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Two‐stage biotransformation of 2,4,6‐trinitrotoluene under nitrogen‐rich and nitrogen‐limiting conditions
Author(s) -
VanderLoop Sarah L.,
Suidan Makram T.,
Moteleb Moustafa A.,
Maloney Stephen W.
Publication year - 1998
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143098x127035
Subject(s) - trinitrotoluene , effluent , chemistry , nitrogen , activated sludge , bioreactor , nitrite , nitrification , anaerobic exercise , denitrification , environmental chemistry , ammonia , biotransformation , anammox , wastewater , denitrifying bacteria , waste management , nitrate , organic chemistry , biology , explosive material , physiology , enzyme , engineering
An anaerobic fluidized‐bed granular activated carbon bioreactor in series with an activated‐sludge reactor was used to treat a wastewater containing 100 mg/L 2,4,6‐trinitrotoluene (TNT). The performance of the system was evaluated under both nitrogen‐rich and nitrogen‐limiting conditions. When 18 mg/L ammonia‐nitrogen was supplied to the system, the mixed anaerobic culture completely transformed the TNT to unknown products. Effluent ammonia‐nitrogen routinely was more than 21 mg/L, and nitrite was also detected in the anaerobic reactor effluent, possibly indicating two distinct methods of nitrogen removal from the ring. The effluent from this reactor was treated further in an activated‐sludge system. A significant fraction of the TNT transformation products was oxidized in the aerobic stage, resulting in recovery of 82% of influent TNT‐nitrogen and at least 73% TNT‐carbon mineralization in the system. When the anaerobic reactor received only TNT as a nitrogen source, anaerobic reactor effluent ammonia levels remained above 3 mg/L, but nitrite was not detected. The resulting TNT biotransformation products could not be completely identified, but they did persist in the final effluent. The inability of the activated sludge to effect further transformation of some of these compounds was quantified as a substantial reduction in inorganic nitrogen recovery. Only 55% of influent TNT‐nitrogen was recovered in the system during the nitrogen‐limited operation.