Municipal Sewage Effluent Research Articles

The effects of a primary-treated municipal effluent on the immune system of rainbow trout ( Oncorhynchus mykiss): Exposure duration and contribution of suspended particles

Municipal sewage effluents are complex mixtures of contaminants known to disrupt both immune and endocrine functions in aquatic organisms. The present study sought to determine the impacts of municipal effluent on the immune systems of juvenile rainbow trout ( Oncorhynchus mykiss), by exposing specimens to low concentrations (0.01%, 0.1%, 1% or 10%) of sewage effluent for periods of 28 or 90 days. The soluble and insoluble fractions of the effluent were also studied to assess the contribution of fractions rich in microorganisms and particles on fish immune systems. To this end, the trout were also exposed to soluble and insoluble fractions of the effluent for a period of 28 days. Immunocompetence was assessed by the following three parameters: phagocytosis, natural cytotoxic cells (NCC) and blastogenesis of lymphocytes under mitogen stimulation. Fish exposed to the 1% sewage effluent concentration for 28 days had enhanced phagocytic activity; at 90 days, phagocytic activity was reduced. T and B lymphocyte proliferation in fish from both groups was similarly stimulated. Phagocytosis and NCC activities were influenced more by the insoluble fraction than the soluble fraction of the effluent. Conversely, mitogen-stimulated T lymphocyte proliferation was enhanced in cells of fish exposed to the soluble fraction of the effluents, with a dampening effect on the insoluble (particulate) fraction of the effluent. In conclusion, the effects of the effluent and its fractions were higher at the cellular-mediated immunity level than at the acquired immunity level. Immunotoxicity data on the soluble fraction of the effluent were more closely associated to data on the unfractionated effluent, but the contribution of the particulate fraction could not be completely ignored for phagocytosis and B lymphocyte proliferation.

Effects of ozone, ultraviolet and peracetic acid disinfection of a primary-treated municipal effluent on the Immune system of rainbow trout ( Oncorhynchus mykiss)

Municipal sewage effluents are complex mixtures that are known to compromise the health condition of aquatic organisms. The aim of this study was to evaluate the impacts of various wastewater disinfection processes on the immune system of juvenile rainbow trout ( Oncorhynchus mykiss). The trout were exposed to a primary-treated effluent for 28 days before and after one of each of the following treatments: ultraviolet (UV) radiation, ozonation and peracetic acid. Immune function was characterized in leucocytes from the anterior head kidney by the following three parameters: phagocytosis activity, natural cytotoxic cells (NCC) function and lymphocyte (B and T) proliferation assays. The results show that the fish mass to length ratio was significantly decreased for the primary-treated and all three disinfection processes. Exposure to the primary-treated effluent led to a significant increase in macrophage-related phagocytosis; the addition of a disinfection step was effective in removing this effect. Both unstimulated and mitogen-stimulated T lymphocyte proliferation in fish decreased dramatically in fish exposed to the ozonated effluent compared to fish exposed to either the primary-treated effluent or to aquarium water. Stimulation of T lymphocytes proliferation was observed with the peracetic acid treatment group. In conclusion, the disinfection strategy used can modify the immune system in fish at the level of T lymphocyte proliferation but was effective to remove the effects on phagocytosis activity.

Anti-androgenic effects of sewage treatment plant effluents in the prosobranch gastropod Nucella lapillus

