Total Coliform Concentrations Research Articles

Spatio temporal variation in octocoral assemblages along a water quality gradient in the northwestern region of Cuba

Rivers are the main sources of nutrients to coastal zones. Therefore, the effects of water quality degradation on octocoral assemblages and their relationship with microbiological and physical-chemical variables were determined in reefs close to river basins in the northwestern region of Cuba. The evaluations were carried out in 1 m2 frames at a depth of 10 m in 13 fore reefs. The highest concentrations of the microbiological variables and hydrochemicals and the lowest horizontal visibility in the water column were detected in the reefs near the river basins. The lowest richness, diversity and octocoral density were related to higher concentrations of fecal coliform, total coliform and fecal streptococcal bacteria, sediment accumulation on the bottom and lower visibility. The structure of the octocoral assemblages varied significantly between reefs due to fecal organic pollution. Water quality deterioration in the reefs near the river basins has negatively affected the octocoral assemblages.

Determinação de bactérias do grupo dos coliformes no tecido mole de Mytella guyanensis extraídas em Cananéia/SP, Brasil

This study aimed to evaluate the microbiological quality of water and tissue samples of Mytella guyanensis (Mollusk: Bivalve),a species of relevant commercial interest and is a direct part of the income and food of traditional communities in coastalregions. This study was carried out in two communities in the Cananeia Estuary known as Retiro and Itanhoapina. Duringthe period of 2017, where the species is collected for human consumption, water and bivalve samples were collectedin the localities in order to determine the concentrations of total and thermotolerant coliforms. The samples of water andM. guyanensis were analyzed to determine the Most Probable Number (MPN) of Coliforms, based on the Multiple TubeTechnique. The results of the analyses showed low concentrations of coliforms in the water samples, with a similar result forthe tissue samples of the individuals collected. The water analysis showed a geometric mean of 34.81 total coliforms and20.70 MPN 100 mL-1 of thermotolerant coliforms. The averages of coliforms in the soft tissues of M. guyanensis were 190MPN g -1 for total coliforms and 174 MPN g -1 for thermotolerant coliforms. The concentrations of coliforms in the tissue ofthe collected specimens showed a positive correlation with temperature and a negative correlation with salinity. There weresignificant differences between seasonality in relation to the concentration of total and thermotolerant coliforms in the tissue.The summer rainy season showed the highest seasonal average of coliforms in M. guyanensis. All values obtained for MPNof coliforms were below the limit established by the legislation.

Suitability of Treated Wastewater Produced in Sudan for Irrigation Plants

The aim of this study was to characterize the quality of treated wastewater of Soba treatment plant, in Khartoum state, in term of its potential to be used in irrigation for different plant products, as well as to study the temporal variations of its physicochemical and biological parameters. Sampling of the treated wastewater was performed during Dec. 2014 and November 2015. The parameters indicating the suitability of such wastewater for irrigation were estimated, these include pH, Total Suspended Solids (TSS), Electrical Conductivity (EC), Total Dissolved Solids (TDS), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Sulphate, Ammonia, Chloride as well as total count, coli from bacteria and parasites. Results showed that, significant variation in values of pH, EC. Chloride, sulphate, BOD, COD was observed throughout the months of year. In spite of variability throughout the year, the values of pH, EC, TDS chlorides and sulphate, in term of their suitability for use in irrigation, fall within the limits set by FAO for irrigation water. Concentration of total coliform and nematodes in treated wastewater, were more than the concentration limit set by WHO, for restricted irrigation, and less than the limit for unrestricted irrigation. The reuse of the treated wastewater in irrigation of non food crops could be carried out without restriction, however, regarding the use of restricted irrigation, it would be necessary to upgrade treatment processes for further reduction in some parameters, providing that, regular testing should be done regularly.

