatment.
- Biosolids. Treated sludge can be beneficially reused in agriculture.
- Which gas is commonly produced in anaerobic digesters?
- Methane. Produced when organic matter decomposes without oxygen.
- Which organisms are utilized in secondary treatment?
- Microorganisms (bacteria and protozoa). These organisms consume organic waste in biological treatment.
- What is the function of a bar screen in sewage treatment?
- To remove large solid objects. Prevents large items from entering treatment systems.
- What is the main objective of tertiary treatment?
- To improve water quality by removing remaining impurities. Final polishing step removes nutrients and pathogens.
- Which type of bacteria performs nitrification in sewage treatment?
- Nitrifying bacteria. Convert ammonia to nitrites then nitrates for removal.
- Name a common method used in tertiary treatment.
- Filtration, chemical treatment, or UV disinfection. These advanced processes remove remaining contaminants.
- What is the purpose of scum removal in sewage treatment?
- To remove floating fats and oils. Grease and oil float and must be skimmed off.
- What does the term 'effluent' refer to in sewage treatment?
- Treated wastewater. The clean water discharged after treatment processes.
- What is the purpose of secondary sewage treatment?
- To degrade organic matter using biological processes. Biological processes break down dissolved organic pollutants.
- Which process follows coagulation in sewage treatment?
- Flocculation. Gentle mixing forms larger particles from coagulated matter.
- Identify a key indicator of nutrient pollution in water.
- High nitrate and phosphate levels. These nutrients cause algal blooms and oxygen depletion.
- What is the main goal of sludge stabilization?
- To reduce pathogens and odors. Biological and chemical processes reduce health risks.
- Identify a common issue with sludge management.
- Odor control. Decomposing organic matter produces unpleasant smells.
- Identify the main goal of primary sewage treatment.
- To remove large solids from wastewater. Physical settling removes debris and suspended particles.
- What is the purpose of disinfection in sewage treatment?
- To kill pathogens in treated water. Prevents disease transmission from contaminated water.
- What are the primary stages of sewage treatment?
- Primary, secondary, and tertiary treatment. These represent physical, biological, and advanced treatment processes.
- Identify the main component of sewage that causes eutrophication.
- Nutrients such as nitrogen and phosphorus. Excess nutrients stimulate algae growth and oxygen depletion.
- What is one environmental benefit of using biosolids?
- Can be used as fertilizer. Provides nutrients for crops while recycling waste.
- Which term describes the measure of organic pollution in water?
- Biochemical Oxygen Demand (BOD). Measures oxygen needed to decompose organic matter.
- What is the role of activated sludge in sewage treatment?
- To break down organic matter using bacteria. Microbes consume organic waste in aeration tanks.
- Identify a method to remove heavy metals in sewage treatment.
- Chemical precipitation. Chemicals bind metals into particles for settling.
- State one advantage of using anaerobic digestion.
- Produces biogas for energy. Methane can be captured and used as renewable fuel.
- Identify a benefit of using UV light for disinfection.
- No chemical residues left in water. No toxic chemical compounds remain after treatment.
- What is the role of a clarifier in sewage treatment?
- To separate solids from liquids. Allows settled particles to separate from clean water.
- Identify a common chemical used for disinfection in sewage treatment.
- Chlorine. Strong oxidizing agent that kills bacteria and viruses.
- What is the primary focus of sludge treatment?
- To reduce volume and pathogens in sludge. Stabilization makes sludge safer for disposal or reuse.
- What is the purpose of grit removal in sewage treatment?
- To remove sand and gravel. Heavy particles can damage equipment and pipes.
- What is a disadvantage of using chlorine for disinfection?
- Formation of harmful by-products. Can create toxic chlorinated compounds like trihalomethanes.
- What is typically measured to assess the effectiveness of disinfection?
- Coliform bacteria levels. Indicates presence of disease-causing microorganisms.