Skip to main content

DENITRIFICATION OF HIGH AMMONIA CONTENT WASTEWATER USING THE NITE/DENITE PROCESS

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

Wastewater generated at Citizens Gas from coking operations is treated in a biological nitrification system. The treatment system consists of a one million-gallon equalization tank, a one million-gallon aeration basin, and a 65ft clarifier. The nitrification reactions generate acid, which is neutralized using 4-8 tons/day of soda ash. The annual soda ash cost at Citizens Gas can range from 240,000 to 480,000, depending on usage rate. In an attempt to reduce chemical cost, a treatability test was conducted to evaluate the potential to reduce soda ash cost by converting the existing nitrification system to a Nite/Denite system. Nite/Denite was developed in 1985 by ENSR Corporation to completely nitrify and denitrify high ammonia content coke plant wastewater in a single reaction tank system. Denitrification would generate alkalinity neutralizing a portion of the acid generated during nitrification. The lower demand for the external source of alkalinity would reduce the annual operational cost.

A continuous stirred tank activated sludge reactor was set up in the laboratory to determine the effectiveness of Nite/Denite in reducing the soda ash consumption at Citizens Gas WWTP. Actual wastewater from the facility was used in the treatability tests. Nite/Denite mode of operation was achieved by turning the airflow to the reactor ‘on’ and ‘off’ during a 60-minute cycle to create aerobic and anaerobic conditions in the same reactor. During the aerobic cycle, ammonia was nitrified to nitrite and nitrate, generating acid. During the anaerobic cycle, nitrite and nitrate were reduced to nitrogen gas, generating alkalinity. This alkalinity neutralized a portion of the acid generated in the aerobic cycle.

Results of the treatability studies indicated that soda ash consumption dropped by approximately 41% in the reactor under the Nite/Denite operating mode, while maintaining 10-ppm ammonia in the reactor.

Citizens Gas could convert the existing nitrification system to a Nite/Denite system with minor design and operational modifications. The only design modification would be the installation of mixing equipment (floating or side entry), which would provide mixing in the aeration basin during the anaerobic cycle. Minor computer programming change would also be required to turn the blowers on and off to create aerobic and anaerobic conditions in the aeration basin. The total cost for the above modifications including engineering is estimated to be less than 50,000.

A preliminary operational cost estimate was also conducted to determine the potential savings that would be realized if the above modifications were made. Converting the existing system to a Nite/Denite system would reduce the total annual soda ash and power costs by approximately 179,225.

Treatability studies also indicated that the extent of denitrification achieved under the current operating conditions is limited by the amount of BOD in the influent wastewater. To increase the extent of denitrification would require that an external source of BOD (e.g. methanol) be added to the wastewater. Although this would increase the design and operational cost, it could potentially further reduce the soda ash cost.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Data/Media
No Metrics

Document Type: Research Article

Publication date: 2002-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more