Fate of microplastics in a coastal wastewater treatment plant: Microfibers could partially break through the integrated membrane system

• Fate of microplastics in integrated membrane system for water reuse was investigated. • Integrated membrane system has high removal efficiency (>98%) for microplastics. • Microplastics (>93%) were mainly removed through membrane bioreactor treatment. • Small scale fiber plastics (<200 μm) could break through reverse osmosis (RO) system. • The flux of microplastics maintained at 2.7 × 10¹¹ MPs/d after the RO treatment. Rare information on the fate of microplastics in the integrated membrane system (IMS) system in full-scale wastewater treatment plant was available. The fate of microplastics in IMS in a coastal reclaimed water plant was investigated. The removal rate of microplastics in the IMS system reached 93.2% after membrane bioreactor (MBR) treatment while that further increased to 98.0% after the reverse osmosis (RO) membrane process. The flux of microplastics in MBR effluent was reduced from 1.5 × 10¹³ MPs/d to 10.2 × 10¹¹ MPs/d while that of the RO treatment decreased to 2.7 × 10¹¹ MPs/d. Small scale fiber plastics (<200 μm) could break through RO system according to the size distribution analysis. The application of the IMS system in the reclaimed water plant could prevent most of the microplastics from being discharged in the coastal water. These findings suggested that the IMS system was more efficient than conventional activated sludge system (CAS) for the removal of microplastics, while the discharge of small scale fiber plastics through the IMS system should also not be neglected because small scale fiber plastics (<200 μm) could break through IMS system equipped with the RO system.     

A2/O工艺脱氮除磷运行效果分析

采用统计学方法对新疆某污水处理厂A2/O工艺进行进水水质数据分析,发现数据存在严重自相关现象,运用主成分消除法和岭回归消除法以消除自相关性。结果表明：TN和TP是污水厂提标改造的关键;碳源匮乏和缺氧区存在溶解氧(DO)是TN去除不佳的主要原因;适当提高污泥浓度(MLSS)和水力停留时间(HRT)是强化TP去除的措施;温度是影响脱氮除磷的主要因素。将温度模型与自相关磷模型相结合,可提高磷模型精度,有利于出水TP的预测。降低DO、增加外碳源,控制MLSS为3 500 mg/L~4 500 mg/L、HRT为5.4 h~8.0 h、厌氧区和好氧区DO为0.3 mg/L和2 mg/L、污泥龄（SRT）为11 d~12 d,可提升工艺脱氮除磷效果。     

烟气干化污泥对颗粒物的去除作用及其影响因素

基于利用烟气余热的污泥低温干化技术,通过模拟试验和结合工程实践,首次分析研究了污泥对烟气中颗粒物的去除作用及其影响因素.结果表明,被试的四种污泥对烟气中PM_2.5、PM₁₀和TSP的去除率分别为18%~42%、32%~55%和39%~62%,污泥对烟气中PM_2.5去除率的大小与污泥的细微结构和有机质含量相关联,烟气中颗粒物的去除率随污泥堆积密度和污泥含水率的增加而增加,随污泥粒度的增加而减少,污泥粒径变小时,污泥中水分更容易蒸发成微小水滴,有利于烟气中的细小颗粒物被吸附和凝结.     

Red soil for sediment capping to control the internal nutrient release under flow conditions

Nitrogen (N) and phosphorus (P) released from the sediment to the surface water is a major source of water quality impairment. Therefore, inhibiting sediment nutrient release seems necessary. In this study, red soil (RS) was employed to control the nutrients released from a black-odorous river sediment under flow conditions. The N and P that were released were effectively controlled by RS capping. Continuous-flow incubations showed that the reduction efficiencies of total N (TN), ammonium (NH ₄ ⁺ -N), total P (TP) and soluble reactive P (SRP) of the overlying water by RS capping were 77%, 63%, 77% and 92%, respectively, and nitrification and denitrification occurred concurrently in the RS system. An increase in the water velocity coincided with a decrease in the nutrient release rate as a result of intensive water aeration.

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The biogeochemical cycles of phosphorus: A review of local and global consequences of the atmospheric input

P‐input from the atmosphere is, in many oligotrophic ecosystems, substantial for the biomass production; in some regions biomass formation may depend fully or partially on the phosphorus input from the atmosphere. As a consequence, phosphorus must be considered as an element participating in cycles involving the atmosphere, like sulfur and nitrogen. Dust and aerosols containing phosphorus are transported worldwide, linking even distant regions. Human activities enhance the amounts of P distributed. Since the concentrations of P in the atmospheric dry and wet input are usually very low, special care in sampling and analysis is a prerequisite to obtain reproducible data. Some values in the literature may be questionable.     

