INTRODUCTION
Wastewater treatment and re-use engineers need a good understanding of
wastewater microbiology for two reasons: first because wastewaters contain
micro-organisms that cause human disease (Chapter 2), and secondly because
most wastewater treatment processes are microbiological (we generally use the
term ‘biological wastewater treatment’ to reflect this, but we should say
‘microbiological wastewater treatment’). Wastewater treatment engineers also
need to understand the effect of untreated, partially treated and fully treated
wastewaters on the biology – really, the aquatic ecology – of the receiving
watercourse.
This chapter provides an introduction to the important groups of microorganisms
in wastewater treatment and reuse: viruses, bacteria, algae,
protozoa and helminths (more detailed information is given in, for example,
Mara and Horan, 2003). It concludes with a brief description of a simplified
technique for the biological assessment of tropical freshwater quality using
aquatic micro-invertebrates.