Optimization of denitrifying phosphorus removal in a predenitrification anaerobic/anoxic/post-aeration+nitrification sequence batch reactor(pre-A_(2)NSBR)system:Nitrate recycling,carbon/nitrogen ratio and carbon source type

Because the efficiency of biological nutrient removal is always limited by the deficient carbon source for the low carbon/nitrogen(C/N)ratio in real domestic sewage,the denitrifying phosphorus removal(DNPR)was developed as a simple and efficient method to remove nitrogen and phosphorous.In addition,this method has the advantage of saving aeration energy while reducing the sludge production.In this context,a pre-denitrification anaerobic/anoxic/post-aeration+nitrification sequence batch reactor(pre-A_(2)NSBR)system,which could also reduce high ammonia effluent concentration in the traditional two-sludge DNPR process,is proposed in this work.The pre-A_(2)NSBR process was mainly composed of a DNPR SBR and a nitrifying SBR,operating as alternating anaerobic/anoxic/post-aeration+nitrification sequence.Herein,the long-term performance of different nitrate recycling ratios(0-300%)and C/N ratios(2.5-8.8),carbon source type,and functional microbial community were studied.The results showed that the removal efficiency of total inorganic nitrogen(TIN,including NH4^(+)-N,NO_(2)^(-)-N,and NO_(3)^(-)-N)gradually increased with the nitrate recycling ratios,and the system reached the highest DNPR efficiency of 94.45% at the nitrate recycling ratio of 300%.The optimum C/N ratio was around 3.9-7.3 with a nitrogen and phosphorus removal efficiency of 80.15%and 93.57%,respectively.The acetate was proved to be a high-quality carbon source for DNPR process.The results of fluorescence in situ hybridization(FISH)analysis indicated that nitrifiers and phosphorus accumulating organisms(PAOs)were accumulated with a proportion of 19.41%and 26.48%,respectively.

Impact of microorganism degradation on hydrocarbon generation of source rocks:A case study of the Bozhong Sag,Bohai Bay Basin

The discovery of the Bozhong 19-6 gas field,the largest integrated condensate gas field in the eastern China in 2018,opened up a new field for the natural gas exploration deep strata in the Bohai Bay Basin,demonstrating there is a great potential for natural gas exploration in oil-type basins.The ethane isotope of the Bozhong 19-6 condensate gas is heavy,showing the characteristics of partial humic gas.In this paper,aimed at the source rocks of the Bozhong 19-6 gas field in the Bohai Bay Basin,the characteristics of the source rocks in the Bozhong 19-6 structural belt were clarified and the reason are explained from impact of microorganism degradation on hydrocarbon generation of source rocks why the condensate oil and gas had heavy carbon isotope and why it showed partial humic characteristics was explored based on the research of parent materials.The following conclusions were obtained:The paleontology of the Bozhong 19-6 structural belt and its surrounding sub-sags is dominated by higher plants,such as angiosperm and gymnosperm.During the formation of source rocks,under the intensive transformation of microorganism,the original sedimentary organic matter such as higher plants was degraded and transformed by defunctionalization.Especially,the transformation of anaerobic microorganisms on source rocks causes the degradation and defunctionalization of a large number of humic products such as higher plants and the increase of hydrogen content.The degradation and transformation of microorganism don't transform the terrestrial humic organic matter into newly formed“sapropel”hydrocarbons,the source rocks are mixed partial humic source rocks.As a result,hydrogen content incrased and the quality of source rocks was improved,forming the partial humic source rocks dominated by humic amorphous bodies.The partial humic source rocks are the main source rocks in the Bozhong 19-6 gas field,and it is also the internal reason why the isotope of natural gas is heavy.

Types of focal mechanism solutions and parameter consistency of the sub-blocks in Sichuan and Yunnan Provinces

Based on P- and S-wave amplitudes and some clear initial P-wave motion data, we calculated focal mechanism solutions of 928 M≥2.5 earthquakes （1994-2005） in four sub-blocks of Sichuan and Yunnan Provinces, namely Sichuan-Qinghai, Yajiang, Central Sichuan and Central Yunnan blocks. Combining these calculation results with those of the focal mechanism solutions of moderately strong earthquakes, we analyzed the stress field characteristics and dislocation types of seismogenic faults that are distributed in the four sub-blocks. The orientation of principal compressive stress for each block is： EW in Sichuan-Qinghai, ESE or SE in Yajiang, Central Sichuan and Central Yunnan blocks. Based on a great deal of focal mechanism data, we designed a program and calculated the directions of the principal stress tensors, σ1, σ2 and σ3, for the four blocks. Meanwhile, we estimated the difference （also referred to as consistency parameter θ^- ） between the force axis direction of focal mechanism solution and the direction of the mean stress tensor of each block. Then we further analyzed the variation of θ^- versus time and the dislocation types of seismogenic faults. Through determination of focal mechanism solutions for each block, we present information on the variation in θ^- value and dislocation types of seismogenic faults.