Question

1) a)Why do water microbiologists rely on detection of indicator bacteria instead of pathogens in water?

b)Of the indicator bacteria commonly used to assess water quality, which indicator organism should be absent in water fit for drinking and why?

c)List one advantage and one disadvantage of the membrane filter technique when applied to water quality assessment?

d)Name two methods for secondary treatment of waste water and sewage.

Answer 1

1) Indicator bacteria which indicates water quality are part of faecal microbiomes. However, pahtogens are not present normally in faecal matter until there is infection with specific pathogen. This is the reason pathogens are not reliable for detecting water quality.

2) bacterias like coliform bacteria are used as indicator bactor. Among them E.coli are known as indicator of that water is recently got contaminated with faecal matter. Thus water which is fit for drinking should be without E.coli.

3) Membrane filtration technique is usesful for rapid assesement of large amount of water. However, membrane filtration do not work properly if the water is turbid as turbid water will block the membrane filter pores.

4)methods such as activated sludge or roughing filters are used as treatment option for secondary treatment for waste water and sewage.