Effluent Discharge Point Research Articles

Analysis of Urban Stream Water with Effluent Discharge in the West Region of Mato Grosso

Between January 9 and 11, 2024, an expedition was conducted across 12 municipalities in the western region of Mato Grosso to assess the water quality of urban streams receiving domestic effluents. For this purpose, the Water Quality Index (WQI) and a Rapid Assessment Protocol (RAP) were used to analyze water pollution and anthropogenic impacts surrounding these watercourses. One water body was selected per municipality. Water samples were collected downstream of the effluent discharge point for both physicochemical and microbiological analyses. Results indicated that some surface water sources were classified as altered or impacted due to the presence of sewage and vegetation cover removal. Variables such as fecal coliforms and phosphorus exceeded legal limits. Additionally, nine municipalities were classified with a poor WQI level. Municipalities with less efficient effluent management exhibited worse water quality. The study concluded that the region faces serious challenges in effluent management and water conservation. The need for investment in sanitation infrastructure and environmental management is highlighted to mitigate negative impacts, protect public health, and preserve local biodiversity.

Environmental Impact of Cassava Processing Waste on Soil Quality in Benue South, Nigeria

Cassava processing plays a critical role in Nigeria’s agricultural sector, but it generates substantial waste that poses environmental risks, particularly to soil quality. This study investigates the environmental impact of cassava processing waste on soil quality in Benue South, Nigeria, focusing on the accumulation of cyanide, heavy metals, phosphates, and nitrates. The study was conducted across three Local Government Areas—Otukpo, Ohimini, and Okpokwu—using soil samples collected at varying depths from cassava processing effluent discharge points. Analytical methods included colorimetry for cyanide detection and atomic absorption spectroscopy for heavy metal analysis. The findings reveal significant contamination by heavy metals, particularly lead, and elevated cyanide levels near processing sites, highlighting the adverse effects of cassava waste on soil health. Phosphate and nitrate concentrations were also assessed, indicating potential risks to soil fertility and groundwater quality. The results underscore the urgent need for improved waste management practices in cassava processing communities to mitigate environmental degradation. This research contributes valuable baseline data for future interventions aimed at promoting sustainable cassava processing and waste utilization, with potential benefits for both environmental health and rural economies.

Impacts of fish pond effluent on the water quality of an afrotropical stream: a comprehensive evaluation using the water quality index

This study highlights the importance of managing fishpond effluent to minimize its impact on aquatic environments. Fish effluents are a major concern worldwide in aquatic environments. It also provides information on the impacts of effluents on the water quality index of streams when released into aquatic environments. Streams and fishponds were sampled bimonthly for two annual cycles, covering different sampling stations both upstream and downstream of the fishpond effluents at 50-m intervals. Water quality parameters associated with in situ conditions were determined in the field. In the laboratory, other physicochemical parameters were determined via proper standard protocols. The results of the study revealed that water quality parameters such as turbidity, total suspended solids, total solids, conductivity, total dissolved solids, dissolved oxygen, biological oxygen demand and organic matter recorded in water samples collected from 50 m upstream at the point of effluent discharge were significantly (p < 0.05) different from those recorded at other sampling stations. The WQI value of the discharge point was higher than the WQI recorded in both the upstream and downstream sections of the stream. The findings of this study showed that the point of discharge of fishpond effluents is particularly concerning for the receiving stream compared with other sampling points. This localized area has experienced marked deterioration in water quality, posing significant threats to the health and biodiversity of aquatic ecosystems. The effluent's impact, though slight when dispersed in the receiving waterbody, underscores the necessity for adequate management practices to mitigate its adverse effects. Effective strategies, including regular monitoring, effluent treatment, and sustainable pond management, are imperative to ensure the long-term health and resilience of the aquatic environment.

