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11.
Chung ‐Min Liao Takaaki Maekawa 《Journal of environmental science and health. Part. B》2013,48(5):1053-1078
Abstract Nitrogen removal by a methane fermentation plus activated sludge process with the intermittent aeration was presented based upon a full‐scale pig farm experiment. Swine wastewater had a T‐N/BOD ratio from 0.2–0.29. The BOD concentration input to the process ranged from 1050–1608 mg l‐1 and the T‐N concentration from 273–350 mg l‐1. More than 90% of organic carbon was removed in each experimental run. Only small concentrations of NO3‐N were found in the effluent and higher than 60% of the T‐N and 73% of NH4‐N which were loaded to the intermittent aeration tank was removed. The nitrogen balance of each run was calculated. Denitrification was estimated to be accountable for 45–90% of the T‐N removed in the intermittent aeration tank. Denitrification rate increased as the BOD concentration increased (> 1300 mg l‐1). The T‐N removal percentage was a function of the T‐N/BOD ratio of the influent. Although higher DO concentration (> 3 mg l‐1) did not enhance the denitrification rate, nitrification did maintain at relative higher rates at a lower DO concentration (ave. 1.5 mg l‐1). An operational condition of intermittent interval of aeration/nonaeration at 1:1 hr is better than that of the condition at 3:1 hr. As a result, T‐N and NH4‐N were removed up to 30% and 40% respectively, and the denitrification rate reached 79% in the intermittent aeration tank. An experimental run in a pilot plant on treating anaerobically pretreated swine wastewater was observed to verify simultaneous nitrification/denitrification. The results of the full‐scale plant experimentation seem to be confirmed by those obtained from the pilot plant runs. 相似文献
12.
A pilot plant two-phase anaerobic digestion system for bioenergy recovery from swine wastes and garbage 总被引:1,自引:0,他引:1
A pilot plant bioenergy recovery system from swine waste and garbage was constructed. A series of experiments was performed using swine feces (SF); a mixture of swine feces and urine (MSFU); a mixture of swine feces, urine and garbage (MSFUG); garbage and a mixture of urine and garbage (AUG). The system performed well for treating the source materials at a high organic loading rate (OLR) and short hydraulic retention time (HRT). In particular, the biogas production for the MSFUG was the highest, accounting for approximately 865-930Lkg(-1)-VS added at the OLR of 5.0-5.3kg-VSm(-3)day(-1) and the HRT of 9 days. The removal of VS was 67-75%, and that of COD was 73-74%. Therefore, co-digestion is a promising method for the recovery of bioenergy from swine waste and garbage. Furthermore, the results obtained from this study provide fundamental information for scaling up a high-performance anaerobic system in the future. 相似文献
13.
Effects of environmental factors on the seasonally change of phytoplankton populations in a closed freshwater pond. 总被引:5,自引:0,他引:5
The effect of environmental factors affecting the population dynamic of phytoplankton population was studied seasonally in a closed freshwater pond with the natural water of Lake Kasumigaura, Japan. The predominant phytoplankton species in the pond were classified as Oscillatoria tenuis, Synedra ulna, Chlamydomonas cingulata and Cyclotella kutzingiana, with dominant species of Melosira italica, Synechococcus sp. and Cryptomonas ovata. The most important limiting factor for filament length and cell size of most of the phytoplankton community was temperature. Availability of most nutrients had profound effects on the phytoplankton growth as nonlimiting factors. Based on our results, it is suggested that cell cycle progression was also temporally regulated by a multiplicity of external factors such as temperature, nutrients, dissolved oxygen (DO) and pH. At high pH and high temperature, consistent increase of cell division of some phytoplanketers such as Synedra, Cyclotella, Chlamydomonas and Melosira occurs, and there also may be species-specific responses for other species of phytoplankters. In addition, the cell divisions of phytoplankters are differentially regulated in different phytoplankton species. 相似文献
14.
