Experimental Research about Denitrification by Box Filler Enhancing MBR Process

[Objective] The reseamh aimed to study removal effects of the organic matter and N by box filler enhancing MBR process. [ Method] By adding box filler into reaction pool of the MBR to treat domestic sewage, removal effects of the organic matter and N by box filler enhancing MBR process were studied. [ Result] COD means in effluent were respectively 26.8 and 24.7 mg/L without and with adding filler. Average removal rates of the NH3-N were respectively 98.44% and 96.37% with and without dosing filler, while average removal rates of the TN were 24.03% and 16.43%, respectively. COD and NH3-N concentrations in effluent were lower than Level-one A cdteda of Discharge Standard of the Pollutant for Municipal Wastewater Treatment Plant （ GB18918 -2002）. NO3^ -N was main existence form of the TN in effluent and occupied 98.06%, while NH3- N and NO2^--N only accounted for.1.22% and 0.72%. Further suggestion for denitrification study was as below. Firstly, the proportion of box filler on volume of the reaction cell should increase to 4% -5%. Secondly, single smaller filler with larger amount of internal fiber ought to be replaced. Thirdly, aeration amount needed to be decreased to right value, making that DO of the MBR reaction cell reduced to 1.5 -3.0 mg/L. [ Conclusion] The research provided theoretical basis for future engineering practice.

Application Study of Trajectory Plume Model in Atmospheric Environmental Impact Assessment

[ Objective] The research aimed to study application of the trajectory plume model in atmospheric environmental impact assessment. [ Method] Trajectory plume model was used to retrospectively evaluate regional atmospheric improvement degree by fuel gas desulfurization project in Mawan Power Plant of Shenzhen. On this basis, we analyzed applicability of the model in atmospheric prediction of the construction project. [- Re- sult~ Under the situation of complex flow field and variable weather condition, the trajectory plume model displayed good prediction accuracy, to- gether with the use of flow field diagnosis model. Under complex weather condition, this model could be complementary to atmospheric environmen- tal quality prediction model recommended by new atmosphere guidelines, which had the value of popularization in future atmospheric environmental evaluation and planning. [ Conduslon~ Trajectory plume model had broad application potential in atmospheric environmental impact assessment.

Divergent responses of soil carbon and nitrogen pools to short-term nitrogen addition between two plantations in Northeast China

Nitrogen(N)deposition has a profound influence on forest soil carbon(C)and N pools,but there was no consensus on the responses of different C and N components in different forest types.In this study,a two-year simulated N deposition experiment with four levels of N(NH4NO3)-addition treatments(0,50,100,and 150 kg N/hm^(2)·a)were conducted in Larix gmelinii(LG)and Quercus mongolica(QM)plantation in Northeast China,in order to investigate the C and N pool dynamics under continuously enhanced N deposition.Soil organic carbon(SOC),soil total N(STN)and their active components(readily oxidizable C,ROC;dissolved organic C,DOC;microbial biomass C,MBC,dissolved organic N,DON;microbial biomass N,MBN)of the forest soil were measured monthly from May to October 2017.C and N contents in LG were observed higher than in QM.N addition had no effect on SOC and STN of LG,but significantly increased SOC and STN of QM at low N addition level.Low N addition generally raised active C components(ROC,DOC,and MBC)in both plantations,whereas high N addition did not significantly affect these components,or even decreased ROC in LG soil.Low N addition also increased STN and MBN of QM,while no significant change in STN and MBN of LG was observed.DON was directly affected by N addition and increased significantly with elevated N addition levels.The results indicated that N addition,especially of low rate,might enhance the C sequestration capacity of the forest soils and mitigate climate change.