Biological treatment of high NH4+-N wastewater using an ammonia-tolerant photosynthetic bacteria strain (ISASWR2014)

Wastewater with high NH4+-N is difficult to treat by traditional methods. So in this paper, a wild strain of photosynthetic bacteria was used for high NH4+-N wastewater treatment together with biomass recovery. Isolation, identification, and characterization of the microorganism were carried out. The strain was inoculated to the biological wastewater treatment unit. The impacts of important factors were examined, including temperature, dissolved oxygen, and light intensity. Results showed that photosynthetic bacteria could effectively treat high NH4+-N wastewater. For wastewater with NH4+-N of 2300 mg · L− 1, COD/N = 1.0, 98.3% of COD was removed, and cell concentration increased by 43 times. The optimal conditions for the strain's cell growth and wastewater treatment were 30 °C, dissolved oxygen of 0.5–1.5 mg · L− 1 and a light intensity of 4000 lx. Photosynthetic bacteria could bear a lower C/N ratio than bacteria in a traditional wastewater treatment process, but the NH4+-N removal was only 20%–40% because small molecule carbon source was used prior to NH4+-N. Also, the use of photosynthetic bacteria in chicken manure wastewater containing NH4+-N about 7000 mg · L− 1 proved that photosynthetic bacteria could remove NH4+-N in a real case, finally, 83.2% of NH4+-N was removed and 66.3% of COD was removed.

The isolated photosynthetic bacteria (PSB) were used to treat chicken manure wastewater contained recalcitrant organic compounds. The total COD value was about 3000 mg · L− 1, and NH4+-N concentration was 7000 mg · L− 1, with a C/N of 0.42. The use of PSB proved to be very efficient in treating such a high NH4+-N and low C/N wastewater. The results indicated that the PSB has special adaptations for survival and reducing the NH4+-N even with an NH4+-N concentration of 7000 mg · L− 1. The COD removal reached 66.3% and the NH4+-N removal reached 83.2%.Figure optionsDownload as PowerPoint slide