响应面法优化污泥炭催化湿式过氧化氢氧化降解间甲酚模拟废水

以污水处理厂剩余污泥为原料制备硝酸改性活性炭,用于催化湿式过氧化氢氧化(CWPO)处理间甲酚模拟废水,以实现剩余污泥的资源化利用.使用物理吸附、程序升温脱附(TPD)、X射线荧光光谱(XRF)等表征方法对污泥炭的物理化学性质进行测定.而后采用响应面法(RSM)优化污泥炭CWPO降解间甲酚的反应条件,选取反应温度、反应时间、初始pH值、过氧化氢(H_2O_2)投加量及催化剂投加量为影响因子,总有机碳(TOC)去除率为响应值,应用中心组合设计(CCD)建立响应值与各影响因子之间关系的二次多项式数学模型,采用后退回归法进行模型精简,并通过方差分析对模型进行可信程度检验.优化结果表明,在反应温度为60℃,反应时间为120 min,初始pH=3.00,H_2O_2投加量为2.03 g·L~(-1),催化剂投加量为0.78 g·L~(-1)的条件下,可达到最佳效果,此时预测模型的TOC去除率为44.6%,间甲酚转化率为100%.通过模型验证实验得到的TOC去除率为46.6%,仅与理论值相差2.0%,在95%的置信区间内,说明该模型具有可靠性.最后采用GC-MS对污泥炭CWPO降解间甲酚中间产物进行分析.     

基于碳源回用目标的剩余污泥水解酸化产物调控研究

剩余污泥水解酸化产生的挥发性脂肪酸(VFAs)等有机物可作为补充碳源回用于低C/N比城市污水脱氮除磷系统中。然而,在污泥水解酸化过程中由于甲烷菌等微生物的作用而难以实现水解酸化产物的有效积累。同时,含有高浓度氮磷的污泥水解酸化液直接回用将进一步增加污水处理的氮磷负荷。本研究基于碳源回用目标,在热碱预处理的基础上,采用添加二溴乙烷磺酸钠(BES,2-Bromoethanesulfonic acid sodium)和Ca O2的方式对城市污水厂剩余污泥水解酸化过程的主要产物即溶解性有机物(SCOD)、VFAs及氮磷的溶出进行优化调控,旨在得到含有高浓度有机物、低浓度氮磷的污泥水解酸化液以回用于低C/N比城市污水脱氮除磷系统,提高出水水质,为剩余污泥的资源化利用提供理论依据。结果表明,污泥经Na OH预处理后,添加BES可有效提高水解酸化过程SCOD、VFAs的积累,其最高质量浓度分别达到6 169.8 mg·L~(-1)及1 335.0 mg·L~(-1),较对照组分别提高66.7%、192.5%,其中,VFAs中乙酸的质量分数达到66.0%。添加CaO_2的实验组酸化液中,NH4_+~-N和PO_4~3--P的溶出量显著降低,分别降至200.7 mg·L~(-1)、9.6 mg·L~(-1),较对照组分别减少了59.6%、65.7%。同时添加BES和CaO_2的组合体系在实现污泥水解酸化过程SCOD、VFAs累积的同时有效降低了氨氮和正磷酸盐的溶出,所获取的剩余污泥水解酸化产物可作为低C/N比城市污水脱氮除磷提标升级的优质碳源,实现了剩余污泥的资源化回用。     

含硫酸根的高碳氮比废水产甲烷强化技术及酶学机制

污泥蛋白质回收已成为剩余污泥资源化的有效途径之一,研究其提取残液的产甲烷强化技术不仅可助力剩余污泥蛋白质提取技术的应用进程,也可为化工、食品行业高硫酸根和高碳氮比废水的厌氧生物处理提供有益参考.结果表明,铁及其螯合物添加不仅可有效促进水解酸化与产甲烷过程关键酶的活性,还可显著抑制亚硫酸盐还原酶的活性,产气效果得到明显提高.当添加10μmol·L~(-1)氨三乙酸与40 mg·L~(-1)零价铁时,累积产气率达196.2 m L·g-1COD,与对照实验相比,提高了123.97%.多糖是含硫酸根的高碳氮比废水产甲烷的主要底物.结合关键酶活性的变化发现,与酸化过程相比,多糖与蛋白质水解是提高产甲烷效果的限速步骤.     

