Characterization of domestic graywater and graywater solids.

The knowledge of loads and concentrations is fundamental for the design of graywater treatment units, but the data on the characteristics of graywater and in particular graywater solids are weak. As general design values regarding graywater treatment facilities are not available for Germany, the objective of this article is to elaborate the characteristics of graywater and graywater solids. This paper describes the results of six sampling campaigns carried out on graywater systems in the German cities Berlin, Lübeck and Kiel. All graywater samples were collected proportional to the flow and the graywater solids were gathered separately. The collected data include graywater volumes and characteristics regarding the organic pollution (chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD5)) and nutrients (total nitrogen (TN), total phosphorus (TP)). The graywater volume fluctuated depending on the location. The specific average flow was 68 litre per inhabitant per day (L/inh.d). Inhabitant-specific loads of 49.3 gCODt/inh·d, 28 gBOD5/inh.d, 1 gTNt/inh.d and 0.38 gTPt/inh.d (subscript 't' = total) were found. Information about the composition of graywater solids in terms of quantity and quality is seriously lacking. Therefore, graywater solids were examined with respect to organic matter (COD) and nutrients (TN, TP). The contribution of graywater solids with particle sizes over 200 microns in relation to the total inhabitant-specific load was approximately 3-8% depending on the parameter. The qualitative and quantitative characteristics of the investigated graywater fractions may serve as a base for the estimation of design values.

Use of matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry for bacterial monitoring in routine analysis at a drinking water treatment plant.

The study of bacterial communities throughout a drinking water treatment plant could provide a basic understanding of the effects of water processing that could then be used to improve the management of such plants. However, it is necessary to develop new analytical techniques that are sufficiently efficient, robust and fast for their effective and useful application in routine analysis. The aim of this study is therefore to assess the performance of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), as compared to the PhenePlate™ system, for routine analysis in a drinking water treatment plant. To this end we studied a total of 277 colonies isolated in different seasons and from different points throughout the water treatment process, including: raw water, sand filtration, ultrafiltration, reverse osmosis and chlorination. The colonies were analysed using MALDI-TOF MS by direct deposition of the cells on the plate. The colonies were also biochemically fingerprinted using the PhenePlate™ system, clustered according to their similarity and a representative strain was selected for 16S rRNA gene sequencing and API® gallery-based identification. The use of MALDI-TOF MS was reliable compared to the PhenePlate™ system and has the advantage of being faster and relatively cheap. Bacteria typing by MALDI-TOF MS is therefore a promising method to replace conventional routine phenotypic methods for the identification of bacteria in drinking water laboratories, thanks to its robustness. The major limiting factor for MALDI-TOF MS is the lack of a suitable mass spectra database; although each laboratory can develop its own library. This methodology will provide a tracking tool for companies to use in risk management and the detection of possible failures in both the water treatment processes and the distribution network, as well as offering characterization of the intrinsic microbial populations.

Prevalence, quantification, and typing of human adenoviruses detected in river water in Taiwan.

The prevalence of human adenoviruses (HAdV) in river waters was investigated in this study. Water samples were collected from 13 rivers in Taiwan, concentrated, and assessed for the presence of HAdVs using nested polymerase chain reaction (PCR). Human AdV positive samples were then subjected to real-time PCR (qPCR) to quantify the viral genomes and further subjected to primer-based genotyping to identify the various serotypes present. For each water sample, several water quality parameters were evaluated, including heterotrophic plate count, total coliform, Escherichia coli, water temperature, pH, conductivity, and dissolved oxygen. Among the 13 rivers examined, four rivers (30.8 %) were found to contain HAdVs. The major genotype was F species HAdV serotype 41. The mean HAdVs concentrations ranged from 6.10 × 10(2) to 8.51 × 10(2) copies/L. No significant differences were observed between the presence of HAdVs, and all of the water quality parameters evaluated (heterotrophic plate count, total coliform, E. coli, water temperature, pH, conductivity, and dissolved oxygen). Given the potential health risks posed by the presence of enteric viruses in environmental waters, further assessment is desirable with respect to possible sources, virus transport, and survival of viruses in the aquatic environment.

Prevalence and distribution of different diarrhoeagenic Escherichia coli virulotypes in major water bodies in Bangladesh.

