Sewage Disposal Site Research Articles

AHP and GIS Based Multi Criteria Analysis for Sustainable Sewage Disposal: A Case Study in Badulla Urban Area

<br /><table class="t1" cellspacing="0" cellpadding="0"><tbody><tr><td class="td1" valign="top"><p class="p2">Sewage waste is one of the major environmental issues in Sri Lanka. Various studies reveal that about 50% of sewage waste is disposed of unscientifically in to open areas or water bodies. It creates problems to both the public health and the environment. As such, this study identified potential locations for sewage disposal sites using the Analytical Hierarchy Process (AHP) based Multi-Criteria Analysis (MCA) methods with Geographical Information System (GIS), for the Badulla Urban Area (BUA). Environmental aspects, geological and topographical aspects, and socio-economic aspects are identified as key parameters to be considered when doing land suitability analysis for sewage disposal in BUA. The study identified that of the total area, 87.36% of was not suitable, 1.10% less suitable, 9.37% moderately suitable, and 2.17% as suitable. Using the resultant classified suitability map, field verification was carried out to determine the final optimal site. Hence, the application of GIS-based MCA has been demonstrated as an appropriate methodology to solve multiple choices in sewage disposal site selection. This would be very much needed in the concept of city planning across the country.<span class="Apple-converted-space"> </span> </td></tr></tbody></table>

Screening and Characterization of Anoxigenic Photosynthetic Bacteria as Producer of Caroteniod Pigments From Palm Liquid Sewages

Palm liquid sewage is organic waste that contains complex compounds such as water, oil, and organic solids. The organic content of palm liquid sewages is an indication of the abundance of microorganisms. This study aims to obtain anoxygenic photosynthetic bacteria (BFA) that produce carotenoid pigments from palm liquid sewages. Therefore, We isolated and screened of BFA from three palm liquid sewage disposal sites in Jambi Province. This research was conducted by an experimental method using a modified mineral medium. BFA isolates that growth and produced carotenoid pigments are visible because of the distribution of reddish-yellow pigments on the culture media. Screening results obtained 11 isolates of BFA sequentially Bg1K201, Bg1K202, Bg2k201, Bg3k201, Mr1k201, Mr1k202, Sl1k201, Sl1k202, Sl2k201, Sl2k202 and Sl3k202. The results of morphological and physiological characterization based on the Bergeys Manual of Determinative Bacteriology show that there are two types of BFA genera that have carotenoid pigments, respectively, the genus Rhodobacter (Bg1k201, Bg1k202, Bg3k201, Sl1k201, Sl1k202, and Sl1k202, and Sl2k202, and Sl1k202, and Sl2k202, and Sl1k202 and Sl2k202, and Sl2k202, and Sl2k202. Sl2k202, and) the genus Rhodopseudomonas (Bg2k201, Mr1k201 and Mr1k202)

Whole-Genome Sequence Analysis of an Extensively Drug-Resistant Salmonella enterica Serovar Agona Isolate from an Australian Silver Gull (Chroicocephalus novaehollandiae) Reveals the Acquisition of Multidrug Resistance Plasmids.

Although most of the approximately 94 million annual human cases of gastroenteritis due to Salmonella enterica resolve without medical intervention, antimicrobial therapy is recommended for patients with severe disease. Wild birds can be natural hosts of Salmonella that pose a threat to human health; however, multiple-drug-resistant serovars of S. enterica have rarely been described. In 2012, silver gull (Chroicocephalus novaehollandiae) chicks at a major breeding colony were shown to host Salmonella, most isolates of which were susceptible to antibiotics. However, multiple-drug-resistant (MDR) Escherichia coli with resistance to carbapenems, ceftazidime, and fluoroquinolones was reported from this breeding colony. In this paper, we describe a novel MDR Salmonella strain subsequently isolated from the same breeding colony. SG17-135, an isolate of S. enterica with phenotypic resistance to 12 individual antibiotics but only nine antibiotic classes including penicillins, cephalosporins, monobactams, macrolides, fluoroquinolones, aminoglycosides, dihydrofolate reductase inhibitors (trimethoprim), sulfonamides, and glycylcyclines was recovered from a gull chick in 2017. Whole-genome sequence (WGS) analysis of SG17-135 identified it as Salmonella enterica serovar Agona (S Agona) with a chromosome comprising 4,813,284 bp, an IncHI2 ST2 plasmid (pSG17-135-HI2) of 311,615 bp, and an IncX1 plasmid (pSG17-135-X) of 27,511 bp. pSG17-135-HI2 housed a complex resistance region comprising 16 antimicrobial resistance genes including blaCTX-M-55 The acquisition of MDR plasmids by S. enterica described here poses a serious threat to human health. Our study highlights the importance of taking a One Health approach to identify environmental reservoirs of drug-resistant pathogens and MDR plasmids.IMPORTANCE Defining environmental reservoirs hosting mobile genetic elements that shuttle critically important antibiotic resistance genes is key to understanding antimicrobial resistance (AMR) from a One Health perspective. Gulls frequent public amenities, parklands, and sewage and other waste disposal sites and carry drug-resistant Escherichia coli Here, we report on SG17-135, a strain of Salmonella enterica serovar Agona isolated from the cloaca of a silver gull chick nesting on an island in geographic proximity to the greater metropolitan area of Sydney, Australia. SG17-135 is closely related to pathogenic strains of S Agona, displays resistance to nine antimicrobial classes, and carries important virulence gene cargo. Most of the antibiotic resistance genes hosted by SG17-135 are clustered on a large IncHI2 plasmid and are flanked by copies of IS26 Wild birds represent an important link in the evolution and transmission of resistance plasmids, and an understanding of their behavior is needed to expose the interplay between clinical and environmental microbial communities.

