Untreated River Water Research Articles

EVALUATION OF ENERGY EFFICIENCY OF CONDENSING ECONOMIZERS FOR STEAM AND HOT WATER BOILERS

An assessment of the feasibility of the development and implementation of a condensing economizer (CE) for the TGM-96A steam generator has been carried out. The CE cools fuel gases from 123 °C to 47 °C, and also has a very high heating capacity, ranging from 21 to 23.5 Gcal/h. The heat recovered due to the CE installation will heat three water circuits: one for untreated river water and two with water from district heating networks (DH). The expected value of the steam generator efficiency will increase by 10.55%. Complete thermal calculations of the condensing economizer have been carried out, and heat transfer fluids have been determined by flow rate and temperature, respectively. On the basis of calculations of heat and mass transfer processes, the heat capacity of the economizer was estimated under conditions of partial condensation of water vapor from flue gases. The analysis carried out allows us to give an objective assessment of the investment of the proposed project, and other financial indicators and environmental benefits that give the investor the opportunity to implement the project. Key words: condensing economizer (CE), exhaust gases, energy efficiency.

MONITORING OF THE CHEMICAL COMPOSITION OF IORI RIVER

The article examines the chemical pollution of the Iori River, one of the most important rivers in Georgia. In addition to Georgia, this river is found in Azerbaijan. The study of this river is crucial as LLC United Water Supply Company of Georgia organizes the water supply of big cities and villages of Georgia through Iori water. Furthermore, the population of two big villages independently uses the river water for various household activities: washing (laundry, products, dishware), livestock watering, and irrigation. They do not use it as drinking water. The water of the Iori River was monitored in two sections: village Sasadilo and village Sartichala. In total, 24 samples were taken over the course of 2018 and 2019 years. Some part of the research was conducted on the site through HI83399-02 | Water Wastewater Multiparameter (with COD) Photometer and pH meter device. These studies included pH, BOD, and the temperature was measured directly during sampling. The same device was used for measuring approximate concentrations of heavy metals. At the next stage of the study, an inhabitants survey was conducted to identify their knowledge of environmental cleanliness and safety concerns. As a result of the study, our recommendation to the population is to refrain or restrict the use of untreated river water directly in domesticities. The results of the survey showed that the population has less information about the likelihood of getting heavy metals in the body and developing tumor diseases.

Restricted access media-imprinted nanomaterials based on a metal-organic framework for highly selective extraction of fluoroquinolones in milk and river water.

A new type of restricted access media-imprinted nanomaterials (RAM-MIPs) were successfully prepared on the surface of metal-organic framework by reversible addition fragmentation chain transfer polymerization technology. Then it was applied as a dispersed solid phase extraction (DSPE) material in analysis of fluoroquinolones (ofloxacin, pefloxacin, norfloxacin, enrofloxacin and gatifloxacin) in untreated milk and river water by HPLC-UV detection. The resulted material has a good binding amounts (60.81mg g-1), rapid binding kinetic (15min) and satisfactory selectivity as well as has a good ability to eliminate matrix interference. Several major factors affecting DSPE efficiency, pH of sample solution, dosage of RAM-MIPs, adsorption time and volume ratios of elution solvent were primarily optimized. In optimization conditions, RAM-MIPs-DSPE was combined with HPLC-UV to enrich fluoroquinolones in untreated milk and river water, achieving satisfactory linear correlation (R2 > 0.9988), good limits of detection (LOD, 1.02-3.15µg L-1 for milk and 0.93-2.87µg L-1 for river water) and better recoveries (80.7-103.5% and 85.1-105.9% with relative standard deviation (RSD) of not higher than 5.3% and 4.7% for milk and river water samples, respectively). The research results illustrate that it provides a simple and efficient method for the direct detection of FQs in complex samples.