Escherichia coli, a prominent waterborne pathogen, causes a variety of gastrointestinal and extraintestinal infections that depend on virulence determinants. To monitor natural aquatic systems for virulence-associated genes of E. coli, multiplex PCR was used in a survey covering 46 major natural water bodies in Bangladesh. DNA was extracted directly from water samples as well as from pre-enriched and enriched cultures during three successive seasons and assessed for E. coli virulotype distribution. From the five virulotypes, genes from the enterotoxigenic (ETEC), enteropathogenic (EPEC), and enterohaemorrhagic (EHEC) virulotypes were detected consistently, but genes from the enteroinvasive (EIEC) and enteroaggregative (EAEC) virulotypes were traced only occasionally. ETEC was the most prevalent virulotype, followed by EPEC. However, EIEC and EAEC virulotypes could not be detected in winter or the rainy season, respectively. Specific regional distribution patterns of different E. coli virulotypes and their temporal fluctuations were identified. These observations may assist with assessing seasonal risk and identifying vulnerable areas of the country prone to E. coli-associated outbreaks.

Physical and chemical effects of ingested plastic debris on short-tailed shearwaters, Puffinus tenuirostris, in the North Pacific Ocean.

We investigated the plastics ingested by short-tailed shearwaters, Puffinus tenuirostris, that were accidentally caught during experimental fishing in the North Pacific Ocean in 2003 and 2005. The mean mass of plastics found in the stomach was 0.23 g per bird (n=99). Plastic mass did not correlate with body weight. Total PCB (sum of 24 congeners) concentrations in the abdominal adipose tissue of 12 birds ranged from 45 to 529 ng/g-lipid. Although total PCBs or higher-chlorinated congeners, the mass of ingested plastic correlated positively with concentrations of lower-chlorinated congeners. The effects of toxic chemicals present in plastic debris on bird physiology should be investigated.

Marine debris impacts to a tidal fringing-marsh in North Carolina.

We evaluated injuries to Spartina alterniflora by debris items common to North Carolina coastal waters as a function of debris type (wire blue crab pots, vehicle tires, and anthropogenic wood) and deployment duration, and monitored S. alterniflora recovery following debris removal. Injuries sustained by S. alterniflora and subsequent recovery, varied considerably between debris types. Differences were likely due to dissimilarities in the structure and composition of debris. Tires caused an immediate (within 3 weeks) and long-term impact to S. alterniflora; tire footprints remained devoid of vegetation 14 months post-removal. Conversely, crab pot impacts were not as abrupt and recovery was short-term (<10 months). We suggest that removal programs specifically target habitats that are susceptible to negative impacts (e.g., salt marsh) and prone to debris accumulation. Management would benefit from the inclusion of habitat information in removal databases.

Characterization of marine debris in North Carolina salt marshes.

Marine debris composition, density, abundance, and accumulation were evaluated in salt marshes in Carteret County, North Carolina seasonally between 2007 and 2009. We assessed relationships between human use patterns and debris type. Wave effects on marine debris density were examined using a GIS-based forecasting tool. We assessed the influence of site wave exposure, period, and height on debris quantity. Presence and abundance of debris were related to wave exposure, vegetation type and proximity of the strata to human population and human use patterns. Plastic pieces accounted for the majority of all debris. Small debris (0-5 cm) was primarily composed of foam pieces and was frequently affiliated with natural wrack. Large debris (>100 cm) was encountered in all marsh habitat types surveyed and was primarily composed of anthropogenic wood and derelict fishing gear. Marsh cleanup efforts should be targeted to specific habitat types or debris types to minimize further damage to sensitive habitats.

Plastic marine debris on the Portuguese coastline: a matter of size?

Plastic debris is a worldwide threat to marine environments and Portugal is not immune to it. Though never quantified, items of all sizes can be found in the Portuguese coastline; therefore the objective of this work is the identification of main size classes in stranded plastic debris. Beaches sediment was sampled and in the laboratory plastic items were sorted in 11 classes from <1 to >10mm, counted and weighted. Plastic size ranged from 50 µm to 20 cm and microplastics (<5mm) were the majority (72%). Most plastic fits in the smaller size classes, due to expected high residence time in the sea enhancing degradation processes, which increase surface exposure and potentially persistent organic pollutants (POP) adsorption. These results point out the important contribution of microplastics to marine debris pollution, its risks, and the need to set a higher focus on this size class.

The abundance, composition and sources of marine debris in coastal seawaters or beaches around the northern South China Sea (China).

