Moawad (1968) observed that the environmental factors which
were favourable for algal growth were unfavourable for the
survival of coliforms. Pathogenic organisms of concern in
wastewater include bacteria such as Salmonella and Shigella,
viruses and protozoa. Bacteria provide the largest component
of the microbial community in all biological wastewater treatment
processes and numbers in the range of 106 bacteria/ml of
wastewater are frequently encountered (Horan, 1990). Experimental
evidence indicates that, the pathogenic bacteria generally
have shorter survival times in the environment than
coliforms, whereas viruses tend to survive longer.