Dissolved oxygen’s effect on ecosystems
Dissolved oxygen (DO) is a measure of the amount of oxygen dissolved in water. It can be caused by a process of aeration of water flowing through rapids or falls, a byproduct of photosynthesis and the atmosphere. Monitoring DO levels in water may be more important than you think. From dead fish washing up on the shores of Singapore, to historically low levels of brown shrimp, DO is having an adverse effect on ecosystems all over the world.
Head to LinkedIn to read our exclusive article about DO, the effects it is having worldwide, and just why it is so important to monitor.
Homeland Security: Managing the Risks
Untitled Document Following the terrorist attacks on the World Trade Center in New York City on September 11, 2001, the U.S. Environmental Protection Agency (EPA) and other federal agencies conducted extensive assessments of the air quality and associated environmental and health effects near the so-called “Ground Zero” site. EPA’s activities included air monitoring and modeling of the fire and debris plume, a toxicological study of fine particulate matter, and...
Measuring Short-Term BOD
Measurement of oxygen uptake rates in activated sludge processes is essential to their satisfactory operation. Traditionally, oxygen uptake rates (OUR) have been determined by using a dissolved oxygen probe to measure the change in dissolved oxygen in a BOD bottle. While this method is rapid, it provides only a snapshot, at a single point in time, of the oxygen uptake rate reaction in a treatment plant. Much more can be learned about the operation of a treatment plant by measuring the oxygen uptake rate over a...
Recovery of Precious Metal Catalysts - A New Process Using Supercritical Water Oxidation
Up to now, the recovery of precious metals used as catalysts in chemical processes has involved the use of incineration. Now, however, a British-Swedish joint venture has developed a process which uses supercritical water oxidation instead, which provides many economic and environmental advantages. Precious metals are used extensively in catalysts in a wide range of industrial chemical processes. Sometimes they are used in a homogeneous form, but more often fixed to a solid support for ease of handling. In many...
Environmental Isolation of Arsenic by Combined Disposal and Recycling Technology
Abstract Environmental isolation of arsenic from process, mine, and from flotation waste liquors by a combined technology consisting in continuous production of insoluble arsenic compounds from process and flotation waste liquors and in consecutive disposal of these solid pecipitates in wastes pond, as well as, in a full recycling of the clarified pond water to the initial process and ore processing water flows. Click Here to Download/View the full document in pdf format (15 Kb)
Water Industry on the Eco Wave?
A wave of privatization is rolling through the water industry – at the environment‘s expense? In order to provide an answer to this question, the Environmental-Rating agency oekom research AG, Munich, put a number of water supply companies and manufacturers of water appliances to the environmental test. In results published today, oekom identifies the British water supplier Severn Trent as the environmental leader of the water supply group with a B grade in the overall Environmental-Rating. The Austrian water...
Troubleshooting the Compost Pile
While composting is a biological process, we as composters must provide the microorganisms that do the work with the conditions they need to do their job. If there is a problem with the system, then look at it from the point of view of the microbe. What does that microbe need to function, and why isn’t it functioning correctly? Microorganisms need a source of energy organic feedstocks to feed on and draw energy. Some of that released energy causes the compost pile to heat. Besides energy, organisms need nutrients...
Composting Key to Meeting Landfill Organics Ban
The Halifax Regional Municipality (HRM) in Nova Scotia took a giant leap in 1998 to reaching a 50 percent diversion goal by 2000. Between July and November, 1998, organics collection carts were distributed to almost 100,000 households in the region. In December, two new composting facilities designed to process those materials, as well as feedstocks from the commercial sector, opened their doors. “The Halifax Regional Municipality’s new integrated solid waste-resource management system is ‘leading edge’ in all...
Environmental Effects of Acid Rain
Air Pollution Creates Acid Rain Scientists have discovered that air pollution from the burning of fossil fuels is the major cause of acid rain. Acidic deposition, or acid rain as it is commonly known, occurs when emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx) react in the atmosphere with water, oxygen, and oxidants to form various acidic compounds. This mixture forms a mild solution of sulfuric acid and nitric acid. Sunlight increases the rate of most of these reactions. These compounds then...
In Situ Physical/Chemical Treatment for Ground Water and Leachate
The main advantage of in situ treatments is that they allow ground water to be treated without being brought to the surface, resulting in significant cost savings. In situ processes, however, generally require longer time periods, and there is less certainty about the uniformity of treatment because of the variability in aquifer characteristics and because the efficacy of the process is more difficult to verify. Physical/chemical treatment uses the physical properties of the contaminants or the contaminated...
Common Treatment Technologies for Halogenated SVOCs in Soil, Sediment, and Sludge
Common treatment technologies for halogenated SVOCs in soil, sediment, and sludge include biodegradation, dehalogenation, incineration, and excavation with off-site disposal. All types of biodegradation, both in situ or ex situ, can be considered to remediate soils: in situ bioremediation, bioventing, composting, controlled solid phase, or landfarming. Slurry phase biological treatment is also applicable but is less widely used. Treatability studies should be conducted to evaluate design parameters, such as...
Introduction Land Treatment is a full-scale bioremediation technology in which contaminated soils, sediments, or sludges are turned over (i.e., tilled) and allowed to interact with the soil and climate at the site. The waste, soil, climate, and biological activity interact dynamically as a system to degrade, transform, and immobilize waste constitutes. Wastes are periodically tilled to aerate the waste. Soil conditions are often controlled to optimize the rate of contaminant degradation. Conditions normally...
In-well Vapor Stripping - Technology Overview
In-well vapor stripping technology involves the creation of a ground-water circulation pattern and simultaneous aeration within the stripping well to volatilize VOCs from the circulating ground-water. Air-lift pumping is used to lift ground-water and strip it of contaminants. Contaminated vapors may be drawn off for aboveground treatment or released to the vadose zone for biodegradation. Partially treated ground-water is forced out of the well into the vadose zone where it reinfiltrates to the water table....
Data Requirements for Soil, Sediment, and Sludge
Site soil conditions frequently limit the selection of a treatment process. Process-limiting characteristics such as pH or moisture content may sometimes be adjusted. In other cases, a treatment technology may be eliminated based upon the soil classification (e.g., particle-size distribution) or other soil characteristics. Soils are inherently variable in their physical and chemical characteristics. Usually the variability is much greater vertically than horizontally, resulting from the variability in the...
Wastewater Treatment: Overview and Background
SummaryWaste discharges from municipal sewage treatment plants are a significant source of water quality problems throughout the country. States report that municipal discharges are the main source of impairment to estuaries and coastal waters, the second leading source of impaired rivers and streams, and also are a major source of pollution in lakes. Pollutants associated with municipal discharges include nutrients (which can stimulate growth of algae that deplete dissolved oxygen in surface water), bacteria and...