Solar Septic Tank: Next Generation Sequencing Reveals Effluent Microbial Community Composition as a Useful Index of System Performance

Septic tanks are widely deployed for off-grid sewage management but are typified by poor treatment performance, discharge of polluting effluents and the requirement for frequent de-sludging. The Solar Septic Tank (SST) is a novel septic tank design that uses passive heat from the sun to raise in-tank temperatures and improves solids degradation, resulting in a cleaner effluent. Treatment has been shown to exceed conventional systems, however, the underlying biology driving treatment in the system is poorly understood. We used next generation sequencing (Illumina Miseq (San Diego, CA, USA), V4 region 16S DNA) to monitor the microbiology in the sludge and effluent of two mature systems, a conventional septic tank and an SST, during four months of routine operation in Bangkok, Thailand, and evaluated the ecology against a suite of operating and performance data collected during the same time period. Significant differences were observed between the microbiome of the sludge and effluent in each system and the dominant taxa in each appeared persistent over time. Furthermore, variation in the microbial community composition in the system effluents correlated with effluent water quality and treatment performance parameters, including the removal of chemical and biochemical oxygen demand and the concentration of fecal and total coliforms in the effluent. Thus, we propose that a wide-scale survey of the biology underlying decentralised biotechnologies for sewage treatment such as the SST could be conducted by sampling system effluent rather than sampling sludge. This is advantageous as accessing sludge during sampling is both hazardous and potentially disruptive to the anaerobic methanogenic consortia underlying treatment in the systems.

Microbiological Contamination of Strawberries from U-Pick Farms in Guangzhou, China.

This study quantified the association of rodent fruit damage and the microbiological quality of irrigation water on the risk of microbiological contamination of strawberries collected from 18 U-pick farms across five different districts in the Guangzhou metropolitan region of southern China. Fifty-four composite strawberries samples, with or without evidence of rodent or avian foraging damage (i.e., bitten), along with 16 irrigation water samples, were collected during the spring of 2014 and winter of 2015 from our cohort of 18 farms. Composite strawberry samples and irrigation water were analyzed for total coliforms, E. coli, Salmonella, E. coli O157, Giardia, and Cryptosporidium. Total coliforms and E. coli were detected in 100% and ~90% of irrigation water samples, respectively. In contrast, Cryptosporidium was detected in only two water samples, while Salmonella, E. coli O157, and Giardia were not detected in any water samples. Strawberries with signs of being bitten by wildlife had significantly higher concentrations of total coliforms and E. coli, compared to strawberries with no physical evidence of rodent damage (p < 0.001). Similarly, Cryptosporidium was detected in 7/18 (39%) of bitten, 4/18 (22%) of edge, and 5/18 (28%) of central strawberry samples, respectively. Concentration of E. coli on strawberries (p < 0.001), air temperature (p = 0.025), and presence of Cryptosporidium in irrigation water (p < 0.001) were all associated with the risk of Cryptosporidium contamination on strawberries. Salmonella and Giardia were detected in <4% strawberry samples and E. coli O157 was not detected in any samples. These results indicate the potential food safety and public health risks of consuming unwashed strawberries from U-pick farms, and the need for improved rodent biosecurity of U-pick strawberry fields and enhanced microbiological quality of irrigation water used at these facilities.

Biological and physicochemical quality from three water sources and its relation to the El Niño and La Niña phenomenon

In the municipality of El Carmen de Viboral, Antioquia, the basin of the La Cimarronas stream and its tributaries Los Andes and La Madera, are the main sources of supply of the local aqueduct. In addition, of these, other five sampling stations located in the upper part of the basin and its tributaries, the physico-chemical, microbiological and biological evaluation was carried out through the use of aquatic macroinvertebrates in three periods of the El Nino hydrological cycle (2016), which were compared with three samplings of the La Nina cycle (2011). The capacity of environmental resilience could be identified under a deficit and excess precipitation of the aquatic system. During the cycle affected by El Nino there was a higher concentration of dissolved oxygen, circumneutral pH, lower water temperature and higher concentrations of nitrites, ammonia nitrogen and total coliforms. During the cycle affected by La Nina, there was a higher water temperature, total solids, hardness, nitrates, total phosphorus and better conditions of biological water quality according to the BMWP index. There were no statistically significant variations in flow, water temperature, electrical conductivity and community indices (diversity, equity, dominance and richness).

