scholarly journals Nutrient Dynamics at the Sediment-Water Interface: Influence of Wastewater Effluents

2021 ◽  
Author(s):  
Meng Zhang ◽  
Robert A. Francis ◽  
Michael A. Chadwick
Keyword(s):  
Nutrient Dynamics ◽  
Treatment Plant ◽  
Nutrient Concentrations ◽  
Biological Processes ◽  
Overlying Water ◽  
Wwtp Effluent ◽  
Approaches To Study ◽  
Experimental Approaches ◽  
Study Sites

Abstract Uptake and regeneration fluxes and concentrations of nutrients, i.e., nitrate (NO3−), ammonium (NH4+), phosphate (PO43−) and dissolved organic carbon (DOC), were evaluated upstream and downstream of a wastewater treatment plant (WWTP) in the River Wandle, UK, from July to October 2019. Using chamber techniques, water-specific nutrient concentrations were measured at two exposures (3 and 10 min) to calculate fluxes. The WWTP effluent contributed to elevated concentrations and modified flux rates, resulting in significant differences at the study sites. Compared with summer, the concentrations of NO3− and DOC increased while NH4+ and PO43− decreased in autumn. Nutrient fluxes varied both temporally and spatially in uptake (i.e., storage in sediments) or regeneration (i.e., release into river water). Under the actions of physical and biological processes, the fluxes of NO3− and NH4+ showed opposite flux directions. Dissolved oxygen (DO) and bioabsorption mainly affected PO43− and DOC fluxes, respectively. Specifically, across all sites, NO3− was −0.01 to +0.02 mg/(m2 s), NH4+ was −29 to +2 μg/(m2 s), PO43− was −2.0 to +0.5 μg/(m2 s), and DOC was −0.01 to +0.05 mg/(m2 s). Further, we did find that these variations were related to nutrient concentrations in the overlying water. Our results provide further evidence to show that reductions in river nutrients are paramount for improving river ecological conditions. Additionally, we suggest that more research is needed to evaluate chamber-based experimental approaches to make them more comparable to in-situ flux methods. Highlights • Sewage effluent resulted in elevated nutrient concentrations and modified fluxes. • Flux was affected by initial nutrient concentrations, DO and microbial activity. • Inexpensive approaches to study nutrient dynamics are needed for river restoration.

scholarly journals Macroinvertebrate interactions stimulate decomposition in WWTP effluent-impacted aquatic ecosystems

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
Tom V. van der Meer ◽  
Gea H. van der Lee ◽  
Ralf C. M. Verdonschot ◽  
Piet F. M. Verdonschot
Keyword(s):  
Aquatic Ecosystems ◽  
Treatment Plant ◽  
Biotic Interactions ◽  
Phosphate Concentration ◽  
Nutrient Concentrations ◽  
Overlying Water ◽  
Wwtp Effluent ◽  
Benthic Environment ◽  
Negative Impacts ◽  
Growth And Reproduction

AbstractAquatic ecosystems worldwide are impacted by an influx of nutrients and sludge particles from wastewater treatment plant (WWTP) effluents, leading to a degradation of benthic habitats and a loss of associated macroinvertebrate taxa. Hence, in habitats impacted by WWTPs, only a few tolerant macroinvertebrate taxa remain. These tolerant detritivore macroinvertebrate taxa play an important role in the degradation of organic matter, and biotic interactions between these taxa may either enhance or reduce the rate of sludge degradation. Therefore, the aim of the present study was to examine if the interaction between asellids and tubificids, both highly abundant in systems impacted by WWTP effluent, enhances the degradation of sludge. To this end, growth and reproduction of both taxa, sludge degradation and nutrient concentrations in the overlying water were measured in a 28-day laboratory experiment, subjecting WWTP sludge to 4 treatments: a control without macroinvertebrates, a tubificid, an asellid, and an asellid + tubificid treatment. Sludge degradation, phosphate concentration in the overlying water and asellid reproduction were enhanced when asellids and tubificids were jointly present, whereas tubificid growth and reproduction were hampered in comparison to the tubificid treatment. Hence, our results suggest that the biotic interactions between these tolerant detritivores stimulate sludge degradation, and thus possibly mitigating the negative impacts of WWTP-derived sludge particles on the benthic environment.

