Nuts and Bolts of Chemical Oxygen Demand

Biochemical Oxygen Demand (BOD) is a definitive indicator of required treatment in wastewater, and estimating BOD is an important part of wastewater treatment process control. The U.S. Environmental Protection Agency (USEPA) requires wastewater treatment plants to bring BOD within limits before discharging treated wastewater, and accurate test results must be recorded for regulatory reporting. Thus, measuring BOD in treated water is an important part of the monitoring process. Many wastewater treatment facilities use a faster Chemical Oxygen Demand (COD) test to estimate BOD levels.
Oxygen demand is an important parameter for determining the amount of organic pollution in water. Testing oxygen demand has its widest application in measuring waste loadings of treatment plants and in evaluating treatment efficiency. Biochemical Oxygen Demand (BOD) is a definitive indicator of required treatment in wastewater, and estimating BOD is an important part of wastewater treatment process control. High influent BOD requires extensive treatment to provide the oxygen necessary to break down the water's organic contents.

THINNING FLAT PANELS

Materials suppliers are thrilled by the flat-panel industry's growth, but are under pressure to trim back on costs

When airline pilot Mick Jaffe and his wife, Chris, went shopping in Hong Kong to replace their television set a few weeks ago, they did not do what producers of flat-screen TVs are expecting. After looking at all the models, the Jaffes left the shop with a traditional 29-inch cathode-ray tube set instead of one of the newer models based on plasma or liquid-crystal technology. "In Taiwan, Frank Wang, a sales manager at local color resist producer Eternal Chemical, says his firm has an advantage in marketing to Taiwanese display manufacturers. "We can offer better service, we have a common language, and we're more familiar with the local market," he says. But he admits that Eternal has a hard time parlaying this advantage into new sales. Customers find it risky to switch to a new supplier whose material might later prove unsuitable. Moreover, display manufacturing equipment made in Japan is often guaranteed to work only with certain Japanese materials.

Warning: Toxic chemical triclosan can turn your toothpaste into chloroform

For years, I have warned people of the danger of personal care products. If you look at the ingredients manufacturers put in their products -- soaps, deodorants, toothpastes and so on -- you will be horrified. These ingredients are highly toxic and cause cancer. They promote leukemia, nervous system disorders and liver problems. Now, some new information has come from Virginia Tech. Researchers that have found that the chemical triclosan, which is found in a lot of antimicrobial soaps and toothpaste products, can react with chlorine in the tap water. Guess what you get? (This is the horrifying part.) Chloroform. This is a toxic chemical that can give you cancer. In the old movies, you might have seen someone give a person chloroform to knock them unconscious. If you breathe enough chloroform, you will die.

Textile Chemicals

During the process of manufacturing, textile has to go through a long process of chemical and non chemical treatments. The Textile finishing procedure includes preparation and pretreatment, dyeing, printing and refinement of fabrics. Certain Textile Chemical Products are highly specialized chemicals such as biocides, flame retardants, water repellents and warp sizes. Others are relatively simple chemicals or mixtures such as emulsified oils and greases, starch, sulfonated oils, waxes and some surfactants. Over sixty distinct textile chemical product classes are used in yarn formation, fabric pretreatment and finishing, textile laminating and coating, and other miscellaneous applications.

Desizing. During weaving, specially for the fabrics made from cotton or blends, the warp threads are coated with an adhesive substance known as 'size'. This is done to prevent the threads from breaking during weaving. Starch and its derivatives are the most common sizing agents. After weaving, the 'size' is removed again in order to prepare the fabric for dyeing and finishing. This is called Desizing. It is done by treating the fabric with chemicals such as acids, alkali or oxidising agents.

Chemical Bonding

Though the periodic table has only 118 or so elements, there are obviously more substances in nature than 118 pure elements. This is because atoms can react with one another to form new substances called compounds (see our Chemical Reactions module). Formed when two or more atoms chemically bond together, the resulting compound is unique both chemically and physically from its parent atoms.
Let's look at an example. The element sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet. The element chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I. When chemically bonded together, these two dangerous substances form the compound sodium chloride, a compound so safe that we eat it every day - common table salt!... by Anthony Carpi, Ph.D.

Chemical in sperm 'may slow ageing process'

The secret of eternal youth? Photo: GETTY/AFP

Researchers in Austria say that human sperm might be the next weapon in the fight against ageing.

A new study by scientists at Graz University found that spermidine, a compound that is found in sperm, slows ageing processes and increases longevity in yeast, flies, worms and mice, as well as human blood cells, by protecting cells from damage

Engineering a new way to study hepatitis C

Tissue engineers have successfully infected liver cells in the laboratory, allowing a better way to test new drugs.
Liver cells in a micropatterned co-culture form tube-like structures (shown here in green) that resemble bile capillaries found in a human liver. Image courtesy of Sangeeta Bhatia lab, MIT
Hepatitis C, a virus that can cause liver failure or cancer, infects about 200 million people worldwide. Existing drugs are not always effective, so many patients end up on long liver-transplant waiting lists.One reason that no better treatment options exist is the lack of a suitable liver tissue model to test new drugs in the laboratory. But now, researchers from MIT and Rockefeller University have successfully grown hepatitis C viruses in otherwise healthy liver cells.In the new tissue model, liver cells are precisely arranged on a specially patterned plate and surrounded by supportive cells, allowing them to live and function for four to six weeks. The cells can be infected with hepatitis C for two to three weeks, giving researchers the chance to study the cells’ responses to different drugs.“With this model system, one can study hepatitis C and its chronic effects in greater mechanistic detail,” says Salman Khetani, former MIT postdoctoral associate and an author of two recent papers on the work. “Since it uses normal human liver cells rather than cancer-derived ones, our system may provide a better understanding of how hepatitis C progresses in humans, and of potential cures.”The research team, led by Sangeeta Bhatia, professor in the Harvard-MIT Division of Health Sciences and Technology and MIT’s Department of Electrical Engineering and Computer Science, and Charles Rice of Rockefeller University, reported the new method in recent papers published in the Proceedings of the National Academy of Sciences and Nature Biotechnology.