人工污水中的N在模拟秋茄湿地系统中的分配循环及其净化效果

在温室中建立模拟红树林植物秋茄湿地系统，系统包括１年生秋茄苗、底泥和潮汐海水，分别用正常、５倍和１０倍浓度的人工制备的城市污水每周定时、定时对模拟系统污灌２次，持续１年。用以研究营养污物Ｎ在系统中的分配循环及被净化的效果。结果表明，加入系统中的污水Ｎ主要留存在土壤中，留存在植物中只有一小部分，４个处理污水浓度组植株中Ｎ元素周转期衣次为４．１年、４．９年、５．３年和４．３年，比２０龄的秋茄群落Ｎ周期     

鄱阳湖自然资源及其特征

本文简述了鄱阳湖土地、水、气候和生物资源现状,分析了它们的特征。鄱阳湖是中国最大的淡水湖泊,但洪、枯水期湖水面积变化很大,枯水期由众多的子湖泊组成。它是一个过水性湖泊,年均迳流量高达1457×10⁸m³,然而年际和月际变化很大,对长江水量调蓄作用不大,也不适时。总体水质良好,但已受到污染。鄱阳湖是本地区的日照时数、水体蒸发量和风能高值区,是气温调节器。鄱阳湖生物资源丰富,形成了完整的水域生态系统和水陆交替的湖滩草洲生态系统。     

The comparison of growth and nutrient removal efficiency of Chlorella pyrenoidosa in settled and activated sewage

The microscopic green alga, Chlorella pyrenoidosa was grown in settled and activated sewage under two different culture systems, batch and semi-continuous. Good growth was obtained in both types of wastewater and the algal production was comparable to and even higher than that found in commercial Bristol medium. The semi-continuous culture supported more growth than the batch system. There was a close relationship between algal growth and the amount of nutrient removed from both settled and activated sewage. A more rapid drop in NH(4)(+)-N was found in settle rather than activated sewage. The NH(4)(+)-N of settled sewage dropped from its initial 27 to 5 mg litre(-1) in both culture systems. On the other hand, the NO(3)(-)-N of activated sewage started to decrease from Day 2 onwards and the final NO(3)(-)-N concentration was less than 1 mg litre(-1) (over 90% removal efficiency). The amount of total inorganic nitrogen being reduced due to algal culture was similar in both types of sewage. The changes of phosphate content followed the same trend in both sewage, the P concentration increased slightly in the first two days then decreased, especially in the semi-continuous cultures. The final ortho-P in the sewage treated by Chlorella in semi-continuous culture was less than 5 mg litre(-1) (about 62% reduction). Such removal efficiency was slightly lower than those reported in previous studies. In general, the semi-continuous algal culture appeared to be a more suitable and efficient way for wastewater treatment than the batch system. With respect to the total reduction of wastewater inorganic N and P by means of Chlorella cells, there was no significant difference between settled and activated sewage.     

Vermicomposting of winery wastes: a laboratory study

In Mediterranean countries, millions of tons of wastes from viticulture and winery industries are produced every year. This study describes the ability of the earthworm Eisenia andrei to compost different winery wastes (spent grape marc, vinasse biosolids, lees cakes, and vine shoots) into valuable agricultural products. The evolution of earthworm biomass and enzyme activities was tracked for 16 weeks of vermicomposting, on a laboratory scale. Increases in earthworm biomass for all winery wastes proved lower than in manure. Changes in hydrolytic enzymes and overall microbial activities during the vermicomposting process indicated the biodegradation of the winery wastes. Vermicomposting improved the agronomic value of the winery wastes by reducing the C:N ratio, conductivity and phytotoxicity, while increasing the humic materials, nutrient contents, and pH in all cases. Thus, winery wastes show potential as raw substrates in vermicomposting, although further research is needed to evaluate the feasibility of such wastes in large-scale vermicomposting systems.     

Do laboratory salinity tolerances of freshwater animals correspond with their field salinity?

The degree to which laboratory derived measures of salinity tolerance reflect the field distributions of freshwater biota is uncertain. In this paper we compare laboratory-derived acute salinity tolerance (LC(50) values) of freshwater macroinvertebrates (range 5.5-76 mS/cm) and fish (range 2.7-82 mS/cm) from southeastern Australia with the salinity from which they have been collected in the field. Only 4% of the macroinvertebrates were collected at salinity levels substantially higher than their 72-h LC(50) obtained from directly transferring animals from low salinity water to the water they were tested (direct transfer LC(50)). This LC(50) value was correlated with the maximum salinity at which a species had been collected. For common macroinvertebrates, the maximum field salinity was approximated by the direct transfer 72-h LC(50). For adult freshwater fish, 21% of species were collected at salinities substantially greater than their acute direct transfer LC(50) and there was a weak relationship between these two variables. Although there was a weak correlation between the direct transfer LC(50) of early life stages of freshwater fish and the maximum field salinity, 58% of the field distribution were in higher than their LC(50) values. In contrast, LC(50) determined from experiments that acclimated adult fish to higher salinity (slow acclimation) provided a better indication of the field distribution: with only one fish species (7%) being in conflict with their maximum field salinity and a strong positive relationship between these variables. This study shows that laboratory measures of acute salinity tolerance can reflect the maximum salinity that macroinvertebrate and fish species inhabit and are consistent with some anecdotal observations from other studies.     

