scholarly journals Negligible isotopic fractionation of nitrogen within temperate <i>Zostera</i> spp. meadows

2018 ◽  
Vol 15 (23) ◽  
pp. 7225-7234
Author(s):  
Douglas G. Russell ◽  
Wei Wen Wong ◽  
Perran L. M. Cook

Abstract. Seagrass meadows form an ecologically important ecosystem in the coastal zone. The 15N∕14N ratio of seagrass is commonly used to assess the extent to which sewage-derived nitrogen may be influencing seagrass beds. There have, however, been few studies comparing the 15N∕14N ratios of seagrass beds, their associated sediments and, of critical importance, the porewater NH4+ pool, which is most bioavailable. Here, we undertook a study of the 15N∕14N ratios of seagrass tissue, sediment porewater NH4+ pool and the bulk sediment to elucidate the extent of any fractionating processes taking place during organic matter mineralisation and nitrogen assimilation. The study was undertaken within two coastal embayments known to receive nitrogen from a range of sources including marine, urban and sewage sources. There was close agreement between the bulk sediment δ15N and seagrass δ15N (r2 of 0.92 and mean offset of 0.9 ‰), illustrating a close coupling between the plant and sediment pools. The δ15N of porewater NH4+ was strongly correlated with the δ15N of both the sediment and the seagrass tissue. For both of these relationships, however, the intercept of the line was not significantly different from 0 and the slopes were not 1:1, reflecting an enrichment of the porewater NH4+ δ15N pool relative to seagrass tissue and bulk sediment δ15N at high δ15N values. We suggest that nitrogen fixation is the most likely explanation for the observation that the δ15N of seagrass tissue is lower than porewater NH4+. Conversely, we suggest that the most likely explanation for the enrichment of porewater NH4+ above bulk sediment was through the preferential mineralisation of isotopically enriched algal material (nitrogen derived from sewage sources) within the sediment as δ15N increased in the vicinity of a sewage treatment plant.

2020 ◽  
Vol 15 (2) ◽  
pp. 142-151
Author(s):  
Peter Lukac ◽  
Lubos Jurik

Abstract:Phosphorus is a major substance that is needed especially for agricultural production or for the industry. At the same time it is an important component of wastewater. At present, the waste management priority is recycling and this requirement is also transferred to wastewater treatment plants. Substances in wastewater can be recovered and utilized. In Europe (in Germany and Austria already legally binding), access to phosphorus-containing sewage treatment is changing. This paper dealt with the issue of phosphorus on the sewage treatment plant in Nitra. There are several industrial areas in Nitra where record major producers in phosphorus production in sewage. The new wastewater treatment plant is built as a mechanicalbiological wastewater treatment plant with simultaneous nitrification and denitrification, sludge regeneration, an anaerobic zone for biological phosphorus removal at the beginning of the process and chemical phosphorus precipitation. The sludge management is anaerobic sludge stabilization with heating and mechanical dewatering of stabilized sludge and gas management. The aim of the work was to document the phosphorus balance in all parts of the wastewater treatment plant - from the inflow of raw water to the outflow of purified water and the production of excess sludge. Balancing quantities in the wastewater treatment plant treatment processes provide information where efficient phosphorus recovery could be possible. The mean daily value of P tot is approximately 122.3 kg/day of these two sources. The mean daily value of P tot is approximately 122.3 kg/day of these two sources. There are also two outflows - drainage of cleaned water to the recipient - the river Nitra - 9.9 kg Ptot/day and Ptot content in sewage sludge - about 120.3 kg Ptot/day - total 130.2 kg Ptot/day.


2008 ◽  
Vol 37 (2) ◽  
Author(s):  
Maciej Walczak

Changes of microbial indices of water quality in the Vistula and Brda rivers as a result of sewage treatment plant operationThis paper reports the results of studies of microbiological changes in the water quality of the Vistula and Brda rivers after the opening of sewage treatment plants in Bydgoszcz. The study involved determining the microbiological parameters of water quality. Based on the results obtained, it was found that the quality of the water in both rivers had improved decidedly after the opening of the plants, although an increased number of individual groups of microorganisms was found at the treated sewage outlet from one of the plants.


2000 ◽  
Vol 36 (4) ◽  
pp. 161-171
Author(s):  
KENITSU KONNO ◽  
NAOKI ABE ◽  
YOSHIRO SATO ◽  
KOJI AKAMATSU ◽  
MAKOTO ABE ◽  
...  