Evaluation of zeolite supported bimetallic nanoparticles of zero-valent iron and copper (Z-nZVI/Cu) in the presence of ultrasonic for simultaneous removal of nitrate and total coliforms from aqueous solutions: optimization and modeling with response surface methodology

In this study, the removal of nitrate and total coliforms by zeolite-supported bimetallic nanoparticles of zero-valent iron and copper (Z-nZVI/Cu) coupled with ultrasonic treatment was studied. The Z-nZVI/Cu catalyst was synthesized by ion exchange method and was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of analyzes were indicative of the appropriate synthesis of catalyst and high distribution of iron and copper nanoparticles on zeolite. The effects of different operating parameters such as initial pH, catalyst concentration, initial concentration of pollutants, and catalyst concentration on removal of nitrate and total coliforms were investigated. The results showed that nitrate removal efficiency decreased with increasing pH and initial concentration of nitrate, while it increased by increasing the concentration of catalyst and ultrasonic frequency. To eliminate total coliform, the same trend was observed, except for increasing the removal efficiency by increasing the total coliform concentration. The results of optimization by response surface methodology (RSM) show that the maximum removal efficiency of nitrate and coliform were 97.77 and 97.77%, respectively. The results of the comparative experiments between the various processes showed that the ultrasonic process alone and ultrasonic coupled with Z-nZVI/Cu catalyst are suitable to provide the highest removal of total Coliforms and nitrate from aqueous solutions, respectively.

Analysis of antibiotic resistance of Escherichia coli isolated from the Yitong River in North-east China

The Yitong River is one of the largest secondary tributaries of the Songhua River. The area where the Yitong River flows is densely populated and contains the livestock and poultry breeding areas of northeast China. These areas introduce a high risk of antibiotic contamination. In this study, the concentrations of four types of typical antibiotics including quinolones, tetracyclines, sulfonamides, and trimethoprim were determined by solid phase extraction-high performance liquid chromatography. The antibiotic resistance of Escherichia coli caused by antibiotic pollution was investigated. The concentration of total coliforms in the Yitong River was detected by the plate counting method. The antibiotic resistance of E. coli to quinolones, tetracyclines, sulfonamides, and trimethoprim was analyzed by the Kirby-Bauer method. The results showed that the concentration of total coliforms in the summer was higher than that in the spring. There was a seasonal difference in the resistance rate of E. coli to antibiotics except trimethoprim. The antibiotic resistance to fluoroquinolones was relatively low. The resistance rate to tetracyclines was higher during the summer. Moreover, resistance to several antibiotics was observed in all sections. This study provides basic data for research on pollution characteristics and prevention of antibiotic exposure in rivers.

An examination of the microbial community and occurrence of potential human pathogens in rainwater harvested from different roofing materials

While harvested rainwater can serve as an alternative water supply, microbial contaminants within the collection system can negatively affect water quality. Here, we investigated the impact of roofing material on the microbial quality of rainwater freshly harvested from pilot-scale roofs (concrete tile, cool, green, Galvalume® metal, and asphalt fiberglass shingle). The microbial quality of freshly harvested rainwater from six rain events over two years was analyzed by high-throughput sequencing and culture-dependent and -independent techniques. The concentrations of total coliform were significantly different among rainwaters harvested from the various roofing materials (p-value >0.05). However, the fecal coliform concentrations and the copy numbers of Enterococcus 23S rRNA genes and total Bacteria 16S rRNA genes did not vary by type of roofing material in a statistically significant way. Potential human pathogens such as Legionella, Escherichia coli O157:H7, Shiga-toxin-producing Escherichia coli, and adenovirus were detected at least once in rainwater harvested from the different roofing materials, even though the lowest occurrence of those potential human pathogens was noted from the metal roof. Also, substantial variation in the microbial communities from the different roofing materials was observed at the family and genus levels. These results demonstrate that the type of roofing material affects the microbial quality of freshly harvested rainwater, indicating that the choice of roofing material could shape the microbial community structure entering a rainwater storage tank. Given that detection of potential pathogens in the freshly harvested rainwater also differed between roofing materials, the type of roofing used to capture rainwater needs to be considered in rainwater harvesting system design, particularly if the water is intended for potable use.