scholarly journals Advanced experimental approaches to marine water-column biogeochemical processes

2017 ◽  
Vol 75 (1) ◽  
pp. 30-42 ◽  
Author(s):  
Louis Legendre ◽  
Richard B Rivkin ◽  
Nianzhi Jiao
Keyword(s):  
Water Column ◽  
Numerical Models ◽  
Free Water ◽  
Sea Surface ◽  
Biogeochemical Processes ◽  
In Situ Experiments ◽  
Technological Developments ◽  
Approaches To Study ◽  
Experimental Approaches

Abstract This “Food for Thought” article examines the potential uses of several novel scientific and technological developments, which are currently available or being developed, to significantly advance or supplement existing experimental approaches to study water-column biogeochemical processes (WCB-processes). After examining the complementary roles of observation, experiments and numerical models to study WCB-processes, we focus on the main experimental approaches of free-water in situ experiments, and at-sea and on-land meso- and macrocosms. We identify some of the incompletely resolved aspects of marine WCB-processes, and explore advanced experimental approaches that could be used to reduce their uncertainties. We examine three such approaches: free-water experiments of lengthened duration using bioArgo floats and gliders, at-sea mesocosms deployed several 100s m below the sea-surface using new biogeochemical sensors, and 50 m-tall on-land macrocosms. These approaches could lead to significant progress in concepts related to marine WCB-processes.

scholarly journals Injection-Triggered Occlusion of Flow Pathways in Geothermal Operations

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Maren Brehme ◽  
Simona Regenspurg ◽  
Peter Leary ◽  
Fatih Bulut ◽  
Harald Milsch ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Statistical Interpretation ◽  
Biological Processes ◽  
Spatially Correlated ◽  
Flow Pathways ◽  
Study Sites ◽  
Physical Boundary ◽  
Geothermal Aquifer ◽  
Operational Data

Reasons for injectivity decline were investigated in a low-enthalpy geothermal aquifer in Klaipeda (Lithuania). It is one of the study sites within the DESTRESS project, which demonstrates different stimulation techniques in geothermal reservoirs. Due to low injectivity, production rates from the Lithuanian field are currently reduced, which lead to negative commercial implications for the site. Productivity from the same wells is measured to be 40 times higher. Injectivity decline in aquifers is often related to clogging processes in spatially correlated highly permeable structures, which control the main flow volume. We subdivided clogging processes into (1) physical, (2) chemical, and (3) biological processes and studied them by analyzing fluid and solid samples as well as operational data. The methods we used are fluid and solid analyses in situ, in the laboratory and in experimental setups, statistical interpretation, and numerical modeling. Our results show that the spatially correlating nature of permeable structures is responsible for exponentially decreasing injectivity because few highly permeable zones clog rapidly by intruded particles. In particular, field operations cause changes of the physical, chemical, and biological processes in the aquifer. Mineral precipitation and corrosion are the main chemical processes observed at our site. Microbial activity causes biofilm while fines migration is caused by changes in physical boundary conditions. Moreover, these processes can affect each other and generate further reactions, for example, microbial activity triggers corrosion in surface pipelines.

scholarly journals Long-term changes in sediment phosphorus below a rural effluent discharge

2009 ◽  
Vol 6 (1) ◽  
pp. 767-789 ◽  
Author(s):  
B. E. Haggard ◽  
R. J. Stoner
Keyword(s):  
Water Column ◽  
Stream Water ◽  
Sampling Site ◽  
Treatment Plant ◽  
Overlying Water ◽  
Wwtp Effluent ◽  
Effluent Discharge ◽  
Benthic Sediments ◽  
Bed Material ◽  
Management Changes

