100 research outputs found

    BOD5 removal in subsurface flow constructed wetlands

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    The frequency of on-site systems for treatment of domestic wastewater is increasing with new residential development in both rural and low-density suburban areas. Subsurface flow constructed wetlands (SFCW) have emerged as a viable option to achieve advanced or secondary treatment of domestic wastewater. The pollutant removal efficiency in SFCW depends on design parameters. Many of these factors have been investigated while others such as aspect ratio, design of water inlet structure and method of dosing the wetland have yet to be fully examined. This study examined the effect of aspect ratio and header design on BOD5 removal efficiency as well as the impact of flow rate on flow distribution in a SFCW. An aspect ratio of 4:1 achieved 10% greater removal of organic matter than a 1:1 ratio. Tracer studies demonstrated that wetlands loaded at a constant rate of 3.8 L/min and 7.6 L/min experienced preferential flow. In addition, tracer studies showed wetlands with leaching chambers as headers failed to achieve equal flow distribution. An improvement in effluent water quality was achieved by replacing the leaching chamber for a perforated manifold as the inlet structure. This study demonstrated the importance of the careful selection of aspect ratio and means by which water is introduced to the wetland in the design of SFCW

    Drinking Water Problems: Nitrates

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    8 pp., 7 figuresHigh levels of nitrates in drinking water can be harmful for very young infants and susceptible adults. This publication explains how people are exposed to nitrates, what health effects are caused by them in drinking water and how to remove them

    Drinking Water Problems: Arsenic

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    8 pp., 5 figuresHigh levels of arsenic in drinking water can poison and even kill people. This publication explains the symptoms of arsenic poisoning and common treatment methods for removing arsenic from your water supply

    Drinking Water Problems: Perchlorate

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    6 pp., 3 illustrationsPerchlorate is a potential contaminate of well water that can have harmful effects on human health. Methods of removing perchlorate from water are described and illustrated. There is information to help well owners select and maintain treatment systems

    The Grizzly, October 9, 2003

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    Choose to Reuse: Recycling at Ursinus • Volunteer Program Breaks the Bank • Get Registered to Get Out the Vote • Meet the Democratic Candidates for President • A Look at the Response to Rape at Ursinus • Opinions: How Safe do we Feel?; Out of the Middle East: End of a Journey; Text Messaging Behind Your S.O.\u27s Back; New Addiction: AIM; Domo Arigato, Dr. Roboto • Guster: Having Fun Being Young • Halloween Fun Around Collegeville • The Eger Gateway • Field Hockey Still Undefeated in Conference Play • Ursinus XC Takes on Div. 1 and 2 Opponents • Volleyball Splits First C.C Matches • Women\u27s Soccer Continues to Impress • Men\u27s Soccer Trying to Battle • Josh Kemp: Changing the Record Bookshttps://digitalcommons.ursinus.edu/grizzlynews/1544/thumbnail.jp

    Subtelomeric assembly of a multi-gene pathway for antimicrobial defense compounds in cereals

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    Non-random gene organization in eukaryotes plays a significant role in genome evolution. Here, we investigate the origin of a biosynthetic gene cluster for production of defence compounds in oat—the avenacin cluster. We elucidate the structure and organisation of this 12-gene cluster, characterise the last two missing pathway steps, and reconstitute the entire pathway in tobacco by transient expression. We show that the cluster has formed de novo since the divergence of oats in a subtelomeric region of the genome that lacks homology with other grasses, and that gene order is approximately colinear with the biosynthetic pathway. We speculate that the positioning of the late pathway genes furthest away from the telomere may mitigate against a ‘self-poisoning’ scenario in which toxic intermediates accumulate as a result of telomeric gene deletions. Our investigations reveal a striking example of adaptive evolution underpinned by remarkable genome plasticity
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