Biosorption of heavy metal arsenic from Industrial Sewage of Davangere District, Karnataka, India, using indigenous fungal isolates

Contamination of soil and water bodies with heavy metals like arsenic (As) is of major concern, since arsenic is non-biodegradable, toxic and causes ill effects to gastrointestinal system, skin, liver, kidney or neurological functions. In addition, animals affected by arsenic pollution through fodder intern enter to food chain. Hence, there is an urgent need to address heavy metal arsenic pollution especially through bioremediation. In this context, biosorption with indigenous microbiota has gained more interest in recent years as it is cost-effective, eco-friendly approach and with no adverse effects. In the present study, arsenic (As III)-resistant strains of fungi were isolated from soil samples collected from various locations of industrial sewage disposal sites of Davangere District, India, and screened. Among five fungal isolates, Aspergillus spp APR-1 and APR-2 showed greater resistance to arsenic in the laboratory conditions. In order to increase the surface area for biosorption, APR-1 and APR-2 isolates were immobilized on Luffa aegyptiaca (sponge gourd) (an agro-waste as biosorbent). With 250 mM arsenic solution, Aspergillus spp APR-1 and APR-2 showed biosorption of 53.94 and 52.54%, respectively, on inductively coupled plasma-optical emission spectrometry analysis and the adsorption of the fungal isolates on sponge gourd was confirmed using scanning electron microscopy. APR-1 isolate was further characterized by 18 s rDNA typing and identified as Aspergillus niger. Industrial scale application perhaps is taken up using selected fungal strains and mitigates the arsenic pollution in urban sewage.

The Dying Water Heritage of Sarkhej Roza

Sarkhej Roza, a fifteenth century complex comprising of the mausoleum, mosque and cascade of natural and man-made lakes, and located in peri-urban Ahmedabad, Gujarat, India, is presently a heritage site of national importance under the Archaeological Survey of India (ASI). Originally, the Sarkhej lake was excavated to serve the religious purpose of ablution, recreation and climate conditioning that were quite functional until the late twentieth century before rapid urbanization in the catchment of its adjacent interconnected feeder Makarba lake took place. Unfettered development in the past two decades has encroached the common catchment of Makarba–Sarkhej lake cascade by almost 50 per cent. The then perennial sacred Sarkhej lake is now a drying sewage disposal site. Sarkhej Roza has received considerable attention for conserving built heritage aesthetically in the past. Since it is the duty of all stakeholders including ASI, Ahmedabad Municipal Corporation, Sarkhej Roza Committee, civil society and communities to work in harmony towards sustaining their natural heritage, this research has undertaken detailed site and stakeholder assessment to understand challenges faced by the lake and its precincts, and derived learnings from the stakeholder’s perspectives on the impact of urbanization on this water heritage. This was done in order to chart out the possibilities of reviving the Markarba–Sarkhej lake cascade before it is too late.

A review of potential factors contributing to epidemic cholera in Yemen.

