Monthly Archives: October 2013

Biological treatment for drinking water?

J. Benner, D.E. Helbling, H.-P. E. Kohler, J. Wittebol, E. Kaiser, C. Prasse, T.A. Ternes, C.N. Albers, J. Aamand, B. Horemans, D. Springael, E. Walravens, N. Boon. Is biological treatment a viable alternative for micropollutant removal in drinking water treatment processes? Water Research. Oct2013, Vol. 47 Issue 16, p5955-5976.

In western societies, clean and safe drinking water is often taken for granted, but there are threats to drinking water resources that should not be underestimated. Contamination of drinking water sources by anthropogenic chemicals is one threat that is particularly widespread in industrialized nations. Recently, a significant amount of attention has been given to the occurrence of micropollutants in the urban water cycle. Micropollutants are bioactive and/or persistent chemicals originating from diverse sources that are frequently detected in water resources in the pg/L to μg/L range. The aim of this review is to critically evaluate the viability of biological treatment processes as a means to remove micropollutants from drinking water resources. We first place the micropollutant problem in context by providing a comprehensive summary of the reported occurrence of micropollutants in raw water used directly for drinking water production and in finished drinking water. We then present a critical discussion on conventional and advanced drinking water treatment processes and their contribution to micropollutant removal. Finally, we propose biological treatment and bioaugmentation as a potential targeted, cost-effective, and sustainable alternative to existing processes while critically examining the technical limitations and scientific challenges that need to be addressed prior to implementation. This review will serve as a valuable source of data and literature for water utilities, water researchers, policy makers, and environmental consultants. Meanwhile this review will open the door to meaningful discussion on the feasibility and application of biological treatment and bioaugmentation in drinking water treatment processes to protect the public from exposure to micropollutants.

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Fluorosis in the Libyan Population

Sunil T K L, Shetty S, Annapoorna B M, Pujari S C, Reddy P S, Nandlal B. A Pioneering Study of Dental Fluorosis in the Libyan Population. J Int Oral Health 2013; 5(3):67-72.

Background: Fluorosis is a condition resulting from excessive ingestion of fluoride during early childhood leading to the formation of defective enamel. The increased fluoride content is thought to result in a metabolic alteration of ameloblasts, which results in defective matrix, and improper calcification of teeth.

Materials and Methods: A total of 6244 patients between the ages of 6yrs to 60yrs, who presented to our outpatient clinic from October 2009 to December 2010 were included in the study. The study subjects were grouped according to their age into the following groups- 6-14 yrs, 15-25 yrs, 26-40 yrs, and 40-60yrs. Only permanent dentition was taken into consideration in this study.

Results: The overall prevalence of fluorosis in this study was 63.34% (3955 of 6244 patients). Men had a slightly higher prevalence of 64.27% compared to 62.28% among women.

Conclusion: Prevention of fluorosis would require efforts at raising awareness among the people about the harmful effects of their dietary choices on their teeth. They also need to be educated about adequate and proper oral hygiene, such as brushing their teeth at least two times daily.

Global ocean warming has decelerated

The ocean plays a very important role in the earth energy budget. For more discussion of this study click here.

Dean Roemmich, W. John Gould, John Gilson. The 135 years of global ocean warming between the Challenger expedition and the Argo Programme. Nature Climate Change. 2:425–428 (2012) DOI:doi:10.1038/nclimate1461

Changing temperature throughout the oceans is a key indicator of climate change. Since the 1960s about 90% of the excess heat added to the Earth’s climate system has been stored in the oceans1, 2. The ocean’s dominant role over the atmosphere, land, or cryosphere comes from its high heat capacity and ability to remove heat from the sea surface by currents and mixing. The longest interval over which instrumental records of subsurface global-scale temperature can be compared is the 135 years between the voyage of HMS Challenger3 (1872–1876) and the modern data set of the Argo Programme4 (2004–2010). Argo’s unprecedented global coverage permits its comparison with any earlier measurements. This, the first global-scale comparison of Challenger and modern data, shows spatial mean warming at the surface of 0.59 °C±0.12, consistent with previous estimates5 of globally averaged sea surface temperature increase. Below the surface the mean warming decreases to 0.39 °C±0.18 at 366 m (200 fathoms) and 0.12 °C±0.07 at 914 m (500 fathoms). The 0.33 °C±0.14 average temperature difference from 0 to 700 m is twice the value observed globally in that depth range over the past 50 years6, implying a centennial timescale for the present rate of global warming. Warming in the Atlantic Ocean is stronger than in the Pacific. Systematic errors in the Challenger data mean that these temperature changes are a lower bound on the actual values. This study underlines the scientific significance of the Challenger expedition and the modern Argo Programme and indicates that globally the oceans have been warming at least since the late-nineteenth or early-twentieth century.

PFOA degradation under natural sunlight

Liu D, Xiu Z, Liu F, Wu G, Adamson D, Newell C, Vikesland P, Tsai AL, Alvarez PJ. Perfluorooctanoic acid degradation in the presence of Fe(III) under natural sunlight. J Hazard Mater. 2013 Sep 8;262C:456-463. doi: 10.1016/j.jhazmat.2013.09.001.