Evaluation of harvested rainwater quality at primary schools of southwest coastal Bangladesh

Rainwater is a typical source of drinking water in the coastal areas of Bangladesh given the acute scarcity of drinking water. This study assessed potability of harvested rainwater of primary schools in southwest coastal Bangladesh. Water samples collected from 23 primary schools of Mongla sub-district under Bagerhat district were evaluated for indicator bacteria (total coliform (TC) and E. coli) and physico-chemical parameters (pH, electrical conductivity, turbidity, total dissolved solid, Fe, Zn, Pb, and Cd). Median concentrations of TC and E. coli in the harvested rainwater samples were respectively 3000cfu/100ml and 6cfu/100ml. However, concentrations of these indicator bacteria were lower at the consumption points which received a prior treatment. Concentration of Pb exceeded the maximum allowable limit for drinking water indicated by WHO and Bangladesh drinking water guideline value in 92% and 61% of the samples respectively, and the mean concentration was 0.08mg/l (8 times higher than the WHO guideline value). The Pb contamination possibly occurred from the painting on roof railing and roof stair room. Therefore, consumption of harvested rainwater at primary schools may cause substantial health risk for the school-going children.

Trace elements and microbiological parameters in farmed Nile tilapia with emphasis on muscle, water, sediment and feed

Fish may bioaccumulate contaminants from the aquatic environment and extend them to the food chain provoking risks to human health. This study evaluated the microbiological parameters of the pond´s water and trace elements concentrations in samples of water, sediment, feed and muscle of farmed Nile tilapia used for human consumption in southern Brazil. A total of 240 fish were collected from 12 tilapia farms. Sediment, tank water and dry ration used in the animals' diet were collected for analysis. Analysis were performed by Energy Dispersion X-ray Fluorescence (EDXRF), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Induced Coupled Plasma Optical Emission Spectrometer (ICP-OES), and Atomic Absorption Spectrometer (AAS-VGA). In addition, the microbiological analysis of the water was carried out. The concentrations of Se, I, Fe, Cu and Zn in fish muscle were higher than the recommended by the Brazilian legislation, considering the advised daily intake for adults. The arsenic element had concentrations above the limit stipulated by the present Brazilian legislation, observed in all samples of muscle, sediment and tank water highlighting a possible environmental and fish contamination by the toxic element. Moreover, the arsenic concentration in the water presented a positive correlation (ρ = 0.33) with arsenic in the muscle, suggesting that tilapia is a good environmental bioindicator, once they properly reflect the levels of arsenic in the water. It is suggested to perform an arsenic speciation for quantification of the inorganic form and accurate assessment of the degree of toxicity in the muscle samples and risks it can bring to human health. Regarding the other potentially toxic elements (Hg, Pb and Cd), and microbiological analysis of water it was verified that the consumption of the fish in question does not raise risks, since the values are within a quality benchmark established by law. The concentration of total and fecal coliforms in pond´s water in the facilities was in agreement with the microbiological indexes required by the legislation of CONAMA class II. Western region presented the lowest concentrations of fecal coliforms when compared to the other regions. There was no significant difference in the microbiological counts of total heterotrophic bacteria, Vibrio spp. and Pseudomonas spp. among the regions.

Bacterial Contamination on Latrine Surfaces in Community and Household Latrines in Kathmandu, Nepal.

A lack of sanitation infrastructure is a major contributor to the global burden of diarrheal disease, particularly in low-income countries. Access to basic sanitation was identified as part of the 2015 United Nations Sustainable Development Goals. However, current definitions of “basic” sanitation infrastructure exclude community or shared sanitation, due to concerns around safety, equity, and cleanliness. The purpose of this study was to measure and compare bacterial contamination on community and household latrine surfaces in Kathmandu, Nepal. One hundred and nineteen swab samples were collected from two community and five household latrines sites. Community latrine samples were taken before and after daily cleaning, while household samples were collected at midday, to reflect normal conditions. Concentrations of total coliforms and Escherichia coli were measured using membrane filtration methods. Results found almost no differences between bacterial contamination on latrine surfaces in community and household latrines, with the exception of latrine slabs/seats that were more contaminated in the community latrines under dirty conditions. The study also identified surfaces with higher levels of contamination. Findings demonstrated that well-maintained community latrines may be as clean, or cleaner, than household latrines and support the use of community latrines for improving access to sanitation infrastructure in a low-income country setting.

Microbial Quality of Drinking Water and Prevalence of Water-Related Diseases in Marigat Urban Centre, Kenya.

