ANDIG4 – Questions

1. What are examples of complex organic matter?

a. Carbohydrates, proteins and fats

b. Sugars, amino acids

c. Fatty acids

d. Methane

2. Anaerobic digestion will not occur if this major element is present?

a. Carbon dioxide

b. Oxygen

c. Calcium chloride

d. Ammonium sulfate

3. Biogas has a typical carbon dioxide content of what percent?

a. Over 60 percent

b. 50 to 60 percent

c. 40 to 50 percent

d. 30 to 40 percent

4. What are the steps of anaerobic digestion (in order)?

a. Methanogenesis, Hydrolysis, Acidogenesis,  Acetogenesis

b. Hydrolysis, Acidogenesis,  Acetogenesis,  Methanogenesis

c. Acidogenesis,  Acetogenesis,  Methanogenesis, Hydrolysis

d. Acetogenesis,  Methanogenesis, Hydrolysis, Acidogenesis

5.  What is the typical methane composition of biogas?

a. Less than 35 percent

b. 35 to 45 percent

c. 45 to 65 percent

d. More than 80 percent

6. How long does it normally take to achieve steady state gas production from an anaerobic digester?

a. Less than four weeks

b. 4 to 8 weeks

c. 2 to 3 months

d. At least six months

7. Purging an anaerobic digester with an inert, non-oxygen gas will reduce the amount of oxygen that goes into solution and gives the anaerobic microorganism an opportunity to reproduce faster.

a. True

b. False

8. How do you start biogas production in a digester?

a. Fill the digester half full of seed sludge and meter in the feedstock until the digester is at capacity.

b. Fill the digester with manure until it is at capacity.

c. Fill the digester with water, bring the water to operational temperature, and then slowly add feedstock.

d. Inject a blend of 75 percent food waste, 25 percent manure and 15 pounds of yeast into the digester.

9. What is the advantage of adding “seed sludge or effluent” for digester start-up?

a. There is no advantage.

b. Biogas production in the winter.

c. Aids in the breakdown of cellulosic materials.

d. Seed sludge or effluent will contain all the ferment ing bacteria to ensure a quicker start up for biogas production.

10. Starting a digester during the winter is easy to do because methanogens are cold-tolerant organisms and will produce copious amounts of biogas when temperatures are below freezing.

a. True

b. False

11. The purpose for operation procedures is to enable a digester to operate on a steady state basis.

a. True

b. False

12. Operational procedures are not designed to prevent possible problems and improve feedstock digestion.

a. True

b. False

13. What are the reasons why digesters fail?

a. Bad design and/or installation

b. Selection of poor equipment and materials

c. Poor farm management

d. Introducing products into the digester that are toxic to anaerobic microorganisms

e. All of the above

14. Why have failure rates been reduced in recent years?

a. Improved system design

b. Better construction practices

c. Increased number of qualified companies to develop anaerobic digestion projects

d. All of the above

15. An engineering review should be conducted to expose any technology failures and validate the design plan with the specific materials for the digester under the specific farm conditions.

a. True

b. False

16. Farmers who are considering installing a digester on their farm should do due diligence in selecting a technology provider to make sure the entity is reputable and uses proven digester technology.

a. True

b. False

17. What toxic products can kill anaerobic microorganisms if they are introduced into the digester?

a. Rumensin and products like it

b. Pesticides

c. Cattle foot bath

d. All of the above

18. Asphyxiation, explosion, burns, electrical shock and falls are human health risks associated with working around an anaerobic digester and associated equipment.

a. True

b. False

19. ____________ is an inflammable, colorless, highly poisonous gas.

a. Sodium chloride

b. Copper sulfate

c. Hydrogen sulfide

d. Carbon dioxide

20. Hydrogen sulfide inhibits __________ transport in the blood, changing the red blood pigment to a brown or olive color.

a. Calcium

b. Oxygen

c. Sodium

d. Iron

21. Hydrogen sulfide has the characteristic odor of __________.

a. Vinegar

b. Sour milk

c. Rose petals

d. Rotten eggs

22. Exposure to low concentrations of hydrogen sulfide causes:

a. Irritation of the mucous membranes (including the eyes)

b. Nausea, vomiting and difficulty in breathing

c. Cyanosis (discoloration of the skin)

d. Delirium and cramps, then respiratory paralysis and cardiac arrest

e. All of the above

23. Improper training on confined space entry is a leading cause of accidents related to anaerobic digestion systems.

a. True

b. False

24. When entering a confined area, it is not necessary to have another person observing outside the confined area.

a. True

b. False

25. _____________, the major component of biogas, is odorless, colorless, and difficult to detect. It is highly explosive if allowed to come into contact with atmospheric air. It is lighter than air and can collect at the top of confined areas.

a. Hydrogen sulfide

b. Hydrogen peroxide

c. Methane

d. Sulfur dioxide

26. Clear warnings must be placed in the respective parts of the facility. Examples include:

a. Fences around pits

b. Signs

c. Both a and b

d. Equipment operation  training

27. The self-assessment tool provides guidance for process and job evaluation with suggestions based on typical potential hazards for farm digester systems and their associated preventive measures.

a. True

b. False