Recent studies performed under laboratory conditions have shown that single exposure to high levels of several xenoestrogens is able to induce imposex in at least two neogastropod species. In an attempt to evaluate if xenoestrogens, at environmentally relevant conditions, do contribute to imposex induction, we have tested the effects of a mixture containing xenoestrogens (municipal sewage effluents) on imposex development in the dogwhelk Nucella lapillus. Exposure for 3 months to the raw (0.25% and 1%) and the final sewage effluent (12.5% and 50%) rendered no increase in the severity of imposex. Conversely, as exposure to high concentrations of natural steroids, estradiol and estrone, had previously been shown to partially rescue imposex development under laboratory conditions, we have also tested if exposure to the final sewage effluent could ameliorated the severity of imposex induction by tributyltin (TBT). The results demonstrated that co-exposure to the final sewage effluent leads to a decrease trend in the severity of imposex in the presence of TBT. Within the studied imposex parameters, the Relative Penis Size index (RPSI) was the most affected with a 50% decrease in the effluent 12.5% plus TBT exposed group and 25% decrease in the effluent 50% plus TBT, if compared with the TBT alone. Overall, our results give further support to the use of imposex in N. lapillus as a specific biomarker of TBT contamination. However, in areas of high inputs of sewage effluents, the assessment of TBT contamination by the use of the imposex phenomenon should ideally also include data on the tissue levels of butyltins.

Occurrence of residues of the veterinary drug crystal (gentian) violet in wild eels caught downstream from municipal sewage treatment plants

Environmental context. Crystal violet (CV), also known as gentian violet, is a triphenylmethane dye used as a veterinary drug for the treatment of ornamental fish infected with the parasitic protozoa Ichthyophthirius multifiliis. CV is a suspected carcinogen not registered for use with food-producing animals in the European Union, Australia, the US and some other countries. The results from this study now demonstrate that residues of leuco CV, the main metabolite of CV, may occur as an organic contaminant in samples of wild eels caused by discharges of municipal sewage effluents. Abstract. Crystal violet (CV) and leucocrystal violet (LCV) were found in the tissues of wild eels caught from surface waters under the influence of effluents discharged by municipal sewage treatment plants (STPs). LCV was the dominant residue detected with total concentrations up to 6.7 μg kg–1 fresh weight in tissues of eels caught from lakes, rivers and a canal in Berlin, Germany. The occurrence of the residues found in 35 out of 45 samples could directly be linked to the presence of discharges by municipal STPs into the receiving surface waters. CV is a multiple-use compound that is also used as a biological stain and to colour materials such as textiles, paints and printing inks. Thus, it seems very likely that the residues of CV found in the eel samples originate from such uses and from legal uses of CV as a veterinary drug for the treatment of ornamental fish. The results obtained from this study are the first report of background contamination by CV found in samples of fish not intentionally treated with this agent. Although the residues of CV and LCV measured in the tissues of the eels were very low, an oral exposure to residues of CV or LCV should be avoided with regard to their mutagenic and carcinogenic potential. According to European Union law, zero tolerance applies to all residues of CV and LCV found in food for human consumption, as CV is not registered for use as a veterinary drug.

Assessing effects of a mining and municipal sewage effluent mixture on fathead minnow ( Pimephales promelas) reproduction using a novel, field-based trophic-transfer artificial stream

The Junction Creek watershed, located in Sudbury, ON, Canada receives effluent from three metal mine wastewater treatment plants, as well as a municipal wastewater (MWW) discharge. Effects on fish have been documented within the creek (decreased egg size and increased metal body burdens). It has been difficult to identify the cause of the effects observed due to the confounded nature of the creek. The objectives of this investigation were to assess the: (1) effects of a mine effluent and municipal wastewater (CCMWW) mixture on fathead minnow (FHM; Pimephales promelas) reproduction in an on-site artificial stream and (2) importance of food ( Chironomus tentans) as a source of exposure using a trophic-transfer system. Exposures to CCMWW through the water significantly decreased egg production and spawning events. Exposure through food and water using the trophic-transfer system significantly increased egg production and spawning events. Embryos produced in the trophic-transfer system showed similar hatching success but increased incidence and severity of deformities after CCMWW exposure. We concluded that effects of CCMWW on FHM were more apparent when exposed through the water. Exposure through food and water may have reduced effluent toxicity, possibly due to increased nutrients and organic matter, which may have reduced metal bioavailability. More detailed examination of metal concentrations in the sediment, water column, prey ( C. tentans) and FHM tissues is recommended to better understand the toxicokinetics of potential causative compounds within the different aquatic compartments when conducting exposures through different pathways.