三唑酮的酸性、中性和碱性水解动力学研究

三唑酮在不同pH值和温度条件下水解动力学的测定结果表明:三唑酮在酸性条件下比较稳定,不易水解,但随体系pH值的升高,水解速度加快。温度升高有利于三唑酮的水解反应,酸性条件下水解活化能最大,温度升高对反应速率的影响最大。     

污泥臭氧化减量技术的影响因子

采用臭氧作为剩余污泥的细胞裂解剂,并与生物接触氧化工艺相结合进行污泥减量的实验研究,臭氧化后的污泥上清液回流入曝气池与污水合并处理。结果表明:在臭氧投量为0.05kgO3/kgMLSS,臭氧化污泥量为进水量的5%条件下,生物接触氧化系统对SCOD和NH4-N的平均去除率分别为87.06%和84.80%,出水水质同对比实验相当;同时获得了0.054(gMLSS/去除1gSCOD)的剩余污泥产率,与对比实验相比降低了78.4%。     

一株油脂降解菌的筛选及其降解条件优化

为实现生活污水中油脂的生物降解和有效处理,从某生活污水处理厂的剩余污泥中分离出一株油脂降解菌用于油脂生物降解的研究。对该菌进行生理生化特性鉴定、16Sr DNA测序分析和系统发育树构建,结果显示该菌株与铜绿假单胞菌(Pseudomonas aeruginosa)具有很高的同源性。按6%(V/V)的接种量将该菌接种到以菜籽油(质量浓度为3 g·L~(-1))为唯一碳源的培养基中,在30℃,150 r·min~(-1)的恒温振荡培养箱中进行培养,采用紫外分光光度法每隔12 h测定油脂浓度,对其降解特性进行初步研究并发现该菌在72h内对油脂的降解率为55.37%。从接种量、pH、温度、NaCl质量浓度4个方面进行单因素培养条件优化实验,得到当接种量为12%(V/V)、pH为8、温度为30℃、NaCl质量浓度为2.5 g·L~(-1)时该菌对油脂的降解率分别为59.42%、61.28%、55.33%、64.14%。另外发现当接种量在2%—14%(V/V)、pH在4.0—9.0、温度在15—40℃、NaCl质量浓度在0—15g·L~(-1)时,该菌对油脂仍有降解效果,说明该菌株对外界环境具有一定的适应能力。将该菌应用于处理实际污水中的有机物,发现在优化条件下该菌对实际污水中的油脂和CODCr的降解率分别为40.50%和45.83%。结果表明在实验过程中该菌对油脂和实际污水中的有机物都具有一定的降解效果,可以为下一阶段的实际应用奠定基础,并为生物处理含油污废水提供更多的菌种选择。     

CWPO体系中污泥炭催化降解头孢氨苄废水

通过加入正丁醇以共沸蒸馏法对剩余污泥进行脱水,再对污泥进行干燥、焙烧和改性得到污泥炭催化剂.将污泥炭催化剂用于催化湿式过氧化氢氧化体系,处理头孢氨苄废水.采用响应面法中的中心组合设计实验,考察反应温度、初始pH和过氧化氢投加量对TOC降解率的影响,反应温度和过氧化氢投加量具有显著交互作用.在最佳实验条件下(T=50℃、pH=3.00、H_2O_2=0.071 mol·L~(-1)),TOC去除率为59%,接近预测的TOC去除率(60%),在95%的置信区间内,说明该模型可靠.SEM、TEM、TPD-MS、XPS和FT-IR等分析结果表明污泥炭表面存在纳米尺寸片状结构,这种结构中存在酚羟基、羰基、羧基等活性官能团和醌类结构,且ICP-OES、EDAX和~(57)Fe穆斯堡尔谱等分析结果表明,污泥炭中含有不同价态的Fe,能有效地催化过氧化氢分解,将头孢氨苄转化为苯甲酸、丁二酮等小分子物质,再进一步完全氧化.     

厌氧条件下剩余污泥中磷及相关指标的释放和变化规律

污水处理过程中产生的剩余污泥富含大量的氮磷元素,从剩余污泥中回收磷是解决磷资源日益缺乏的一种有效途径。探寻出剩余污泥中磷的释放规律是实现剩余污泥中磷回收的首要前提。因此,以实际污水处理厂污泥为研究对象,建立污泥停留时间为5d的中试模型系统。通过系统分析5d停留时间的厌氧条件下污泥中污泥浓度、上清液总磷和氨氮浓度的变化情况,为后续的污泥磷回收提供支撑条件。研究结果表明,在中试系统污泥停留时间5d的厌氧条件下,剩余污泥微生物衰亡自溶或被分解,胞内物质释放,从而使固态物质转化为液态,污泥中磷及相关的氮等物质得到了较大的释放,污泥上清液总磷和氨氮质量浓度可分别达到100和40 mg·L^-1以上。所释放出的氮磷浓度足以满足鸟粪石回收氮磷方法所需的最低经济性要求,为污泥进行厌氧消化后采用鸟粪石的方法回收释放的氮磷提供了重要的基础依据。研究中还发现5d停留时间下, SS和VSS都有不同程度的降低,二者分别减少8.34%和10.14%以上,其中VSS的减少量占SS减少量的65%左右。同时,进入厌氧反应系统的初始污泥浓度对于氮磷的释放有着较大的影响,反应系统的SS在6300~7200 mg·L^-1的条件下,磷和氮的单位质量污泥释放量达到最佳,分别达到单位干污泥0.015和0.006 mg·mg^-1。研究结果为剩余污泥中回收氮磷提供了重要的依据。     

