Sewage Dispersion Research Articles

Spatiotemporal variation of sterols in sediment as markers of primary production and ocean sewage dumping in the southwestern East Sea (Japan Sea)

The sedimentation of organic carbon in the Ulleung Basin, in the southwestern East Sea (Japan Sea) was investigated using radiocarbon and sterols. The accumulation rates of organic carbon and the contents of brassicasterol and dinosterol were higher on the slope than in the central basin, reflecting the surface water productivity, whereas cholesterol showed similar or higher contents in the central basin. The coprostanol concentration in surface sediments reflected the dispersion of sewage dumped in this region. The vertical distribution showed that the coprostanol concentration was the highest in the top 5-cm layer near the Korea Strait, close to one of the two dumping sites. A high coprostanol concentration was also found near the coast further north, where the content peaked at ∼10 cm depth. The vertical distribution of coprostanol helped to estimate the sediment accumulation rate at sites where radiocarbon gradient was too small or the values were too variable.

On dispersion of solute in steady flow through a channel with absorption boundary: an application to sewage dispersion

The paper describes the longitudinal dispersion of passive tracer materials released into an incompressible viscous fluid, flowing through a channel with walls having first-order reaction. Its model is based on a steady advection–diffusion equation with Dirichlet’s and mixed boundary conditions, and whose solution represents the concentration of the tracers in different downstream stations. For imposing the boundary conditions properly, artanh transformation is used to convert the infinite solution space to a finite one. A finite difference implicit scheme is used to solve the advection–diffusion equation in the computational region, and an inverse transformation is employed for the solution in the physical region. It is shown how the mixing of the tracer molecule influenced by the shear flow and due to the action of the absorption parameter at both the walls of the channel. For convection-dominated flow, uniform mesh is failed to capture the layer phenomena along the different downstream stations and a piecewise uniform mesh; namely, Shishkin mesh is used. The results are compared with existing experimental and numerical data available in the literature, and we have achieved an excellent agreement with them. The study plays a significant role to understand the basic mechanisms of sewage dispersion.

Green Residential Community Domestic Sewage Treatment and Recycling Analysis

The accelerate of urbanization process in our country, because of the raising of water consumption, causing the urban domestic sewage increases, the rate of urban domestic sewage tackle is barely 57.4% in 2008. Using the experience of international domestic sewage tackle as a resource of reference, considering the residential community domestic sewage dispersion tackle is a effective way, and analysing the water quantity balance, tackle technics choose and economical efficiency combined with engineering project, finally to table a proposal for the residential community domestic sewage tackle and recycling .

Carbon and nitrogen stable isotopes in coastal benthic populations under multiple organic enrichment sources

In a dispersive coastal area under multiple organic enrichment sources, stable isotopes were used to trace organic sources of carbon and nitrogen in sediments and benthic macrofauna. The Bivalve Abra alba and the Polychaetes Nephtys sp. and Pectinaria (Lagis) koreni were reliable indicators of the input of terrestrial-derived organic matter into this coastal area, either originated in outfall sewage discharges or estuarine outflow. An isotopic depletion was observed up to 250m from the outfall branches, much stronger in the biota than in the sediments. An enrichment of 2‰ in the sediments, and 2–6‰ in the species was noticed in sites located farther than 1500m from the outfall. Depositivores and carnivores/omnivores gave the best picture of the extension of the sewage dispersion and incorporation into the food web.

Detecting Anthropogenic Stress in an Ecosystem: 3. Mesoscale Variability and Biotic Indices

Previous work in the Ria Formosa Lagoon has revealed that it is possible to use macrofauna community structure as an indicator of contamination effects. Communities at sites adjacent to sewage outfalls indicated contamination but no pollution gradients were observed. In this study, macrofauna within a sub-section of the earlier work were investigated to determine the extent of mesoscale (10–100 m) variability and new indices of biological community structure. The results were evaluated using univariate (Marine Biotic Index; BI) and multivariate statistical methods (PCA). The computer program Barrier (usually used with genetic data) was also applied to detect “barriers” between spatially referenced samples. PCA identified the most significant factor effecting the distribution of the organisms in the study area to be the mud content of the sediment (% < 63 μm). Communities at sandy sites consisted of suspension feeders and detrital browsers, whilst communities at muddy sites were composed mainly of deposit feeders. The second principal component produced a vector characterized by a contamination gradient. The effects of the sewage discharge appeared to be concentrated at the outfall as it had the highest TOC (10.4%) content and was the only site to be characterized by the BI as slightly polluted. With the use of the BI and Barrier two gradients were observed in the transition of sites from an unpolluted to a polluted state. These gradients appeared not to follow the flow of the channel as expected (high % TOC of sites along the channel), and instead extended west and south from the sewage source. In conclusion, weak gradients were observeable; the multiple approaches of BI, PCA and Barrier analyses in concert were able to confirm the sewage dispersion route through the area.

