Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Author:Mazular Dubei
Language:English (Spanish)
Published (Last):27 February 2014
PDF File Size:15.30 Mb
ePub File Size:1.27 Mb
Price:Free* [*Free Regsitration Required]

David Stensel j Dr. John Sheaffer 21 John Marsh 24 J. Tim Wirth III. Lundahl Falmouth, Massachusetts 89 Dr. Has coordinated citizen campaigns for stronger water laws over the past several years. An attorney who ao- authored Water Wasteland, a landmark oritique of federal cleanup pro- grams, he has played a leading part in several national citizen campaigns for environmental law reform.

This first conference is being videotaped by the Environmental Protection Agency, so that this unique gathering of technical experts, citizens, and the many others here may be packaged in short form and then be available for use by citizens around the country that were not able to attend these conferences.

Conference proceedings will be produced after both conferences are over, and will be sent to all participants. You participants are an extremely diverse and unique group. This ought to be described as the first sewage summit, the first time that the top national experts in the technologies have come together with the regulators, local officials, taxpayers, and the citizens who have to face paying the bills and living with the results.

The costs of mistakes are high. The decisions that our communities will have to make on the kinds of technologies to adopt, ways to pay for it, the ways to control them and operate them--these decisions will affect the future of our fishing waters, the safety of our drinking water, the size of our sewer bills and tax bills, our community budgets, the well-being of our neighborhoods and of our farms.

They will shape the face of this country in the years to come. It's important to do the best we can. We need facts, but especially at the local level, facts can be very hard to get. Arguments bolstered by contending technical claims are among the weapons in struggles over competing notions of what the problem is and how it should be solved. Local officials often feel in the dark in dealing with these complicated questions.

Citizens feel more in the dark, and even the so-called experts, the trained technicians, sometimes don't know as much about the available solutions as they think they know or claim to know. The purpose of this conference is to begin to narrow that knowledge gap. In doing so, it's not possible to avoid controversy. To do that would fail to expose you to what you are going to run into, as you and others begin to raise these questions in your own communities.

Our purpose will be to enlighten that controversy, so that better choices can be made. Denver, Colorado. The main sponsors of both conferences are the Environmental Policy Institute and the Clean Water Fund, two national organizations that are working with a grant from the National Science Foundation's Science for Citizens Program. Then, in addition, the Environmental Protection Agency has helped in funding this second conference in Denver.

On behalf of the Colorado Open Space Council and Coloradoans interested in water issues, we'd like to welcome you to the Western session of the sewer summit. As they say, about eight weeks ago, I couldn't really spell "sewage expert" and today I are one.

It's amazing to see the number of people, geographic spread, occupational background, and interest of all of you who are turning out and giving up a weekend to get into this subject. With the Open Space Council, I've tried to promote sewage treatment as a coming issue of the 's and we've been telling people that they really should get in on the ground floor. But have you ever noticed how people look at you real funny when you talk about sewage? It's very interesting how our culture is set up to avoid even the discussion; even some of our water people said, "Well, I'm really just into drinking water.

Very few people are on top of this issue and following it. We have altogether at this conference, this weekend, approximately people. Half of them are from Colorado and the other half are from 30 other states.

Every single state west of the Missis- sippi I think, except Alaska, is represented. There are also a few stray Easterners who missed the D. We hope that by the time it's over, you'll find out that the issue of sew- age can be fun. Colorado Open Space Council was formed in , as a coalition of 23 citizen groups who are interested in promoting a better environment in Colorado. We believe that working with diverse groups of people to achieve common goals is very important and we very much welcome the diverse group that's here today.

The effort to become better shoppers for sewage treatment is clearly worth it. We can't afford to waste water, valuable resources, money, or to lose our agricultural land. The aim of this conference is to give us the information we need to better protect our communities, our water, and our pocketbooks.

To give us that information, we have assembled a stable of stars, the top experts from around the nation on several topics. We're especially proud that so many of those experts are from right here in Colorado. Our aim, however, is not to make all of us experts. We don't plan to graduate Ph. Our aim is to better enable us to control the expert: to give us the background we need to be able to know when important decisions are being made, to be able to stop problems and find the appropriate answers, to know when we need more information, to know where we can go to get that information, and most important, to know some of the action steps we can begin to take to achieve the sensible results that we want.

The first speaker today is Michael Gravitz. Mike is from the Environmental Policy Institute and is its director and the organizer for these Shopping for Sewage Treatment conferences. As the director of research for the Clean Water Action Project, he studied obstacles to innovation in wastewater treatment technology. He prepared the recommendations which shaped the changes in the latest amendments to the Clean Water Act.