Occurrence of emerging contaminants in three river basins impacted by wastewater treatment plant effluents: Spatio-seasonal patterns and environmental risk assessment

The concern on the fate and distribution of contaminants of emerging concern (CECs) is a burning topic due to their widespread occurrence and potential harmful effects. Particularly, antibiotics have received great attention due to their implications in antimicrobial resistance occurrence. The impact of wastewater treatment plants (WWTP) is remarkable, being one of the main pathways for the introduction of CECs into aquatic systems. The combination of novel analytical methodologies and risk assessment strategies is a promising tool to find out environmentally relevant compounds posing major concerns in freshwater ecosystems impacted by those wastewater effluents. Within this context, a multi-target approach was applied in three Spanish river basins affected by different WWTP treated effluents for spatio-temporal monitoring of their chemical status. Solid phase extraction followed by ultra-high-performance liquid chromatography were used for the quantification of a large panel of compounds (n = 270), including pharmaceuticals and other consumer products, pesticides and industrial chemicals. To this end, water samples were collected in four sampling campaigns at three locations in each basin: (i) upstream from the WWTPs; (ii) WWTP effluent discharge points (effluent outfall); and (iii) downstream from the WWTPs (500 m downriver from the effluent outfall). Likewise, 24-h composite effluent samples from each of the WWTPs were provided in all sampling periods. First the occurrence and distribution of these compounds were assessed. Diverse seasonal trends were observed depending on the group of emerging compounds, though COVID-19 outbreak affected variations of certain pharmaceuticals. Detection frequencies and concentrations in effluents generally exceeded those in river samples and concentrations measured upstream WWTPs were generally low or non-quantifiable. Finally, risks associated with maximum contamination levels were evaluated using two different approaches to account for antibiotic resistance selection as well. From all studied compounds, 89 evidenced environmental risk on at least one occasion in this study.

Tracking the impact of perfluoroalkyl acid emissions on antibiotic resistance gene profiles in receiving water by metagenomic analysis

The ecological risks posed by perfluoroalkyl acids (PFAAs) to the aquatic environment have recently been of great concern. However, little information was available on the impact of PFAAs on antibiotic resistance genes (ARGs) profiles. In this study, the receiving river of the largest fluoropolymer production facility in China was selected to investigate the effects of PFAAs on ARGs profiles. The highest PFAAs concentration for water samples near the industrial effluent discharge point was 310.9 μg/L, which was thousands times of higher than the average concentration collected at upstream sites. Perfluorooctanoic acid accounted for more than 67.2 % of ∑PFAAs concentration in water samples collected at the downstream sites, followed by perfluorohexanoic acid (3.6 %–15.9 %). 145 ARG subtypes including high-risk ARGs were detected by metagenomic technology. The results indicated that the discharge of PFAA-containing effluents had a significant impact on the abundance and diversity of ARGs in receiving waters, and PFAAs and water quality parameters (e.g., pH, NH3N, CODMn, TP) could largely affect ARG profiles. Specifically, short-chain PFAAs had similar impacts on ARG profiles compared to the restricted long-chain PFAAs. This study confirmed the potential effects of PFAAs on ARGs in aquatic environment and provided more insights into the ecological risk raised by PFAAs.

International Journal of Scientific Research in Science and Technology

The coastal zone is an interface between land and sea. The interaction between land and sea involves physical and chemical processes, which produce characteristic shapes of coast line. Thus, in a coastal zone the terrestrial ecosystem has its influence on the sea and vice versa. Veraval is one of the important port cities located along the western coast of Gujarat in India. The Veraval coast is situated in Gujarat state and its water is polluted by the discharge of Fish processing industry effluent. The intertidal area of Fish processing industry at Veraval coast was selected for the study and the investigation was carried out at Veraval at Lat 210 35’N; Long 690 36E’. Survey was conducted during pre-monsoon, monsoon and post monsoon seasons during the year of 2018. In order to achieve the aims of the present study, following parameters were studied to assess species diversity of seaweeds along increasing distance from the discharge point. Number of seaweed species showed a trend similar to that of species diversity was more related to species richness. Ratio of species number for Green, Brown and Red algae indicated that red algae were in greater proportion than green and brown algae. Seaweed species diversity was minimum near Chemical industry effluent discharge point during post-monsoon, pre-monsoon and monsoon seasons, whereas the diversity increased as the discharge point from the outfall increased.

