Study on simultaneously carbon and nitrogen removing from domestic wastewater with immobilized nitrogen bacteria

This study was to investigate the simultaneous removal of carbon and nitrogen with Achromobacter oxylosoxidans and Pseudomonas stutzeri from synthetically-made domestic wastewater, and to verify the simultaneous nitrification and denitrification（SND）. First of all, using a batch experiments to analyze the SND reaction of suspended cells and immobilized cells. Furthermore, continuous-flow test was performed with synthetically-made domestic wastewater use to evaluate the availability of removing nitrogen from wastewater, and to find the optimum operation as a guideline for the treating wastewater as the same time. At the last, DGGE-based investigation was also performed by using immobilized cells to verify the feasibility in the continuous-flow system.
Experiment testified that Achromobacter oxylosoxidans and Pseudomonas stutzeri have the ability to simultaneously remove carbon and nitrogen from synthetically-made domestic wastewater, and also have the appearance of SND. In our researches, in addition to prove the immobilized cells ability of feasibility in the continuous-flow system, nitrification and denitrification are demonstrated efficiently under high DO level. Furthermore, especially for mixed-culture groups which provide 39 % nitrification efficiency, and 71 % total nitrogen removal as T-N= 40 mg/L, COD= 765 mg/L, C/N= 19 for the better operation.
Although the immobilized cells can treat synthetically-made domestic wastewater with 53~67 % total nitrogen removal rate, the system produces too much sludge and ammonia residue and achieves the effluent-standard which limits its feasibility in real operations. Hence, autotrophic nitrifiers were suggested to be applied for enhancing the nitrification efficiency.
Tracing the strain in the immobilized cells with DGGE method after the continuous-flow test shows that the strain can be conserved in the immobilized cells well and it appears that immobilized technique can successfully maintains the strains from being washed out after long-term operations.