Lanthanum fixation by Myxococcus xanthus: cellular location and extracellular polysaccharide observation

Myxococcus xanthus is a soil bacterium of the myxobacteria group and is abundant in almost all soils. Its role in soil ecology is considered significant. One noteworthy characteristic of the bacterium is that it produces large quantities of extracellular polymeric substances (EPS). It is also known that its biomass has the capacity to fix heavy metals. Here it is reported that M. xanthus was able to accumulate 0.6 mmol of La per g of wet biomass and/or 0.99 mmol per g of dry biomass. Transmission Electron Microscopy (TEM) observation of M. xanthus cells treated with La showed that a substantial amount of this cation was fixed in the EPS and in the cell wall. Smaller amounts were also observed in the cytoplasm. Fixed La appeared as phosphate in all cellular locations. The results given here also show that the use of La enables TEM observation of the M. xanthus EPS as a dense fibrillar net surrounding the cells. This technique is relatively easy and prevents EPS collapse, which occurs frequently during the fixation and dehydration procedures commonly used in preparations for TEM observations. Since antibodies are no longer required, the La stain can be carried out without delaying bacterial cell cultivation or isolation. In addition, the presence of La in cell cytoplasm without cell degeneration suggests that this microorganism could be used as a model in the study of bacteria-lanthanide interactions.     

Myxococcus xanthus'' killed cells as inducers of struvite crystallization. Its possible role in the biomineralization processes

We studied the possibility of struvite formation using killed cells of Myxococcus xanthus. Cells were killed by heat, UV light and sonication. In all cases, we show that struvite crystallization occurs and we propose that the dead cells or cell debris can act by themselves as heterogeneous crystallization nuclei. We also show that the slime, produced by Myxococcus in a large quantities, is not involved in this process.     

Fate of nitrogen during composting of chicken litter

Chicken litter (a mixture of chicken manure, wood shavings, waste feed, and feathers) was composted in forced-aeration piles to understand the changes and losses of nitrogen (N) during composting. During the composting process, the chemical [different N fractions, organic matter (OM), organic carbon (C), and C:N ratio], physical, and microbial properties of the chicken litter were examined. Cumulative losses and mass balances of N and organic matter were also quantified to determine actual losses during composting. The changes in total N concentration of the chicken litter piles were essentially equal to those of the organic N. The inorganic N concentrations were low, and that organic N was the major nitrogenous constituent. The ammonium (NH(4)(+))-N concentration decreased dramatically during first 35 days of composting. However, the rapid decrease in NH(4)(+)-N during composting did not coincide with a rapid increase in (NO(3)(-)+NO(2)(-))-N concentration. The concentration of (NO(3)(-)+NO(2)(-))-N was very low (<0.5 g kg(-1)) at day 0, and this level remained unchanged during the first 35 days of composting suggesting that N was lost during composting. Losses of N in this composting process were governed mainly by volatilization of ammonia (NH(3)) as the pile temperatures were high and the pH values were above 7. The narrow C:N ratio (<20:1) have also contributed to losses of N in the chicken litter. The OM and total organic C mass decreased with composting time. About 42 kg of the organic C was converted to CO(2). On the other hand, 18 kg was lost during composting. This loss was more than half (59%) of the initial N mass of the piles. Such a finding demonstrates that composting reduced the value of the chicken litter as N fertilizer. However, the composted chicken contained a more humified (stabilized) OM compared with the uncomposted chicken litter, which would enhance its value as a soil conditioner.     

Membrane-based wet electrostatic precipitation

Emissions of fine particulate matter, PM2.5, in both primary and secondary form, are difficult to capture in typical dry electrostatic precipitators (ESPs). Wet (or water-based) ESPs are well suited for collection of acid aerosols and fine particulates because of greater corona power and virtually no re-entrainment. However, field disruptions because of spraying (misting) of water, formation of dry spots (channeling), and collector surface corrosion limit the applicability of current wet ESPs in the control of secondary PM2.5. Researchers at Ohio University have patented novel membrane collection surfaces to address these problems. Water-based cleaning in membrane collectors made of corrosion-resistant fibers is facilitated by capillary action between the fibers, maintaining an even distribution of water. This paper presents collection efficiency results of lab-scale and pilot-scale testing at FirstEnergy's Bruce Mansfield Plant for the membrane-based wet ESP. The data indicate that a membrane wet ESP was more effective at collecting fine particulates, acid aerosols, and oxidized mercury than the metal-plate wet ESP, even with approximately 15% less collecting area.     

Composting of spent pig litter in turned and forced-aerated piles

A study was carried out to compare the compositing efficiency of spent litter (a mixture of partially decomposed pig manure and sawdust) in turned and forced-aerated piles. Duplicate piles were built with manual turning (every 4 days) during composting, and duplicate piles were set up with forced aeration using an air pump. The present study demonstrated that the efficiency of composting in the turned and forced-aerated piles was similar. Spent litter in these piles reached maturity at the same time (60 days). The forced-aerated piles went through similar physical, chemical, and microbial changes with the turned piles during composting. The forced-aerated composting system was also as effective as the turned system in eliminating Salmonella sp. in the spent litter. These results suggest that a forced-aerated composting system could be used as an alternative method in composting spent litter. The similarities in temporal changes in temperature, chemical, and microbiological properties of the forced-aerated piles, compared with the turned piles, indicate that addition of a bulking agent under forced aerated composting of spent litter is not necessary. The partially decomposed sawdust in the spent litter provided enough free air space, allowing the delivery of oxygen for the microorganisms in the spent litter piles.