What is the “carbon:nitrogen:phosphorus” ratio required for bacterial growth?
The answer to this question is D, 100:5:1. The population of microorganism or in lagoon systems, algae, depends on the amount of carbon, nitrogen and phosphorus available. The universally accepted ratio is 100:5:1. If you lack one of these established nutrients, your facility would be deficient and have difficulty achieving proper growth of organisms. If you lack one of these nutrients, that nutrient would be considered a rate limiting factor. This useful factor is a good troubleshooting step.
Which membrane classification can be used for softening water containing calcium and magnesium ions and to reduce the concentration of natural organic matter?
The answer is C, nanofiltration (NF). The pore sizes found within elements designed for membrane softening and removal of disinfection byproduct precursors are small enough to reject these contaminants at much lower pressure than reverse osmosis units. Nanofiltration units typically operate with pressure in the 70 to 120 psi range, whereas RO units designed for desalination operate at pressures ranging from 100 psi to 1,200 psi, depending on feedwater salinity.
