1. Mechanical ventilation of a lift station is required to _.
a. lower the temperature
b. reduce chlorine demand
c. eliminate the presence of harmful gases
d. increase D.O. in raw wastewater
2. What is the minimum D.O. to prevent formation of hydrogen sulfide in at a treatment plant?
3. What is the maximum holding time for BOD?
a. 24 hours
b. 48 hours
c. 72 hours
d. 96 hours
4. What is the maximum length of time a sample can be held for suspended solids testing?
a. 3 days
b. 5 days
c. 7 days
d. 9 days
5. D.O., pH, temperature and residual chlorine are obtained by _.
a. composite samples
b. grab samples
c. flow proportional samples