1. The Redfield ratio is an index of concentration of

A. carbon, hydrogen and oxygen
B. nitrogen, potassium and iron
C. carbon, nitrogen and phosphorous
D. carbon, phosphorous and sulfur

2. Removal of solids is generally considered as a

A. Primary treatment
B. Secondary treatment
C. Tertiary treatment
D. None of these

3. All of the following species are considered coliforms except

A. Enterobacter aerogenes
B. Klebsiella pneumoniae
C. Salmonella typhi
D. Escherichia coli

4. The sulfur pearl of Namibia, Thiomargarita namibiensis

A. is the worlds largest bacterium
B. stores high concentrations of nitrate in a huge internal vacuole which takes up 98% of the organisms volume
C. Both (a) and (b)
D. is the worlds smallest bacterium

5. Chemical precipitation of phosphorus is

A. primary treatment
B. secondary treatment
C. tertiary treatment
D. both (a) and (b)