ee experiment group 4 - SUN YAT-SEN UNIVERSITY Department...

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SUN YAT-SEN UNIVERSITY Department of Civil Engineering Year I (2009-2010 2 nd semester) Environmental Engineering Laboratory Report Group 4: Yang Kengran, Yang Yunfan, Tian Yunfan, Wang Yilong, Lv Chenxi Venue: Environmental Engineering Laboratory, Room 230, Haking Wong Building Experiment Date: June 1st, 2010 Submission Date: June 23th, 2010 Contents COD Test………………………………. ..3 BOD Test……………………………….13 Color Detection………………………. ..23 Measurement of Salinity……………….29
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Measurement of Dissolved oxygen(DO)………………. ..32 Measurement of PH…………………….38 Experiment: COD Test Objective To determine the COD of given samples by Closed Reflux Method. Apparatus Culture Tubes (PYREX NO.9826)*3 Conical Flask (PYREX NO.1000)*1 Volumetric Pipette*1 50 ml Burette (BS-846)*1 Preheated Oven*1 Tags Reagents Standard potassium dichromate digestion solution: 0.0167M = 0.10N Sulfuric acid reagent:5.5g Ag 2 SO 4 / kg H 2 SO 4 Standard ferrous ammonium sulfate FAS Ferroin indicator Influent, Effluent and DI water Background The chemical oxygen demand (COD) is the amount of oxygen needed to chemically oxidize the wastes. It is a measured quantity that does not depend either on the ability
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of microorganisms to degrade the waste or on knowledge of the particular substances in question. The COD test is much quicker than a biochemical oxygen demand (BOD) test, taking only a matter of hours, because we use strong oxidizing agent like acidified potassium dichromate to do the job instead of microorganisms. The measured value of COD is higher than BOD, because the wastewater contains some organic wastes, which can be degraded chemically, but not biologically and some inorganic reductive substances. For easily biodegradable matter, the two will be similar. So the COD test is sometimes used as a way to estimate the ultimate BOD. It is expressed in milligrams per liter ( mg / L ), which indicates the mass of oxygen consumed per liter of solution . Theory In the experiment, we use the Closed Reflux Method to measure the value of COD. The potassium dichromate (K 2 Cr 2 O 7 ) in the acidic medium is to be used as a strong oxidizing agent in the experiment and s ilver sulphate (Ag 2 SO 4 ) is used as the catalyst. Place the sample in preheated oven at 150 for 2 hours to ensure all the organic compounds are oxidized by potassium dichromate. The redox reaction between organic compounds and potassium dichromate can be expressed as the equation Organic Compounds + Cr 2 O 7 2- + H + →Cr 3+ +CO 2 +H 2 O Then we add Ferroin indicator into the sample to indicate the color. And the sample will titrated with standard FAS solution. Since there are still dichromate ions left, at the same time, the ferrous ions are present in standard FAS solution. The redox reaction between dichromate ions and ferrous ions can be expressed as the equation When all the dichromate ions change to be chromium ions, the color of the sample
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This note was uploaded on 10/02/2010 for the course CIVIL ENGI 09332005 taught by Professor Kaiminshi during the Spring '10 term at Hong Kong Baptist University, China.

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ee experiment group 4 - SUN YAT-SEN UNIVERSITY Department...

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