AWWA ACE56260

High nitrate levels in drinking water are the primary cause of methemoglobinemia, and evidence points to a potential linkage between nitrate intake and cancer. The concentration of nitrate in water sources has steadily risen in developed countries. An attractive alternative to physical and chemical treatment for removing nitrate is biological denitrification. Autotrophic denitrification is recommended over heterotrophic denitrification because of downstream instability issues associated with heterotrophic denitrification. In this research, hydrogenotrophic denitrifiers were used along with a dead-end Hollow Fiber Membrane Bioreactor (HFMB). The HFMB increased the mass transfer of H2 to improve the denitrification rates and negate any combustion issues affiliated with H2 gas. Also, the HFMB supported a high biomass density. The objectives of this project were to compare the denitrification rates and water quality with previous research, control biofouling, and investigate effects of partial H2 pressure and mixotrophic metabolism on denitrification rates. The research resulted in denitrification within 24 hours of startup, along with denitrification rates comparable to previous research. Controlling the biofilm by shearing with N2 gas improved both the average denitrification rates and effluent turbidity, TOC/DOC, and heterotrophic plate counts. The mixotrophic metabolism resulted in a slight increase in average denitrification rate over an autotrophic environment. However, the concerns associated with an organic carbon source carryover questions the practicality of the mixotrophic concept. Includes 28 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/16/2002

Number of Pages:

19

File Size:

1 file , 400 KB