Analysis of Heavy Metals and Gene Expression of African Arowana Fish (Heterotis niloticus) obtained from Igbalegbe River, Ughelli, Delta State, Nigeria

Heavy metal pollution in aquatic ecosystems can be assessed with suitable biomarkers in fish. This study was carried out to determine the concentration of heavy metals and gene expression of African Arowana Fish (Heterotis niloticus) obtained from Igbalegbe River, Ughelli, Delta State, Nigeria using Atomic Absorption Spectrophotometer (Varian 220 Fast sequential) for the metals and Polymerase chain reaction (PCR) for the gene expression study. Results of the study showed that fishes in the downstream sectionof the river and the effluent discharge point recorded higher metal pollution Index (MPI) compared to the upstream station. The concentration of heavy metals in the fish tissue were generally within the limits of Food and Agricultural Organisation (FAO)/World health Organisation (WHO) except for that of Cadmium and Lead in the discharge station. The selected genes investigated were biomarkers for general stress (HSP70), xenobiotic metabolism (CYPA1), antioxidative defence (SOD), Insulin growth factor-1 (IGF-1) and hypoxia inducible factor (HIF) respectively. The expression of the genes revealed significant variations (P&lt;0.05) in the fishes obtained from the different stations of the river. Some of the genes were down-regulated and suppressed while others were upregulated to enable the fish cope with stress while adapting to environmental pollution. Changes in biomarkers can therefore be considered as early signals of stress in the selected fish species.

Escherichia coli in urban marine sediments: interpreting virulence, biofilm formation, halotolerance, and antibiotic resistance to infer contamination or naturalization.

Marine sediments have been suggested as a reservoir for pathogenic bacteria, including Escherichia coli. The origins, and properties promoting survival of E. coli in marine sediments (including osmotolerance, biofilm formation capacity, and antibiotic resistance), have not been well-characterized. Phenotypes and genotypes of 37 E. coli isolates from coastal marine sediments were characterized. The isolates were diverse: 30 sequence types were identified that have been previously documented in humans, livestock, and other animals. Virulence genes were found in all isolates, with more virulence genes found in isolates sampled from sediment closer to the effluent discharge point of a wastewater treatment plant. Antibiotic resistance was demonstrated phenotypically for one isolate, which also carried tetracycline resistance genes on a plasmid. Biofilm formation capacity varied for the different isolates, with most biofilm formed by phylogroup B1 isolates. All isolates were halotolerant, growing at 3.5% NaCl. This suggests that the properties of some isolates may facilitate survival in marine environments and can explain in part how marine sediments can be a reservoir for pathogenic E. coli. As disturbance of sediment could resuspend bacteria, this should be considered as a potential contributor to compromised bathing water quality at nearby beaches.

Assessment of the Physico-chemical Parameters and Heavy Metal Concentration of Delimi Wastewater in Jos North Local Government Area, Plateau State.

The high-water demand for domestic, agricultural, and industrial uses has increased water scarcity and is becoming alarming as natural or anthropogenic sources sometimes pollute the available water resources. Wastewater at Delimi was analyzed for physicochemical parameters and heavy metal concentration before and after the discharge of effluents into the water. Standard analytical methods were employed to analyze the physicochemical parameters, while the chemical analysis for the heavy metals was done using an Atomic Absorption Spectrophotometer (AAS). Results of the analysis showed the following ranges: temperature 20.30°C -24.40°C, pH 7.46 - 8.45, conductivity 310.40 - 481.68 µs/cm, total solids 318 - 481.00 mg/L, suspended solid 132.40 - 194.50 mg/L, dissolved solids 186. 40 - 287.00 mg/L, total hardness 496.20 - 651.00 mg/L, calcium hardness 121.37 - 147, 82 mg/L, magnesium hardness 103.00 - 124.00 mg/L, chloride 90.00 - 132.00 mg/L and sulphate 183.00 - 247.20 mg/L. All parameters assessed were within the WHO permissible limits except for chloride. Before the point of discharge, the wastewater recorded heavy metal concentration in the range of 0.00 – 5.80 ppm and 0.06 – 11.26 ppm after the point of effluent discharge. Iron recorded the highest value, which is above the WHO permissible limit, and lead, the lowest value, while Nickel and Manganese were not detected. Wastewater after the point of effluent discharge recorded higher concentration values, indicating the negative effects on the heavy metal concentration of the effluent discharges in the water. The resulting discharge increased the heavy metal concentration in the water, posing health challenges to the people within the environment. Using this wastewater for agricultural irrigation and laundry purposes could bring about exposure to heavy metals contained in it.

