Experimental Study on the Removal of Nitrate Nitrogen from Water Using Common Crop Straw as Carbon Source
In order to optimize the denitrification process using crop straw as a solid carbon source for nitrate pollution re-moval,the optimal addition amount is selected,and how to regulate the suitable environmental factors.In this paper,we experimentally investigated the effect of using common crop residues(wheat,corn,soybean)as carbon source on nitrate nitrogen removal and the influence factors of suitable environment.The results showed that denitrification using corn stover as a carbon source had the best effect,with the highest nitrate nitrogen concentration of 98.6％and the lowest nitrite nitro-gen concentration removed,and the ammonia nitrogen concentration started to decrease very early,which was more favora-ble for microbial utilization.When the C/N ratio was 2,the nitrate removal rate was the fastest,the nitrite and ammonia nitrogen concentrations were also lower,and the denitrification efficiency was the highest.During denitrification,the fastest removal rate of nitrate nitrogen and nitrite nitrogen and the lowest concentration of ammonia nitrogen were observed when the pH was 7.As the temperature of denitrification experiment was raised to 30 ℃ and 40 ℃,the reduction of nitrate nitrogen concentration in the experiment was obviously accelerated,which indicated that denitrification was more effective under these two temperature conditions.When corn stover and biochar were used together as the carbon source,the nitrate remov-al rate was as high as 99.7％,and the nitrite and ammonia nitrogen concentrations were reduced;this study provides a the-oretical basis and practical reference for the biological management of nitrate pollution.
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