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11.
Autoheated thermophilic aerobic sludge digestion and metal bioleaching
in a two-stage reactor system
A two-stage process has been developed for stabilization of sludge and removal of heavy metals from the secondary activated sludge with high rate of energy and time conservation.The first stage of the process involves autoheated thermophilic aerobic digestion at 55-60°C inoculated with less-acidophilic thermophilic sulfur-oxidizing microorganisms(ATAD).The results show that it is possible to maintain the autoheated conditions(55-60°C) in the ATAD reactor up to 24 hr,leading to reduction of 21% total solids(TS),27% volatile solids(VS),27% suspended solids(SS) and 33% volatile suspended solids(VSS) from the sludge.The sludge pH also decreased from 7 to 4.6 due to the activity of less-acidophilic thermophilic microorganisms.In the second stage operation,the digested sludge(pH 4.6,TS 31.6 g/L) from stage one was subjected to bioleaching in a continuous stirred tank reactor,operated at mean hydraulic retention times(HRTs) of 12,24 and 36 hr at 30°C.An HRT of 24 hr was found to be sufficient for removal of 70% Cu,70% Mn,75% Ni,and 80% Zn from the sludge.In all,39% VSS,76% Cu,78.2% Mn,79.5% Ni and 84.2% Zn were removed from the sludge in both the stages. 相似文献
12.
Journal of Material Cycles and Waste Management - The tar formed within the producer gas is a major problem in the biomass gasification process. The catalytic cracking of tar is the best method to... 相似文献
13.
The mid altitudinal oak, Quercus floribunda forms predominantly evergreen forest in Central Himalaya between 2000–2400 m. It is late successional, mature phase species
that has limited regeneration on disturbance prone sites. This oak produces mast seed crops at an interval of 2–3 years. During
masting in Q. floribunda the seed fall and germination is upto ten times greater than in normal years, emphasizing the importance of mast year crop
in forest maintenance. However, no mast year in this species since the last nine years (1997–2005) is a matter of serious
concern. The rise in the summer and winter temperature over a period of 15 years appear to have affected the frequency of
masting in this oak. The importance of masting can be adjudged from the fact that 97% of the surviving seedlings m−2 are of the mast year crop. 相似文献
14.
India's Unnao region is home to many leather-treatment facilities and related industries. Industrial and agricultural waste leads to heavy metal contamination that infiltrates groundwater and leads to human health hazards. This work measured the amount of heavy metal in groundwater at specific sites near the industrial facilities in Unnao and identified potential sources of contamination as anthropogenic or lithogenic. Groundwater samples were taken from 10 bore well sites chosen for depth and proximity to industry. Data obtained from sample sites was interpreted using a multivariate statistical analytical approach, i.e., principal component analysis, clustering analysis, and correlation analysis. The results of the multivariate analysis showed that cadmium, copper, manganese, nickel, lead, and zinc were correlated with anthropogenic sources, while iron and chromium were associated with lithogenic sources. These findings provide information on the possible sources of heavy metal contamination and could be a model for assessing and monitoring heavy metal pollution in groundwater in other locales. This study analyzed a selection of heavy metals chosen on the basis of industries located in the study area, which might not provide a complete range of information about the sources and availability of all heavy metals. Therefore, an extended investigation on heavy metal fractions will be developed in further studies. 相似文献
15.
Forest vegetation of a community managed forest (Van Panchayat) located between 1570–1700 m elevation was studied along four
aspects. Quercus leucotrichophora was the dominant species on three of the four aspects. Across the aspects the total tree density ranged between 150 and 490
ind/ha, sapling density between 100 and 370 ind/ha, seedling density varied from 241 to 1090 ind/ha. The shrub density ranged
from 166 to 690 ind/ha and herb density from 6000–17100 ind/ha. The total basal area of tree layer varied from 9.78 to 13.5
m2/ha showing that the forest is young. Species diversity value for tree layer varied from 0.14 to 1.69. Quercus leucotrichophora were regenerating well due to effective forest management by local communities. The higher proportion of seedlings of Quercus leucotrichophora indicating that the Van Panchayat are playing important role in conservation of oak forest of Himalaya. 相似文献
16.
Vegetation structure, niche width, niche overlap and types
of competition in temperate grazingland of Garhwal Himalaya, India 总被引:2,自引:0,他引:2
Smriti Anthwal Ajay B. Bhatt Bhagwati P. Nautiyal Ashish Anthwal 《The Environmentalist》2008,28(3):261-273
Temperate grazing lands in Garhwal Himalaya are rich in herbaceous vegetation and extensively used for grazing by locally
owned livestock. Capillipedium parviflorum is a frequently occurring and dominant grass species under Pine canopy in associate with several herbs. Beside, grazing and
extensive fire, interactions among associated species is a determining factor of community structure. In this article the
dominant diversity pattern of vegetation in temperate grazing land along two different altitudes and having different slope
aspects is described. Interaction between dominant and co-dominant species with their niche appearance and niche overlap measurement
was also observed and presented here. South and west facing slopes had maximum species and diversity values while east north
facing slopes had higher species dominant. Capillipedium parviflorum and other grasses had maximum niche values and were dominant and co dominant species. Three types of interspecific interaction
were observed between species and grasses were observed as succeeding species in all sites of different topographic conditions.
Dominant diversity pattern along with resource partitioning and interspecific competition is discussed and presented here. 相似文献
17.
Singh Namita Ashish Kumar Naresh Raghu H. V. Bhand Sunil Chandra Sudhir Sharma Pradeep Kumar 《Environmental Chemistry Letters》2019,17(2):1097-1103
Environmental Chemistry Letters - Aflatoxin M1 contamination in milk and dairy products is a major issue worldwide. Aflatoxin is a carcinogen that enters into the milk through animals feed. Here,... 相似文献
18.
Ashish Premkumar Jessica T. Fry Janelle R. Bolden William A. Grobman Kelly N. Michelson 《黑龙江环境通报》2023,43(6):792-797
Maternal-fetal interventions—such as prenatal fetal myelomeningocele (MMC) repair—are at the forefront of clinical innovation within maternal-fetal medicine, pediatric surgery, and neonatology. Many centers determine eligibility for innovative procedures using pre-determined inclusion and exclusion criteria based on seminal studies, for example, the “Management of Myelomeningocele Study” for prenatal MMC repair. What if a person's clinical presentation does not conform to predetermined criteria for maternal-fetal intervention? Does changing criteria on a case-by-case basis (i.e., ad hoc) constitute an innovation in practice and flexible personalized care or transgression of commonly held standards with potential negative consequences? We outline principle-based, bioethically justified answers to these questions using fetal MMC repair as an example. We pay special attention to the historical origins of inclusion and exclusion criteria, risks and benefits to the pregnant person and the fetus, and team dynamics. We include recommendations for maternal-fetal centers facing these questions. 相似文献
19.
Palmate Santosh S. Wagner Paul D. Fohrer Nicola Pandey Ashish 《Environmental Modeling and Assessment》2022,27(2):275-293
Environmental Modeling & Assessment - Uncertainty in future land use change modelling is crucial to study as it may result in varying spatial characteristics and features of the model. An... 相似文献
20.
Nihalani Seema Meeruty Ashish 《Environmental science and pollution research international》2021,28(45):63523-63531
Environmental Science and Pollution Research - Water quality index (WQI) is used for representing the overall water quality in the form of a number to qualify its use for domestic, irrigation,... 相似文献