Impact of wastewater reuse on contaminants of emerging concern in an effluent-dominated river

Contaminants of emerging concern such as pharmaceuticals, personal care products, per- and polyfluoroalkyl substances, and plasticizers, are ubiquitous in effluent-dominated rivers and have potential adverse effects on humans and aquatic life. Demands on water supply have prompted conservation and water reuse measures, impacting the discharge in these rivers, yet the effects of these management decisions on water quality are largely intuited and not quantified. This research examines how changes in water reuse practices will impact concentrations of contaminants of emerging concern, specifically carbamazepine, diclofenac, galaxolide, gemfibrozil, 4-nonylphenol, and perfluorooctane sulfonic acid (PFOS), in the effluent-dominated Los Angeles River (Los Angeles County, California). A water quality module was added to a calibrated hydrologic model of the system and parametrized with observed water quality monitoring data in EPA SWMM. Results indicate that water reuse (i.e., reduced effluent flow) will consistently improve in-stream water quality for all compounds studied except PFOS. However, the improvements are often not substantial enough to mitigate high concentrations directly downstream of treated effluent discharge points. Concentrations of these pharmaceuticals are substantially reduced through attenuation as dilution and degradation occur downstream, though the rate of this attenuation is variable and based on the contaminant. In contrast, concentrations of PFOS increase under some wastewater reuse scenarios and decrease under others but remain below the recommended environmental screening levels. Our work also highlights that management decisions regarding water quantity should integrate water quality modeling to help identify priority monitoring locations and constituents.

Fluvial responses towards the tannery effluent: Tracing the anthropogenic foot-prints

Tannery-effluent is one of the top-ranked hazardous waste which is generally discharged into the river. To study the fluvial response toward the tannery-effluents and to trace anthropogenic foot-prints in the fluvial-system, a suite of systematically collected sediment and water samples were analyzed for radioactive (226Ra, 232Th, and 40K) and non-radioactive elements (Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, and Pb). Neutron activation analysis and atomic absorption spectroscopy were used for elemental analysis, whereas HPGe-gamma-detector was used for measuring the primordial-radionuclides. Ranges of Cr-abundances in sediment and water were 63–4373 μg.g−1 and 15.6–52.2 μg.L−1, respectively which were ∼4–14 times higher than the geological background. Radioactivity concentrations of 226Ra, 232Th, and 40K ranged from 17.7–48.5, 36.1–81.6, and 687–1041 Bq.kg−1, respectively which were significantly depleted in effluent discharge point. Hence, primordial-radionuclides were used as natural tracers for tracing anthropogenic foot-prints which were explained in terms of dilution effect, redox environment and differential geo-environmental events/characteristics. From statistical-approaches and geochemical reasoning, elemental sources and responses in fluvial system were explored. Surprisingly, ecological & radiological risks were reduced while sediment quality guideline-based ecotoxicity & water-mediated health risks were increased by the incorporation of tannery effluents. This study describes the sedimentary response toward the received tannery effluents which is particularly explored by the primordial radionuclides.

