Effect Of Ammonia Nitrogen On Activity Of Anaerobic Microbe And Biological Nitrogen Removal In Scale Piggery Wastewater Treatment

Ammonia nitrogen would affect the activity of anaerobic microbe, and with the synergistic reaction of ammonization, the effect was consolidated in the anaerobic digestion process of scale piggery wastewater. Through anaerobic toxicity assay and sludge activity recovery test, the effect of ammonia nitrogen on activity of anaerobic microbe in simulated wastewater and scale piggery wastewater were studied in this paper. The results showed that the ammonia nitrogen of simulated wastewater affect the methanogenic activity of anaerobic granular sludge, the effect appeared multiplicity. When the ammonia nitrogen concentration was below 400mg/L, the methanogenic activity was accelerated. When the ammonia nitrogen concentration was equal to 800mg/L, the methanogenic activity was restrained, and with the ammonia nitrogen concentration rising, the inhibition was enhanced. The methanogenic activity was restrained in any kind concentration of scale piggery wastewater. The median lethal concentration (50%IC) of simulated wastewater was 1900.1 mg/L, and the median lethal concentration (50%IC) of scale piggery wastewater was 1725.9 mg/L. When the inhibition extent was the same, the ammonia nitrogen concentration of simulated wastewater was above scale piggery wastewater, the average value was 594.1 mg/L.The ammonia nitrogen concentration of scale piggery wastewater and pH value in anaerobic digestion process affected the ammonia nitrogen percent conversion and organics removal. The results showed that when the ammonia nitrogen concentration increased, the ammonia nitrogen percent conversion decreased, but the COD removal rate increased with ammonia nitrogen concentration. The pH values were in the range of 7.0, 7.5 and 8.0, the ammonia nitrogen percent conversion was highest for the pH of 7.5; when the pH was equal to 7.0, the COD removal rate and methane production were higher than the others, and the reaction systems for pH of 7.0 and 7.5 were superior to the pH of 8.0. The ammonia nitrogen conversion velocity was rapid, most of organics were aminated in front of 4 hours. Considering the ammonia nitrogen percent conversion and the COD removal rate, the optimal anaerobic digestion treatment time was 24 hours, pH was 7.5.The aerobic activated sludge was cultivated by anaerobic granular sludge. After 53 days of activated sludge cultivation, the influent ammonia nitrogen concentration reached 716.8mg/L, ammonia nitrogen removal rate and COD removal rate were 98.2% and 90%, respectively. These showed that the activated sludge was mature, and the next experiment could carry on. The piggery wastewater which pretreated by anaerobic digestion was treated by SBR, the optimal running process of biological denitrification was following: Firstly, wastewater was filled rapidly and then anoxic mixed round 40 minutes; secondly, the intermixture was aerated for 6 hours; thirdly, stop aeration and anoxic mix round 60 minutes, and then sedimentation for 1 hours, the last step was drawing for 40 minutes, the whole running cycle was 10 hours. The optimal running parameters were following: C/N was 10.4, DO was 2.0 mg/L and MLSS was 5000 mg/L. The experiment was conducted under the optimal running parameters for one cycle, the total nitrogen removal rate reached 69.4%, COD removal rate reached 90.1% and ammonia nitrogen reached 93.9%, the effluent can met one degree of livestock production for discharge GB18596-2001.