On the effects of nitrogen and phosphorus on microbial growth
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1. The book states that microorganisms grow rapidly when there is an abundance of substrates. However, nitrogen and phosphorus are essential elements for their synthesis; if these elements are lacking despite an adequate supply of substrates, won’t the growth of microorganisms be restricted? 2. Does moss growing on wastewater indicate an abundance of nitrogen and phosphorus, or does moss growth occur only when there is an excess of nitrogen?
1. Won’t the growth of microorganisms be unaffected in the absence of nitrogen or phosphorus? Microorganisms that require nitrogen and phosphorus are needed for growth; it is essential to maintain a BOD5:N:P ratio of around 100:5:1. 2. Does the presence of moss on wastewater indicate an adequate supply of nitrogen and phosphorus, or does moss growth occur simply when there is an excess of nitrogen? The fact that moss grows in the presence of nitrogen or phosphorus does not indicate whether both nitrogen and phosphorus are sufficient.
With an adequate supply of substrates, but a lack of nitrogen and phosphorus, microorganisms are unable to synthesize cytoplasm and thus cannot reproduce. Over time, the microorganisms will age and die.