The menace of cholera epidemic occurrence in Yemen was reported in early 2017. Recent reports revealed that an estimated 500,000 people are infected with cholera whereas 2,000 deaths have been reported in Yemen. Cholera is transmitted through contaminated water and food. Yemen is the least developed country among the Middle East countries in terms of wastewater and solid waste management. The population of Yemen is about 24.5 million and generates about 70-100 million m3 of sewage. An estimated 7% of the population has sewerage systems. It has been revealed that 31.2 million m3 of untreated sewage is used for irrigation purposes especially for vegetables and Khat trees. In addition, more than 70% of the population in Yemen has no potable water. They depend on water wells as a water source which are located close to sewage disposal sites. The present review focuses on the current status of water, wastewater as well as solid waste management in Yemen and their roles in the outbreak of cholera. Future prospects for waste management have been proposed.

Accumulation and persistence of sewage and fish cannery pollution in coastal sediments (northern Adriatic Sea)

The study was carried out in sediments exposed to three different types of sewage pollution: primary treated sewage waters, urban/fish cannery untreated effluents, and discharges from boats (harbors) to evaluate the level and sources of pollution and the relationships between organic contaminants and chemical-physical factors that affect their accumulation and persistence in sediments. For this purpose, the occurrence and distribution of sterols, fecal indicator bacteria, hydrocarbons, granulometry, and redox conditions in sediments were analyzed. Sediment cores were collected by scuba divers and redox potential was determined in situ by vertical penetration of Pt electrode. For determining the granulometric composition, samples were wet sieved through ASTM sieves. The fraction <0.063 mm was analyzed using the Sedigraph method of particle sizing. Fecal coliforms (FC) and fecal streptococci (FS) were determined using the multiple test tube most probable number method. Sterols (foremost: coprostanol COP; cholesterol CHL) and hydrocarbons (n-alkanes and polycyclic aromatic PAH) were analyzed by GC/MSD. Specific ratios and plots of sterols were used as diagnostic tools for sources and levels of sewage contamination. The occurrence and diagnostic ratios of n-alkanes and PAHs have been used to trace the pollution and origin of hydrocarbons. At the sewage disposal site, COP, FC, and FS correlated and decreased with distance from the outfall, being predominantly associated with the very fine sand fraction. The primary treatment of sewage waters was ineffective and fecal pollution was diagnosed in a radius of 300 m around the outfall. The grain size composition of surface sediments was altered in comparison to the deeper sediments. In the sediments within the reach of the fish cannery effluents, CHL predominated or paralleled β-sitosterol, the principal sterol in harbors. COP was not correlated to FC or FS. PAHs within the extent of spread of the fish cannery effluents were comparable to those in the harbor sediments, regardless of considerably lower traffic intensity. In all sediments, PAHs were of pyrogenic origin. At the sewage disposal site, the level of pollution and the alterations in the granulometric composition of surface sediments followed a pattern consistent with dominant current direction. Accumulation of organic matter around the outfalls created highly anoxic conditions that favored persistence of fecal pollution, in situ formation of COP, enhanced accumulation of PAHs, and/or prolonged survival of fecal bacteria in the sediment. The industrial outfall, even if smaller than the urban, affected the sediment similarly.

Pollutant Removal Efficiency of Hybrid Constructed Wetland System for Recycling the Sewage by Utilizing Aquatic Plants

The sewage waters are used as potential source of irrigation for raising vegetables and fodder crops around the sewage disposal sites. Soil contamination by sewage and industrial effluents has affected adversely both soil health and crop productivity. A study was conducted to evaluate the pollutant removal efficiency of lab scale hybrid constructed wetland system (HCWS) for recycling the sewage water for agriculture. Native aquatic plants viz., Brachiaria humidicola and Typha angustifolia were selected and utilized for the lab scale study. The results of this HCWS showed that removal efficiencies of BOD, COD was higher with the hydraulic retention time (HRT) of 5 days due to the combined effect of HF and VF by using the native aquatic plants like Brachiaria humidicola and Typha angustifolia.

The Use of Sodium to Calibrate the Transport Modeling of Water Pollution in Sandy Formations Around an Uninsulated Sewage Disposal Site

In the present paper we suggest a novel calibration method of the model for hydrodynamic and contaminant transport using the example of a sewage disposal site set up uninsulated in a sandy environment. With the hydrodynamic model we applied time-dependent model calculations in order to fit the individual hydrodynamic parameters. For the calibration of the transport model, sodium was chosen, which has a negligible retardation factor. We demonstrated that this approach is suitable for creating a model that provides calculated results comparable to the actually measured, experimental ones. The created model proved to be appropriate for use in the estimation of the maximal spatial extension of the contamination, which—in the case of the investigated sewage disposal site—was found to be 0.1 km2 in the near-surface (1–3 m deep) layers, whereas it was three times higher at a depth of 40–60 m.