Gross channel changes along the Durance River, Southern France, over the last 100 years using cartographic data

Gross channel changes for the Durance were determined using topographic maps from the 1890s and 1980s. Various width parameters were measured at 1 km intervals over 189 km from the Rhône junction at Avignon to La Saulce, some 31 km downstream of the dam at Serre Ponc¸on. During this period channel size has been considerably reduced. This can be attributed to four factors, two natural and two human induced. Firstly, there was a reduction in effective runoff at the end of the Little Ice Age (late 19th century). Secondly, runoff was further reduced with lower precipitation after about 1940. Thirdly, channel widths have been reduced by bank protection and by flood mitigation works. Finally, large-scale river regulation by EDF (Electricité de France), completed in the early 1960s, includes large dams to store alpine runoff, concrete canals to convey released water through some 20 power stations, and barrages to intercept tributary runoff and divert flows into the canals. In the lower Mediterranean part of the river, some of the diverted waters are discharged into irrigation and urban water canals (about 114 m3 s−1) and the rest into the Etang de Berre. Only about 1% of the mean discharge now reaches the Rhône. Discussion of available research provides insight into the four impacts, including additional comparative post-regulatory evidence from the Syndicat Mixte, a group concerned with environmental problems in the lower river. Evidence for channel change in lower parts of tributaries and for bed incision was found to be less conclusive. Such impacts may have been reduced by the interruptions of long-profile continuity by barrages and dams, and by lower discharges. Such discontinuities have adversely affected the ecology, low environmental flows and treated sewage dispersion. With some exceptions, environmental sustainability has not been a major issue because the Durance is such an important economic resource in terms of power, urban and irrigation waters, and building materials. Copyright © 2000 John Wiley & Sons, Ltd.

Sewage dispersion in an estuary with distinct ebb and flood channels

As a result of a combination of the European Communities (EC) Bathing Water and Urban Waste Water Treatment Directives, the option of discharging biologically treated effluent into estuaries and shallow coasteal waters through short outfalls is being increasingly considered. This has meant that sewage disposal models are now required to resolve water movements in inshore waters. As part of an environmental assessment into the options for the treatment and disposal of sewage from Felixstowe, Harwich and Dovercourt, Anglian Water commissioned WRc to produce a bacterial dispersion model of the area. It was necessary to quantify the complex flows suspected in Harwich Harbour and to be able to simulate their impact on effluent dispersion. This paper describes the development and application of this model. A detailed 2D hydrodynamic model was calibrated against Vessel Mounted Acoustic Doppler Current Profiler data gathered in the area. A bacterial dispersion model driven by this hydrodynamic model was validated using bacteriophage tracer releases. The model has been applied to demonstrate that the treatment options under consideration will comply fully with the Bathing Water Directive and are constant with the Anglian Water Environmental Policy.

Sewage influence in a macrotidal estuary: Fatty acid and sterol distributions

Estuarine surface sediment and suspended matter from the Morlaix River estuary were analysed for fatty acids and sterols by HPLC and GC. This estuary represents a typical example of a coastal river estuary subjected to strong tides and receiving domestic wastes in its upper reaches. Wastewater fatty acid and sterol distribution patterns have been used to estimate the anthropogenic matter influx and its behaviour as an estuarine organic matter component. The 5 β -stanols, specific to fecal material and relatively persistent in the environment, provide a spatial view of sewage dispersion in estuarine waters and sediments and are used to calculate the relative importance of anthropogenic inputs in the degradable organic matter. Their distribution at high and low water indicates that anthropogenic particles are distributed throughout the estuary and may reach the coastal areas. However, owing to the dilution and the sedimentation processes, the anthropogenic matter contribution to the total organic matter is low in the outer estuary. By contrast, sediments from the upper estuary are strongly influenced by fresh anthropogenic inputs which may be detected by fatty acid fingerprint. The 18:1( n − 7)/18:1( n − 9) ratio which indicates the ability of the sediment to degrade the anthropogenic fresh material demonstrates a perturbation all along the narrow upper estuary.