Prevalence of antibiotic resistance genes and virulence factors in the sediment of WWTP effluent-dominated rivers

In the context of increasing aridity due to climate changes, effluent from wastewater treatment plants (WWTPs) became dominant in some rivers. However, the prevalence of antibiotic resistance genes (ARGs) and virulence factors (VFs) in effluent-dominated rivers was rarely investigated. In this study, the profiles of ARGs and VFs in the sediment of two effluent-dominated rivers were revealed through the metagenomic sequencing technique. In each river, samples from the effluent discharge point (P site) and approximately 500 m downstream (D site) were collected. Results showed that the abundances of ARGs and VFs were both higher in D sites than those in P sites, indicating higher risks in the downstream areas. The compositions of ARGs were similar in the P sites of two rivers while being distinct in the D sites. The same was true for changes in the VFs compositions. Microbial community structure variations were the main driver for the changes in ARGs and VFs. Network analysis revealed that the interaction of ARGs and VF genes (VFGs) in sediment was intense. Two VFGs and eleven ARGs were identified to play important roles in the network. Metagenome-assembled genomes (MAGs) were generated to evaluate the coexistence of ARGs and VFGs at the single genome level. It was found that 38.4 % of the MAGs contained both ARGs and VFGs, and two MAGs were from pathogenic genera. These results suggested that high microbiological risks existed in effluent-dominated rivers, and necessary measures should be taken to prevent the potential threat to public health.

Antibiotic, Heavy Metal, and Biocide Concentrations in a Wastewater Treatment Plant and Its Receiving Water Body Exceed PNEC Limits: Potential for Antimicrobial Resistance Selective Pressure.

Although the rise in antimicrobial resistance has been attributed mainly to the extensive and indiscriminate use of antimicrobials such as antibiotics and biocides in humans, animals and on plants, studies investigating the impact of this use on water environments in Africa are minimal. This study quantified selected antibiotics, heavy metals, and biocides in an urban wastewater treatment plant (WWTP) and its receiving water body in Kwazulu-Natal, South Africa, in the context of the predicted no-effect concentrations (PNEC) for the selection of antimicrobial resistance (AMR). Water samples were collected from the WWTP effluent discharge point and upstream and downstream from this point. Heavy metals were identified and quantified using the United States Environmental Protection Agency (US EPA) method 200.7. Biocides and antibiotic residues were determined using validated ultra-high-performance liquid chromatography with tandem mass spectrometry-based methods. The overall highest mean antibiotic, metal and biocide concentrations were observed for sulfamethoxazole (286.180 µg/L), neodymium (Nd; 27.734 mg/L), and benzalkonium chloride (BAC 12) (7.805 µg/L), respectively. In decreasing order per sampling site, the pollutant concentrations were effluent > downstream > upstream. This implies that the WWTP significantly contributed to the observed pollution in the receiving water. Furthermore, most of the pollutants measured recorded values exceeding the recommended predicted no-effect concentration (PNEC) values, suggesting that the microbes in such water environments were at risk of developing resistance due to the selection pressure exerted by these antimicrobials. Further studies are required to establish such a relationship.

Dynamics of antibiotic resistance markers and Escherichia coli invasion in riverine heterotrophic biofilms facing increasing heat and flow stagnation

As motivation to address environmental dissemination of antimicrobial resistance (AMR) is mounting, there is a need to characterize mechanisms by which AMR can propagate under environmental conditions. Here we investigated the effect of temperature and stagnation on the persistence of wastewater-associated antibiotic resistance markers in riverine biofilms and the invasion success of genetically-tagged Escherichia coli. Biofilms grown on glass slides incubated in-situ downstream of a wastewater treatment plant effluent discharge point were transferred to laboratory-scale flumes fed with filtered river water under potentially stressful temperature and flow conditions: recirculation flow at 20 °C, stagnation at 20 °C, and stagnation at 30 °C. After 14 days, quantitative PCR and amplicon sequencing were used to quantify bacteria, biofilms diversity, resistance markers (sul1, sul2, ermB, tetW, tetM, tetB, blaCTX-M-1, intI1) and E. coli. Resistance markers significantly decreased over time regardless of the treatment applied. Although invading E. coli were initially able to colonize the biofilms, its abundance subsequently declined. Stagnation was associated with a shift in biofilm taxonomic composition, but there was no apparent effect of flow conditions or the simulated river-pool warming (30 °C) on AMR persistence or invasion success of E. coli. Results however indicated that antibiotic resistance markers in the riverine biofilms decreased under the experimental conditions in the absence of exposure to external inputs of antibiotics and AMR.