Butyltin occurrence and risk assessment in the sediments of the Iberian Peninsula

The occurrence of butyltin (BT) compounds in more than 50 recent sediment samples of the Iberian Peninsula, collected in the harbours of the western Mediterranean Sea (Spain) and the North Atlantic Ocean (Portugal), including domestic and industrial sewage disposal sites, has been assessed. The highest levels of tributyltin (TBT) (7673 μg kg −1 dry wt.) were detected in commercial harbours associated with inputs from large vessels. However, relatively high TBT values (about 2150 μg kg −1 dry wt.) were also detected in fishing and recreational boating areas. Spanish marinas and harbours are more polluted in terms of TBT (5–7673 μg kg −1 dry wt.) compared to those in Portugal (4–12 μg kg −1 dry wt.). Generally, the Mediterranean sediments show a BT distribution characterized by the predominance of TBT over the degradation products dibutyl (DBT) and monobutyltin (MBT), indicating the presence of recent inputs, in contrast to the Portuguese coastal distribution. Calculation of butyltin degradation indexes (BDI) confirmed a different trend, depending on the area. Furthermore, a comparative study of the occurrence of BT in different sewage sludge disposal sites shows that domestic primary sewage sludge effluents can contribute to coastal BT pollution, but to a lesser extent when compared with harbours. Historical trends (1995–2003) for Barcelona harbour reveal that BT regulations on the use of TBT-based antifouling paints have not been fully effective. Finally, a comparison against the existing sediment quality guidelines (SQGs) indicated that acute toxic effects could only be expected for TBT in some Mediterranean harbours; conversely, in every North Atlantic Ocean station, a lesser environmental threat for the harbour benthic community is expected.

Groundwater Pollution of the Quaternary Aquifer in Northern United Arab Emirates

Natural conditions and human activities have caused serious quality degradation of the Quaternary aquifer in the north of the United Arab Emirates (UAE). The aquifer within Ajman City is unconfined, receiving limited recharge (12 542 m3/day) from the east and large pollutants flux (4,800 m3/day) from land surface. Field survey and laboratory analyses revealed anomalies in groundwater salinity (TDS), total hardness (TH), dissolved oxygen (DO), cations (Ca2+, Mg2+, Na+ and K+), anions (\({\text{HCO}}_3^ - \), \({\text{SO}}_4^{2 - } \), Cl− and \({\text{NO}}_3^ - \)) and trace elements (Fe, Pb, Cd and Cr), which can be correlated to point and non-point pollution sources. Concentrations of trace elements are more responsive to anthropogenic sources than natural ones. High Fe and Pb levels were measured close to the untreated sewage disposal site, while high Cd and Cr contents were observed near hospitals and clinics. Iso-concentration maps of salinity and major ions, in addition to hydrochemical profiles were used to define the seawater–groundwater interface in Ajman City. The potentiometric surface map of the Quaternary aquifer within the study area shows that groundwater flows from the east towards the Arabian Gulf in the west. The proposed landfill site is suitable because it lies within a topographic low, receiving groundwater flow from all directions.

Macrobenthic Distribution Patterns at a Sewage Disposal Site in the Inner Shelf off Mar del Plata (SW Atlantic)*

Abstract The inner shelf (5–15 m depth) off Mar del Plata (Argentina, Southwestern Atlantic) was studied to assess the influence of an intertidal sewage effluent on macrobenthic populations and to provide baseline information for a future monitoring program. Bottom samples were obtained with van Veen grabs at 49 stations. Macrobenthic organisms retained in a 0.5 mm mesh screen were used for biological analysis. Very fine sand-bottoms with a Natica–Owenia association occur in shallower sites, while patchy coarse sand bottoms plus gravel-sized shell debris inhabited by an association of patchy populations of Melita–Prionospio–Kalliapseudes–Caulleriella characterize the rest of the area. Low organic matter content in the area (from 0.78 to 2.05 %), and absence of any known indicator species (such as Prionospio spp.) in relation to distance to effluent, suggest that local benthic populations remain relatively undisturbed in spite of the heavy input of organic matter. The major factor contributing to this situ...