Ultra-violet absorption as a tracing technique for sewage dispersion and water masses in two red sea coastal lagoons in Jeddah

The u.v. absorbance is measured in water samples, collected on six successive cruises made within 1 year, from two Saudi sewage-affected fjord-like lagoons in Jeddah (Arbacen and Reayat Al-Shabab). The hydrochemical elements, salinity, phosphate and ammonia are also measured. The horizontal and vertical distribution pattern of u.v. absorbance and that for the other hydrochemical elements are found to coincide with each other to a great extent. The direction of the discharged wastewater spread at the surface can be easily identified. Three distinct water layers are observed. The surface layer is diluted by sewage effluent containing high values of u.v. absorbance, phosphate and ammonia. The intermediary layer has almost the same properties as the water outside the lagoon mouth at the same level where it is less diluted (i.e. less polluted). The third layer at the bottom (old water) where the water is dammed by the sills is more saline. It has exceptionally high values out of the four elements studied. This situation prevails almost throughout the year except during the intermittent flushing periods in winter and early spring, when the stratification is disturbed. The advantage of using u.v. absorbance measurement is that it can be read directly in the water samples without any chemical pre-treatment and so no special training is needed.

Dispersion of Sewage Wastes in Nearshore Coastal Waters: Applicability of Water Quality Criteria

Deepwater outfalls can be satisfactorily designed to ensure rapid dilution of sewage wastes, and allow for conventional water quality criteria which prescribe low bacterial levels in areas used for recreational purposes and shellfish harvesting, to be achieved. However, surface shoreline discharges of similar wastes dissipate far less readily, and normally result in shoreline bacterial levels far in excess of desirable criteria. The absolute assessment of water quality in suspect areas should ideally also include viral counts as well as epidemiological information on infections of persons exposed to contaminated seawater or seafood.

Bacillus Phages as Tracers of Water Movement

Vegetative bacterial cells, bacterial spores and bacterial viruses have all been used to trace the dispersion of sewage from coastal outfalls. The phages are considered to have advantages over other mlcroblal tracers in that they can be prepared in high titres (lO13 particles ml−1) and can be assayed In less than 8h. Furthermore, because these viruses only Infect bacteria they represent no health risk. In this paper we describe the selection of five Bacillus phages. from our collection, for use as tracers. They each have distinct, clear plaque morphologies and specific bacterial host ranges. The stability of these phages in sea water was compared to that of E. coll and some other phages. We report on the use of a membrane filtration technique to assay phages in 100ml volumes of sea water and present data from a field study where one of these tracers was released from a coastal outfall.

Geochemical mapping of bottom sediments as an aid to marine waste disposal in Hong Kong

Geochemical maps of bottom sediments are used as an aid to marine waste disposal. In Victoria Harbour, tidal flushing is slowly removing only a small fraction of the effluents received. In Tolo Harbour, the accumulation of natural inputs of lead and zinc in the bottom sediments appears to be assisted by the eutrophic effects of organic agricultural wastes. Copper shows a strong positive correlation with organic carbon and is a good natural tracer of sewage dispersion. Geochemical maps provide indications of the long term sediment dispersion pattern. The use of heavy metals as a “natural” tracer is an important advantage over hydrographic surveys.

The use of Serratia indica and Bacillus subtilis var. niger spores for tracing sewage dispersion in the sea.

SummaryExperiments were conducted at 2 coastal sites to evaluate the suitability of Serratia indica and spores of Bacillus subtilis var. niger for tracing offshore and longshore dispersion of sewage released from submarine outfalls. Neither organism was found in the sea or the rivers studied prior to an experimental release and, whereas tracer spores persisted in the sea and the littoral zone for some days after release, S. indica disappeared within a few days. Where S. indica was released continuously from an outfall, it dispersed similarly to coli‐aerogenes bacteria. Both tracers were killed rapidly in seawater exposed to sunlight, but their mortality kinetics differed. Tracer spores did not die or germinate in the dark when suspended in sewage during 24 h or in seawater during 9 days, but death occured after 3 days in seawater exposed to sunlight. Spores dispersed offshore similarly to K82Br and to S. indica; because of this and their stability, it was thought that they could be used for measuring physical dilution independently of mortality. The continuous release of S. indica into the sea is suitable for measuring the pollution field around a discharge; adding single doses of either tracer yields information on dispersion processes and transit times to the shore.

Effet des courants secondaires sur la diffusion des rejets en canaux et rivières

The velocity distribution in a now due to wall friction causes transverse forces which generate secondary currents tending to give the main or primary flow a helicoidal appearance. Attempts to explain the formation of such currents in straight canals and rivers are still very unsatisfactory. There is a considerable difference between flows on a solid bed (Fig. 1) and on a loose one (Fig. 4). In the latter case, the combined secondary current and sediment bed load result in meandering flow, becoming more marked with increasing bank roughness. In river or canal sections featuring a change in direction (e.g. a bend, converging section, fork, etc.) formation of the secondary current is readily explained by the fact that the high-velocity flow nucleus or core tends to keep to its direction for as long as possible by displacing any lower-velocity streamlines on the bottom and by the banks towards the inside of the change in direction. The effect of these currents on sewage dispersion is discussed while making a distinction between floating bodies, suspended solutions and solids, and bed load. The discharge positions most conducive to dispersion are stated for each case.