Ohmichi K Komiyama M Matsuno Y Takanashi Y Miyamoto H Kadota T Maekawa M Toyama Y Tatsugi Y Kohno T Ohmichi M Mori C 《Environmental science and pollution research international》2006,13(2):120-124
Goal, Scope and Background Cadavers for gross anatomy laboratories are usually prepared by using embalming fluid which contains formaldehyde (FA) as
a principal component. During the process of dissection, FA vapors are emitted from the cadavers, resulting in the exposure
of medical students and their instructors to elevated levels of FA in the laboratory. The American Conference of Governmental
Industrial Hygienists (ACGIH) has set a ceiling limit for FA at 0.3 ppm. In Japan, the Ministry of Health, Labour and Welfare
has set an air quality guideline defining two limit values for environmental exposure to FA: 0.08 ppm as an average for general
workplaces and 0.25 ppm for specific workplaces such as an FA factory. Although there are many reports on indoor FA concentrations
in gross anatomy laboratories, only a few reports have described personal FA exposure levels. The purpose of the present study
was to clarify personal exposure levels as well as indoor FA concentrations in our laboratory in order to investigate the
relationship between them.
Methods The gross anatomy laboratory was evaluated in the 4th, 10th and 18th sessions of 20 laboratory sessions in total over a period
of 10 weeks. Air samples were collected using a diffusive sampling device for organic carbonyl compounds. Area samples were
taken in the center and four corners of the laboratory during the entire time of each session (4-6 hours). Personal samples
were collected from instructors and students using a sampling device pinned on each person's lapel, and they were 1.1 to 6
hours in duration. Analysis was carried out using high performance liquid chromatography.
Results and Discussion Room averages of FA concentrations were 0.45, 0.38 and 0.68 ppm for the 4th, 10th and 18th sessions, respectively, ranging
from 0.23 to 1.03 ppm. These levels were comparable to or relatively lower than the levels reported previously, but were still
higher than the guideline limit for specific workplaces in Japan and the ACGIH ceiling limit. The indoor FA concentrations
varied depending on the contents of laboratory sessions and seemed to increase when body cavity or deep structures were being
dissected. In all sessions but the 4th, FA levels at the center of the room were higher than those in the corners. This might
be related to the arrangement of air supply diffusers and return grills. However, it cannot be ruled out that FA levels in
the corners were lowered by leakage of FA through the doors and windows. Average personal exposure levels were 0.80, 0.45
and 0.51 ppm for instructors and 1.02, 1.08 and 0.89 ppm for students for the 4th, 10th and 18th session, respectively. The
exposure levels of students were significantly higher than the mean indoor FA concentrations in the 4th and 10th sessions,
and the same tendency was also observed in the 18th session. The personal exposure level of instructors was also significantly
higher than the indoor FA level in the 4th session, while they were almost the same in the 10th and 18th sessions. Differences
in behavior during the sessions might reflect the differential personal exposure levels between students and instructors.
Conclusion The present study revealed that, if a person is close to the cadavers during the gross anatomy laboratory, his/her personal
exposure level is possibly 2 to 3-fold higher than the mean indoor FA concentration. This should be considered in the risk
assessment of FA in gross anatomy laboratories.
Recommendation and Outlook If the risk of FA in gross anatomy laboratories is assessed based on the indoor FA levels, the possibility that personal
exposure levels are 2 to 3-fold higher than the mean indoor FA level should be taken into account. Otherwise, the risk should
be assessed based on the personal exposure levels. However, it is hard to measure everyone's exposure level. Therefore, further
studies are necessary to develop a method of personal exposure assessment from the indoor FA concentration. 相似文献
15.
《淮河流域可持续发展战略研究》采取系统科学的方法,提出了较为完整的淮河流可持续发展战略体系,既是中国水利事业步入“大水利”举措的尝试,也弥补了从整体上研究中国大河流域可持续发展战略的不足,对于其他大河流域的可持续发展战略研究具有借鉴意义。 相似文献
16.
Saida H Maekawa T Satake T Higashi Y Seki H 《Environmental pollution (Barking, Essex : 1987)》2000,109(2):293-301
Species succession of a natural bacterial community was indicated by the Gram stain index (GSI) using an experimental nutrient gradient in an oligotrophic pond created with an in situ gradostat. Various trophic conditions, ranging from eutrophic to mesotrophic, were formed experimentally with continuous inflow of sterile peptone solution in the gradostat, while the water mass outside the gradostat was oligotrophic. The GSI spectra of the natural bacterial populations show different profiles in accordance with the trophic level of the ambient water and the time progression of adaptation to different levels of eutrophication. Therefore, GSI can be used as a potential indicator of organic pollution in aquatic environments. 相似文献
17.