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (δ18O and δ2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have δ18O and δ2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (δ15N–NO3) values above 10 ‰ in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (δ15N–NO3 = 4.6–4.9 ‰), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N,N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil’s Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin.

Enrichment and fractionation of heavy metals in bed sediments of River Narmada, India

A metal fractionation study on bed sediments of River Narmada in Central India has been carried out to examine the enrichment and partitioning of different metal species between five geochemical phases (exchangeable fraction, carbonate fraction, Fe/Mn oxide fraction, organic fraction and residual fraction). The river receives toxic substances through a large number of tributaries and drains flowing in the catchment of the river. The toxic substances of particular interest are heavy metals derived from urban runoff as well as municipal sewage and industrial effluents. Heavy metals entering the river get adsorbed onto the suspended sediments, which in due course of time settle down in the bottom of the river. In this study fractionation of metal ions has been carried out with the objective to determine the eco-toxic potential of metal ions. Although, in most cases (except iron) the average trace/heavy metal concentrations in sediments were higher than the standard shale values, the risk assessment code as applied to the present study reveals that only about 1-3% of manganese, <1% of copper, 16-19% of nickel, 4-20% of chromium, 1-4% of lead, 8-13% of cadmium and 1-3% of zinc exist in exchangeable fraction and therefore falls under low to medium risk category. According to the Geo-accumulation Index (GAI), cadmium shows high accumulation in the river sediments, rest of other metals are under unpolluted to moderately polluted class.

Effects of Montreal municipal sewage effluents on immune responses of juvenile female rainbow trout ( Oncorhynchus mykiss)

The objective of this study was to examine the immunotoxicity of treated Montreal sewage effluents on juvenile female rainbow trout ( Oncorhynchus mykiss). A comprehensive panel of immunological assays was used to evaluate the effects of exposure for 1 and 4 weeks to 1, 3, 10 and 20% sewage effluent. Phagocytic ingestion of fluorescent latex beads by head kidney macrophages and granulocytes was suppressed following 1-week of exposure, with the highest exposure concentration being the most suppressive. Phagocytic activity returned to control levels after 4 weeks of exposure. The cytotoxic activity of head kidney derived non-specific cytotoxic cells was enhanced after a 1-week exposure, especially at the lowest exposure concentration, and returned to control levels after 4 weeks of exposure. In vitro lymphocyte proliferation in response to LPS and ConA activation was not affected following sewage effluent exposure, but nonactivated, spontaneous proliferation of lymphocytes was suppressed in a dose-dependent manner after 4 weeks of exposure. Plasma lysozyme activity was elevated at lowest exposure concentration after 4 weeks. No changes were noted in either the blood leukocyte/erythrocyte ratio or in the proportion of circulating lymphocytes and thrombocytes. The proportion of circulating granulocytes increased following exposure for 4 weeks to the low effluent concentration. Plasma cortisol levels were not affected by effluent exposure suggesting that mechanisms other than stress influenced the observed immunomodulation. In summary, this study demonstrates that sewage effluent can alter the immune functions of rainbow trout.

Metal Fractionation Study on Bed Sediments of Lake Nainital, Uttaranchal, India

Lake Nainital in the heart of Nainital Town in the State of Uttaranchal (India) receives toxic substances through various open drains through the catchment of the lake. The toxic substances of particular interest are heavy metals derived from urban runoff as well as municipal sewage and industrial effluents. Heavy metals entering the lake get adsorbed onto the suspended sediments, which in turn settle down in the bottom of the lake. In this study fractionation of metal ions has been studied on the bed sediments of lake Nainital with the objective to determine the eco-toxic potential of metal ions. Comparison of sediments with average shae values indicated anthropogenic enrichment with nickel, lead, cadmium and zinc. The risk assessment code as applied to the present study reveals that 4-13% of manganese, 4-8% of copper, 17-24% of nickel, 3-5% of chromium, 13-26% of lead, 14-23% of cadmium and 2-3% of zinc exist in exchangeable fraction and therefore comes under low to medium risk category and may enter into food chain. The association of these metals with exchangeable fraction may cause deleterious effects to aquatic life. The present database will help in formulating guidelines for carrying out dredging operations and/or restoration programmes in the Nainital lake.

