|M.Sc Student||Nof Keren|
|Subject||Nitrogen Compounds Removal From River Water in India Using|
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Emeritus Michal Green|
|Full Thesis text|
Moving Bed Bio Reactor (MBBR) pilot plant has been constructed and operated for the removal of pollutants (BODtotal of 29 mg/l and NH4 of 17.9 mg/l) from Yamuna River water (India), with special emphasis on nitrogen compounds removal. The pilot plant was designed to treat 100 m3/d to attain drinking water quality (BODsoluble of 2.0 mg/l, NH4 of 1.65 mg/l and nitrate of 9.0 mg/l), and has been in operation for one year and nine months. The MBBR consisted of five stages and free-floating polyethylene particles were used as the carriers for the biofilm.
This work reviews the most common technologies to remove nitrogen compounds from river water and analyses the results obtained from the seven months pilot plant operation. The influence of various parameters such as water temperature, the contribution of each stage of the process and the nitrogen removal rates are examined.
The pilot plant results show that the system consistently produced the required effluent quality with regard to nitrogen compounds, reducing pollutant levels to below the required concentrations.
Even during the winter, with temperatures between13 and 22°C the results showed ammonia removal of 91-94%. During the warm season, with temperatures between 23 to 32°C, higher ammonia removal was obtained, 97-99%.
Even though nitrate levels (monthly average) after the nitrification process were most of the time below the required value, ethanol was added to the deox stage in order to reduce the dissolved oxygen concentration and to supply electrons for the denitrification process. The amount of ethanol added was about 25 times higher than that required for the nitrate reduction, which obviously is unacceptable from both economical and environmental point of view. These results indicate that the deox stage was not designed properly for denitrification ) enabled substantial aeration).
Low denitrification rates were observed despite the low DO concentration and high C:N ratio in the anoxic stage. This may also be explained by inadequate nitrate lab tests as was also verified by the alkalinity results.