Abstract. Effluent discharge often increases the amount of phosphorus (P) in the water column and bed material of receiving water bodies. The goal of this study was to evaluate changes in sediment-P interactions in an effluent-driven stream over a 4-year period where hydrology and watershed P management changed dramatically. Specifically, this study evaluated (i) the equilibrium between benthic sediments and stream water dissolved P; and (ii) the amounts of select P fractions in the bed material within the fluvial channel. Sediment and water samples were collected at Columbia Hollow in northwest Arkansas from October 2003 through September 2007, and the sampling site was approximately 3 km downstream from the Decatur wastewater treatment plant (WWTP). Monthly average effluent total P (TP) concentrations were highly variable (0.30–4.80 mg L−1) from October 2003 until December 2005; however, the Decatur WWTP implemented new P management strategies in 2006 that reduced the variability in effluent TP (0.28–0.95 mg L−1). Soluble reactive P (SRP) concentrations at Columbia Hollow 3 km downstream from the effluent discharge followed the same pattern; these concentrations were positively correlated to the effluent TP (r=0.73; p<0.001). Sediment equilibrium concentrations (EPC0) were significantly less (ln transformed data, p<0.001) after the WWTP effluent reduced TP concentrations, and sediment EPC0 suggested that the stream bed material acted as a P source to the overlying water at Columbia Hollow. The effects of this effluent discharge and the WWTP management changes on sediment P dynamics were profound. Prior to implementation of WWTP P management, the effluent TP concentrations were the driving factor related to SRP concentrations in the water column and sediment EPC0. Conversely, after the P management changes the benthic sediments became the important factor likely regulating dissolved P concentrations in the stream water.

scholarly journals Leaf nutrients of two Cycas L. species contrast among in situ and ex situ locations

2020 ◽  
Vol 12 (13) ◽  
pp. 16831-16839 ◽  
Author(s):  
Thomas E. Marler ◽  
Anders Lindstrom
Keyword(s):  
Nutrient Dynamics ◽  
Essential Elements ◽  
Tree Canopy ◽  
Ex Situ ◽  
Nutrient Concentrations ◽  
Sampling Protocols ◽  
Leaf Nutrient Concentrations ◽  
Lateral Orientation ◽  
Nutrient Relations

An understanding of leaf nutrient relations is required for tree conservation and horticulture success.  The study of cycad leaf nutrient dynamics has expanded in recent years, but direct comparisons among reports remains equivocal due to varying sampling protocols.  We used Cycas micronesica K.D. Hill and Cycas nongnoochiae K.D. Hill trees to determine the influence on leaf nutrient concentrations of in situ versus ex situ locations and orientation of leaves within the tree canopy.  Nitrogen, phosphorus, and potassium concentrations of leaves from ex situ plants exceeded those from in situ plants, and the differences were not explained by soil nutrient differences.  Calcium concentrations of leaves varied among the site pairs, with differences primarily explained by soil calcium.  Magnesium concentrations of leaves were not different among all location pairs even though soil magnesium concentrations varied among the sites more than any of the other elements.  Differences in leaf macronutrient concentrations among four C. micronesica provenances were minimal when grown in a common garden.  Lateral orientation of leaves did not influence any of the essential elements for either of the species.  These findings indicate that the lateral orientation of cycad leaves does not influence leaf nutrient concentrations, leaf nutrient relations of cycad plants in managed ex situ settings do not align with leaf nutrient relations in habitat, and these differences are not explained by soil nutrition for most elements.  We suggest that leaf nutrient concentrations should be determined in all niche habitats within the geographic range of a cycad species in order to fully understand the leaf physiology of each species. 