Effect of municipal sewage effluent on soil and crops cultivated on a hyper-arid zone sandy soil

The effects of sewage effluent from Sebha Municipal Area in the Fezzan region of Libya on certain physicochemical properties of a hyper-arid zone sandy soil and growth of two plants were studied. The soil had been treated daily with 25, 50, 75 and 100% effluent; and barley (Hordeum vulgare) and broad beans (Vicia faba) had been grown on the soils in pots. Soil samples were analysed for water-soluble salts, electrical conductivity, cation exchange capacity, pH, organic matter, sodium, potassium and phosphorus. At all the concentrations of effluent used there was a significant increase in all the soil properties tested. The greatest changes were observed with 100% effluent. The soils supporting crops were found to have lower concentrations of nutrients than those without crops. There was an increase in dry matter production by plants grown in effluent treated soils. The results indicate that sewage effluent could be considered as one of the possible and alternate sources of irrigation water.

Influence of Drought and Municipal Sewage Effluents on the Baseflow Water Chemistry of an Upper Piedmont River

The Reedy River in South Carolina is affected by the urban area of Greenville, the third most populous city in the state, and by the effluents from two large-scale municipal wastewater treatment plants (WWTPs) located on the river. Riverine water chemistry was characterized using grab samples collected annually under spring season baseflow conditions. During the 4-year time period associated with this study, climatic variations included two severe drought spring seasons (2001 and 2002), one above-normal precipitation spring season (2003), and one below-normal precipitation spring season (2004). The influence of drought and human activities on the baseflow chemistry of the river was evaluated by comparing concentrations of dissolved anions, total metals, and other important water chemistry parameters for these different years. Concentrations of copper and zinc, common non-point source contaminants related to urban activities, were not substantially elevated in the river within the urban area under baseflow conditions when compared with headwater and tributary samples. In contrast, nitrate concentrations increased from 1.2-1.6 mg/l up to 2.6-2.9 mg/l through the urban stream reach. Concentrations of other major anions (e.g., sulfate, nitrate) also increased along the reach, suggesting that the river receives continuous inputs of these species from within the urban area. The highest concentrations of major cations and anions typically were observed immediately downstream from the two WWTP effluent discharge locations. Attenuation of nitrate downstream from the WWTPs did not always track chloride changes, suggesting that nitrate concentrations were being controlled by biochemical processes in addition to physical processes. The relative trends in decreasing nitrate concentrations with downstream distance appeared to depend on drought versus non-drought conditions, with biological processes presumably serving as a more important control during non-drought spring seasons.

Determination of the androgenic potency of whole effluents using mosquitofish and trout bioassays