2017 ◽  
Vol 1 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Athar Hussain ◽  
Manjeeta Priyadarshi ◽  
Saif Said ◽  
Suraj Negi

Most of the industrial sewage effluents used for irrigation contains heavy metals which cause toxicity to crop plants as the soils are able to accumulate heavy metal for many years. The vegetables grown for the present study were irrigated with treated wastewater brought from a nearby full-scale sewage treatment plant at different compositions along with tap water as a control. The concentration levels of the Cd, Co, Cu, Mn and Zn in the soil were found to below the toxic limits as prescribed in literature. Daily Intake Metals (DIM) values suggest that the consumption of plants grown in treated wastewater and tap water is nearly free of risks, as the dietary intake limits of Cu, Fe, Zn and Mn. The Enrichment Factor for the treated wastewater irrigated soil was found in order Zn> Ni> Pb> Cr> Cu> Co> Mn> Cd. Thus, treated wastewater can be effectively used for irrigation. This will have twofold significant environmental advantages: (1) helpful to reduce the groundwater usage for irrigation and (2) helpful to reduce the stress on surface water resources.


1995 ◽  
Vol 30 (4) ◽  
pp. 565-592 ◽  
Author(s):  
A.F. Gemza

Abstract Severn Sound continues to exhibit signs of eutrophication despite initial identification of the problem in 1969 and the construction of several sewage treatment plants since then. In general, improvements in trophic state indicators have been marginal, suggesting that the sewage treatment plants have had limited success in controlling phosphorus concentrations. These discharges likely contributed to the increased total phosphorus levels and consequently the higher phytoplankton densities of the nearshore waters. Phytoplankton biovolumes were on average one order of magnitude higher than in the open waters of Lake Huron with mean summer biovolumes as high as 8.0 mm/L. Algal biovolumes were most dense in Penetang Bay, which experienced limited exchange with the main waters of the sound. No significant long-term trends were observed. Water clarity was declining significantly, however, at a rate of -0.60 to -0.78 m/year throughout the sound except in Sturgeon Bay. Total phosphorus levels were highly variable from year to year; however, concentrations from a 20-year perspective were declining in the open waters at a rate of 0.70 µg/L/year, but response was limited in nearshore areas. In Sturgeon Bay, mean annual euphotic zone total phosphorus as well as soluble reactive phosphorus levels declined by as much as 50% following the construction of a sewage treatment plant with tertiary treatment. Phytoplankton genera typical of eutrophic waters continued to dominate the algal assemblage but members indicative of mesotrophic conditions have become apparent in some areas of the sound.


1972 ◽  
Vol 7 (1) ◽  
pp. 13-20
Author(s):  
D.D.P. Cane ◽  
G.J. Farguhar

Abstract A case of filamentous activated sludge bulking was investigated at an extended aeration plant treating wastes from a highway service centre. The purpose of the study was to find an effective control measure for the bulking and, if possible, to determine the cause of the bulking condition. Experiments were conducted to determine the effects upon bulking of: (a) a controlled copper dosage to the mixed liquor, (b) variations in the organic loading rate, and (c) maintenance of high and low dissolved oxygen concentrations in the mixed liquor. The microorganism responsible for the bulking condition was tentatively identified as Sphaerotilus natans. Extensive growths of these bacteria occurred in the sludge when the mixed liquor dissolved oxygen concentration dropped below 0.5 mg/1. Such dissolved oxygen levels had frequently occurred at this plant due to the use of timed aeration cycles and the use of insufficient air supply during peak loading periods. Variations in organic loading rates were found to have no adverse effect on sludge settleability. When bulking was slight, the condition could be improved by increasing the dissolved oxygen level to 1.5 mg/1, or more. The rate at which the filamentous growths could be eliminated from a highly filamentous sludge by increased aeration was very slow, but could be greatly increased by the simultaneous feeding of copper to the mixed liquor at a dosage rate of 1.0 mg/1, based on the raw sewage flows.


1990 ◽  
Vol 22 (1-2) ◽  
pp. 251-259 ◽  
Author(s):  
R. Pujol

The sewage treatment plant of Metabief (East of France) has been monitored during three weeks in winter 1988. The treatment associates a physico-chemical treatment with a biological process of biofiltration. The first step eliminates about 60 % of the organic matter (COD and BOD). The biofliters improve the treatment removing 60 % of COD influent and 65 % of TSS. The process is efficient (N excepted) under conditions of the experiment but nitrification is limited by cold temperatures (&lt; 10°C). Important results related to biological sludge product are presented (sludge characteristic, microscopic data, sludge production). Power consumption of biofliters represents 70 % of the total plant needs. Adequate control of washing cycles and close survey of numerous movable devices are of the utmost importance to guarantee the proper operating of biofliters.


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