Hydrochemical interfaces and spatial assessment of Usuma River water quality in North-Central Nigeria

Surface water contagion resulting from anthropogenic deeds and bad effluent management due to swift urbanization has cause a dramatic deterioration in river water quality and has threatened the aquatic ecosystem health of Nigeria. Thus, treated and untreated river water usage for domestic purposes is uncertain and, accordingly, requires scientific investigation. Research on the quality of surface water resources and hydrochemical interfaces is vital for monitoring and for determining water contaminant sources. Therefore, river samplings were obtained from 5 sampling points, for a total of 25 water samplings from the Usuma River in Abuja, Nigeria, and these samples were examined for physicochemical parameters by means of standard techniques. Additionally, the results acquired were subjected to hydrochemical scrutinizes and the examined water quality variables demonstrated wide discrepancies from one sampling station to another. The result also showed that Conductivity had the highest mean (50.68mg/l), followed by TDS (37.32mg/l) whereas Nitrite had the lowest mean (0.09mg/l). Similarly, Chloride had the highest Standard deviation (12.77mg/l).This was followed by Conductivity (11.82mg/l) while Nitrite had the lowest value of 0.01mg/l. Furthermore, most parameter (Temp, Turbidity, DO, COD, BOD and Total coliform) for every water samples examined surpassed the maximum permissible criterions of the WHO specifications for drinking water quality. The highest point of substantial correlation was found between chloride and DO (r = 0.92, α = 0.05). Four principal components were obtained that accounted for 23.87% drop in dimensionality that defined 76.13% of the total variance signifying the impact of mineral suspension and human-related actions on the hydrochemistry of the region. Two hydrochemical clusters were recognized with noticeably apportioned water quality. Advance analysis divulged that 43.7, 20.2 and 37.1% of the samples were of the (S04-Cl-Ca, S04 - Cl- CO3HC03-Ca-Mg and Mg - Ca) types, respectively. Multiple pollution effects, anthropogenic activities, the changing ecosystem, and innate features of aquatic ecosystems produce multifaceted data that pose a threat to river water quality in the study locality and this requires serious attention. There is also a need for the schedule monitoring of the Usuma River in Abuja and buffer regions at the riparian zone to enervate the deleterious effects of catchment urbanization.

Estimation of physicochemical characteristics and associated metal contamination risk in the Narmada River, India

River Narmada is the fifth largest holy river of Madhya Pradesh (M.P) flowing in the central part of India. The river receives large quantity of untreated/partially treated wastewater enriched with heavy metals and supplementary toxic organic pollutants. This study aims to assess the water quality status in river Narmada using indices like comprehensive pollution index (CPI), heavy metal pollution index (HPI), risk assessment index (RAI) and cancer risk index (CRI), for human use. The presence of faecal coliform and high chemical oxygen demand > 20 mg/L indicates that the water is unsuitable for drinking purposes. The average CPI and HPI evaluated to be 1.98, and 1.35, respectively signifies the moderately polluted river water. Considerably, the RAI > 1 and CRI > 1 is obtained at all sampling locations that alarms the possible cancer risk to human if untreated river water is used. Principal component analysis of data confirmed pollution in the river from both natural and anthropogenic sources. The strongest Pearson correlation coefficient between Cu-Pb (0.998) and Zn-Cu (0.986) indicates the input of wastewater in the river probably from electroplating industries. The river water is unsuitable for human intake. It is required to control direct flow of wastewater in river to restore ecological health.

Impact of rock alum pretreatment on biosand filter performance in Cambodia

Abstract Alum is often recommended by WASH agencies as a pretreatment flocculent to improve filtration in biosand filters (BSFs) for communities using a turbid drinking water source. Floating villages on the Tonle Sap Lake in Cambodia using BSFs encounter severe declines in filtration rates while using alum, resulting in reduced use of the BSF. We tested the effect of rock alum treatment on flow rate and turbidity. The flow rate of all BSFs declined over time, but degradation of flow was more rapid for alum-treated water than untreated water. Rock alum treatments significantly reduced the turbidity of borrow pit source water. Filters switched to untreated river water decreased in turbidity to levels ≤ rock alum-treated river water. Rock alum treatments increased aluminum in source water 4–15 times, but filtration by BSFs decreased levels of aluminum to near 0.05 mg/L. Though rock alum effectively reduces turbidity in source water, we believe it continues its coagulation inside the BSF during pause periods, negatively impacting flow rates.