This study combined bioassay-derived and direct chemical analysis of steroidal compounds in pulp and paper and municipal sewage effluent in order to determine the cause of masculinization of female mosquitofish. The bioassays used in this study consisted of androgen and estrogen receptor binding, and aromatase inhibition using tissues from rainbow trout. This study observed no masculinization of female mosquitofish from a pulp and paper mill effluent that was previously observed to cause this effect. Mosquitofish sampled from the receiving environment of the same mill verified that masculinization was not occurring in the wild. The municipal sewage effluent also had no masculinizing effect. In vitro bioassays indicated significant sources of both androgens and estrogens in the effluents tested with sewage effluent having both the highest estradiol (41 ng/L) and testosterone (182 ng/L) equivalent concentration. These results could not be attributed to any particular compounds measured in the effluents. Two compounds implicated in the masculinization of mosquitofish by pulp and paper effluent, androstenedione and androstadienedione required relatively large (10–100 μg/L) waterborne concentrations to elicit a masculinizing effect and neither of these compounds are likely to occur at levels this high in the natural environment. The potent aromatase inhibitor, 4-hydroxyandrostenedione also did not cause masculinization at 100 μg/L indicating that masculinization did not occur through this mechanism. The mammalian anti-androgen, cyproterone acetate was only partially effective in mosquitofish and reduced the severity of masculinization in the presence of methyl testosterone. While neither effluent masculinized mosquitofish, there was a significant reduction of in vitro ovarian steroid production with the most severe effects observed with the sewage effluent. Overall, this study found the disappearance of a masculinizing effect that had been previously observed; concluded that based on 21 days aqueous exposures androstenedione and androstadienedione are not likely candidates for mosquitofish masculinization, and showed that masculinization and in vitro steroid production are unrelated biological endpoints.

Phosphorus uptake by cattail plants in a laboratory-scale experiment related to constructed treatment wetlands

This paper describes a laboratory-scale study of phosphorus (P) uptake by broad-leaf cattail plants (Typha latifolia) growing in gravel substrate. The cattails were fed synthetic wastewater at P concentrations representative of primary and secondary municipal sewage effluent. Phosphorus uptake to the upper and lower portions of the cattail plants, adsorption to the gravel substrate, and the pore water concentration were measured over a simulated growing season. The objective was to quantify the mass of phosphorus accumulated in each compartment as the growing season progressed. The experimental results show that the partitioning of P between the upper and lower portions of the plants varied throughout the simulated growing season. At the end of the season uptake by cattails had removed about 40% and 45% of the P mass input under the primary and secondary effluent conditions, respectively. Adsorption of P to the gravel substrate and other fine sediments removed about 43% and 56% of the P mass input under the primary and secondary effluent conditions, respectively. The results provide insight into the potential timing and effectiveness of cattail harvesting for removal of P from constructed treatment wetland systems. Key words: constructed treatment wetland, cattail (Typha latifolia), laboratory-scale study, phosphorus removal, phosphorus uptake, phosphorus adsorption, phosphorus mass balance.

Incidence of Mentum Deformities in Midge Larvae (Diptera:Chironomidae) from Northern Nova Scotia, Canada

Deformities in the mouthparts of larval Chironomidae, particularly of the teeth on the mentum, have been proposed as a bioindicator of sediment quality and environmental stress. Most work to date has concentrated on relatively few abundant, responsive genera common in soft-bottom lakes. We examined mentum deformities in 25 genera of Chironominae, Orthocladiinae and Diamesinae (one genus) from streams and a lake in rural Nova Scotia where farming and forestry are the principal land uses. Incidence of deformity at similar stream sites varied across genera from zero to >10%. Average frequencies of deformity across all three subfamilies at sites with no known sources of contamination ranged from <4% to 8%, and increased to nearly 15% at a site receiving treated municipal sewage effluent. Differences in chironomid community structure and rates of leaf litter decomposition above and below the sewage effluent outfall were congruent with the difference in mentum deformities. Frequencies of deformity observed here are an order of magnitude greater than in similar studies of rural areas. Low-level stress from agriculture or forest harvesting may be widespread in rural regions even in aquatic ecosystems that are seemingly free of industrial discharges or sediment contamination.

