Phosphorus recovery from biogas fermentation liquid by Ca-Mg loaded biochar

Shortage in phosphorus(P) resources and P wastewater pollution is considered as a serious problem worldwide. The application of modified biochar for P recovery from wastewater and reuse of recovered P as agricultural fertilizer is a preferred process. This work aims to develop a calcium and magnesium loaded biochar(Ca–Mg/biochar) application for P recovery from biogas fermentation liquid. The physico-chemical characterization, adsorption efficiency, adsorption selectivity, and postsorption availability of Ca-Mg/biochar were investigated. The synthesized Ca–Mg/biochar was rich in organic functional groups and in Ca O and Mg O nanoparticles. With the increase in synthesis temperature, the yield decreased, C content increased, H content decreased, N content remained the same basically, and BET surface area increased. The P adsorption of Ca–Mg/biochar could be accelerated by nano-Ca O and nano-Mg O particles and reached equilibrium after 360 min.The process was endothermic, spontaneous, and showed an increase in the disorder of the solid–liquid interface. Moreover, it could be fitted by the Freundlich model. The maximum P adsorption amounts were 294.22, 315.33, and 326.63 mg/g. The P adsorption selectivity of Ca–Mg/biochar could not be significantly influenced by the typical p H level of biogas fermentation liquid. The nano-Ca O and nano-Mg O particles of Ca–Mg/biochar could reduce the negative interaction effects of coexisting ions. The P releasing amounts of postsorption Ca–Mg/biochar were in the order of Ca–Mg/B600 Ca–Mg/B450 Ca–Mg/B300. Results revealed that postsorption Ca–Mg/biochar can continually release P and is more suitable for an acid environment.     

开发和建设西南能源基地是解决我国能源短缺的重要途径

西南地区是我国第二大能源基地，水能蕴藏可开发年发电量１．０３万亿ｋｗ·ｈ，占全国的５４％，煤炭保有储量７７０亿ｔ左右，占全国的１０％。和以山西为中心的能源基地一起，形成了“北煤南运”和“西电东送”两个格局。但是西南能源基地的水能资源开发程度很低，按发电量计算，仅占水电可开发总量的１．３％。目前能源短缺已成为我国工业发展中的突出问题。因此，合理布局、综合开发和建设西南能源基地，是解决我国能源短缺的重要途径。     

涟水县农业区域开发规划

搞好综合开发是建设现代化农业的战略措施之一,而要搞好综合开发,必先搞好农业区域开发规划。本文根据涟水地区的自然资源、社会经济条件和市场对农副产品及其制品需求出发,把涟水县域划分为2个开发区域,从分析开发的潜力入手,通过投资和效益的分析,提出了区域近、远期的开发目标、步骤和相应的开发措施。     

湖北省近40年旱涝轻重程度的次序确定

本文用旱涝指标(即H=P/E)式计算了湖北省解放以来各年月的旱涝指数,它对给定的时间和空间上的旱涝轻重程度具有明显的分辨能力,由此确定了历年各自然季节的旱涝轻重年份的次序。     

重大工业危险源(罐区)监控预警系统

系统建立了管理软件和硬件监控相结合的安全生产监控预警系统，在安全管理的基 础上，把罐区诸多的危险参数给予实时监测、报警和控制。本系统实现了生产过程控制与安全监控 相结合，安全监测报警与事故预案相结合，既满足了生产控制又实现了动态的安全管理，对安全生产 具有较大意义。     

《地震学刊》的刊徽设计

提出了刊徽设计的原则和要求。所设计的《地震学刊》的刊徽是个由经纬网格所构成的公转着的地球。经纬网格由ＳＪ两个字母和两条细线所组成。ＳＪ为《地震学刊》英文名和江苏的汉语拼音名的缩写。Ｓ表示大地震所激发的地球自由振动的一阶振型；两条细线既表示经线，又表示地球自由振动的基振型。     

Composting of vegetable waste.

The effects of the aeration, seeding, and agitation on the composting of vegetable waste were studied in a laboratory-scale reactor. Experimental results showed that the final product at the end of a 4-day composting period met multiple maturity indices suggested by many researchers. The evolution of carbon dioxide during the composting process could be modelled with a modified Gompertz equation that described the bacteria growth successfully. Multivariate regression analysis was used to study the effects of operating parameters on the carbon conversion. The response surface contour plots were constructed using the regression equation for the examination of the dependence of carbon conversion on operating parameters. The maximum carbon conversion of 14.54% was obtained when the percentage of seeding was set at 14.5%, the air suction rate was set at 2.6 L kg(-1) dry-solid min(-1), and the agitator operated half of the time, alternating on and off for every 5 min. Future work will focus on the application of the data and the experience gained in this work to composters of pilot and semi-commercial scales.     

Differences in nitrous oxide fluxes from red soil under different land uses in mid-subtropical China

Red soil may play an important role in nitrous oxide (N₂O) emissions due to its recent land use change pattern. To predict the land use change effect on N₂O emissions, we examined the relationship between soil N₂O flux and environmental determinants in four different types of land uses in subtropical red soil. During two years of study (January 2005-January 2007), biweekly N₂O fluxes were measured from 09:00 to 11:00 a.m. using static closed chamber method. Objectives were to estimate the seasonal and annual N₂O flux differences from land use change and, reveal the controlling factors of soil N₂O emission by studying the relationship of dissolved organic carbon (DOC), microbial biomass carbon (MBC), water filled pore space (WFPS) and soil temperature with soil N₂O flux. Nitrous oxide fluxes were significantly higher in hot-humid season than in the cool-dry season. Significant differences in soil N₂O fluxes were observed among four land uses; 2.9, 1.9 and 1.7 times increased N₂O emissions were observed after conventional land use conversion from woodland to paddy, orchard and upland, respectively. The mean annual budgets of N₂O emission were 0.71-2.21 kg N₂O-N ha⁻¹ year⁻¹ from four land use types. The differences were partly attributed to increased fertilizer use in agriculture land uses. In all land uses, N₂O fluxes were positively related to soil temperature and DOC accounting for 22-48% and 30-46% of the seasonal N₂O flux variability, respectively. Nitrous oxide fluxes did significantly correlate with WFPS in orchard and upland only. Nitrous oxide fluxes responded positively to MBC in all land use types except orchard which had the lowest WFPS. We conclude that (1) land use conversion from woodland to agriculture land uses leads to increased soil N₂O fluxes, partly due increased fertilizer use, and (2) irrespective of land use, soil N₂O fluxes are under environmental controls, the main variables being soil temperature and DOC, both of which control the supply of nitrification and denitrification substrates.