高效液相色谱串联质谱法测定污水污泥中4种磺胺类药物及其乙酰化代谢物

本文建立了一种检测污水及污泥中4种磺胺类抗生素及其相应的乙酰化代谢物的分析方法,包括磺胺嘧啶(SD)、磺胺甲基嘧啶(SM1)、磺胺二甲基嘧啶(SM2)、磺胺甲恶唑(SMZ)以及它们相对应的乙酰化代谢物.本文采用了固相萃取(SPE)的方法作为前处理,并优化了固相萃取条件.计算了样品中复杂的基质效应,并使用内标法来抵消基质效应.该方法在污水中检测限(LOD)和定量限(LOQ)分别为0.12—2.06 ng·L~(-1)和0.43—5.12 ng·L~(-1),在污泥中分别为0.28—2.31 ng·g~(-1)和0.88—6.77 ng·g~(-1),在污水和污泥中的回收率为分别为70.8%—130.6%,88.0%—129.2%.本方法成功应用于检测污水处理厂中的污水及污泥中的目标化合物.     

超高效液相色谱串联质谱法同时测定城市污水处理厂污泥中12种抗生素

建立了一种固相萃取-超高效液相色谱-串联质谱法同时测定污泥中4类12种抗生素的方法.采用SAX串联Oasis HLB固相萃取柱净化富集污泥样品中的抗生素,选定p H 3、洗脱体积8 m L作为最佳前处理条件.采用超高效液相色谱-串联质谱检测抗生素样品,以0.3%的甲酸和乙腈作为流动相,经梯度洗脱进行分离,在多反应检测模式下进行测定.经测定,污泥样品中磺胺类抗生素、脱水红霉素和罗红霉素平均回收率为50%—80%,其余抗生素的平均回收率为82%—119%,12种抗生素在污泥中的定量限为0.001—0.008μg·kg~(-1)dw.并用该法对天津市某污水处理厂污泥样品进行检测,证明该方法可满足实际检测要求.     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Cost‐effective conservation of an endangered frog under uncertainty

How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

Parasitic wasps orient to green leaf volatiles

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

Patterns and biases of climate change threats in the IUCN Red List

International Union for Conservation of Nature (IUCN) Red List assessments rely on published data and expert inputs, and biases can be introduced where underlying definitions and concepts are ambiguous. Consideration of climate change threat is no exception, and recently numerous approaches to assessing the threat of climate change to species have been developed. We explored IUCN Red List assessments of amphibians and birds to determine whether species listed as threatened by climate change display distinct patterns in terms of habitat occupied and additional nonclimatic threats faced. We compared IUCN Red List data with a published data set of species’ biological and ecological traits believed to infer high vulnerability to climate change and determined whether distributions of climate change‐threatened species on the IUCN Red List concur with those of climate change‐threatened species identified with the trait‐based approach and whether species possessing these traits are more likely to have climate change listed as a threat on the IUCN Red List. Species in some ecosystems (e.g., grassland, shrubland) and subject to particular threats (e.g., invasive species) were more likely to have climate change as a listed threat. Geographical patterns of climate change‐threatened amphibians and birds on the IUCN Red List were incongruent with patterns of global species richness and patterns identified using trait‐based approaches. Certain traits were linked to increases or decreases in the likelihood of a species being threatened by climate change. Broad temperature tolerance of a species was consistently related to an increased likelihood of climate change threat, indicating counterintuitive relationships in IUCN assessments. To improve the robustness of species assessments of the vulnerability or extinction risk associated with climate change, we suggest IUCN adopt a more cohesive approach whereby specific traits highlighted by our results are considered in Red List assessments. To achieve this and to strengthen the climate change‐vulnerability assessments approach, it is necessary to identify and implement logical avenues for further research into traits that make species vulnerable to climate change (including population‐level threats).