For the trade and business press
Singapore - Thursday, December 14, 2006
Press Conference Water Technologies Asia / Pacific
Siemens: New solutions for disinfecting drinking water and wastewater improve water quality and reduce risks to health
The price and availability of water will have a similar influence on the Asian economies as oil and gas imports do today. "Through further development of our product lines and systems for disinfection we are making a contribution to meeting the rising demand for fresh water from industry and the population," explained Roger Radke, who is responsible for global water business at Siemens within the Industrial Solutions and Services Group (I&S). He said the increasing microorganism load in rivers was jeopardizing human health, and making it more difficult to make optimum use of water as a raw material. "It is only with additional water treatments and closed-circuit solutions that greater demand and higher expectations of water quality can be satisfied", continued Radke. "Siemens currently has the broadest range of products and process knowledge for every stage of water treatment and provides all-embracing solutions for industry and municipalities."
Almost half of the world's population lives in urban areas. Of these, more than 1.2 billion obtain their drinking water from groundwater reserves according to information from UN-Habitat. 1.8 billion people rely on obtaining their water from lakes, rivers or streams. It is becoming more and more common for organic, pathogenic and microbiological pollutants from agriculture, households and industry to make the water undrinkable. The World Health Organization (WHO) puts the number of deaths caused by diarrhea at around 1.8 million people per year. Better hygiene and disinfected water can dramatically reduce the number of cases of cholera, salmonella, shigellosis, typhoid, hepatitis, trachoma and other water-borne diseases.
Because of inadequate wastewater disposal, in many countries drinking water is heavily polluted. The main problems are the lack of an appropriate supply infrastructure and the uncontrolled release of pollutants from industry and agriculture. At the same time the demand for fresh water from industry and municipalities is increasing: Over the next thirty years the UN anticipates that regional water demand in the major cities of Asia will grow five-fold. "It is barely possible any more to cover this increase with the available natural resources," stressed Radke. "There is a need for solutions to recycle wastewater and surface water." Proven methods of disinfection treatment are UV irradiation or the addition of chlorine or chlorine dioxide. These technologies kill pathogenic bacteria and viruses and prevent re-infestation in the pipe network.
Disinfection with chlorine or chlorine dioxide
On-site electrolytic chlorination (OSEC) using the open tubular cell or membrane method has many advantages in terms of safety over conventional chlorination installations, as it is no longer necessary to work with or transport chlorine gas cylinders. The electrolytic systems produce a highly effective sodium hypochlorite solution directly where it is needed, from saturated brine, softened water and direct current. The sodium hypochlorite solution is added to the drinking water or service water. With the new OSEC B-Pak system, Siemens now offers a solution for retrofitting to existing chlorination systems with little available space or for decentralized installations where there is no constant supervision. The system stands out thanks to virtually maintenance-free operation and low running costs. The "plug & play" design makes project-specific design work and commissioning much easier. All that needs to be done at the installation site is connect the power and service water and install the metering system. The new OSEC-A system offers exceptionally high and reliable disinfection capacity for smaller water supply applications. With OSEC-NT, Siemens offers a membrane-type electrolytic chlorination system that treats larger volumes of water for breweries, canneries and food factories, metal production, paper manufacture or the chemical industry.
The DIOX-A chorine dioxide system is an alternative to the purification process that uses chlorine. Dilute hydrochloric acid and dilute sodium chlorite solution are used as the starting materials. The chlorine dioxide that is produced has a significantly higher oxidizing effect and can also act on substances, bacteria, spores and viruses that are not affected by chlorine. Unpleasant odors and flavors in water due to phenols, algae or their decomposition products are oxidized and transformed by chlorine dioxide into substances that are neutral in respect of taste and smell. Especially in fighting legionella in pipe systems, chlorine dioxide is an effective means of destroying biofilms, the main biosphere of legionella bacteria. The new DIOX-C system produces up to 4500 g/h of chlorine dioxide, using exclusively sodium chlorite solution and chlorine gas. The plant can be integrated into higher-level automation and data networks, enabling it to be used flexibly and in accordance with needs for disinfection, oxidation and deodorizing tasks in industry and in drinking water supply and wastewater treatment.
The Millennium III series generators of Siemens Water Technologies combine a 25% sodium chlorite solution with chlorine gas (or 12.5% sodium hypochlorite and 15% hydrochloric acid to form chlorine in-situ) under vacuum conditions to generate chlorine dioxide safely and efficiently. Efficiency and yield are maximized by reaction of chemical reactants in their concentrated form. These reaction conditions favor the immediate formation of chlorine dioxide and therefore minimize byproduct formation found in other types of generators. The generators comply with the USEPA's Stage 2 Microbials/Disinfection Byproducts (M/DBP) cluster of rules.
Disinfection with UV radiation
UV radiation is also used as an alternative to chemical disinfectants. Because they act directly on the DNA of microorganisms, UV disinfection systems provide good protection against parasites, cryptosporidium or legionella. As a rule no byproducts are produced in UV systems and the taste and odor of the water remain unaffected. In comparison with conventional UV systems of the same output, the low-pressure UV systems with amalgam lamps of the new Barrier A series need fewer lamps. Barrier A systems are mainly intended for disinfecting drinking water, industrial water and process water. They are used in fish farms, the beverage, pharmaceutical and chemical industries and in semiconductor manufacture.
The compact Barrier M series is certified according to the rigorous, industry-leading DVGW W 294 protocol (worldwide certification protocol) and is based on powerful medium-pressure lamps which emit a broad UV spectrum, disinfect the water effectively and prevent potential photo-reactivation reactions by the microorganisms. In typical wastewater applications the quality of the water to be treated varies. In order to take account of the varying conditions, each Barrier M system has a disinfection control function. Changes in transmission and flow rate are detected by a sensor, and the intensity of the lamps is readjusted accordingly. This allows energy-saving operation.
The DIOX chlorine dioxide systems are not available for sale in North and South America.
Siemens Water Technologies delivers cost-effective, reliable water and wastewater treatment systems and services to municipal, industrial, commercial and institutional customers worldwide. The division "Water Technologies" is part of Siemens' Industrial Solutions and Services Group (I&S) which is a system and solution provider for industrial and infrastructure facilities and global service provider for the plant and projects business covering planning, installation, operation and the entire life cycle. In fiscal 2006 (to September 30), I&S employed a total of 36,200 people worldwide and achieved total sales of EUR 8.819 billion.
Visit company websites at http://www.siemens.com/water