Spatio-seasonal patterns of the impact of wastewater treatment plant effluents on antibiotic resistance in river sediments

There is a growing concern about the risk of antibiotic resistance emergence and dissemination in the environment. Here, we evaluated the spatio-seasonal patterns of the impact of wastewater treatment plant (WWTP) effluents on antibiotic resistance in river sediments. To this purpose, sediment samples were collected in three river basins affected by WWTP effluents in wet (high-water period) and dry (low-water period) hydrological conditions at three locations: (i) upstream the WWTPs; (ii) WWTP effluent discharge points (effluent outfall); and (iii) downstream the WWTPs (500 m downriver from the effluent outfall). The absolute and relative abundances of 9 antibiotic resistance genes (ARGs), 3 mobile genetic element (MGE) genes, and 4 metal resistance genes (MRGs) were quantified in sediment samples, as well as a variety of physicochemical parameters, metal contents, and antibiotic concentrations in both sediment and water samples. In sediments, significantly higher relative abundances of most genes were observed in downstream vs. upstream sampling points. Seasonal changes (higher values in low-water vs. high-water period) were observed for both ARG absolute and relative abundances in sediment samples. Chemical data revealed the contribution of effluents from WWTPs as a source of antibiotic and metal contamination in river ecosystems. The observed positive correlations between ARG and MGE genes relative abundances point out to the role of horizontal gene transfer in antibiotic resistance dissemination. Monitoring plans that take into consideration spatio-temporal patterns must be implemented to properly assess the environmental fate of WWTP-related emerging contaminants in river ecosystems.

Bioavailability of metals in the Funtua textile wastewater, north western Nigeria

Textile wastewater pose a significant threat to surface water especially the water bodies closer to the textile industry locations. The study investigated the bioavailability of cobalt (Co), copper (Cu), lead (Pb), nickel (Ni) and chromium (Cr) in wastewater from ten sampling points including wastewater from point of effluent discharge in Funtua textile across Funtua region. The trends in the metal bioavailability (mg/L) among the fractions were; Zn Cu: total&gt; mobile &gt; dissolved &gt; particulate; Pb: total&gt; particulate &gt; mobile&gt; dissolved; Ni: total&gt; particulate &gt; dissolved&gt; mobile; Cr: total &gt; particulate &gt; mobile &gt; dissolved, respectively. All the concentrations of the metal ions were above the WHO (2006) and USEPA (2000) tolerable limits across the sites, with the exception of Co which was not detected in all the fractions. While lead and chromium was detected in S1, S2 and S1, S10, respectively. The order of the metals bioavailability was; total&gt;mobile&gt;dissolved&gt;particulate, with more than 50% found in the bioavailable phase. Hence, the surface waters within the vicinity of the textile industry were greatly at risk of being polluted by these toxic metals and subsequently affecting the inhabitants who use the water for agricultural and other domestic activities untreated, through the food chain transfer. The health implications associated with the toxic metals include an irreversible damage to nervous system, gastric and intestinal disorder, heart disease, liver, brain damage, mental retardation and teratogenic effects.

Effect of Industrial Effluent on Irrigation Water Quality of Choba River in the Niger Delta Region of Nigeria

Poor irrigation water quality due to oil spillage on surface water can result in food insecurity, health and economic challenges. This paper investigated the effect of total petroleum hydrocarbon (TPHC) and lead (Pb) on irrigation water quality in the oil spill prone area of the Niger Delta region of Nigeria. Water samples were taken from five different sections labelled A, B, C, D, and E along the Choba River, in Rivers State, Nigeria. Sections B, C, D and E were direct industrial effluent discharge points while section A was without direct industrial effluent discharge. Standard methods were employed in the water sampling and analysis. Suitability of Choba river water for irrigation was assessed by comprehensive pollution index (CPI) that incorporated salinity, sodicity, and permeability hazard potentials as well as the specific toxicity hazard potentials of TPHC and Pb. Results showed that all primary water parameters except pH were within the Food and Agriculture Organization (FAO) guidelines. The pH was low, ranging between 4.48 and 5.6. TPHC values for four out of the five samples were greater than the 10mg/l guideline as recommended by the Directorate of Petroleum Resources for surface water. TPHC for the four samples ranged between 14.52 and 174.32mg/l. The parameters with the most impact on CPI include EC, PI and TPHC with TPHC having the most impact. Water samples from sections A, B and E with CPI values 0.14, 0.37, and 0.8 respectively were classified in the clean, sub clean and slightly polluted categories respectively, while water samples from sections C and D with CPI values greater than 1 range from moderately to heavily polluted and not suitable for agricultural irrigation. Only water sample A was found suitable for irrigation.

