Method for removing nitrates in underground water through utilizing rice straws and entrapping denitrifying bacteria

Abstract

The invention discloses a method for biologically removing nitrates from underground water polluted by the nitrates. The method which is based on a traditional biological denitrifying principle treats rice straws as a solid carbon source and utilizes entrapping denitrifying bacteria to biologically remove the nitrates in the underground water. Celluloses in the rice straws are hydrolyzed and release carbon, and the entrapping denitrifying bacteria utilize the released carbon source to denitrify electron donors. A denitrifying nitrogen removal process comprises two parts, the smaller part of the denitrifying process is completed through denitrifying bacteria in biomembranes growing on the surfaces of the rice straws, and the larger part of the denitrifying action is completed through denitrifying bacterial particles. The method disclosed in the invention can realize the resource utilization of wastes, and simultaneously the entrapping denitrifying bacteria can well adapt to environmental factors comprising the temperature and the like, so the method combining the solid carbon source with the entrapping bacteria has a large application potential in the removal of the nitrates from the underground water.

Description

technical field [0001] The invention relates to a method for repairing groundwater nitrate pollution. More precisely, it is a method of removing nitrate in groundwater by using rice straw and embedding denitrifying bacteria. Using rice straw and embedded denitrifying bacteria as the reaction medium to strengthen solid-state reverse nitrification, and then remove nitrate in groundwater. Background technique [0002] The application of excessive agricultural nitrogen fertilizers, the unreasonable disposal of industrial nitrogenous wastewater and urban domestic sewage, and the improper treatment of livestock excreta and septic tanks have caused the highest concentration of nitrate in groundwater (especially shallow groundwater) worldwide. Pollution is widespread, and its pollution level is still increasing, and the situation in our country is roughly the same. The pollution of nitrate nitrogen in water will bring great harm to humans and other organisms. Therefore, the rese...

AI Technical Summary

Problems solved by technology

Compared with the potential safety hazards of physical and chemical methods, biological methods have become the most economical and effective method to remove nitrate nitrogen from water. However, for the most widely used heterotrophic denitrification method, it was found There are still some problems. Due to the filtering effect of the soil, the organic carbon source and denitrification bacteria in the groundwater are generally less, and the biological denitrification effect is relatively weak. It is necessary to supplement enough dissolved organic carbon to promote the growth of denitrifying bacteria.

The traditional method is to add liquid organic carbon sources such as methanol, ethanol and sodium acetate to the groundwater body, but due to the addition of nutrients and oxygen through injection wells, it is sometimes blocked by overgrown microorganisms, and there is a possibility of secondary pollution , it is more difficult to implement in aquifers with poor permeability. Therefore, in recent years, there have been more and more researches on the biological denitrification carbon source of solid organic carbon source used to remove nitrate in groundwater at home and abroad.

However, there are few bacterial species in groundwater, and the problem that the low temperature of groundwater affects the activity of denitrifying bacteria still needs to be solved.