Termite soldiers are the most specialized caste of social insects in terms of their morphology and function. Soldier development
requires increased juvenile hormone (JH) titer and the two molts via a presoldier stage. These molts are accompanied by dramatic
morphological changes, including the exaggeration and regression of certain organs. Soldiers of the most apical termitid subfamily
Nasutitermitinae possess not only a horn-like frontal tube, called the nasus, for the projection of defensive chemicals from
the frontal gland reservoir but also regressed mandibles. Although candidate genes regulating soldier mandibular growth were
reported in a relatively basal termite species, the regulatory mechanisms of mandibular regression remain unknown. To clarify
these mechanisms, we performed morphological and histological examinations of the mandibles during soldier differentiation
in Nasutitermes takasagoensis. Mandibular size reduced dramatically during soldier differentiation, and mandibular regression occurred just prior to the
presoldier molt. Spotted TUNEL signals were observed in regressing mandibles of presoldiers, suggesting that the regression
involved programmed cell death. Because soldiers of N. takasagoensis possess exaggerated organs (nasus and frontal gland), the present results suggest that JH-dependent regressive mechanisms
exist in the mandibles without interfering with the formation of the exaggerated organs. 相似文献
18.
19.
Ammonia removal from pretreated methane fermentation effluent through a soil trench system: a column experiment 总被引:1,自引:0,他引:1
In order to find the optimal running conditions and mechanisms of ammonia removal through a soil trench system that is designed for treating pretreated methane fermentation effluent, a soil column whose structure was similar to the soil trench system was prepared, and irrigated with wastewater below 30 °C. At the beginning, ammonia was mainly adsorbed by the soils, and the ammonia adsorption capacity of soils gradually saturated. After the 12th day, nitrification began in the soil column; the ammonia in the soil column decreased sharply, and the nitrite and nitrate peak appeared sequentially as the wastewater application rate decreased from 0.74 to 0.37 l h−1. When the nitrification in the soil column reached a steady-state, 98% of all the ammonia in the influent was transformed into nitrate.
By changing the running conditions such as temperature, aeration, and wastewater application rate, it was found that the ammonia removal efficiency can be improved by aeration and impeded by low temperature. In these three variables, wastewater application rate has much greater affect on the ammonia removal efficiency; a lower wastewater application rate can increase the ammonia removal efficiency substantially because of the longer travel time. 相似文献
20.
V.?Krishna?PrasadEmail author Ben?Stinner Deb?Stinner John?Cardina Richard?Moore Prabhat?K.?Gupta Harao?Tsuruta Kiyoto?Tanabe K.?V.?S.?Badarinath Casey?Hoy 《Regional Environmental Change》2003,3(4):154-161
We studied trends in food production and nitrous oxide emissions from India's agricultural sector between 1961 and 2000. Data
from Food and Agricultural Statistics (FAO) have been gathered covering production, consumption, fertilizer use and livestock
details. IPCC 1996 revised guidelines were followed in studying the variations in N2O-N emissions. Results suggest that total N2O-N emissions (direct, animal waste and indirect sources) increased ~6.1 times from ~0.048 to ~0.294 Tg N2O-N, over 40 years. Source-wise breakdown of emissions from 1961–2000 indicated that during 1961 most of the N2O-N inputs were from crop residues (61%) and biological nitrogen fixation (25%), while during 2000 the main sources were synthetic
fertilizer (~48%) and crop residues (19%). Direct emissions increased from ~0.031 to ~0.183 Tg. It is estimated that ~3.1%
of global N2O-N emissions comes from India. Trends in food production, primarily cereals (rice, wheat and coarse grains) and pulses, and
fertilizer consumption from 1961–2000 suggest that food production (cereals and pulses) increased only 3.7 times, while nitrogenous
fertilizer consumption increased ~43 times over this period, leading to extensive release of nitrogen to the atmosphere. From
this study, we infer that the challenge for Indian agriculture lies not only in increasing production but also in achieving
production stability while minimizing the impact to the environment, through various management and mitigation options. 相似文献