The abundance and composition of marine debris including floating marine debris (FMD), seafloor marine debris (SMD) and beached marine debris (BMD) were investigated in coastal seawaters/beaches around the northern South China Sea during 2009 and 2010. The FMD density was 4.947 (0.282-16.891) items/km², with plastics (44.9%) and Styrofoam (23.2%) dominating. More than 99.0% of FMD was small or medium size floating marine debris. The SMD and BMD densities of were 0.693 (0.147-5.000) and 32.82 (2.83-375.00) items/km², respectively. SMD was composed of plastics (47.0%), wood (15.2%), fabric/fiber (13.6%) and glass (12.1%), while BMD was composed of plastics (42.0%) and wood (33.7%). More than 90% of FMD, 75% of SMD and 95% of BMD were not ocean-based sources but land-based sources, mostly attributed to coastal/recreational activity, because of the effect of human activities in the areas.

Microbial risk assessment for recreational use of the Chicago area waterway system.

A microbial risk assessment was conducted to estimate the human health risks from incidental contact recreational activities such as canoeing, boating and fishing in the Chicago Area Waterway System (CAWS) receiving secondary treated, but non-disinfected, effluent from three municipal water reclamation plants. Actual concentrations of the pathogens (pathogenic E. coli [estimated], Giardia, Cryptosporidium, adenovirus, norovirus, enteric virus) detected from the waterway field data collection at locations upstream and downstream of the effluent outfall during dry and wet weather conditions within the recreation season were included in the risk assessment. The results under the current treatment scheme with no disinfection indicated that the total expected gastrointestinal illness (GI) rate per 1000 incidental contact recreational exposure events during combined weather (dry and wet) conditions ranged from 0.10 to 2.78 in the CAWS, which is below the eight illnesses per 1000 swimmers considered tolerable by the United States Environmental Protection Agency. Wet weather conditions contribute to elevated pathogen load to the CAWS; therefore this study determined that disinfecting the effluents of three major WRPs that discharge to the CAWS would result in an extremely small reduction in the aggregate recreation season risk to incidental contact recreators.

Quantitative analysis of human and cow-specific 16S rRNA gene markers for assessment of fecal pollution in river waters by real-time PCR.

The base sequences representing human and cow-specific 16S rRNA gene markers identified in the T-RFLP analysis were recovered from clone libraries. The human and cow-specific primers were designed from these sequences and their specificities were analyzed with fecal DNAs from human, cow, and pig. AllBac primer set showed positive results for all human, cow, and pig samples, while human-specific primer set showed positive result only for human sample but not for cow or pig samples. Likewise, cow-specific primer set showed positive results only for cow sample but not for human or pig samples. Real-time PCR assay with these primers was developed for the identification and quantification of fecal pollution in the river water. The human and cow-specific markers were detected in the order of 9 log(10) copies per gram wet feces which were two orders of magnitude lower than those of total Bacteroidales. For the river water samples, the human-specific marker was detected in 1.7-6.2 log(10) copies/100 ml water which was 2.4-4.9 orders of magnitude lower than those of total Bacteroidales. There was no significant correlation between total Bacteroidales and conventional fecal indicators, but there was a high correlation between Bacteroidales and human-specific marker. This assay could reliably identify and quantify the fecal pollution sources, enabling effective measures in the watersheds and facilitating water quality management.

[Epidemic hazard of water use in the reactivation of bacteria after disinfection].

Variability in the cultural and biochemical properties of indicator, opportunistic, and pathogenic bacteria and possibilities of their reactivation after exposure to chlorine-containing reagents and during photo-activated disinfection processes in the presence of photosensitizes were experimentally studied to enhance the epidemic reliability and adequacy of microbiological monitoring in the evaluation of the decontamination efficiency of water of its various use types. Reactivation of coliform bacteria, enterococci, salmonellas, and the total number of microbes were estimated after exposure to the bacteriostatic doses of sodium hypochlorite and chlorine dioxide when the river and waste waters were decontaminated. During photo-activated disinfection under the action of the photosensitizers methylene blue and proflavin acetate given in the bacteriostatic doses, there was transition into the uncultivated state, followed by 1-5-day reactivation of both museum strains and strains isolated from waste waters, such as Salmonella infantis spp, Salmonella enteritidis spp, Salmonella enteritidis 5765 ATCC, Pseudomonas aeruginosa 10145, Pseudomonas aeruginosa spp, Escherichia coli 1257, Staphylococcus aureus 906, and Enterococcus faecalis 29212. Moreover, Pseudomonas and Salmonellas not only regained their viability, but also multiplied up to the control level. Recommendations are given how to improve methods for monitoring the efficiency of disinfection, by taking into account a possible variability in the cultural and biochemical properties of bacteria and for reactivation by monitoring the trend in the process during 5 days.

Chemometric approach to validating faecal sterols as source tracer for faecal contamination in water.