A geometallurgical characterization study of the Crystalkop Reef at the Great Noligwa Mine, Klerksdorp Goldfield, South Africa

2017 ◽  
Vol 120 (3) ◽  
pp. 303-322
Author(s):  
D. Pienaar ◽  
B.M. Guy ◽  
C. Pienaar ◽  
K.S. Viljoen
Keyword(s):  
South Africa ◽  
Treatment Plant ◽  
Processing Parameters ◽  
Processing Plant ◽  
Small Contribution ◽  
Gold Cyanide ◽  
Three Samples ◽  
Characterization Study ◽  
Different Sources

Abstract Mineralogical and textural variability of ores from different sources commonly leads to processing inefficiencies, particularly when a processing plant is designed to treat ore from a single source (i.e. ore of a relatively uniform composition). The bulk of the Witwatersrand ore in the Klerksdorp goldfield, processed at the AngloGold Ashanti Great Noligwa treatment plant, is derived from the Vaal Reef (>90%), with a comparatively small contribution obtained from the Crystalkop Reef (or C-Reef). Despite the uneven contribution, it is of critical importance to ensure that the processing parameters are optimized for the treatment of both the Vaal and C-Reefs. This paper serves to document the results of a geometallurgical study of the C-Reef at the Great Noligwa gold mine in the Klerksdorp goldfield of South Africa, with the primary aim of assessing the suitability of the processing parameters that are in use at the Great Noligwa plant. The paper also draws comparisons between the C-Reef and the Vaal Reef A-facies (Vaal Reef) and attempts to explain minor differences in the recovery of gold and uranium from these two sources. Three samples of the C-Reef were collected in-situ from the underground operations at Great Noligwa mine for mineralogical analyses and metallurgical tests. Laboratory-scale leach tests for gold (cyanide) and uranium (sulphuric acid) were carried out using dissolution conditions similar to that in use at the Great Noligwa plant, followed by further diagnostic leaching in the case of gold. The gold in the ore was found to be readily leachable with recoveries ranging from 95% to 97% (as opposed to 89% to 93% for the Vaal Reef). Additional recoveries were achieved in the presence of excess cyanide (96% to 98%). The recovery of uranium varied between 72% and 76% (as opposed to 30% to 64% for the Vaal Reef), which is substantially higher than predicted, given the amount of brannerite in the ore, which is generally regarded as refractory. Thus, the higher uranium recoveries from the C-Reef imply that a proportion of the uranium was recovered by the partial dissolution of brannerite. As the Vaal Reef contain high amounts of chlorite (3% to 8%), which is an important acid consumer, it is considered likely that this could have reduced the effectiveness of the H2SO4 leach in the case of the ore of the Vaal Reef. Since the gold and uranium recoveries from the C-Reef were higher than the recoveries from the Vaal Reef, the results demonstrate that the processing parameters used for treatment of the Vaal Reef are equally suited to the treatment of the C-Reef. Moreover, small processing modifications, such as increased milling and leach retention times, may well increase the recovery of gold (particularly when e.g. coarse gold, or unexposed gold, is present).

scholarly journals Modelling the Quality of Bathing Waters in the Adriatic Sea

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1525
Author(s):  
Christian Ferrarin ◽  
Pierluigi Penna ◽  
Antonella Penna ◽  
Vedrana Spada ◽  
Fabio Ricci ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Management Tool ◽  
Negative Consequences ◽  
Sea Temperature ◽  
Bathing Water Directive ◽  
Bathing Waters ◽  
Diffusion Dynamics ◽  
Study Sites

The aim of this study is to develop a relocatable modelling system able to describe the microbial contamination that affects the quality of coastal bathing waters. Pollution events are mainly triggered by urban sewer outflows during massive rainy events, with relevant negative consequences on the marine environment and tourism and related activities of coastal towns. A finite element hydrodynamic model was applied to five study areas in the Adriatic Sea, which differ for urban, oceanographic and morphological conditions. With the help of transport-diffusion and microbial decay modules, the distribution of Escherichia coli was investigated during significant events. The numerical investigation was supported by detailed in situ observational datasets. The model results were evaluated against water level, sea temperature, salinity and E. coli concentrations acquired in situ, demonstrating the capacity of the modelling suite in simulating the circulation in the coastal areas of the Adriatic Sea, as well as several main transport and diffusion dynamics, such as riverine and polluted waters dispersion. Moreover, the results of the simulations were used to perform a comparative analysis among the different study sites, demonstrating that dilution and mixing, mostly induced by the tidal action, had a stronger effect on bacteria reduction with respect to microbial decay. Stratification and estuarine dynamics also play an important role in governing microbial concentration. The modelling suite can be used as a beach management tool for improving protection of public health, as required by the EU Bathing Water Directive.

