Abstract
How to simplify the nitrogen removal process, reduce the cost and improve the efficiency has become an urgent problem to be solved. In this research, the isolated HNAD (heterotrophic nitrification and aerobic denitrification) bacteria were used to remove<br /> the nitrogen in wastewater. Modified absorbent stone was used as high-efficiency and<br /> low-cost immobilized material. The modification effect was determined by the changes<br /> in mechanical strength, Zeta potential, pore structure, micrographs and biomass. The<br /> practicability of the modified carrier was further proved by experiments of environmental effect and reuse. The modified carrier had excellent performance. By comparing the<br /> degradation effects of immobilized microorganism and free microorganism, it was proved<br /> that the immobilized microorganisms have broad application prospects and strong adaptability to environmental factors. Under the optimum conditions (temperature of 30 oC,<br /> pH of 7, dissolved oxygen of 3.5 mg L–1), the removal efficiency of ammonia nitrogen<br /> reached 100 % in 40 hours, the removal efficiency of total nitrogen reached 60.11 % in<br /> 50 hours, and the removal rate of total nitrogen was 2.404 mg-NL–1 h–1 by immobilized<br /> microorganisms with the treatment of simulated nitrogen-containing wastewater. This<br /> research provides new material for the immobilization of HN-AD bacteria and a new way for nitrogen removal.
Highlights
With the rapid development of economy, the demand for nitrogen-containing raw materials is increasing[1]
The discovery of HN-AD bacteria has compensated for some shortcomings of previous nitrogen removal processes, many studies have reported that nitrite had accumulated with the use of the HN-AD bacteria[28,29]
The strains with ammonia nitrogen removal efficiency above 60 %, and total nitrogen (TN) degradation rate above 30 % were selected for the color reaction of nitrite
Summary
With the rapid development of economy, the demand for nitrogen-containing raw materials is increasing[1]. A great amount of nitrogen-containing wastewater is discharged. This can cause many serious consequences, e.g., the eutrophi cation of surface water, destruction of the ecological environment on which aquatic animals and plants depend, and tremendous impact on drinking water safety[2,3]. It is urgent to develop an efficient and stable technology for nitrogen removal. Biological treatment for nitrogen removal has attracted extensive attention for its advantages of high efficiency, low energy consumption, and no secondary pollution[4]. Traditional biological treatment generally includes nitrification and denitrification operations. The one-step nitrogen removal technology is in great demand
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