Faecal sterols detection is a promising method for identifying sources of faecal pollution. In this study, faecal contamination in water samples from point source (sewage treatment plants, chicken farms, quail farms and horse stables) was extracted using the solid phase extraction (SPE) technique. Faecal sterols (coprostanol, cholesterol, stigmasterol, beta-sitosterol and stigmastanol) were selected as parameters to differentiate the source of faecal pollution. The results indicated that coprostanol, cholesterol and beta-sitosterol were the most significant parameters that can be used as source tracers for faecal contamination. Chemometric techniques, such as cluster analysis, principal component analysis and discriminant analysis were applied to the data set on faecal contamination in water from various pollution sources in order to validate the faecal sterols' profiles. Cluster analysis generated three clusters: coprostanol was in cluster 1, cholesterol and beta-sitosterol formed cluster 2, while cluster 3 contained stigmasterol and stigmastanol. Discriminant analysis suggested that coprostanol, cholesterol and beta-sitosterol were the most significant parameters to discriminate between the faecal pollution source. The use of chemometric techniques provides useful and promising indicators in tracing the source of faecal contamination.

Seasonal variation in membrane fouling in membrane bioreactors (MBRs) treating municipal wastewater.

We investigated seasonal variation in membrane fouling in membrane bioreactors (MBRs) treating municipal wastewater regarding the difference between physically reversible and irreversible fouling. Two separate MBRs with different solid retention times (SRTs) operated in parallel for about 200 days including high- and low-temperature periods to evaluate the effect of operating conditions on seasonal variation of membrane fouling. Seasonal variations of both types of membrane fouling (i.e., physically reversible and irreversible fouling) were observed for the MBR with short SRT (13 days). However, in the MBR with long SRT (50 days), there were no significant seasonal variations in both types of membrane fouling. In the MBR with short SRT, the trends in the seasonal variation in the development rates of physically reversible and irreversible fouling were different. Physically reversible fouling was more significant in the low-temperature period, while physically irreversible fouling developed more rapidly in the high-temperature period. The development rates of physically reversible fouling can be related to the concentration of dissolved organic matter in the mixed liquor suspension of MBRs; whereas those of physically irreversible fouling could not be explained by the concentration of dissolved organic matter. The characteristics of dissolved organic matter differed depending on the temperature period, and the trends of dissolved organic matter variation in mixed liquor were similar with those of foulants that caused physically irreversible fouling. The results obtained in this study indicated that seasonal variation in physically reversible and irreversible fouling is related to changes in quantity and quality of organic matter, respectively.

Formation of categories from structure-activity relationships to allow read-across for risk assessment: toxicity of alpha,beta-unsaturated carbonyl compounds.

alpha,beta-Unsaturated carbonyl compounds are common environmental pollutants that are able to interact with proteins, enzymes, and DNA through various mechanisms. As such, they are able to stimulate a range of environmental toxicities and adverse health effects. In this study, a "category" of alpha,beta-unsaturated carbonyl compounds (aldehydes and ketones), assumed to act by a common mechanism of action (Michael type addition), was formed. This toxicologically and mechanistically important category was formed on the premise of structure-activity relationships. The acute aquatic toxicities to Tetrahymena pyriformis of compounds within the category were obtained in an effort to develop approaches for (qualitative) read-across. In addition, Salmonella typhimurium (strain TA100) mutagenicity data were analyzed to establish the structural differences between mutagenic and nonmutagenic compounds. These structural differences were compared with the structural characteristics of molecules associated with acute aquatic toxicity in excess of narcosis as well as other end points, for example, skin sensitization. The results indicate that a category can be formed that allows structural information and boundaries to be elucidated. This knowledge will guide future toxicity prediction within this category and assist in the development of category formation.

A discrete, stochastic model and correction method for bacterial source tracking.

We have developed a model to test several underlying assumptions of bacterial source tracking (BST) when the BST method is based on detection of discrete genetic markers from source-specific bacteria. The model consists of an environment and discrete-time input signals that represent sources of contamination partitioned into marker-bearing and nonmarker-bearing units "shed" into the environment. Simulations run for different types of environmental contamination patterns indicate that if hosts shed different percentages of BST markers, the environment cannot be accurately characterized unless a correction method is used. The correction method, which requires the solution to a linear system, reduces the mean error in estimating the proportions of host contamination to below 3%. The effectiveness of the method depends on accurate knowledge of the occurrence and prevalence of markers in the various hosts; this may be a challenging task, especially if these values vary across populations in space and time. In addition, the correction method does not compensate for environments with low-density or unmixed contamination. In conclusion, our simulations highlight several fundamental challenges that may prevent absolute quantification of fecal input using discrete marker BST.

