Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Zhantao Han , Badruddeen Sani , Wojciech Mrozik , Martin Obst , Barbara Beckingham , Hrissi K. Karapanagioti , David Werner This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m 2 /g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m 2 /g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): A.C. Akram , S. Noman , R. Moniri-Javid , J.P. Gizicki , E.A. Reed , S.B. Singh , A.S. Basu , F. Banno , M. Fujimoto , J.L. Ram Methods for verifying ballast water treatments in foreign vessels are needed to protect the Great Lakes from the discharge of live non-native organisms or pathogens. A prototype automated viability test system using fluorescein diacetate (FDA), a membrane permeable fluorogen, to differentiate live from dead bacteria and algae is described. The automated fluorescence intensity detection device (AFIDD) captures cultured algae or organisms in Detroit River water (simulated ballast water) on 0.2 μm filters, backwashes them from the filter into a cuvette with buffer and FDA for subsequent fluorescence intensity measurements, and washes the filters with sterile water for serial automated reuse. Preliminary manual versions of these procedures were also tested. Tests of various buffers determined N,N-Bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, N,N-Bis(2-hydroxyethyl)taurine (BES) and 3-(N-morpholino)propanesulfonic acid (MOPS) at pH 7.0 to be the best buffers, causing the least spontaneous FDA breakdown without inhibiting enzymatic activity. Fluorescence in the presence of live organisms increased linearly over time, and the rate of increase was dependent on the sample concentration. Following simulated ballast water treatments with heat or chlorine, the fluorescence produced by Detroit River samples decreased to near control (sterile water) levels. Automated measurements of FDA hydrolysis with a reusable filter backwash system should be applicable to near real-time remote-controlled monitoring of live organisms in ballast water. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Yusak Hartanto , Seonho Yun , Bo Jin , Sheng Dai Stimuli-responsive hydrogels were recently proposed for energy-saving forward osmosis (FO) process. However, their low water flux and dewatering ability for reuse make them less attractive for industrial desalination process. In this work, the co-polymer microgels of N-isopropylacrylamide and acrylic acid with different mixing ratios were synthesized using surfactant-free emulsion polymerization to produce submicron-size hydrogels with high surface area and fast swelling-deswelling response. The microgels were employed as draw agents in a laboratory scale FO desalination system. The microgel-based FO process performed a high water flux up to 23.8 LMH and high water recovery ability of 72.4%. In addition, we explored a new conductivity measurement method to online analyze water flux of the FO system. This on-line conductivity analysis approach appeared to be an accurate and efficient method for evaluating microgel-based FO desalination performance. Our experimental data revealed that the stimuli-responsive microgel was an efficient draw agent for FO desalination. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): S. Beecham , M. Razzaghmanesh Low-energy pollutant removal strategies are now being sought for water sensitive urban design. This paper describes investigations into the water quality and quantity of sixteen, low-maintenance and unfertilized intensive and extensive green roof beds. The factors of Slope (1° and 25°), Depth (100 mm and 300 mm), Growing media (type A, type B and type C) and Species (P1, P2 and P3) were randomized according to a split–split plot design. This consisted of twelve vegetated green roof beds and four non-vegetated beds as controls. Stormwater runoff was collected from drainage points that were installed in each area. Samples of run-off were collected for five rainfall events and analysed for water retention capacity and the water quality parameters of NO 2 , NO 3 , NH 4 , PO 4 , pH, EC, TDS, Turbidity, Na, Ca, Mg and K. The results indicated significant differences in terms of stormwater water quality and quantity between the outflows of vegetated and non-vegetated systems. The water retention was between 51% and 96% and this range was attributed to the green roof configurations in the experiment. Comparing the quality of rainfall as inflow, and the quality of runoff from the systems showed that green roofs generally acted as a source of pollutants in this study. In the vegetated beds, the intensive green roofs performed better than the extensive beds with regard to outflow quality while in the non-vegetated beds, the extensive beds performed better than intensive systems. This highlights the importance of vegetation in improving water retention capacity as well as the role of vegetation in enhancing pollutant removal in green roof systems. In addition growing media with less organic matter had better water quality performance. Comparison of these results with national and international standards for water reuse confirmed that the green roof outflow was suitable for non-potable uses such as landscape irrigation and toilet flushing.