Organotin contamination in sediments from the Western Mediterranean enclosures following 10 years of TBT regulation

Organotin (OT) compounds, namely butyl and phenyl, were measured in 38 recent sediments collected in harbours of the Western Mediterranean Sea (Northern: 4 and Southern: 9) and domestic and industrial sewage disposal sites (Northern: 9 and Southern: 1). Butyltins were the predominant tin species identified as being tributyltin (TBT) widespread in the whole area which suggests recent inputs of OTs. The highest levels of TBT were detected in commercial harbours associated with inputs from large vessels (average value: 5.0 μg TBT g −1). Moreover, relatively high TBT values were also detected in fishing and recreational boating areas (average level ca. 1.0 μg TBT g −1). Phenyltin derivatives occurred at lower levels than butyltins being the monophenyltin the predominant compound (average values 45–945 ng g −1). The large predominance of the phenyltin degradation products (i.e. mono and diphenyltin) over the parent compound (i.e. triphenyltin) suggests that there are almost no recent inputs of these compounds. Furthermore, a comparative study of the OT occurrence in the sewage sludge disposal sites offshore Barcelona and Almerı́a (domestic) and into the Tarragona harbour (industrial) shows that domestic primary sewage sludge effluents can contribute to coastal OT pollution (244 ng TBT g −1). Nevertheless, sewage sludge is a secondary source of OT contamination in the coastal environment in comparison to commercial harbours. In a comparative study with previous data collected in the late 1980s, the present study reveals that OT regulations established in the Mediterranean region in 1991 on the use of TBT-based antifouling paints have been effective in marinas, but reveals a significant TBT contamination in commercial and fishing harbours.

Workshop discusses community models for coastal sediment transport

Numerical models of coastal sediment transport are increasingly used to address problems ranging from remediation of contaminated sediments, to siting of sewage outfalls and disposal sites, to evaluating impacts of coastal development. They are also used as a test bed for sediment‐transport algorithms, to provide realistic settings for biological and geochemical models, and for a variety of other research, both fundamental and applied. However, there are few full‐featured, publicly available coastal sediment‐transport models, and fewer still that are well tested and have been widely applied.This was the motivation for a workshop in Woods Hole, Massachusetts, on June 22–23, 2000, that explored the establishment of community models for coastal sediment‐transport processes.

Organic carbon cycling in abyssal benthic food chains: numerical simulations of bioenhancement by sewage sludge

The hypothetical bioenhancement of the endemic benthic biota on an oligotrophic abyssal plain by organic carbon has been investigated with mathematical simulation experiments. First, the responses of the biomass and respiration to seasonal variations in the rain of organic carbon (POC) have been simulated in a simplified benthic assemblage (sediment organic carbon, sediment-dwelling heterotrophs (bacteria, meiofauna, macrofauna and detritus feeding megafauna) and predatory megafauna), with no added organic matter. These calculations were based on measured standing stocks and respiration in the central North Pacific (5.8 km depth, 31°N Lat.×159°W Long.). The dynamic relationships in this natural "oligotrophic" food chain were then subjected to added inputs of organic carbon presumed to be in sewage sludge. Two examples are presented: a modest but continuous input of organic carbon (100 mg C m −2 d −1) and a year-long pulse of the same intensity. The continuous input forced the biomass and community respiration to steadily increase until they reached steady state in 15 years at values similar to those found on a typical continental shelf. The pulse exhibited the same pattern, but biomass and respiration returned to levels found under natural oligotrophic conditions several years after cessation of intensified carbon loading. The responses of the sediment community to added organic matter were validated using information from a deep-ocean sewage disposal site (DWD106) off the coast of New Jersey. The models are also used to illustrate an approach for estimating possible transfers of potentially toxic contaminants, such as total polycyclic aromatic hydrocarbons (tPAHs), in lipid-rich eggs. In the future it will be necessary to validate model results with deep-ocean in situ experiments.

Spatial distribution, vertical profiles and budget of organochlorine compounds in Western Mediterranean seawater