First Occurrence of Saffold Virus in Sewage and River Water Samples in Karaj, Iran.

Saffold virus as a newly discovered virus, which seems to be related to acute gastroenteritis as with other enteric viruses and to human airway diseases in children belongs to Cardiovirus genus in picornaviridae family with 11 genotypes. Saffold virus initially was detected in America from infant stool sample. Saffold virus has also been detected in environmental water samples. Until now, two reports have demonstrated that sewage water sources are contaminated with Saffold viruses. Molecular detection of Saffold virus mostly depended on reverse transcription PCR methods and RT-qPCR, which had targeted 5'UTR region of the viral genome. The present study aims to evaluate the molecular detection and quantity of Saffold virus in sewage water and river water specimens by RT-qPCR assay in Karaj, Iran. Fifty samples collected from environmental waters containing treated and untreated sewage water and river water samples were included in this study. After viral RNA extraction, the Real-time PCR was developed to amplify the 5'UTR sequence of Saffold virus genome and viral load was assessed. Out of the 50 samples tested (consisting 28 river water samples and 22 sewage water samples), the Saffold virus genomic RNA was identified in 10/28 (35.7%) of river water samples and in 4/12 (33.3%) of treated and 4/10 (40%) of untreated sewage samples. The maximum viral load was 6.8 × 106 copies/l in untreated sewage water sample in December, and the lower viral load was 1.2 × 106 copies/l related to treated sewage water taken in October. Our results for the first time indicate that Saffold virus has apparently been circulating among Iranian peoples. Also, the viral prevalence of Saffold virus in each of the three sets of tested samples was within moderate to high in range.

Environmental monitoring of Aichi virus and human bocavirus in samples from wastewater treatment plant, drain, and River Nile in Egypt.

Wastewater plays a major role in water pollution causing transmission of several viral pathogens, including Aichi virus (AiV) and human bocavirus (HBoV), associated with gastrointestinal illness in humans. In this study, we investigated the presence of AiV and HBoV in aquatic, sludge, sediment matrices collected from Abu-Rawash wastewater treatment plant (WWTP), El-Rahawy drain, Rosetta branch of the River Nile in Egypt by conventional polymerase chain reaction (PCR). AiV RNA was detected in 16.6% (2/12), 8.3% (1/12), 8.3% (1/12), 22% (16/72), 12.5% (3/24), 4% (1/24), and 0/24 (0%) of untreated raw sewage, treated sewage, sewage sludge, drainage water, drain sediment, river water, and river sediment, respectively. On the other hand, HBoV DNA was detected in 41.6% (5/12), 25% (3/12), 16.6% (2/12), 48.6% (35/72), 29% (7/24), 3/24 (12.5%), 4% (1/24) of untreated raw sewage, treated raw sewage, sewage sludge, drainage water, drain sediment, river water, and river sediment, respectively. This study provides data on the presence of these viruses in various types of water samples that are valuable to environmental risk assessment. In addition, the current study demonstrates the importance of environmental monitoring as an additional tool to investigate the epidemiology of AiV and HBoV circulating in a given community.

<i>In Vivo</i> effects of zinc oxide-<i>Chromolaena odorata</i> nanoparticle treated Oyun river water

