CWEA GRADE 1 LAB ANALYST|2023/24 UPDATE|GRADED A+

Define reagent grade water Water with no detectable concentration of compound or element to be analyzed i.e it is below the method's detection level. What is osmosis? The net movement of water through a semipermeable membrane towards an area of higher solute concentration. What are the various ways reagent grade water is prepared? Distillation, reverse osmosis, ion exchange, carbon adsorption, filtration, ultrafiltration, ultraviolet oxidation. Standard Methods is a compilation of approved methods by which agency? The EPA. What is accuracy? How close a measurement is to a known value What is precision? How close measurements are to each other Define standard deviation. The amount of variation in measurements What is a mean? A median? The mean is the average. The median is the middle number. Why is pH important in biological wastewater treatment? pH is important because microorganisms can only remain sufficiently active in a narrow pH range between 6.5 and 8. Outside of this range pH can inhibit or stop biological activity. What is the pH of typical raw wastewater? What does a departure from this pH indicate? pH of 7. Significant departures may indicate industrial or other non domestic discharges. What can low pH coupled with other observations such as sulfide odors and black color indicate? This can indicate septic reactions in the collection system or within the treatment process. Also, nitrification reactions in the secondary aeration basins may reduce pH enough to inhibit biological activity in some low-alkalinity systems. What is alkalinity and why is it important in wastewater treatment? How is it reported? Alkalinity is a measure of the ability of wastewater to neutralize acid. It is important because the characteristics of raw wastewater supply can influence alkalinity and contribute to hard water (high alkalinity) or soft water (low alkalinity). It is measured in mg/L CaCO3. Who, ultimately, is responsible for establishing and enforcing a lab safety program? The lab director. What is the responsibility of the safety officer? Make sure that PPE is available, periodic inspections of emergency equipment such as alarms, fire extinguishers, eyewash and safety showers; periodic inspections of the lab to uncover overlooked hazards, observe that personnel are following rules, remind others of safe practices. What type of info should be included in a safety report? who, what, when, where, what injuries (time and nature of accident is helpful). Only accidents causing major injury is required to be reported to OSHA (Occupational Safety and Health Act). What does the OSHA "Hazard Communication Standard" or "Right-to-Know Regulation" specify? A method of employee notification about hazards in the workplace. Exposed personnel must be educated on safe work practices and must be under direct supervision and observation by a qualified individual. Personnel have the right to know of hazardous materials present, specific hazards created by those materials, and required procedures to protect against the hazards. Types of fire extinguishers Type A: water-type extinguishers for ordinary combustibles such as wood, paper, rags Type B: dry-chemical type extinguishers for flammable liquids and metals and electrical fires Type C: Carbon dioxide types for flammable liquids and limited use around electronic instrumentation and equipment Type ABC: multipurpose fire extinguishers How should flammable solvents be stored? Flammable solvents should be stored in properly vented cabinets approved by the National Fire Protection Association or in a safety refrigerator. Use special containers for quantities 2 L or when the cumulative amount of flammable solvents in a room exceed 8 L. Define flammable solvents liquids with a flash point (enough to ignite in air) below 60 degree Celsius and a vapor pressure exceeding 275 kPa atmospheric at 38 degree Celsius. Fume hoods know the air-moving capacity of the entire system; check air flow on a scheduled basis with an anemometer; sash hood position required to obtain an airflow of 30 m/min should be marked with tape or pen. When should respirators be worn? What chemicals require the use of a respirator? What type of respirator is preferred? Emergency situations in which dangerous gases, fumes, or aerosols may be formed and the room must be entered before thorough ventilation. Toxic gases such as boron trifluoride, chlorine, dimethylamine, ethylene oxide, fluorine, and hydrogen bromide. A Self-Contained Breathing Apparatus (SCBA) is preferred. What are Occupational Safety and Health Personal Exposure limits and American Conference of Governmental Industrial Hygienist's Threshold Limit Values (TLV)? What kinds of hazards do these apply to and why? They are permissible exposure limits and threshold limit values that indicate the max air conc. to which workers may be exposed. These apply to many inorganic acids and bases because their fumes cause severe eye and respiratory system irritation and liquids can quickly cause burns of the skin and eyes. How should acids and bases be stored? How should they be transported? Separately from each other and away from volatile organic and oxidizable materials. They should be transported using rubber or plastic buckets. Why is perchloric acid (HClO4) so dangerous? It reacts violently or explosively on contact with organic material so fume hoods used with perchloric acid should not be used for organic reagents, esp. volatile solvents. It also produces severe burns on skin, eyes and respiratory tract.