Microbial and Enzymatic Removal of Ammonia and Nitrate in Wastewater

Microbial and Enzymatic Removal of Ammonia and Nitrate in Wastewater
Lecture-Seminar by Prof. Young Je Yoo (School of Chemical and Biological Engineering, Seoul National University, Korea)

February 8, 2011 - 8:00-11:00 am
Rigney Hall, USC Talamban Campus

For more details, contact the Department of Chemical Engineering (Tel. No. 3446783 or 2300100 loc 103)

Abstract of Lecture

Part 1. Nitrate Removal
Nitrate has lots of harmful effects to environment and human body. Many kinds of nitrate removal processes have been developed. Among them, biological method is the most widely accepted because of its economic and environmental advantages. However, biological denitrification process has some disadvantages. Since the biological process employs microorganisms, carbon sources have to be fed for microbial activities. The carbon sources lead to cost increase and secondarily, pollution of water environments. To solve this problem, a new technology was developed. Permeabilized microorganism was used as biocatalyst containing 4 enzymes – nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase. The permeabilized microorganisms did not require carbon sources for maintaining microbial activities. The biocatalyst and conducting material mixture formed three-dimensional structure and this was used as a bioelectrode. The electrons for denitrification were transferred to the biocatalyst in the bioelectrode. High denitrification efficiency was obtained using this electrode system. The system is currently under pilot plant test.

Part 2. Ammonia Removal
Ammonia in wastewater or sewage treatment plant is to be removed. Usually, ammonia is converted to nitrate via nitrite under aerobic condition, and the nitrate is converted to nitrogen gas under anaerobic condition. A new technology has been developed to remove ammonia. One example: ammonia is converted to nitrite, which in turn is converted to nitrogen. A technology is being developed based on this process and employing the bioelectrode system. Another example is ANAMMOX technology by which ammonia and nitrite can be converted to nitrogen using anaerobic microorganism. This technology is being improved using enzyme engineering, details of which will be presented and discussed.