This study evaluated the purifying effect of the zinc oxide-Chromolaena odorata (ZnO-CO) nanoparticle on water samples collected from Oyun River water. Physicochemical and bacteriological characteristics of untreated and treated Oyun river water were determined and their effects on hematological parameters, liver and kidney of rats were also investigated. Thirty-two albino rats (with mean weight ± SD of 132.00 ± 7.50g) were randomized into four groups (A-D). Rats in groups A, B, C and D were maintained on distilled water, untreated Oyun river water (UW), ZnO-CO-treated Oyun river water (ZW), and alum-treated Oyun river water (AW), respectively for 30 days. Thermo-tolerant and enteric bacteria were undetectable in UW samples after treatment with the ZnO-CO nanoparticle. WBC, RBC and platelet counts of rats maintained on UW, ZW, and AW were significantly different from those in the control. Liver aspartate aminotransferase (AST), alanine aminotransferase (ALT) and acid phosphatase (ACP) activities of rats maintained on ZW were increased significantly (p<0.05) when compared to the control. Serum globulin and creatinine concentrations of rats maintained on ZW also increased significantly when compared with the control. The results of this study suggest that Oyun river water is polluted, and its consumption may produce deleterious effects in humans. Treatment of Oyun river water with the synthesized ZnO-CO nanoparticle is more effective than alum in purifying the polluted water. However, ZW also impacted negatively on the liver and renal functions of rats. Hence, ZnO-CO nanoparticle treated water may not be safe as drinking water.

Occurrence of Salivirus in Sewage and River Water Samples in Karaj, Iran.

Salivirus is a newly discovered virus which seems to be related to acute gastroenteritis in children. Salivirus may infect susceptible children by fecal-oral route after exposure to contaminated water. The present study aims to evaluate the occurrence and quantity of Salivirus in treated and untreated sewage water and river water samples collected in the city of Karaj, Iran by reverse transcription-quantitative PCR assay. A total of 50 samples were collected from environmental waters containing 22 treated and untreated sewage water in volume of 1l and 28 river water samples in volume of 5l were included in this study. After viral RNA extraction, the Real-time PCR was performed to amplify the 5'UTR sequence of Salivirus genome and viral load was assessed. Out of the 50 samples tested, the Salivirus genomic RNA was identified in 5/12 (41.6%) of treated and 3/10 (30%) of untreated sewage samples and in 8/28 (28.5%) of river water samples. The maximum viral load was 4.8 × 106 copies/l in treated sewage water sample in September and the lower viral load was 4 × 105 copies/l related to treated sewage water taken in December. This is the first report of Salivirus occurrence in the environmental waters in Iran. The viral prevalence of Salivirus in each of the three sets of tested samples was within low to moderate in range.

Identification of pathogenic Escherichia coli strain from river and sewage water in Bangladesh

The study was conducted to isolate and identify the presence of Shiga toxin producing Escherichia coli (STEC) strains in water samples of the Old Brahmaputra River and Sewage water at Mymensingh Municipality. A total of 20 water samples were collected for this experiment. Samples were cultured on EMB agar, stained and PCR was done to detect the pathogenic E. coli. The Old Brahmaputra River is used as a sink of all types of municipal sewage, agricultural wastes, domestic wastes and religious ritual wastes through unplanned sewerage to the river water body. Low quality sanitation system and open defecation are also considerable problems to deteriorate river water quality. Due to accumulation of municipal untreated wastes to river body, it is possible to contain various pathogens. After investigation and identification, fourteen isolates of E. coli was found to contain stx-1 gene with none of stx-2 gene among twenty isolates which indicate pathogenic STEC. There may present major health risk to human and animal due to STEC. Several human diseases like mild diarrhea, bloody diarrhea or even severe hemolytic-uremic syndrome (HUS) may occur for drinking of untreated river water. Domestic ruminants can act as a reservoir for STEC and play a significant role in the epidemiology of human infections.

ROLE OF SOME ORGANIC AND MINERALS MATERIALS ON REMOVALS OF HEAVY METALS OF SEWAGE AND ITS EFFECTS ON GROWTH OF CORN IN TOW CALCAREOUS SOILS.