scholarly journals Bacterial Communities and Enzymatic Activities in Sediments of Long-Term Fish and Crab Aquaculture Ponds

2021 ◽  
Vol 9 (3) ◽  
pp. 501
Author(s):  
Zhimin Zhang ◽  
Qinghui Deng ◽  
Lingling Wan ◽  
Xiuyun Cao ◽  
Yiyong Zhou ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Enzymatic Activities ◽  
Nutrient Concentrations ◽  
Biological Processes ◽  
Farming Practices ◽  
Mitten Crab ◽  
Aquaculture Ponds ◽  
Pond Sediments ◽  
Sediment Ph

Aquaculture is among the most important and fastest growing agriculture sectors worldwide; however, it generates environmental impacts by introducing nutrient accumulations in ponds, which are possibly different and further result in complex biological processes in the sediments based on diverse farming practices. In this study, we investigated the effects of long-term farming practices of representative aquatic animals dominated by grass carp (GC, Ctenopharyngodon idella) or Chinese mitten crab (CMC, Eriocheir sinensis) on the bacterial community and enzyme activity of sediments from more than 15 years of aquaculture ponds, and the differences associated with sediment properties were explored in the two farming practices. Compared to CMC ponds, GC ponds had lower contents of TC, TN, and TP in sediments, and similar trends for sediment pH and moisture content. Sediment bacterial communities were significantly different between GC and CMC ponds, with higher bacterial richness and diversity in GC ponds. The bacterial communities among the pond sediments were closely associated with sediment pH, TC, and TN. Additionally, the results showed profoundly lower activities of β-1,4-glucosidase, leucine aminopeptidase, and phosphatase in the sediments of GC ponds than CMC ponds. Pearson’s correlation analysis further revealed strong positive correlations between the hydrolytic enzyme activities and nutrient concentrations among the aquaculture ponds, indicating microbial enzyme regulation response to sediment nutrient dynamics. Our study herein reveals that farming practices of fish and crab differently affect bacterial communities and enzymatic activities in pond sediments, suggesting nutrient-driven sediment biological processes in aquaculture ponds for different farming practices.

Model-based comparison of two ways to enhance WWTP capacity under stormwater conditions

2009 ◽  
Vol 60 (7) ◽  
pp. 1875-1883 ◽  
Author(s):  
M. Ahnert ◽  
J. Tränckner ◽  
N. Günther ◽  
S. Hoeft ◽  
P. Krebs
Keyword(s):  
Treatment Plant ◽  
Combined Sewer Overflows ◽  
Worst Case ◽  
Wwtp Effluent ◽  
Combined Sewer ◽  
Total Ammonia ◽  
Rain Events ◽  
Simulated Time ◽  
Simulated Time Series ◽  
Receiving Water

Two different approaches to increase the fraction of combined water treated in the wastewater treatment plant (WWTP) which would otherwise contribute to combined sewer overflows (CSO) are presented and compared based on modelling results with regard to their efficiencies during various rain events. The first option is to generally increase the WWTP inflow according to its actual capacity rather than pre-setting a maximum that applies to worst case loading. In the second option the WWTP inflow is also increased, however, the extra inflow of combined water is bypassing the activated sludge tank and directly discharged to the secondary clarifier. Both approaches have their advantages. For the simulated time series with various rain events, the reduction of total COD load from CSOs and WWTP effluent discharged to the receiving water was up to 20% for both approaches. The total ammonia load reduction was between 6% for the bypass and 11% for inflow increase. A combination of both approaches minimises the adverse effects and the overall emission to the receiving water.

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