As Clean Water Action Project's Research Director, Gravitz studied obstacles to innovation in waste treatment technology, preparing re- commendations which shaped changes in the Clean Water Ast.

Sewage is about I'd like to talk to you about the other. We're dealing with a sub- stance that is very dilute; it's mostly just water. There is organic material in sewage. Any compound with at least carbon, hydrogen and oxygen in it is organic.

Many bodily waste pro- ducts are organic materials decomposed. Why are we concerned about organic materials in sewage? Why bother? When they do this, the bacteria consume oxygen. They breathe oxygen, not quite like we do, but I can use the word breathe very freely I hope. If there's too much organic material in the sewage, or in the stream, then too much oxygen is taken out of the water, and fish or shellfish, which also need oxygen to live, can't get enough and therefore they either can't live in those areas of the streams and they avoid them, or they grow much more slowly.

Water without oxygen in it also tends to smell very bad. There are bacteria that live in water without oxygen called anaerobic bacteria. They don't use oxygen to breathe and they give off commonly a hydrogen sulfide--or rotten egg--kind of smell.

Let me deal very quickly with some of the technical terms that engineers use all the time to quantify the amount of organic material in sewage. I think it'll be very useful to you, and I'm going to try to explain it very simply, so let me emphasize they're used all the time.

I think that's why they're valuable to understand. Engineers call the amount of organic material in sewage BOD, which stands for biochemical oxygen demand. They calculate the amount of organic material in sewage, the BOD, by following several steps.

First, they measure how much oxygen is dissolved in sewage or water initially. Then they put this sewage into a bottle or closed container for about 5 days, at a certain temperature. They let the bacteria eat the organic material. They then measure the oxygen content of the water or sewage again and the amount of oxygen used up during this 5-day period, or whatever period it is, is an indication of the amount of organic material in sewage.

If the period had been 5 days, the scientific way they would say it goes like this: "the 5-day BOD is such-and-such " It's an indirect measure, not a direct measure, of this organic material. Engineers also use the terms parts per million, or ppm, or milligrams per liter, as units to measure the amount of pollutants in water or sewage. So that shouldn't confuse you, if people switch back and forth between them, or use one and not the other.

For example, there are about parts per million oi" irri 11 igrams per liter of organic material in sewage when it comes into a sewage treatment plant.

To give you an idea about how little this really is, although the number sounds relatively high, one part per million is equivalent to one inch in 16 miles, or one minute in 1. But even these very small quantities of materials strongly affect a stream's health or the things that live in the stream. What else is in sewage? There are a lot of nutrients, or fertilizers, in sewage. Sewage contains a lot of nitrogen and phosphorus. For example, each person puts about 12 pounds of nitrogen per year into a sewage treatment system, and about 3 pounds of phosphorus.

It may not sound like a lot but when you multiply it by 10, or 50, people, you have an enormous amount of fertilizer going into a stream. Just like the farmer who applies nitrogen and phos- phorus to a cornfield and expects it to help the corn yield go up because of the fertilizer, applying nitrogen and phosphorus to rivers and lakes increases the amount of plants and algae that grow in those rivers and lakes.

Algae are just microscopic green plants. Why are nutrients a problem? Well, it's not really a problem until there's too much of those fertilizers going into those streams. Like a lot of pollutants, there are low levels at which we don't have problems, but there are higher levels at which we begin to have problems. If there are too many nutrients in the water, we have too many algae.

Those algae die. They get eaten by the bacteria, because they are organic materials also. This is the process called eutrophication. In addition, swimming in water that has a lot of algae growing on it, is a very unpleasant experience. It could be dangerous too because you can't see what's in front of you, in the water.

And decaying algae smell a lot. They often smell like rotten eggs.


Methylation of DNA in Prokaryotes

DNA Methylation pp Cite as. A much wider variety of biological functions of postreplicative DNA methylation is observed in prokaryotes than in eukaryotes. In eukaryotes DNA methylation is primarily a means of the control of gene expression. Many chapters of this book are devoted to various aspects of this function. In prokaryotes, DNA methylation affects such diverse phenomena as determination of accessibility of DNA to digestion by endonucleases, control of initiation of DNA replication, and the definition of origins of packaging in the maturation of phage DNA, which will be dealt with in this article. We shall also be concerned with the enzymes, which facilitate methylation, the DNA methyltransferases.



Related Articles