Teaching TIPS All students should be encouraged to develop understanding of natural resources and conserving those resources . They also should be guided to inquire about various chemical process in nature to achieve a sustainable environment. Focus points during discussions : Guide the discussion towards Oxygen demand , eutrophication, BOD (Biological Oxygen Demand), and hydrological cycle. Precautions : Methylene Blue is colorless in the absence of oxygen and is of blue color in the presence of oxygen. The amount of biodegradable material decides the time for the color change. Thus students should be told to observe the reaction carefully in lab. It is important to discuss the significance of the decomposition in breaking down the organic material. Safety Measures: Though this is a safe practicle activity, students need to be careful in dealing with the methylene blue - as it can cause irritation and nausua .DO capsules should not be consumed and they should be added just at the time to experiment in order to better observe the reaction happening.
Teacher’s Preparation • Show photos or overheads of various biological treatment processes. • Hand out Fact Sheet. • Lecture on the concepts of biological treatment and the BOD test. • Hand out Student Exercise Directions and Data Sheet. • Explain the Explore activity. The objective is to demonstrate that over a period of days the dissolved oxygen concentration in the bottles will decrease because the bacteria are metabolizing the organics and, in so doing, using up the oxygen. • Have the students develop a hypothesis about what they expect will happen to the DO during the test period.
Detective Terry's 3 tasks Task 1: 60 mins to read and respond to the questions. Task 2: 120 mins to read write and discuss the answers in the class. Task 3: Research activity Group size : 4 students Time: 30 mins : explain the activity and make groups 120 mins : Let the group perform the experiment, and write a brief lab report . 60 mins : discuss the results in class, and then answer the four "thought provoking" questions. Activity plan Students need to take up the following 3 tasks : Task 1,2 and 3 have been described in the following slides .
Detective Terry Hello! I am Terry, I have been to the city's water treatment plant. Though I was detailed on the working of each component there. I am still puzzled about the functioning of some of the water treatment component. also I want to pet a fish in the water I had collected from the inlet/outlet of the waste water treatment plant in two different jars .
Here is the flowchart of what I saw and learned at the waste water treatment plant. water from our flush ---------->-
They gave me a handout about BOD BOD (Biological Oxygen Demand) value is used to estimate the amount of biodegradable organic material in a sample. BOD is a chemical process by which we can determine the dissolved oxygen required by the micro-organisms present in water . It is usually measured as milligrams of oxygen required per Liter of sample. Usually water sample is preserved in BOD bottles for 5 days at around 20 degree celcius.During waste water treatment process the bacteria decomposes the organic matter in the waste water sample. activated sludge , trickling filters, oxidation ditches are used in WWTP for the purpose of biological decomposition of organic matter.
Task1: I forgot some of it ! I need to write a report about the working of the wwtp . But unfornately I forgot about the "biological treatment" in the wwtp. Can you help me write about that part of the report ? I need to summarize this part of the report in not more than 1000 words. I need to explain the following points . 1. What is the general biochemical reaction showing decomposition of organic matter ? 2. How does aeration in activated sludge treatment plants or in trickling filters contribute to the biochemical reaction ?
In this water sample, fish would live well. In this water sample, fish would die. I want a pet fish as well ....
Task 2. Can you help me with ...... I brought samples from the influent and effluent sewage pipes. Unfortunately I forgot to label them then. I want to pet a fish in the clean water, but I really dont know which jar has the water from effluent and influent stream of the waste water treatment plant. I decided to calculate the BOD of both the samples using my school's lab BOD meter. After the test results were: Jar 1 has a BOD reading of 740 mg/l Jar 2 has a BOD reading of 600 mg/l I really don't understand the significance of this reading . please help me understand the relation of these values . And also help me decide- in which jar should I keep my pet fish ?
Task 3: Research activity for students Aim : To know about the effect of biodegradable waste on the DO of the water sample. Experiment : Take two jars and label them as jar A and Jar B. In Jar A : In a graduated cylinder add 5 ml water milk 5 ml milk . (hydrate the yeast until just before the lab. 1 ml of dry yeast dissolved into 10 ml of tap water) . To this mixture ,quickly add 1 ml of yeast mixture . Invert test tube 4 times and place in the test tube rack. There after add 3 drops of methylene blue to the samples ,and let the students note the time taken for the color change in the test tube. In Jar B : In another graduated cylinder add 10 ml water add a DO capsule . Plug the test-tube and shake it well. Then quickly add 3 drops of methylene blue to this mixture. Students should then be asked to note the time for color change in the test tube.
Background When oxygen is present and methylene blue is in its oxidized state, it is blue in color. When sufficient oxygen is no longer available, methylene blue becomes reduced it and is colorless. Methylene blue (oxidized) blue------>methylene blue (reduced) colorless.
Evaluation criteria for the research activity : Criteria 1: Students need to prepare short lab report . (maximum of 3 pages). Criteria 2: They also need to write answers to the following "thought provoking question" questions : 1. In which Jar do they think the decomposition took place. 2. what was the food ,and which was the decomposer that they had added in the decomposition jar ? 4. Why do you think the oxygen in the decomposition Jar was all used up? 3.Why do you think the waste water treatment plant ,want to calculate the BOD values of water flowing out of the effluent streams of their (Waste Water Treatment Plant ) WWTP ?
References http://www.enviroliteracy.org/article.php?id=1158&print=1 http://esa21.kennesaw.edu/activities/ww-treatment/ww-treat-after-flush-epa.pdf http://www.uas.alaska.edu/attac/ampdf/activity21.pdf