反硝化除磷污泥的厌氧释磷与缺氧吸磷特性研究

为研究厌氧释磷过程中的影响因素,以连续流A 2N双污泥中试污泥为样品,考察了碳源种类、碳源浓度、pH值以及温度对反硝化除磷污泥厌氧释磷的影响。结果表明:乙酸为碳源时释磷效果最佳,其次是葡萄糖,甲醇为碳源时释磷效果较差。MLSS为1 200 mg/L左右时,投加200 mg/L的COD即可保证充分释磷。pH值为6.3~8.8,对厌氧释磷效果影响不大,适当提高pH值有利于提高释磷速率。温度为20~30℃,释磷效果较好。另外,实验同时研究了反硝化除磷污泥分别利用不同电子受体(硝氮、氧气)的吸磷特性。以硝氮为电子受体的反硝化吸磷过程中,前15min的反硝化吸磷脱氮速率最高,吸磷速率与反硝化速率分别为11.5、10.4 mgN/gVSS·h;以氧气为电子受体的好氧吸磷过程中,前15 min的好氧吸磷速率最高,达到20.4 mgP/gVSS·h,大约为反硝化吸磷的2倍。     

Alum split applications strengthened phosphorus fixation and phosphate sorption in high legacy phosphorus calcareous soil

High phosphorus (P) saturation arising from historic P inputs to protected vegetable fields (PVFs) drives high P mobilisation to waterbodies. Amendment of soils with alum has shown potential in terms of fixing labile P and protecting water quality. The present 15 month pot experiment investigated P stabilisation across single alum application (Alum-1 treatment, 20 g alum/kg soil incorporated into soil before the maize was sown), alum split applications (Alum-4 treatment, 5 g alum/kg soil incorporated into soil before each crop was sown i.e. 4 × 5 g/kg) and soil only treatment (Control). Results showed that the Alum-1 treatment caused the strongest stabilisation of soil labile P after maize plant removal, whereas the P stabilisation effect was gradually weakened due to the transformation of soil non-labile P to labile P and the reduced active Al³⁺ in soil solution. For the Alum-4 treatment, soil labile P decreased gradually with each crop planting and was lower than the Alum-1 treatment at the end of the final crop removal, without any impairment on plant growth. The better P stabilisation at the end of Alum-4 treatment was closely correlated with a progressive supply of Al³⁺ and a gradual decrease of pH, which resulted in higher contents of poorly-crystalline Al, Fe and exchangeable Ca. These aspects were conducive to increasing the soil P stabilisation and phosphate sorption. In terms of management, growers in continuous cropping systems could utilise split alum applications as a strategy to alleviate P losses in high-P enriched calcareous soil.     

薄层离子交换树脂光度法测定水中痕量磷

利用积分球装置，交袁附磷钼蓝的阴离子交换树脂制成一薄层片，于７００ｎｍ长处测定吸光值，既保持了填充树脂光度法的高灵敏度，又提高了分析的精密性。     

滆湖大型底栖动物群落分布和氮磷因子的相关分析

于2012年12月—2013年11月对滆湖水体进行了调查,分析了水体氮、磷及大型底栖动物的时空分布,初步探讨大型底栖动物群落结构与氮、磷环境因子的关系。结果表明,滆湖水体的ρ(TN)在冬春季较高,ρ(TP)四季的差异不大,在空间分布上,北部湖区的ρ(TN)、ρ(TP)均高于南部湖区;大型底栖动物出现频率最高的为霍甫水丝蚓和中国长足摇蚊,其丰度在时间上均表现为秋季夏季冬季春季,在空间上的规律性不明显;CCA分析表明滆湖大型底栖动物群落结构随季节变化规律显著,且氮含量是滆湖底栖动物群落结构的重要影响因子;对优势种的丰度与氮磷的相关性分析结果显示,滆湖底栖动物优势种与TN和NO_3~--N有显著的负相关关系。     

A review of recent substance flow analyses of phosphorus to identify priority management areas at different geographical scales

