REHS Exam Wastewater Treatment With 100% Correct And Verified Answers, Exams of Advanced Education

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REHS Exam Wastewater Treatment With 100% Correct And Verified Answers What are the treatment processes in PRELIMINARY Wastewater Treatment? - Correct Answer-Screening Comminution Grit Removal Pre-Aeration Flow Metering / Sampling What are the treatment processes in PRIMARY Wastewater Treatment? - Correct Answer-Sedimentation / Flotation What are the treatment processes in SECONDARY Wastewater Treatment? - Correct Answer-Biological Treatment (ie activated sludge, trickling filters, rotating biological contactor (RBC)) Sedimentation What are the treatment processes in TERTIARY Wastewater Treatment? - Correct Answer-Filtration Chemical / biological treatment of nutrients Sedimentation (optional) What are the treatment processes in the DISINFECTION step in Wastewater Treatment? - Correct Answer-Chlorination Ultraviolet Ozone What are the treatment processes in the SOLIDS TREATMENT step in Wastewater Treatment? - Correct Answer-Dewatering Digestion Disposal What are the steps in the Wastewater Treatment Process? - Correct Answer- Preliminary Treatment (screening, comminution, grit removal, pre-aeration, flow metering/sampling) Primary Treatment (sedimentation/flotation) Secondary Treatment (biological treatment, sedimentation) Tertiary Treatment (filtration, chemical/biological treatment of nutrients, sedimentation (optional)) Disinfection (chlorination, ultraviolet, ozone) Solids Treatment (dewatering, digestion, disposal) What are some diseases that are common concerns in wastewater? - Correct Answer- Cholera, dysentery, salmonella, typhoid fever mainly Less commonly, anthrax What are some protozoa that are concerns in wastewater? - Correct Answer-Giardia and Cryptosporidium What are some viruses that are common concerns in wastewater? - Correct Answer- Polio and Hepatitis What is NJ's ultimate goal for wastewater treatment? - Correct Answer-The protection of NJ's waterways (receiving streams). All waterways fishable, swimmable, and drinkable. What is the purpose of wastewater treatment? - Correct Answer-Remove solids Stabilize organic matter Remove pathogenic organisms What are some examples of inorganic wastes? - Correct Answer-Salts, metal, gravel, sand What are the usual sources of inorganic wastes? - Correct Answer-Nature and Industry Define organic waste - Correct Answer-Carbon based and can be broken down biologically What are the usual sources of organic wastes? - Correct Answer-Residential and Industry Define infiltration / inflow - Correct Answer-Stuff that leaks in Cryptosporidium in wastewater is removed by ___________. - Correct Answer- Diatomaceous Earth What is the purpose of the NPDES and NJPDES system? What are some characteristics of it? - Correct Answer-Purpose is to keep our waterways simmable, fishable, and suitable for recreation. What is another name for a sedimentation tanks? - Correct Answer-Clarifier Which sedimentation tanks (clarifiers) handle to the most dense sludge? - Correct Answer-Primary clarifiers, then secondary, then final (tertiary) clarifiers. How does a sedimentation tank (clarifier) work? - Correct Answer-Solids settle to the bottom of the tank and are either scraped to one end (rectangular tank) or to the middle hopper (circular tank). Solids are pumped from that tank to the solids handling facility. Scrape scum on top. Gray water sent to next step in treatment process (biological treatment). What is the relationship between water temperature and settling rate during sedimentation/flotation? - Correct Answer-Settling rate increases with water temperature Biological Treatment takes place during which part of Wastewater Treatment? What is the purpose of Biological Treatment? - Correct Answer-Secondary Treatment Remove lighter suspended/dissolved solids that exert a strong BOD on receiving waters. What does biological treatment do and what are the 3 main elements of biological treatment? - Correct Answer-Breakdown of organic material via micro-organisms (bacteria). Three main elements are: Food (organic pollutants measured by BOD) Micro-organisms (bacteria that eat pollutants) Oxygen (respiration for bacteria) What are 3 types of biological treatment? - Correct Answer-Activated sludge Trickling filters Rotating Biological Contactors (RBC) Trickling Filters are used during which part of Wastewater Treatment? What is the purpose of Trickling Filters? - Correct Answer-Secondary Treatment (Biological) Breakdown organic material What are the characteristics of a Trickling Filter and how does it work? - Correct Answer-Large diameter, shallow, cylindrical structure filled with stone (rock, coal, plastic, etc). Overhead distributor distributes water on top of stone. It is a tank with media and a distribution arm. No air needs to be added to the system It is operator intensive How does a Trickling Filter work? - Correct Answer-Overhead distributor distributes water on top of stone. It is a tank with media and a distribution arm. Process where wastewater trickles over media and forms biomass/slimes, which contain organisms that feed upon and remove wastes from water being treated. Growth occurs on the media. Microbes stabilize waste by breaking them down into water and CO2, in addition to using much of the suspended, colloidal, and dissolved solids. What are the 3 basic parts of a Trickling Filter? - Correct Answer-The media (retaining structure) The underdrain system The distribution system Rotating Biological Contactors (RBC's) are used during which part of Wastewater Treatment? What is the purpose of RBC's? How does it work? What are some drawbacks? - Correct Answer-Secondary Treatment (Biological) Breakdown organic material Biomass gets attached to RBC and slowly rotates into water Media usually made of plastic and 40% of media is usually immersed in water Drawbacks: lots of maintenance, biomass buildup Activated Sludge is used during which part of Wastewater Treatment? What is the purpose of Activated Sludge? - Correct Answer-Secondary Treatment (Biological) Breakdown organic material What are the characteristics of Activated Sludge? - Correct Answer-Activated Sludge requires: aeration tank aeration equipment settling tanks return/waste sludge support equipment It utilizes suspended growth Microbes stabilize waste Microbes are referred to as activated sludge How does Activated Sludge work? - Correct Answer-Wastewater is mixed with Return Activated Sludge (RAS), forming a Mixed Liquor. Mixed Liquor is aerated for a period of time, allowing microbes to feed on available organic matter. Produces stable solids, known as activated sludge. Activated sludge separated from WW by clarification (sedimentation tanks). Settled activated sludge sent to head of aeration tank. Excessive solids removed from system. Define Activated Sludge - Correct Answer-floc or solid formed by microbes Define Mean Cell Resident Time (MCRT) in Activated Sludge? - Correct Answer- Average length of time a mixed liquor suspended solid particle remained in the activated process What is the Mixed Liquor in Activated Sludge comprised of? - Correct Answer-Return Activated Sludge (RAS) mixed with wastewater, that then flows into the aeration tank. The mixed liquor is WHAT's under aeration. Define Mixed Liquor Suspended Solids (MLSS) - Correct Answer-Suspended solids concentration in the mixed liquor. Common qualitative reference to amount of microbes in activated sludge process. Define Return Activated Sludge (RAS) - Correct Answer-Biomass being used. The solids returned from the secondary clarifier to the head of the aeration tank. Define Sludge Age - Correct Answer-how old your sludge is Define Waste Activated Sludge (WAS) - Correct Answer-Solids (microbes) being removed from activated sludge process. Adding new microbes so sludge is not all old microbes. What is the optimal pH for activated sludge microbes? - Correct Answer-pH = 6.5-8.5