With the rapid development of economy of the Three Gorges Resevoir area, a large amount of high salinity and high nitrogen organic wastewater about 3,5 million m3 per year is discharged by The Fuling Mustard Tuber Industry. It poses a serious threat to the water environtment of reservoir.
High salinity is a key problem that affects the processes of biological treatment for Fuling Mustard Tuber waste water. In recent years, the effects of salinity on the activities of microorganism in bioreactors were studied. The studies have showed that high salinity in wastewater typically dampens the degrading enzymes and decreases cell activity, can even cauuse cell plasmolysis, and its also have negative effects on organic removal. Generally, high salinity wastewater needs to be diluted before treating , it means the long process flow and low operation load which demand gigantic investment and high operating cost. Consequently, building a microbial communityof salt-tolerant halophilic microorganisms that can improve the adaptability of system to high salinity is the key to treat the high salinity wastewater.
How to remove the nitrogen high salinity and high nitrogenorganic wastewater is another key problem. Traditionally, the nitrogen removal process were based on the autotrophic nitrification and heterotrophic denitrification. But high salinity wastewater can effect the conventional processes of ammonium oxidation, nitrification and denitrification. the traditional process of autotrophic nitrification was inhibited by organic matter.Therefore, the simultaneous removal efficiency of nitrogen and COD was low, Meanwhile, the low organic loading of outotrophic nitrification reactor can lead to large reactor volume, high investment and high operating cost. With the proposed concept of the heterotrophic nitrification and aerobic denitrification, heterotropic nitrification bacteria gradually was known by the public. Comparing with traditional nitrogen removal methods, neterotrophic nitrification has swveral advantages. Heterophic nitrification bacteria can remove COD and nitrogen simultaneouslyin one reactor via simultaneous nitrification and denitrification. Heterotrophic nitrification bacteria have the ability to utilize different kinds of materials. And it is conducive to coexist with other strains. Meanwhile, some species of heterotrophic nitrification bacteria have the charactheristic of high level ammonia resistant.These features of heterotrophic nitrification bacteria have great significance for treating the high salinity and high nitrogen organic wastewater. Recent studies of heterotrophic nitrification bacteria mainly focused on substrate removal, accumulation of intermediates, and the removal of COD and nitrogen via simultaneous nitrification and denitrification. But the applications of the heterotrophic nitrification -aerobic denitrificationhave been isolated, but they could not perform well in nitrogen removal with high salinity.
In this study, a simultaneous nitrogen removal system for high salinity and high nitrogen organic wastewater via heterotrophic nitrification was developed in a pressurized biofilm reactor. During the experiment, there is no anaerobic-aerobic conditionsand no excess sludge discharge in the single stage reactor. The perfomance of COD and nitrogen removal were examined. Meanwhile, PCR-DGGE was used to detectthe microbial diversity and community structure. This study can provide a more efficient and feasible solution to treat the high salinity and high nitrogen organic wastewater.