The dwindling global reserves of extractable phosphorus (P) and its growing demand to produce the required food for a burgeoning global population (the global P crisis) necessitate the sustainable use of this crucial resource. To advert the crisis requires informed policy decisions which can only be obtained by a better understanding of the nature and magnitude of P flow through different systems at different geographical scales. Through a systematic and in-depth review of twenty one recent substance flow analyses of P, we have assessed the key P inflows, outflows, stocks, internal flows, and recycling flows at the city, regional, and country scales. The assessment has revealed, the main inflow and outflow of P at the city scale occurs through food and wastewater respectively, while the main stock of P occurs in landfill. At the regional scale, mineral ore is the main P inflow and chemical P fertilizer is the main outflow particularly in the regions that have P fertilizer production sector. In contrast, either chemical P fertilizer or animal feed is the key inflow and either food and agricultural products or soil losses (erosion, runoff, and/or leaching) is the major outflow especially in the regions without P fertilizer production sector. At the country scale, the key P inflow occurs either through mineral ore or chemical P fertilizer and the key outflow takes place either as food and agricultural products, waste (both solid and liquid), or soil losses (erosion, runoff, and/or leaching). The main stock of P both at the regional and country scales occurs in the soil of the agricultural production sector. As identified in this assessment, the key unproductive outflows and stocks at different geographical scales indicate that there is a potential scope to improve P management through the increased P recovery and recycling, and by the utilization of available soil P stocks. In many of the studies at all the geographical scales, P recycling flow has been found to be less than 20% of the total inflow, and even in some studies at the country scale, P recycling has been found to be entirely absent, which is a clear indication of poor P management. This study has also identified, there is a clear knowledge gap in relation to understanding the P flow over multiple years at the regional scale. The information about the key flows and stocks at different geographical scales as we identified can be utilized to make better P policy and management decisions for a city, region, or country. The information can also be used to guide future research that aims to analyze P flow at the city, regional, and country scales.     

A comparison of on-site nutrient and energy recycling technologies in algal oil production

Research on biofuel production pathways from algae continues because among other potential advantages they avoid key consequential effects of terrestrial oil crops, such as competition for cropland. However, the economics, energetic balance, and climate change emissions from algal biofuels pathways do not always show great potential, due in part to high fertilizer demand. Nutrient recycling from algal biomass residue is likely to be essential for reducing the environmental impacts and cost associated with algae-derived fuels. After a review of available technologies, anaerobic digestion (AD) and hydrothermal liquefaction (HTL) were selected and compared on their nutrient recycling and energy recovery potential for lipid-extracted algal biomass using the microalgae strain Scenedesmus dimorphus. For 1 kg (dry weight) of algae cultivated in an open raceway pond, 40.7 g N and 3.8 g P can be recycled through AD, while 26.0 g N and 6.8 g P can be recycled through HTL. In terms of energy production, 2.49 MJ heat and 2.61 MJ electricity are generated from AD biogas combustion to meet production system demands, while 3.30 MJ heat and 0.95 MJ electricity from HTL products are generated and used within the production system.Assuming recycled nutrient products from AD or HTL technologies displace demand for synthetic fertilizers, and energy products displace natural gas and electricity, the life cycle greenhouse gas reduction achieved by adding AD to the simulated algal oil production system is between 622 and 808 g carbon dioxide equivalent (CO₂e)/kg biomass depending on substitution assumptions, while the life cycle GHG reduction achieved by HTL is between 513 and 535 g CO₂e/kg biomass depending on substitution assumptions. Based on the effectiveness of nutrient recycling and energy recovery, as well as technology maturity, AD appears to perform better than HTL as a nutrient and energy recycling technology in algae oil production systems.     

高产水稻田氮磷排放监测及特征分析

通过设立田间定位监测点，对高产水稻田的水及氮、磷的输入和排出进行了3年的定点监测，根据监测结果分析了稻田的氮、磷迁移特征和规律。结果表明，每667m^2稻田氮排出量约3000g，磷排出量约82g；随降雨及灌溉水带人的氮约1600g，磷约59g；两者相抵，表观净排出氮约为1400g，磷约23g。稻田氮、磷排出与稻田排水量及基面肥施用量有关。改进稻田氮肥施用时间和施用方法，合理管理稻田水量，减少排水，是减少高产水稻田氮、磷排放的关键技术措施。