Water Treatment Advanced Exam Questions with Complete Solutions

Contamination - Answer-introduction into water or microorganisms, chemicals, toxic substances, wastes or wastewater in a concentration that makes the water unfit for it's intended use. Disinfection - Answer-the killing or inactivation of MOST microorganisms including all pathogenic bacteria Sterilization - Answer-Complete destruction of all forms of microbial life What are the four categories of contaminants? - Answer-Physical: temp, taste, color, odor, turbidity Chemical: inorganic, organic, general mineral Biological: Virus, Bacteria, Protozoans Radiological What are the three types of microbial contaminants? - Answer-Virus, Bacteria, Protozoans Virus - Answer-What is the smallest of all contaminants? List 5 properties of Chlorine gas - Answer-1) Greenish yellow liquid 2) 2 ½ times heavier than air 3) Expands 450 to 1 4) Non flammable 5) Supports combustion (will not smother a fire) List four factors that influence disinfection - Answer-1) pH Lower is better 2) Temp Higher is better 3) Contact time 4) Concentration of disinfectant List three physical means of disinfection - Answer-1) UV Rays 2) Heat 3) Ultrasonic Waves Free Available Chlorine vs. Combined - Answer-Free: The portion of total available residual chlorine composed of chlorine gas, hypochlorous acid, or hypochlorite ion. This does not include chlorine combined with ammonia, nitrogen, or other compounds. Combined: The portion of chlorine residual which is combined with ammonia, nitrogen, or other compounds, and is still able to help kill bacteria Chlorine and Water - Answer-When chlorine is added to water, two acids are formed