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

Effects of Nutrient Level and Growth Rate on the Conjugation Process That Transfers Mobile Antibiotic Resistance Genes in Continuous Cultures.

Bacteria in the effluent of wastewater treatment plants (WWTPs) can transfer antibiotic resistance genes (ARGs) to the bacteria in receiving water through conjugation; however, there is a lack of quantitative assessment of this phenomenon in continuous cultures. Our objective was to determine the effects of background nutrient levels in river water column and growth rates of bacteria on the conjugation frequency of ARGs from effluent bacteria to river bacteria, as well as on the resulting resistance level (i.e., MICs) of the river bacteria. Chemostats were employed to simulate the discharge points of WWTPs into rivers, where effluent bacteria (donor cells) meet river bacteria (recipient cells). Both donor and recipient cells were Escherichia coli cells, and the donor cells were constructed by filter mating with bacteria in the effluent of a local WWTP. Results showed that higher bacterial growth rate (0.45 h-1 versus 0.15 h-1) led to higher conjugation frequencies (10-4 versus 10-6 transconjugant per recipient). The nutrient level also significantly affected the conjugation frequency, albeit to a lesser extent than the growth rate. The MIC against tetracycline increased from 2 mg/L in the recipient to 64 to 128 mg/L in transconjugants. In comparison, the MIC only increased to as high as 8 mg/L in mutants. Whole-genome sequencing showed that the tet-containing plasmid in both the donor and the transconjugant cells also occur in other fecal bacterial genera. The quantitative information obtained from this study can inform hazard identification related to the proliferation of wastewater-associated ARGs in surface water. IMPORTANCE WWTPs have been regarded as an important hot spot of ARGs. The discharge point of WWTP effluent, where ARGs may be horizontally transferred from bacteria of treated wastewater to bacteria of receiving water, is an important interface between the human-dominated ecosystem and the natural environment. The use of batch cultures in previous studies cannot adequately simulate the nutrient conditions and growth rates in receiving water. In this study, chemostats were employed to simulate the continuous growth of bacteria in receiving water. Furthermore, the experimental setup allowed for separate investigations on the effects of nutrient levels (i.e., simulating background nutrients in river water) and bacterial growth rates on conjugation frequencies and resulting resistance levels. The study generates statistically sound ecological data that can be used to estimate the risk of wastewater-originated ARGs as part of the One Health framework.

Evaluation of the Water Quality Parameters in Surface Water of Iyesi Stream, Ogun State, Nigeria

The quality of surface water could have positive or negative impact on its consumption and use. This study is aimed at examining the quality of surface water of Iyesi Stream. In achieving this, sixteen (16) samples were taken at four different periods (four samples per batch) from October, 2017 to May, 2018 and analyzed for selected water quality parameters namely pH, alkalinity, BOD, COD, TDS, some anions (PO43-, NO3-, SO42-) and trace cations (Fe, Cr and Ni) according to APHA (1992) methods of analysis. The trace metals were analyzed using UNICAM AAS after sample digestion. An average pH range of 5.90±0.86 to 6.85±0.19 was recorded for the samples. SWR-2 had highest average levels of alkalinity, TH, BOD, COD, TDS, SO42-, Fe, Cr and Ni. The higher values at SWR-2 could be attributable to the fact that it is in close proximity to the effluent discharge point of the industrial estate in its environ. It was observed from this study that SWR-3 had higher nitrate and phosphate levels of 4.01±1.95mg\L and 0.19±0.04mg\L respectively. Overall, the water source is grossly organically polluted and could require suitable treatment options like coagulation with Alum or Ferric chloride.