Occurrence,removal, and environmental risks of pharmaceuticals in wastewater treatment plants in south China

Pharmaceutically active compounds in wastewater released from human consumption have received considerable attention because of their possible risks for aquatic environments. In this study, the occurrence and removal of 10 pharmaceuticals in three municipal wastewater treatment plants in southern China were investigated and the environmental risks they posed were assessed. Nifedipine, atenolol, metoprolol, valsartan and pravastatin were detected in the influent wastewater. The highest average concentration in the influents was observed for metoprolol (164.6 ng/L), followed by valsartan (120.3 ng/L) in August, while median concentrations were higher in November than in August. The total average daily mass loadings of the pharmaceuticals in the three plants were 289.52 mg/d/person, 430.46 mg/d/person and 368.67 mg/d/person, respectively. Elimination in the treatment plants studied was incomplete, with metoprolol levels increasing during biological treatment. Biological treatment was the most effective step for PhACs removal in all of the plants studied. Moreover, the removal of PhACs was observed with higher efficiencies in August than in November. The WWTP equipped with an Unitank process exhibited similar removals of most PhACs as other WWTPs equipped with an anoxic/oxic (A/O) process or various anaerobic-anoxic-oxic (A²/O) process. The environmental risk assessment concluded that all of the single PhAC in the effluents displayed a low risk (RQ<0.1) to the aquatic environments.

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Origins and scales of hypoxia on the Louisiana shelf: Importance of seasonal plankton dynamics and river nutrients and discharge

Management plans for the Mississippi River Basin call for reductions in nutrient concentrations up to 40% or more to reduce hypoxia in the Gulf of Mexico (GOM), while at the same time the government is considering new farm subsidies to promote development of biofuels from corn. Thus there are possibilities of both increasing and decreasing river nutrients depending on national priorities. River flow rates which also influence the extent of hypoxia on the shelf may be altered by global climate change. We have therefore developed a series of simulations to forecast ecosystem response to alterations in nutrient loading and river flow. We simulate ecosystem response and hypoxia events using a linked model consisting of multiple phytoplankton groups competing for nitrogen, phosphorus and light, zooplankton grazing that is influenced by prey edibility and stoichiometry, sub-pycnocline water-column metabolism that is influenced by sinking fecal pellets and algal cells, and multi-element sediment diagenesis. This model formulation depicts four areas of increasing salinity moving westward away from the Mississippi River point of discharge, where the surface mixed layer, four bottom layers and underlying sediments are represented in each area. The model supports the contention that a 40% decrease in river nutrient will substantially reduce the duration and areal extent of hypoxia on the shelf. But it also suggests that in low and middle salinity areas the hypoxia response is saturated with respect to nutrients, and that in high salinity regions small increases in nutrient and river flow will have disproportionally large effects on GOM hypoxia. The model simulations also suggest that river discharge is a stronger factor influencing hypoxia than river nutrients in the Mississippi River plume. Finally, the model simulations suggest that primary production in the low salinity regions is light limited while primary production in the higher salinity zones is phosphate limited during the May to October period when hypoxia is prevalent in the Mississippi River plume.     

美人蕉对西安护城河水体净化功能的初步研究

以西安护城河污染较严重的北门段水体为研究对象,利用浮床技术种植美人蕉净化重污染水体。研究表明,美人蕉对西安护城河北门段河水TN、TP、COD、NH3-N等的去除率分别为77.4%、89%、93%、97%;这为利用美人蕉浮床系统对西安市护城河水体修复提供了科学依据。     

黄河上游沉积物中磷含量分布及其环境意义

本文采用欧洲标准测试委员会框架下发展的磷含量测定法（简称SMT法）和H2SO4-HClO4消化法对黄河上游段青海玛多、甘肃西固、宁夏中卫等六处的黄河表层沉积物中无机磷（IP）、有机磷（OP）及总磷（TP）含量进行了分析。实验结果表明：IP含量范围为288.66-742.27μg.g^-1,OP含量范围为17.53-83.18μg.g^-1TP含量范围是350.52-781.44μg.g^-1;无机磷含量变化规律并不明显,有机磷的含量从青海玛多至石嘴山大致呈现降低趋势,总磷中无机磷的含量占80%以上,因此总磷的变化趋势与无机磷的相似;从TP的测定结果可知H2SO4-HClO4消化法比STM法的测定值略大些,总磷提取的较为完全,但SMT法也可用于测黄河沉积物样的的分析,结果具有一定的可靠性。     

饮用水中溴酸盐控制方法和去除技术研究进展

溴酸盐是一种潜在致癌物,通常产生于含溴离子水源水的臭氧消毒过程中,我国和世界卫生组织饮用水标准中规定溴酸盐的最高浓度为10μg/L。重点综述了近7年来溴酸盐生成的控制方法(如优化臭氧投加量、降低溶液pH值、加氨等)以及溴酸盐离子去除技术(如吸附法、还原法、离子交换法、生物法等)的研究进展,并对各种技术的优缺点进行了评述。