A study was conducted in the Collage of Agriculture/University of Baghdad-Abugraib the alternative location for the University of Anbar during the spring 2017, to evaluate the efficiency of some materials organic and mineral in treating sewage from heavy metals and its effect on some soil characters and growth of corn plants (Zea Mays L.). Eexperiment was done using tow types soil clay loam and loam using pots to study the effect of using treated sewage with Phosphate rock, Bentonite, Peat moss and Soil and the untreated sewage and river water. Treated sewage prepared by making columns of materials used for treatment with 40 cm depth, then sewage mixed with heavy metals (concentration of 10 mg. L-1) poured through the column from the top and then filtered water collected and used to water corn plants where pots were watered according to treatments. At the end of the experiment some phenotypic growth indicators were measured and heavy metals concentrations measured in green leaves and in soil. experiment results showed Plant height was increased in both soils when irrigated with sewage treated with phosphate rocks and sewage treated with organic matter and the percent was 20.85 and 6.62 for both soils compared to untreated sewage. Significant difference in plant height recorded for plants irrigated with sewage treated with phosphate rocks by percent of 7.54% compared with plants irrigated with river water Plant dry weight was increased for maize plants watered using sewage treated with phosphate rocks, peat moss, bentonite and soil and the rate of increase was 45.61, 12.51, 17.77 and 4.68 % respectively compared to the dry weight when untreated sewage used. Cadmium concentration was increased as a result of using untreated sewage for irrigation compared to cadmium concentration in the soil. Differences in (Cd, Pb and Cu) concentration between treatments where it was reduced in soil when watered with sewage treated by phosphate rock. Cadmium, couplet and Copper concentration in leaves reduced by irrigating using sewage treated with phosphate rock, bentonite, peat moss and soil compared to irrigation treatment with untreated sewage for both soils.

Chitosan/Ag-hydroxyapatite nanocomposite beads as a potential adsorbent for the efficient removal of toxic aquatic pollutants

In the present study, the potential of synthesized chitosan/Ag-substituted hydroxyapatite nanocomposite beads to remove basic dye, heavy metal and microbes from aqueous solutions was investigated. Beads were prepared in different ratios via embedding of Ag-hydroxyapatite (Ag-HA) into chitosan (CS) solution. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) in order to get an insight of the functional groups and morphology. Batch adsorption studies were conducted with copper ions (Cu (II)) and rhodamine B (RhB) dye by changing several parameters such as Ag-HA to Cs ratio, contact time, solution pH and initial concentration of pollutants. The antibacterial efficiency of beads was tested under dynamic contact conditions against commonly found bacteria in water, Escherichia coli. The adsorption isotherm data were best fitted with Langmuir model. The maximum Langmuir adsorption capabilities for Cu (II) ions and rhodamine B were found to be 40.11 mg/g and 127.61 mg/g, respectively. The adsorption process could be best described by pseudo-second-order kinetic model for both rhodamine B and Cu(II). The percentage removal efficiency of Cu (II) and rhodamine B from tap water and untreated river water ranged from 86.7 to 94.4% along with 99.99% of decontamination of microbial load.

Detection of drinking water contamination event with Mahalanobis distance method, using on-line monitoring sensors and manual measurement data

Abstract Concerns about drinking water (DW) quality contamination during water distribution raise a need for real-time monitoring and rapid contamination detection. Early warning systems (EWS) are a potential solution. The EWS consist of multiple conventional sensors that provide the real-time measurements and algorithms that allow the recognizing of contamination events from normal operating conditions. In most cases, these algorithms have been established with artificial data, while data from real and biological contamination events are limited. The goal of the study was the event detection performance of the Mahalanobis distance method in combination with on-line DW quality monitoring sensors and manual measurements of grab samples for potential DW biological contamination scenarios. In this study three contamination scenarios were simulated in a pilot-scale DW distribution system: untreated river water, groundwater and wastewater intrusion, which represent realistic contamination scenarios and imply biological contamination. Temperature, electrical conductivity (EC), total organic carbon (TOC), chlorine ion (Cl-), oxidation–reduction potential (ORP), pH sensors and turbidity measurements were used as on-line sensors and for manual measurements. Novel adenosine-triphosphate and flow cytometric measurements were used for biological water quality evaluation. The results showed contamination detection probability from 56% to 89%, where the best performance was obtained with manual measurements. The probability of false alarm was 5–6% both for on-line and manual measurements. The Mahalanobis distance method with DW quality sensors has a good potential to be applied in EWS. However, the sustainability of the on-line measurement system and/or the detection algorithm should be improved.

