A thesis submitted in partial fulfillment of the requirements for t he degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1989

A pilot-scale aquatic primary treatment pond system was carried out using two major plants namely, water hyacinth and azolla to treat AIT campus wastewater under directly comparable conditions . In the first period, three parallel channels were separately stocked with azolla nilotica as first pond; water hyacinths as as second pond and control (without plants ) as third pond at a mean BOD loading o f 94 kg BOD/ha.d and HRT of 9 days. In the second period, three separate channels were stocked with combined water hyacinths and azolla nilotica as t h e first pond, water hyacinths as second pond a nd control as third pond at mean BOD loading of 89 Kg. BOD/ha . ct. a nd HRT of of 8 days. All experimental results revealed t hat the water hyacinth pond showed an over-all superiority in treatment efficiency followed by azolla and control pond s for both period s. However, an increase in treatment efficiency was observe d with azolla- water hyacinth pond in the second period compared with the azolla pond in the first period.