Identification of culturable stream water bacteria from urban, agricultural, and forested watersheds using 16S rRNA gene sequencing.

Bacteria present in water samples taken on a weekly basis, from June 2004 through June 2005, from three streams, were cultured on Coliscan Easygel agar plates. Colonies representative of a variety of colors and morphologies were subjected to amplification and sequencing of a 1000-1100 nt portion of the 16S rRNA gene. A total of 528 colonies were sequenced; these categorized into 26 genera and 78 species. Of 175 dark blue/purple colonies presumed to be E. coli, sequence analysis indicated that 45 (25%) were actually other genera. For the urban stream Gwynns Falls Gwynns Run, E. coli was the most common genus/species encountered, followed by Klebsiella and Aeromonas. For Pond Branch, a stream located in a forested watershed, it was Serratia, followed by Yersinia and Aeromonas. For McDonogh (MCDN), a stream associated with Zea mays (corn) row crop agriculture, E. coli was the most frequently isolated genus/species, followed by Aeromonas and Enterobacter. ERIC-PCR genotyping of isolates from the most prevalent genera/species, indicated a high degree of diversity within-stream for E. coli and K. pneumoniae. Conversely, genotyping of Y. enterocolitica isolates indicated that some were shared between different streams.

Comparisons of water quality parameters from diverse catchments during dry periods and following rain events.

In this study, 12 catchments sites located along the north coast of New South Wales in Australia were grouped into the four categories of septic, cattle, sewage treatment plant (STP) and forested sites via cluster analysis based on their land use patterns. Water samples from all these sites were collected between October 2004 and June 2006 at a regular monthly interval and within 48 h of rain events. The samples were analyzed for bacterial counts including faecal coliform and total coliform; faecal sterols including coprostanol, epicoprostanol, cholesterol, cholestanol, 24-ethylcoprostanol, campesterol, stigmasterol and beta-sitosterol; and the elements including Na, Rb, Sr, Ag, Cd, Sn, Cs, Ba, Hg, Tl, Pb, Bi, U, Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, K, As, Se, P and Mo. Over the course of the sampling period, the STP site had the highest average coprostanol level of 1693+/-567 ng/L which was significantly higher (p<0.05) than the septic sites (190+/-71 ng/L), the cattle sites (163+/-94 ng/L) and forested sites (14+/-4 ng/L). As expected, the forested sites had significantly lower average level of faecal coliforms (373+/-87 cfu/100 mL) compared with the STP (1395+/-574 cfu/100 mL), septic (1243+/-494 cfu/100 mL) and cattle sites (535+/-112 cfu/100 mL). The concentrations of coprostanol were not correlated with the numbers of faecal coliform bacteria when the entire data set was evaluated. The forested sites generally had the lowest average levels of elemental compositions, with significantly lower levels noted for Na, U, Mg, V, Cu, Sr, K, As, P and Mo, whereas Fe was the only element notably higher in the forested sites. Temporal and rain events analyses of the data set revealed that elevated levels of both coprostanol and faecal coliforms were not exclusive to rain events. The average coprostanol levels in rain event samples at each site were not significantly different compared with the corresponding dry event samples. Conversely, faecal coliform numbers increased by 2-4 times in rain events samples from septic, cattle and forested sites, but did not alter in the STP site. Multivariate analyses identified coprostanol and Sr as major contributing factors for the discrimination of septic, cattle, STP and forested sites for both rain and dry events samples. It was clear that each land use type of catchment could be characterized by biochemical, bacteriological and elemental parameters.

Comparative quantitative structure-activity-activity relationships for toxicity to Tetrahymena pyriformis and Pimephales promelas.

An approach for predicting acute aquatic toxicity, in the form of a quantitative structure-activity-activity relationship (QSAAR), is described. This study assessed relative toxic effects to a fish, Pimephales promelas, and a ciliate, Tetrahymena pyriformis, and attempted to form relationships between them. A good agreement between toxic potencies (R2 = 0.754) was found for a chemically diverse dataset of 364 compounds, when using toxicity to the ciliate as a surrogate to that for fish. This relationship was extended by adding three theoretical structural descriptors of the molecules. The inclusion of these descriptors improved the relationship further (R2 = 0.824). The structural features that were found to improve the extrapolation between the toxicity to the two different species were related to the electron distribution of the carbon skeleton of the toxicant, its hydrogen-bonding ability, and its relative nitrogen content. Such a QSAAR approach provides a potential tool for predicting the toxicities of chemicals for environmental risk assessment and thus for reducing animal tests.