Nitrogen Pollution Control and Treatment in Water Bodies

Author: | published date:2013-11-30

Nitrogen is the key element of protein and nucleic acid, which therefore is the fundamental element for all different kinds of lives. Seventy-eight percent of atmosphere is nitrogen; the nitrogen cycle plays a significant role in circulation of materials and ecosystem. Different types of human activities will release nitrogen element into natural environment. However, if the nitrogen element exceeds its standard level in ecosystem, the balance of the nitrogen cycle will be destroyed, and different kinds of nitrogen pollution may occur. For example, the release of nitrogen may cause acid deposition and lake eutrophication. Once the oxides of nitrogen get into the upper atmosphere, they will destroy the ozone layer through a series of catalytic reactions, which in the long run could lead to the global climate change and other environmental and ecological environment problems. Nitrites are strong carcinogenic, which could cause methemoglobin and even death. Long-term drinking of the water with high concentration of nitrate may cause miscarriage of pregnant women and newborn Blue Baby Syndrome, even cancer. Almost all persistent organic pollutions (POPs) such as quinoline, carbazole and azoic compound, and other typical pollutants in wastewater from the chemical industry, are carcinogenic. Nitrobenzene, an industrial product or intermediate, is also very toxic, which can lead to the liver cirrhosis, liver cancer and leukemia.

Nitrogen water pollution is currently a very urgent problem in China. To meet the national requirements for solving the nitrogen water pollution, breakthroughs regarding the nitrogen water pollution control and treatment have been achieved in the past several years, including advanced nitrogen removal technology for municipal sewage, efficient nitrogen removal techniques for industrial wastewater, ecological treatment of sewage in rural area, and the control of non-point (distributed) sources of regional nitrogen contamination.

a)        Novel microorganisms for efficient nitrogen removal: In order to solve the key problems of advanced nitrogen removal in municipal wastewater treatment plants, a series of heterotrophic nitrification and aerobic denitrification microorganisms have been successfully isolated and cultured, with which the nitrification and denitrification could be simultaneously achieved in single aerobic environment. As a result, the conventional technological bottleneck for simultaneous removal of nitrogen is solved. The wastewater treatment plant can be upgraded with more cost-effective, energy-efficient, land-saving and environment-friendly ways through merging the novel microorganisms with different conventional wastewater treatment systems.

b)       Immobilized microorganism techniques: In order to facilitate the degradation of highly toxic organic pollutants from industrial wastewater, the macroporous functional carriers, which could enhance the microbial tolerance to toxic substances and high ammonia nitrogen, have been fabricated. The immobilized microbial systems suitable for industrial wastewater treatment have been developed. This technique could simultaneously remove ammonia nitrogen and total nitrogen, and can apply to the efficient treatment of wastewater with high ammonia nitrogen and persistent organic pollutions.

c)        Sewage treatment in rural areas and regional nitrogen pollution control: In order to solve the problems of ineffective denitrification process, biological-ecological multi-medium techniques, which could greatly improve the abundance of denitrification functional bacteria, have been developed and successfully used to treat the sewage in rural areas. Moreover, great efforts have also been devoted to control the regional nitrogen pollution. Models about the nutrients controls and attenuations, and water quality response have been developed. In addition, several reliable ways to control regional nitrogen pollution have been also proposed.

        Overall, in this research field, more than 20 invention patents have been issued and around 30 papers have been published in international journals. These techniques have already been applied to treating landfill leachate, coking wastewater, pharmaceutical wastewater, pollution control in middle line of the south-to-north water diversion project and over 30 projects of sewage treatment plants. The research has won the First Prize for Science and Technology Progress in 2008.