Investigation of the fouling effect on a commercial semi-permeable membrane in the pressure retarded osmosis (PRO) process

Abstract One of the main challenges for generating osmotic power by using PRO technology is the membrane fouling which reduces the permeate flux and consequently increases the cost and decreases the osmotic power generation. In this research, different feed waters with various qualities were used to investigate the effect of fouling on a commercial membrane in PRO mode in continuous conditions. Also, the fouling mechanisms were investigated in order to study the cleaning of the membrane in PRO mode in the future research. In addition, four classic fouling models such as complete blocking model (CBM), intermediate blocking model (IBM), standard blocking model (SBM) and cake filtration model (CFM) were used. Cake enhanced osmotic pressure as a new mechanism for osmotically driven membranes was studied as well. According to the results, the fouling rate when the draw solution was synthetic salt water followed the order of: untreated river water > multimedia sand filter > microfiltration > ultrafiltration effluents. The fouling rate in ultrafiltration and microfiltration effluents using sea water occurred faster compared to the results for untreated synthetic salt water. Complete fouling (permeate flux was negligible) occurred after 580 h using feed water from ultrafiltration unit. It was observed that cake filtration and cake enhanced osmotic pressure were the main fouling mechanisms that governed the membrane fouling. These models could describe the membrane fouling in PRO processes.

Protocol for a cluster randomised stepped wedge trial assessing the impact of a community-level hygiene intervention and a water intervention using riverbank filtration technology on diarrhoeal prevalence in India

IntroductionDiarrhoea is a leading cause of death globally, mostly occurring as a result of insufficient or unsafe water supplies, inadequate sanitation and poor hygiene. Our study aims to investigate the...

Quantitative microbial risk assessment (QMRA) shows increased public health risk associated with exposure to river water under conditions of riverbed sediment resuspension

Although higher microbial concentrations have been reported in sediments than in the overlying water column, most quantitative microbial risk assessment (QMRA) studies have not clearly indicated the contribution of sediment-borne pathogens to estimated risks. Thus, the present study aimed at determining the public health risk associated with exposure to pathogenic bacteria in polluted river water under undisturbed conditions and conditions of sediment resuspension in the Apies River, Gauteng, South Africa. Microbial pathogens were isolated and identified using culture and molecular methods. The beta-Poisson dose-response model was used to estimate the probability of infection (Pi) with the various pathogens, following accidental/intentional ingestion of 1mL or 100mL (or 50mL) of untreated river water. Mean wet season Escherichia coli counts ranged between 5.8E+01 and 8.8E+04MPN/100mL (water column) and between 2.40E+03 and 1.28E+05MPN/100mL (sediments). Mean dry season E. coli counts ranged between 5.11E+00 and 3.40E+03MPN/100mL (water column) and between 5.09E+00 and 6.30E+03MPN/100mL (sediments). Overall (water and sediments) Vibrio cholerae was the most detected pathogen (58.8%) followed by Salmonella spp. (23.9%) and Shigella (10.1%). Ingestion of 1mL of river water could lead to 0%–4% and 1%–74% Pi with E. coli during the dry and wet season, respectively. During the dry season, the Pi with V. cholerae, Salmonella spp. and Shigella spp. were 0%–1.39%, 0%–4.11% and 0%–0.16% respectively, depending on volume of water ingested. The risks of infections with all microorganisms increased during the wet season. A 2-log increase in water E. coli count following sediments disturbance led to approximately 10 times higher Pi with E. coli than when sediments were undisturbed. Therefore, the use of the untreated water from the Apies River for drinking, household purposes or recreational activities poses a potential health risk to the users of the river.