Background:Accessibility to potable water is a fundamental right for dignity and well-being. Despite this observation, more than 1.1 billion people lack access to safe drinking water. This is particularly true in the Sub-Saharan Africa and South East Asia regions.Objective:The main aim of this study was to assess microbial quality of drinking water and prevalence of water-related diseases in Marigat town, Baringo County, Kenya.Methods:Samples of drinking water were collected from water sources (boreholes, rivers, and wells) and at the point of use (households) and analyzed for Escherichia coli and total coliform (TC) bacteria using the most probable number method. In situ measurements of pH and temperature were performed using a Wagtech International portable meter. Clinical health records from the local health centers were also reviewed to assess the prevalence rates of some of the water-related diseases.Results:There were significant differences among water sources during dry season for E coli (F2,21 = 3.629, P < .05) and TC (F2,21 = 4.041, P < .05). Similar observations were made during wet season for E coli (F2,21 = 4.090, P < .05) and TC (F2,21 = 1.893, P < .05). Furthermore, there were significant interactions between the water sources and season for E coli (F2,42 = 7.66, P < .01) and TC (F2,42 = 5.494, P < .05). Drinking water in large plastic storage containers (herein referred to as sky-plast) had the highest E coli and TC concentrations. Typhoid was the most prevalent water-related disease during the dry season (10%), whereas diarrhea (3%) was the most prevalent during the wet season.Conclusions and recommendations:All drinking water at abstraction and point of use for Marigat residents are microbiologically contaminated and therefore pose serious health risks to consumers of such water. Thus, there is need for public health awareness campaigns on household water management to curb incidences of water-related diseases. Public health practitioners at county and national levels need to ensure that households have adequate access to potable water and improved sanitation.

Assessment of Physico-Chemical and Bacteriological Quality of Drinking Water at the Source, Storage, Point-of-Use, Dry and Wet Season in Damot Sore Woreda, Southern Regional State, Ethiopia

Source to in-house and seasonal contamination of drinking-water quality is a persistent problem in developing countries. This study was conducted in Damot Sore Woreda, Southern Ethiopia to examine physico chemical and bacteriological quality of drinking water. For this study, four Kebele administrations were selected by purposive sampling technique. Location map and water quality sampling point were prepared using Arc GIS 9.2 software. A total of 55 water samples were taken and examined for physico-chemical and bacteriological parameters;11from source,11 from household containers,11 from drinking cup,11 for dry and 11 for wet season. One way ANOVA and correlation was employed to see the statistical difference of the variables at 5% significant level and to observe associations of variables. The result of water quality revealed that average value of all selected physico chemical parameters showed variation from source to storage. But only the value of temperature decrease significantly from supplied source to household storage (p=0.036). However, other parameters showed no significant change from source to storage. Bacteriological parameters showed variation from source to household storage and from storage to point of use. The concentration of total coliform increases significantly from supplied source to point of use (p=0.024). The dry and wet season measurement showed variations in physico-chemical and bacteriological parameters. However, statistically no significant difference observed between dry and wet season in all parameters studied. The result of water quality test revealed that average values for all selected physico-chemical parameters were found within the acceptable limit of ES and WHO standards, except Temperature and Phosphate. But the result of bacteriological water quality for all sampled sites exceeded the ES and WHO standards. So, supplied water in the area is bacteriologically contaminated and therefore not suitable for domestic purposes unless treated. Keywords: water quality, source, storage, dry season, wet season.

Factors Affecting Microbiological Quality of Vegetable- and Meat-Based Meals Served at Cafeterias in the Republic of Korea

A total of 364 samples of vegetable- and meat-based meals were collected at three processing steps: step I, preparation of raw ingredients; step II, processing and cooking; and step III, finished meals. Microbiological quality was evaluated by using data for the prevalence and concentration of the aerobic plate counts, total coliforms (TC), fecal coliforms (FC), and Escherichia coli. The data were analyzed for differences between cafeterias, seasons, raw materials, and processing steps. Fourteen (15.2%) of the 92 finished meal samples were microbiologically unsatisfactory. Neither cafeteria nor season was significantly associated with microbiological quality ( P > 0.05). However, the type of raw ingredients and processing steps were significantly associated with differences in microbiological quality. Vegetable-based meals had higher TC concentrations than meat-based meals because salad and seasoned and fermented vegetables are not cooked, unlike heat-processed meat products. Microbial counts tended to decrease through the processing steps, and E. coli, which could only be enumerated on uncooked chicken breast (1.6 log CFU/g) and sliced pork (2.6 log CFU/g), was totally eliminated by boiling and roasting. However, the presence of FC was not completely eliminated, even by cooking, and so this group of organisms should be considered as an important indicator of hygienic meal preparation in cafeterias. Although pathogenic E. coli was not isolated in this study, continuous microbiological monitoring of composite foods served in cafeterias should be performed as the presence of TC and FC in finished meals indicates the potential for contamination by pathogenic E. coli.