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Clémence Sicard , Chad Glen , Brandon Aubie , Dan Wallace , Sana Jahanshahi-Anbuhi , Kevin Pennings , Glen T. Daigger , Robert Pelton , John D. Brennan , Carlos D.M. Filipe In this paper we describe a combination of paper-based sensors and a novel smart-phone application for on-site quantification of colorimetric readouts as an ultra-low cost solution to monitoring water quality. The system utilizes a paper-based analytical device (μPAD) that produces a colorimetric signal that is dependent on the concentration of a specific target; a cell phone equipped with a camera for capturing images of two μPADs – one tested with a water sample and the other tested with clean water that is used as a control; and an on-site image processing app that uses a novel algorithm for quantifying color intensity and relating this to contaminant concentration. The cell phone app utilizes a pixel counting algorithm that performs with less bias and user subjectivity than the typically used lab-based software, ImageJ . The use of a test and control strip reduces bias from variations in ambient lighting, making it possible to acquire and process images on-site. The cell phone is also able to GPS tag the location of the test, and transmit results to a newly developed website, WaterMap.ca™, that displays the quantitative results from the water samples on a map. We demonstrate our approach using a previously developed μPAD that detects the presence of organophosphate pesticides based on the inhibition of immobilized acetylcholinesterase by these contaminants. The objective of this paper is to highlight the importance and potential of developing and integrated monitoring system consisting of μPADs, cell-phones and a centralized web portal for low-cost monitoring environmental contaminants at a large-scale. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Yiping Cao , Meredith R. Raith , John F. Griffith Despite wide application to beach water monitoring and microbial source identification, results produced by quantitative PCR (qPCR) methods are subject to bias introduced by reliance on quantitative standards. Digital PCR technology provides direct, standards-free quantification and may potentially alleviate or greatly reduce other qPCR limitations such as difficulty in multiplexing and susceptibility to PCR inhibition. This study examined the efficacy of employing a duplex droplet digital PCR (ddPCR) assay that simultaneously quantifies Enterococcus spp. and the human fecal-associated HF183 marker for water quality assessment. Duplex ddPCR performance was evaluated side-by-side with qPCR and simplex ddPCR using reference material and 131 fecal and water samples. Results for fecal and water samples were highly correlated between ddPCR and simplex qPCR (coefficients > 0.93, p 〈 0.001). Duplexing Enterococcus and HF183 in qPCR led to competition and resulted in non-detection or underestimation of the target with low concentration relative to the other, while results produced by simplex and duplex ddPCR were consistent and often indistinguishable from one another. ddPCR showed greater tolerance for inhibition, with no discernable effect on quantification at inhibitor concentrations one to two orders of magnitude higher than that tolerated by qPCR. Overall, ddPCR also exhibited improved precision, higher run-to-run repeatability, similar diagnostic sensitivity and specificity on the HF183 marker, but a lower upper limit of quantification than qPCR. Digital PCR has the potential to become a reliable and economical alternative to qPCR for recreational water monitoring and fecal source identification. Findings from this study may also be of interest to other aspects of water research such as detection of pathogens and antibiotic resistance genes. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Yiwen Liu , Bing-Jie Ni , Ramon Ganigué , Ursula Werner , Keshab R. Sharma , Zhiguo Yuan Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m 2 ·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH 4 /m 2 ·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Xiaoyan Sun , Guangming Jiang , Philip L. Bond , Jurg Keller , Zhiguo Yuan Improved technologies are currently required for mitigating microbially induced concrete corrosion caused by the oxidation of sulfide to sulfuric acid in sewer systems. This study presents a novel strategy for reducing H 2 S oxidation on concrete surfaces that accommodate an active corrosion biofilm. The strategy aims to reduce biological