Northern Rivers Ecosystem Initiative: Distribution and Effects of Contaminants

In response to a number of recommendations following the Northern Rivers Basin Studies (NRBS) contaminant program, the Northern Rivers Ecosystem Initiative (NREI) focused considerable attention on assessing contaminants from specific sources including pulp mill effluents, atmospheric transport of mercury and the Alberta oil sands operations. NRBS identified a number of major contaminants of concern including polychlorinated biphenyls, dioxins and furans, mercury and various hydrocarbons. Together, the NRBS and the NREI studies have demonstrated major declines in the levels of dioxins and furans over the last decade as pulp and paper mills have changed their process and treatment strategies in response to new Federal regulations. Polychlorinated biphenyls however, continue to be a concern for the region as their levels have not declined in fish and sediments over the course of these studies. Higher levels in sediments downstream of Grande Prairie and Hinton were identified, but the source of these contaminants remains unknown. Chlorinated pesticides were also investigated, and although toxaphene, DDT and other chlorinated organic pesticides were detected in fish tissue, they were present at very low levels. Studies on the oil sands industry in northern Alberta demonstrated limited impacts on the Athabasca River to date, although studies did identify slight to moderate impacts of natural oil seeps on fish and benthic communities in tributary streams. NREI studies also identified endocrine active compounds in the three pulp and paper mill effluents tested, but endocrine disruptive effects in wild fish were minimal. Municipal sewage effluents also contain endocrine active compounds and it is recommended that monitoring continue around these point sources.

Anal Fin Morphology and Gonadal Histopathology in Mosquitofish (Gambusia holbrooki) Exposed to Treated Municipal Sewage Effluent

Feral mosquitofish living in undiluted treated municipal sewage in Queensland, Australia, were examined for morphologic abnormalities indicative of reproductive dysfunction. Male and female mosquitofish were captured at two sites receiving undiluted treated sewage and compared with those captured at a reference site. Several morphologic end points were examined, including length of the fourth and sixth anal fin rays and gonadal histology. Both male and female mosquitofish at one site exhibited minor elongation of the fourth anal fin ray consistent with exposure to androgenic stimulation, although the spatial extent of the effect was limited and not significant at other sites further downstream. No incidences of intersex were found. These findings suggest that the level of treatment of domestic sewage at the two sewage treatment plants assessed is adequate to prevent reproductive abnormalities in exposed mosquitofish populations.

Role of aquifer storage in water reuse

Two case studies are described that explain the role, value, limitations and policy requirements for storing reclaimed water in aquifers for indirect reuse. The first case involves aquifer storage and recovery of water, the product of tertiary treated municipal sewage effluent, via a single injection and recovery well at Bolivar, South Australia. The recovered water, like the source water for injection, is used for unrestricted irrigation of horticulture. A limestone aquifer at a depth of 100 to 160 m confined by clay and containing brackish groundwater provides the storage zone. In the second case, located at Alice Springs, trials are proceeding to assist in the design and establishment of a soil–aquifer treatment system which will allow water derived from secondary treatment of municipal sewage effluent to be stored in an unconfined alluvial aquifer for irrigation of horticulture. Intermittent infiltration from basins provides supplementary water treatment. In each case, the motivations, choice of methods, required investigations, public consultation processes, and economics of subsurface storage are presented. The lessons learned that may assist with development of policies to facilitate environmentally sustainable subsurface storage of water in water reuse projects are discussed.

Accumulation of Hormonally Active Substances by Wild White Sucker (Catostomus commersoni) Exposed to Effluents Discharged to the Wabigoon River

Abstract A study was initiated in the spring of 2001 to determine if hormonally active chemicals are bioavailable to white sucker (Catostomus commersoni) residing in the Wabigoon River, downstream of the bleached kraft pulp mill and municipal sewage outfall located in Dryden, Ontario. Females collected during spawning migrations in May 2001 at a near-field exposure site exhibited increased condition factor, liver size and fecundity relative to those collected from a reference site. Liver samples within each site were pooled, soxhlet extracted and fractionated by gel permeation chromatography and HPLC according to octanol/water partition coefficient (Kow). Fractions were then tested to determine if fish accumulated ligands which bind to the goldfish testicular androgen receptor (AR) and sex steroid binding protein (SSBP). The levels of hormonally active substances were low in males whereas females had accumulated significant amounts of several chemicals capable of binding to the hormone receptors. The levels of ligands detected in pulp mill effluent samples were substantially reduced after secondary treatment. Fractionation of final effluent extracts showed only ligands for the AR in the hydrophobic region (log Kow &amp;gt;5), which corresponded to the activities detected in fish tissues from both sexes. It can be concluded that ligands for fish sex steroid receptors are present in final effluent after treatment at the pulp mill and chemicals with the same Kow are bioavailable to fish under spring freshet conditions. Further work at this site is necessary to determine the contribution of pulp mill and municipal sewage effluents to the physiological performance of fish in the Wabigoon River and to their burden of accumulated compounds.