Bioaerosol emissions associated with pit latrine emptying operations

Pit latrines are the most common sanitation option in the developing world. They are simple to build but require periodic emptying which results in widespread dispersion of fecal pathogens in the environment. While much is known about the health risks of fecal-oral exposure, little is known about those resulting from the aerosolization of pathogens from fecal material. Bioaerosols were sampled around seven pit latrines before, after, and during emptying in Blantyre, Malawi. Bioaerosols were collected directly onto nutrient and selective medium agar plates using an impact sampler. DNA was extracted from some plates and analyzed for selected enteric pathogens. Total heterotrophic bacteria in the air during active emptying ranged from 198 to >13,000 colony forming units (CFU) per m3, and generally increased above background levels during pit emptying. At about one meter from the pit latrine emptying, E. coli and total coliforms concentrations in air reached up to 350 and 790 CFU m−3, respectively. Additionally, at four out of the seven pit latrines sites sampled, enterotoxigenic E. coli (ETEC) LT/ST was confirmed to be present in bioaerosols. This work demonstrates the potential for airborne dispersion of enteric pathogens during pit latrine emptying operations.

Seasonal Abundance of Fecal Indicators and Opportunistic Pathogens in Roof-Harvested Rainwater Tanks

Here we provide seasonal data on the concentrations of total coliform, Escherichia coli and Enterococcus spp. and six opportunistic pathogens (Acanthamoeba spp., Legionella spp., Legionella pneumophila, Mycobacterium avium, Mycobacterium intracellulare, and Pseudomonas aeruginosa) of public health significance in 24 tank water samples over six monthly sampling events from August 2015 to March 2006. Quantitative PCR (qPCR) assays were chosen for the quantification of six opportunistic pathogens and culture-based methods were used for the enumeration of fecal indicators. The data fle has been stored in a publicly available repository. The data on concentrations of opportunistic pathogens in RHRW will provide information for rainwater users regarding potential seasonality of risks. Quantitative data presented in this study can be used to perform quantitative microbial risk assessment (QMRA) of RHRW for various potable and nonpotable uses. Data can be used by health regulators to develop guidelines related to RHRW. Funding statement: This research was undertaken and funded as part of a Fulbright-CSIRO Postgraduate Scholarship sponsored by the CSIRO Land and Water Flagship.

Tradeoffs between pathogen inactivation and disinfection byproduct formation during sequential chlorine and chloramine disinfection for wastewater reuse

Treatment of fully nitrified municipal wastewater effluents with chlorine followed by chloramines (i.e., sequential chlorine disinfection) upstream of advanced treatment trains can contribute pathogen inactivation credits for potable reuse while leaving a chloramine residual to control biofouling on membrane units in the advanced treatment train. However, free chlorine exposures must be optimized to maximize pathogen inactivation while minimizing the formation of disinfection byproducts (DBPs) that are challenging to remove in the advanced treatment train. Using a pilot-scale disinfection contactor receiving fully-nitrified, tertiary municipal wastewater effluent, this study found that a 3 mg × min/L free chlorine CT (i.e., the product of the chlorine residual “C” and the contact time “T”) followed by a 140 mg × min/L chloramine CT could reliably achieve 5-log inactivation of MS2 bacteriophage and reduce median total coliform concentrations below 2.2 MPN/100 mL. Free chlorine disinfection was equally effective when chlorine was dosed to exceed the breakpoint for 1 mg/L of ammonia as N. At this free chlorine exposure, regulated trihalomethane (THM) and haloacetic acid (HAA) formation remained below their Maximum Contaminant Levels (MCLs), but NDMA concentrations of ∼30 ng/L were above the 10 ng/L California Notification Level. Increasing the free chlorine exposure to ∼30 mg × min/L increased THM and HAA formation, with regulated THMs approaching or exceeding the MCL. Although this free chlorine exposure prevented NDMA formation during chloramination, the ∼10 ng/L background NDMA formation in the tertiary effluent remained. Increasing the free chlorine exposure also increased the formation of unregulated halogenated DBP classes that may be significant contributors to the DBP-associated toxicity of the disinfected wastewater. The results indicate that sequential chlorination can be used to optimize the benefits of free chlorine (virus and NDMA control) and chloramine disinfection (THM, HAA, and coliform control).