oxidation of sulfide through treating the corrosion biofilm with free nitrous acid (FNA, i.e. HNO 2 ). Two concrete coupons with active corrosion activity and surface pH of 3.8 ± 0.3 and 2.7 ± 0.2 were sprayed with nitrite. For both coupons, the H 2 S uptake rates were reduced by 84%–92% 15 days after the nitrite spray. No obvious recovery of the H 2 S uptake rate was observed during the entire experimental period (up to 12 months after the spray), indicating the long-term effectiveness of the FNA treatment in controlling the activity of the corrosion-causing biofilms. Live/Dead staining tests on the microorganisms on the concrete coupon surfaces demonstrated that viable bacterial cells decreased by > 80% 39 h after the nitrite spray, suggesting that biofilm cells were killed by the treatment. Examination of a corrosion layer within a suspended solution, containing the corrosion-causing biofilms, indicated that biological activity (ATP level and ratio of viable bacterial cells) was severely decreased by the treatment, confirming the bactericidal effect of FNA on the microorganisms in the biofilms. While field trials are still required to verify its effectiveness, it has been demonstrated here that the FNA spray is potentially a very cheap and effective strategy to reduce sewer corrosion. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Bing Han , Man Zhang , Dongye Zhao , Yucheng Feng Manganese oxide (MnO 2 ) was reported to be effective for degrading aqueous pharmaceutical chemicals. However, little is known about its potential use for degrading soil-sorbed contaminants. To bridge this knowledge gap, we synthesized, for the first time, a class of stabilized MnO 2 nanoparticles using carboxymethyl celluloses (CMC) as a stabilizer, and tested their effectiveness for degrading aqueous and soil-sorbed estradiol. The most desired particles (highest reactivity and soil deliverability) were obtained at a CMC/MnO 2 molar ratio of 1.39 × 10 −3 , which yielded a mean hydrodynamic size of 39.5 nm and a narrow size distribution (SD = 0.8 nm). While non-stabilized MnO 2 particles rapidly aggregated and were not transportable through a soil column, CMC-stabilized nanoparticles remained fully dispersed in water and were soil deliverable. At typical aquatic pH (6–7), CMC-stabilized MnO 2 exhibited faster degradation kinetics for oxidation of 17β-estradiol than non-stabilized MnO 2 . The reactivity advantage becomes more evident when used for treating soil-sorbed estradiol owing to the ability of CMC to complex with metal ions and prevent the reactive sites from binding with inhibitive soil components. A retarded first-order rate model was able to interpret the oxidation kinetics for CMC-stabilized MnO 2 . When used for degrading soil-sorbed estradiol, several factors may inhibit the oxidation effectiveness, including desorption rate, soil–MnO 2 interactions, and soil-released metals and reductants. CMC-stabilized MnO 2 nanoparticles hold the potential for facilitating in situ oxidative degradation of various emerging contaminants in soil and groundwater. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Nadine Ruchter , Bernd Sures Platinum is part of traffic-emitted metals since the introduction of automotive catalyst converters. Still, automobile emissions are one of the major sources for metals in European river systems. However, field data on Pt is scarce and there is a lack of knowledge concerning the distribution and biological availability of Pt. Therefore, the distribution of traffic related metals (Cd, Cr, Cu, Ni, Pb, Pt, and Zn) was analyzed in sediment samples and in the Asian clam Corbicula sp. Samples were taken from three transects following road runoff inlets. Pt was introduced into the river by road runoff. The highest Pt concentrations in sediments were analyzed in the silt/clay fraction (45 ng/g), while the highest total Pt burden was obtained for the sand fraction, that makes up more than 60% of the sediment. Metal concentrations were related to the area of the drained street section as well as to their distance from the discharge point, and to grain size distribution within the sediment. Pt and other traffic related metals were accumulated by clams. Due to the feeding behavior of the freshwater mussel Corbicula sp. Pt concentrations in the soft tissue remain relatively low (max Pt concentration: 1.3 ng/g freeze dried soft tissue) and acute lethal or toxic effects therefore appear to be unlikely. Nonetheless, chronic exposure effects still have to be examined. Graphical abstract