Contribution of effluents from hospitals and private households to the total loads of diclofenac and carbamazepine in municipal sewage effluents—modeling versus measurements

The anti-epileptic drug carbamazepine and the non-steroidal anti-inflammatory drug diclofenac are frequently found as residues in the aquatic environment and also in samples of ground and drinking water. For both compounds, their loads occurring in the effluents from a military hospital and in the combined (household and hospital) sewage of a sewage pumping station (SPS) and a large municipal sewage treatment plant (STP) were predicted and measured within a field trial by collecting and analyzing defined composite samples over a time period of 1 week. The use of pharmacokinetic data and precise information on the administration of the individual medicinal formulation was found to be essential for the validity of the predicted data. The measured data confirmed the validity of the predicted loads with recoveries between 63 and 102% for carbamazepine and around 35% for diclofenac in the hospital wastewater. A comparison of the weekly loads predicted and measured in the influents and effluents of a STP in Berlin (Germany) yielded a very low removal rate for diclofenac (less than 15%) and a removal rate of up to 40% for carbamazepine. In total, 2.0 kg of carbamazepine per week (105 kg/a) and 4.4 kg of diclofenac per week (226 kg/a) were discharged into Berlin's surface water by the municipal STP, which treats both household sewage from approximately one million inhabitants and large amounts of hospital effluents (approximately 12,060 hospital beds).

Sex and low-level sampling stress modify the impacts of sewage effluent on the rainbow trout ( Oncorhynchus mykiss) immune system

The objective of the present study was to investigate the influence of chronic exposure to municipal sewage treatment effluent at environmentally relevant concentrations on immune parameters in rainbow trout ( Oncorhynchus mykiss), including the assessment of potential differences in reactivity between sexually mature male and female fish. Trout were exposed to 1.5 and 15% (v/v) secondary treated municipal sewage effluent for 32 weeks. Fish were injected intra-peritoneally either with inactivated Aeromonas salmonicida to simulate an infection or with PBS as control for this immune challenge 6 weeks prior to sampling. Exposure to effluent resulted in a decrease in A. salmonicida-specific serum antibody level and blood lymphocyte numbers in mature females, but not in male fish. Injection of A. salmonicida resulted in enhanced serum lysozyme activity in mature male trout, which were not exposed to effluent. This stimulating effect of A. salmonicida could not be found in effluent-exposed trout, again potentially revealing a suppressive effect of the effluent. An influence of sampling fish on two consecutive days was observed in many immune parameters, most likely reflecting handling stress. Leucocyte and lymphocyte numbers in peripheral blood were consistently lower in male and female fish on the second sampling day. Phagocytosis in head kidney macrophages from male trout was also influenced by sampling day, whereby a stimulation of this reaction occurred on the second day of sampling. Liver mixed function oxygenase activity was found to be enhanced in mature male trout exposed to 15% effluent. In conclusion, the study showed, that exposure to sewage treatment plant effluent, in surface water relevant concentrations, can lead to potentially adverse effects on selected immune reactions in rainbow trout. However, this study also demonstrated that both handling stress and the sex of mature fish have distinct influences on the immune response detected in male and female fish and are likely to influence measured immune parameters to the extent that subtle effluent induced changes may be difficult to detect.