A research study submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1986

The activities of nitrogen transformation including nitrification, denitrification, ammonia release and ammonia adsorption were studied. River water and sediment at three different points on Chao Phraya River were collected and their bacteria activities were examined using batch experiments. Sediments can play an important role in ammonia transformation processes. Sediments contain much of the nitrification and denitrification bacteria and increase the rates significantly. Nitrifying activity decreased with increasing the pollution. Ammonia release from sediments reflects that sediments can keep large amount of ammonia. Ammonia adsorption by the suspended silt and by the sediments was not clearly shown. However, sediment may play important role in ammonia adsorption because sediments contain clay like zeolite and the release of ammonia from sediment was observed. Low ammonia content in Chao Phraya River, which receives Bangkok city domestic sewage and many factory discharges along the river with insuffi- cient treatment, can be due to high ammonia transformation activities. High nitrification and denitrification potentials decrease the ammonia concen- tration rather quickly after it was discharged.