Water use practices, water quality, and households' diarrheal encounters in communities along the Boro-Thamalakane-Boteti river system, Northern Botswana.

BackgroundSome rural African communities residing along rivers use the untreated river water for domestic purposes, making them vulnerable to waterborne diseases such as diarrhea.MethodsWe determined water use practices and water quality, relating them to prevalence of diarrhea in communities along the Boro-Thamalakane-Boteti river system, northern Botswana. A total of 452 households were interviewed and 196 water samples collected show during February, May, September, and December 2012 in settlements of Boro, Maun, Xobe, Samedupi, Chanoga, and Motopi. Information was sought on water use practices (collection, storage, and handling) and diarrheal experience using questionnaires. Water quality was assessed for physicochemical and microbiological parameters using portable field meters and laboratory analysis, respectively.ResultsAll (100 %) of the river water samples collected were fecally contaminated and unsuitable for domestic use without prior treatment. Samples had Escherichia coli (E.coli) and fecal streptococci levels reaching up to 186 and 140 CFU/100 ml, respectively. Study revealed high dependence on the fecally contaminated river water with low uptake of water treatment techniques. Up to 48 % of households indicated that they experience diarrhea, with most cases occurring during the early flooding season (May). Nonetheless, there was no significant relationship between river water quality and households’ diarrheal experience across studied settlements (p > 0.05). Failure to treat river water before use was a significant predictor of diarrhea (p = 0.028).ConclusionsEven though the river water was unsafe for domestic use, results imply further recontamination of water at household level highlighting the need for simple and affordable household water treatment techniques.

Biofouling on polymeric heat exchanger surfaces with E. coli and native biofilms

The biofouling affinity of different polymeric surfaces (polypropylene, polysulfone, polyethylene terephthalate, and polyether ether ketone) in comparison to stainless steel (SS) was studied for the model bacterium Escherichia coli K12 DSM 498 and native biofilms originating from Rhine water. The biofilm mass deposited on the polymer surfaces was minimized by several magnitudes compared to SS. The cell count and the accumulated biomass of E. coli on the polymer surfaces showed an opposing linear trend. The promising low biofilm formation on the polymers is attributed to the combination of inherent surface properties (roughness, surface energy and hydrophobicity) when compared to SS. The fouling characteristics of E. coli biofilms show good conformity with the more complex native biofilms investigated. The results can be utilized for the development of new polymer heat exchangers when using untreated river water as coolant or for other processes needing antifouling materials.

Impact of seasonal variation on Escherichia coli concentrations in the riverbed sediments in the Apies River, South Africa

Many South Africans living in resource-poor settings with little or no access to pipe-borne water still rely on rivers as alternative water sources for drinking and other purposes. The poor microbial quality of such water bodies calls for appropriate monitoring. However, routine monitoring only takes into consideration the microbial quality of the water column, and does not include monitoring of the riverbed sediments for microbial pollution. This study sought to investigate the microbial quality of riverbed sediments in the Apies River, Gauteng Province, South Africa, using Escherichia coli as a faecal indicator organism and to investigate the impact of seasonal variation on its abundance. Weekly samples were collected at 10 sampling sites on the Apies River between May and August 2013 (dry season) and between January and February 2014 (wet season). E. coli was enumerated using the Colilert®-18 Quanti-Tray® 2000 system. All sites tested positive for E. coli. Wastewater treatment work effluents had the highest negative impact on the river water quality. Seasonal variations had an impact on the concentration of E. coli both in water and sediments with concentrations increasing during the wet season. A strong positive correlation was observed between temperature and the E. coli concentrations. We therefore conclude that the sediments of the Apies River are heavily polluted with faecal indicator bacteria and could also harbour other microorganisms including pathogens. The release of such pathogens into the water column as a result of the resuspension of sediments due to extreme events like floods or human activities could increase the health risk of the populations using the untreated river water for recreation and other household purposes. There is therefore an urgent need to reconsider and review the current South African guidelines for water quality monitoring to include sediments, so as to protect human health and other aquatic lives.