Due to the high bond dissociation energy (BDE) of CF bonds (116kcal/mol), perfluorooctanoic acid (PFOA) is a highly recalcitrant pollutant. Herein, we demonstrate a novel method to decompose PFOA in the presence of sunlight and ferric iron (Fe(III)). Under such conditions, 97.8±1.7% of 50μM PFOA decomposed within 28 days into shorter-chain intermediates and fluoride (F-), with an overall defluorination extent of 12.7±0.5%. No PFOA was removed under visible light, indicating that UV radiation is required for PFOA decomposition. Spectroscopic analysis indicates that the decomposition reaction is likely initiated by electron-transfer from PFOA to Fe(III), forming Fe(II) and an unstable organic carboxyl radical. An alternative mechanism for the formation of this organic radical involves hydroxyl radicals, detected by electron paramagnetic resonance (EPR). The observation that PFOA can be degraded by Fe(III) under solar irradiation provides mechanistic insight into a possibly overlooked natural attenuation process. Because Fe(III) is abundant in natural waters and sunlight is essentially free, this work represents a potentially important step toward the development of simple and inexpensive remediation strategies for PFOA-contaminated water.

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Fluoride removal using bauxite

Atasoy AD, Yesilnacar MI, Sahin MO. Removal of Fluoride from Contaminated Ground Water Using Raw and Modified Bauxite. Bull Environ Contam Toxicol. 2013 Sep 27.

Endemic fluorosis affects millions of people worldwide. Fluorosis arises from the consumption of fluorine (F) contaminated water and was observed also in some parts of Turkey with volcanic rocks and geothermal resources. In the present study the removal of F from drinking water by raw and modified bauxite at the laboratory scale was investigated using a batch mode. Modified bauxite was prepared by using Na and Mg incorporated (B-Na, B-Mg) bauxite and calcination of Mg incorporated bauxite at 500°C (B-Mg-500). The equilibration time for F between bauxite and water was identified to be 3 h. Adsorption of F increased with increasing adsorbent dose. Moreover, F adsorption isotherms fitted well with the Freundlich model. Low F adsorption was obtained onto the raw and incorporated bauxite. In contrast, maximum F adsorption was found for B-Mg-500, with Kf value of 0.247. This observation may be explained by the meaningfully stabilized and elevated number of positively charged sites in B-Mg-500.

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Adenovirus and polyomavirus as indicators of human sewage contamination

Hewitt J, Greening GE, Leonard M, Lewis GD. Evaluation of human adenovirus and human polyomavirus as indicators of human sewage contamination in the aquatic environment. Water Res. 2013 Sep 19. pii: S0043-1354(13)00678-7. doi: 10.1016/j.watres.2013.09.001.

Discharge of inadequately treated human wastewater into surface waters used for recreation, drinking water, irrigation and shellfish cultivation may present a public health hazard due to the potential shedding of high concentrations of pathogenic viruses from the human gastrointestinal tract. Human adenovirus (HAdV) and human polyomavirus (HPyV) are ubiquitous in humans and have excellent survival characteristics in the environment, so are potential candidates for indicators of human sewage contamination. Using qPCR assays, the prevalence and quantity of HAdV and HPyV JC and BK were determined in influent and effluent wastewater and receiving waters (river, urban stream, estuarine), then compared with norovirus (NoV) presence, a significant human pathogen which is not necessarily ubiquitously excreted into the environment. HAdV and HPyV were frequently detected in high concentrations in wastewater and wastewater-contaminated waters confirming their use as potential indicators for the presence of human sewage. Overall, there was a correlation between the presence of HAdV and HPyV with NoV but there were some notable exceptions including the higher frequency of NoV compared to HAdV and HPyV in estuarine waters impacted by wastewater overflows. We found that HAdV and HPyV detection by qPCR was a suitable tool for evaluating water quality and that their detection can aid in determining pollution sources, thus providing useful information for health risk assessments.

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Pharmaceuticals in US wastewater treatment plant effluents

Kostich MS, Batt AL, Lazorchak JM. Concentrations of prioritized pharmaceuticals in effluents from 50 large wastewater treatment plants in the US and implications for risk estimation. Environ Pollut. 2013 Oct 2;184C:354-359. doi: 10.1016/j.envpol.2013.09.013.

We measured concentrations of 56 active pharmaceutical ingredients (APIs) in effluent samples from 50 large wastewater treatment plants across the US. Hydrochlorothiazide was found in every sample. Metoprolol, atenolol, and carbamazepine were found in over 90% of the samples. Valsartan had the highest concentration (5300 ng/L), and also had the highest average concentration (1600 ng/L) across all 50 samples. Estimates of potential risks to healthy human adults were greatest for six anti-hypertensive APIs (lisinopril, hydrochlorothiazide, valsartan, atenolol, enalaprilat, and metoprolol), but nevertheless suggest risks of exposure to individual APIs as well as their mixtures are generally very low. Estimates of potential risks to aquatic life were also low for most APIs, but suggest more detailed study of potential ecological impacts from four analytes (sertraline, propranolol, desmethylsertraline, and valsartan).

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