Related Questions

The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by
A TOD > BOD > COD
B TOD > COD > BOD
C BOD > COD > TOD
D COD > BOD > TOD
In sewage having fully oxidised organic matter, the nitrogen exists in the form of
A Nitrites
B Nitrates
C Free ammonia
D Aluminoid nitrogen
How the biological oxygen demand gets affected with the increased presence of organic matter in water?
A the oxygen demand increases
B the oxygen demand decreases
C the oxygen demand remains unchanged
D none of the mentioned
WHO অনুমোদিত, পানি দূষনের COD (Chemical Oxygen Demand) এর সর্বোচ্চ মাত্রা কত ?
A 20.0 mg/L
B 15.0 mg/L
C 10.0 mg/L
D 05.0 mg/L
when demand for factory's products is high . more money is spent at the factory for safety precautions and machinery maintenance than when demand is low. thus the average number of on -the-job accidents per employee each month should be lower during perids when demand is high than when demand is low and less money is available for safety precautions and machinery maintenance .when demand for its products is high, casts the most serious doubt on the conclusion drawn above?
A Employees demand for higher wages than they do at other times.
B Authority hires new workers but lacks the time to rain them properly.
C Employees are less likely to lose their jobs than are at other times.
D Authority sponsors a monthly safety award for each division in the factory.
When demand for a factory's products is high, more money is spent at the factory for safety precautions and machinery maintenance than demand is low. Thus the average number of on-the-job accidents per employee each month should be bower during periods when demand is high than when demand is low and less money is available for safety precautions and machinery maintenance. Which of the following,if true about a factory when demand for its product is high casts the most serious doubt on the conclusion drawn above?
A Its employees ask for higher wages than they do at other times.
B Its management hires new workers but lacks the time to train them properly.
C Its employees are less likely to lose their jobs than they are at other times.
D Its management sponsors a monthly safety award for each division in the factory.
একটি ড্রেন থেকে 1000 mL ময়লা পানি সংগ্রহ করে তার COD নির্ণয়ের জন্য DO পরিমাণ করতে গিয়ে দেখা গেল 50 mL নমুনা পানির জন্য 0.015 N Na2S2O3  দ্রবণের 10mL লেগেছে। ঐ নমুনা পানিতে H2SO4 ও         K2Cr2O7 যোগ করার 3 ঘণ্টা পর পুনরায় DO নির্ণয় করতে গিয়ে দেখা গেল এর 50 mL পানির জন্য    0.15 N Na2S2O3 দ্রবণের 3.5 mL লেগেছে। ঐ নমুনা পানির COD গণনা কর।
A 15.6 ppm
B 17.6 ppm
C 19.6ppm
D 21.6ppm
The pH value of oxidised sewage is about
A 1.8
B 6.2
C 7.3
D 13.4
Main component of sewage gas produced during aneorobic decomposition of organic waste (by suitable bacteria) during sewage disposal is
A H2
B CH4
C CO2
D N2
COD of raw municipal sewage may be in the range of about __________ mg/litre.
A 1-2
B 5-10
C 90-120
D 1500-2500

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