Recently, algae biocrude has drawn considerable attention as algae are considered to be one of the major fuel feedstocks of the future. Based on some impressive results achieved under appropriate conditions, the algae hydrothermal liquefaction (HTL) process has proven to be energy efficient. However, the HTL of biocrude is characterized by a high nitrogen content, which prevents its use in the field of transportation due to the associated nitrogen oxide emissions. Despite this toxicity, few research efforts have focused on the denitrogenation of algae biocrude. In this study, we review the effect of different strain-specific operation parameters and process upgrades with respect to the nitrogen content of biocrude. To achieve denitrogenation, chemical engineering may be required, although some improvements in biocrude properties have been achieved in a number of process upgrades. The use of similar successful pathways has the potential to improve the field of HTL biocrude denitrogenation. These methods, including the adsorptive and extractive denitrogenations of fossil fuels and the hydrodenitrogenation of the main nitrogen compounds, are helpful for developing a better understanding of the potential of denitrogenation for algae HTL biocrude. We also recommend the use of some available catalysts and corresponding operation parameters to promote continued research on denitrogenation.

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In order to achieve high efficiency of biofilm and removing nitrogen with low consumption, people have developed a new eco-ceramic concrete filler, used for the denitrification in treating municipal wastewater. When the water temperature is 25 ~ 30°C, the pH of influent is 7.0 ~ 7.5, the concentration of DO is 2.5 ~ 3.0mg /L, and the removal rates of COD, ammonia and total nitrogen are 78.6 ~ 91.8%, 83.4 ~93.6% and 63.4 ~ 73.8 % respectively. The removal of the pollutants mainly concentrates on the front and center of the reactor. We can also draw a conclusion from the experiment that, SOUR, the dry weight of biofilm and the thickness of biofilm present a pattern of diminishing along the corridor. The average decreasing ratio of each filler are 0.81%, 1.3% and 1.05%, respectively. And the activity of per unit mass of biofilm has increased along the corridor, and the end of it is 51.5% more than the front, which indicates that the system has good ability of resistance.

In order to ensure the stable and standard discharge of mixed nitrogen sewage, Guangzhou Datansha Wastewater Treatment Plant has made a test using an inverted A2/ O process, with the actual Wastewater as entry water. When the ratio of mixed fecal sewage is 0.33%, the results showed that, extending the HRT(Hydraulic Retention Time) can help to enhance the effect of removing nitrogen, and HRT should be ensured at least 8 hours under the test conditions. And the increase of the concentration of dissolved oxygen can promote the effect of removing nitrogen ranging from 1.0 to 1.5 mg/L. And the sludge reflux ratio should be remained at 60%. Besides, the growth of sludge age has positive effect on nitrification, so the sludge age should be controlled in more than 20 days under the experimental conditions.