The Modelling Approach for Predicting Coastal Pollutions using Rainfall Distributions over Different Land Use/Land Cover

Bae, H.-K., 2018. The modelling approach for predicting costal pollutions using rainfall distributions over different land use/land cover. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 11–15. Coconut Creek (Florida), ISSN 0749-0208.In this study, a modeling approach using rainfall distribution over different land use/land cover was developed and tested to predict coastal pollutions at the Aliso Beach, California, USA. Rainfall distributions over each land use/land cover of the study area, Aliso Creek Watershed, were calculated to use as input variables for the approach. In addition to rainfall distributions, streamflow and previous total coliform concentrations were also used as input variables. Six-hour. averages of rainfall and streamflow data were used since the approach estimated total coliform concentrations for every Six-hour. The estimations from the previous step, previous total coliform concentration, were used for last input variable if observation data were not available since total coliform concentrations were measured once every three days. Six different model scenarios were tested mainly focusing on rainfall events. As the model scenarios became more complicated, better estimations were shown. The approach showed the possibilities for finer time scale prediction, such as 1 hr. or less time scale or even real-time predictions, since precipitation and streamflow can be available for finer time scale and estimated previous concentrations would be used if observation data were not available.

Microbiological quality and antimicrobial resistance characterization of Salmonella spp. in fresh milk value chains in Ghana

Consumer perception of poor hygiene of fresh milk products is a major barrier to promotion of milk consumption as an intervention to alleviate the burden of malnutrition in Ghana. Fresh milk is retailed raw, boiled, or processed into unfermented cheese and spontaneously fermented products in unlicensed outlets. In this study, we have determined microbiological quality of informally retailed fresh milk products and characterized the genomic diversity and antimicrobial resistance (AMR) patterns of non-typhoidal Salmonella (NTS) in implicated products.A total of 159 common dairy products were purchased from five traditional milk markets in Accra. Samples were analysed for concentrations of aerobic bacteria, total and fecal coliforms, Escherichia coli, staphylococci, lactic acid bacteria and yeast and moulds. The presence of Salmonella, E. coli O157:H7, Listeria monocytogenes and Staphylococcus aureus were determined. AMR of Salmonella against 18 antibiotics was experimentally determined. Genome sequencing of 19 Salmonella isolates allowed determination of serovars, antigenic profiles, prediction of AMR genes in silico and inference of phylogenetic relatedness between strains.Raw and heat-treated milk did not differ significantly in overall bacterial quality (P = 0.851). E. coli O157:H7 and Staphylococcus aureus were present in 34.3% and 12.9% of dairy products respectively. Multidrug resistant (MDR) Salmonella enterica serovars Muenster and Legon were identified in 11.8% and 5.9% of unfermented cheese samples respectively. Pan genome analysis revealed a total of 3712 core genes. All Salmonella strains were resistant to Trimethoprim/Sulfamethoxazole, Cefoxitin, Cefuroxime Axetil and Cefuroxime. Resistance to Chloramphenicol (18%) and Ciprofloxacin (100%), which are first line antibiotics used in treatment of NTS bacteremia in Ghana, was evident. AMR was attributed to presence and/or mutations in the following genes: golS, sdiA for cephalosporins, aac(6′)-Iy, ant(9) for aminoglycosides, mdtK, gyrA, gyrB, parC, parE for quinolones and cat1, cat4 for phenicols. Phylogenetic analysis based on accessory genes clustered S. Legon strains separately from the S. Muenster strains. These strains were from different markets suggesting local circulation of related strains.Our study justifies consumer resistance to consumption of unripened soft cheese without further lethal heat treatment, and provides evidence that supports the Ghana Health Service recommendation for use of 3rd generation cephalosporins for the treatment of MDR NTS infections.