Individual PCB congeners (IUPAC Nos. 28, 52, 44, 70, 101, 118, 153, 138, 187, 128, 180, and 170), hexachlorocyclohexanes (HCHs) and dichlorodiphenylethanes (DDTs) were determined in 15 samples of suspended particulate matter (> 0.7 μm) (SPM) collected in the Catalan Sea and the Gulf of Lions. Furthermore, 6 vertical profiles were sampled at the Ebro and Rhoˆne River mouths, Sicilian and Gibraltar Straits, off-shore Barcelona and in the open sea. Finally, 6 dissolved phase samples from the Catalan Sea were taken and analysed. The highest PCB and DDT concentrations were detected offshore Valencia (26 and 2.8 pg l−1, respectively). Other sources of pollution were identified at the Ebro transect. Spatial variability shows an enrichment of organochlorine compounds (OCs) in a thermohaline front located midway between the Iberian Peninsula and the Balearic Islands. Vertical profiles of OCs in the SPM show for the first time, a surface enrichment pattern exhibiting concentration maxima in phyto- and zooplankton zones and declining OC concentrations with depth, except nearby sewage disposal sites offshore from Barcelona. Concentrations of PCBs (28–63 pg l−1) and DDTs (0.8–4.3 pg l−1) in the dissolved phase were one order of magnitude higher than in the corresponding particulate phase (1.7–16.6 and 0.16–0.98 pg l−1, respectively). Residence times of the SPM were estimated at every depositional area ranging from 1.46 to 8.05 years for PCBs and from 0.46 to 1.32 years for DDTs. Concurrently, sedimentation rates of SPM ranged from 0.37 to 0.78 m d−1 for PCBs and 1.18 to 4.68 m d−1 for DDTs. The PCB budget in the seawater of the western Mediterranean was computed using a three ☐ model accounting for 2.4 and 14.1 t in the particulate and dissolved phases, respectively. The DDTs budget was estimated to be ca. 179 and 717 kg in the particulate and dissolved phases respectively. Finally, the input of PCBs through the Gibraltar and the output through Sicilian Straits amounted for 1.5 and 1.3 t y−1, respectively. Concurrently the corresponding input and output for PCBs were 92 and 82 kg y−1 through Gibraltar and Sicilian Straits, respectively.

Immobilization of heavy metals in a polluted soil of a sewage farm by application of a modified aluminosilicate: a laboratory and numerical displacement study

The efficiency of the modified alumino-silicate “Berengite” to fix heavy metals in contaminated soils was studied using a soil from a former sewage disposal site with high loads of Zn and Cd. The immobilization effects for different additions of Berengite were described on the laboratory scale with the cation exchange capacity and a two component Freundlich sorption isotherm. Long term displacement of Cd and Zn were calculated with a numerical simulation model. The simulation studies show a rather high immobilization of Zn and Cd in the solid phase for the next 80 years. Far more Berengite is required for the fixation of Cd than for Zn.

Near-Bottom Pelagic Bacteria at a Deep-Water Sewage Sludge Disposal Site

The epibenthic bacterial community at deep-ocean sewage sludge disposal site DWD-106, located approximately 106 miles (ca. 196 km) off the coast of New Jersey, was assessed for changes associated with the introduction of large amounts of sewage sludge. Mixed cultures and bacterial isolates obtained from water overlying sediment core samples collected at the deep-water (2,500 m) municipal sewage disposal site were tested for the ability to grow under in situ conditions of temperature and pressure. The responses of cultures collected at a DWD-106 station heavily impacted by sewage sludge were compared with those of samples collected from a station at the same depth which was not contaminated by sewage sludge. Significant differences were observed in the ability of mixed bacterial cultures and isolates from the two sites to grow under deep-sea pressure and temperature conditions. The levels of sludge contamination were established by enumerating Clostridium perfringens, a sewage indicator bacterium, in sediment samples from the two sites. The results of hybridization experiments in which DNAs extracted directly from the water overlying sediment core samples were used indicate that the reference site epibenthic community, the disposal site epibenthic community, and the community in a surface sludge plume share many members. Decreased culturability of reference site mixed cultures in the presence of sewage sludge was observed. Thus, the culturable portions of both the autochthonous and allochthonous bacterial communities at the disposal site may be inhibited in situ, the former by sewage sludge and the latter by high pressure and low temperature.

Effects of sewage disposal into the White Nile on the plankton community

Twenty water samples and 30 plankton samples were taken from the sewage disposal site (El Lamab, south of Khartoum), from 250 m upstream and 250 m downstream during January–March, 1987 and Februar–April, 1988. The water samples were examined for physical and chemical characteristics. Plankton samples were examined for species composition and relative abundance of phytoplankton and zooplankton.

A study of metal concentrations in relation to gill color and pathology in the rock crab

Gills of adult rock crabs,Cancer irroratus Say, collected near a sewage disposal site in the New York Bight apex were analyzed for copper, lead, cadmium, and silver. One gill from each animal was processed for histologic study to document pathological conditions within the tissues, and the presence or absence of fouling organisms on gill surfaces. Comparisons are made between metal concentrations in rock crab gills and published data on crustaceans from other locations.