CHLORINE DIOXIDE GENERATIING SYSTEM

Du Pont's IDI patented OXYCHLOR® II chlorine dioxide generating system is based on the reaction of either sodium chlorite and chlorine gas in solution, or sodium chlorite, sodium hypochlorite and hydrochloric acid solution. The latter process is available from IDI when chlorine gas is not desired.

1. Operating costs of the OXYCHLOR® systems are reduced due to the high yields achieved.
2. Maintenance problems minimized due to the use of dilution water with the reaction chemicals resulting in minimal salting or clogging maintenance.
3. A patented on-board pH meter gives operators an indication of improper chemicals usage, minimizing unreacted sodium chlorite and excess chlorine while reducing unwanted by-products.

• Without motive water, no vacuum can occur; therefore chemical mixing will not take place.
• Leaks in fittings and piping will draw air in under vacuum, resulting in a pH alarm condition.
• The system requires motive water to create vacuum, which draws chemicals into the eductor mixing zone, so no concentrated chemicals can react in the system.
• Reaction in dilution water increases safety as the concentration typically range between 1000-3000 ppm; never exceeding critical physical properties.
• Homogenous reaction minimizes activation chemicals and unreacted sodium chlorite.
• Combining chemicals in dilution water minimizes activation chemicals and unreacted sodium chlorite.
• On-board pH meter gives operators real-time indication of proper generator operations, and can provide electronic control capabilities.
• Sight glass gives operators an added visual check on quality.
• Process integratable PLC (Programmable Logic Control) for remote monitoring and on-line analysis.

• Loss of chlorine supply
• Loss of sodium chlorite
• Loss of low pressure in water supply
• Loss of power
• pH imbalance

• Taste and odor control
• Iron and manganese control
• Improved disinfection credits
• Cryptosporidium and giardia control
• Color removal and algae control
• Zebra mussel control
• Biofilm removal
• Microbial control of flumes, processing waters, retort waters, such as hydrocoolers, cooling canals, warmers and coolers
• Fruit and vegetable rinses
• Uncut and unpleeled, as well as cut and peeled (potable rinse required)
• Food contact surface sanitizer for all processing equipment surfaces
• Cooling towers for biological control
• Potable water /Process water treatment

TASTE AND ODOR CONTROL

Many potable water plants have experienced unpleasant tastes and odors in finished waters with descriptions such as medicinal, musty, earthy, fishy, metallic or rotten egg. These odor causing compounds have been identified as Geosmin, 2-methylisoborneal (MM), pyrazine chlorophenols, actinomycetes, sulfur species or other odorous by-products of microscopic organisms. These substances generally are produced in raw waters by various algae or bacterial microorganisms.
Chlorine dioxide is effective at oxidizing low threshold-odor compounds like Geosmin and MIB at typical treatment dosages. Chlorine dioxide has an advantage in that its use for controlling tastes and odors will not chlorinate organics.

• Iron & manganese reduction
• Improved disinfection credits
• Trihalomethane & HAA control
• Color removal & algae control
• Cryptosporidium and giardia inactivation
• Zebra mussel control
• Biofilm removal

ODOR ABATEMENT WITH CHLORINE DIOXIDE

Many plants have experienced complaints associated with unpleasant odors resulting from production operations. These complaints plus increasing governmental regulations on water discharges and air emissions have necessitated new approaches in order, while making traditional oxidative treatments obsolete.

Chlorine dioxide, a powerful oxidant, contains no VOC's and is used very effectively to control noxious, irritating or pungent odors from numerous processing, waste or air quality control applications where air scrubbers are in use. Its unique selective properties permit it to be more effective and less costly than chlorine, hypochlorite, peroxide, permanganate or ozone.

Chlorine dioxide has an added advantage over traditional oxidative chemistries in that its use for controlling odors will not chlorinate organics, form volatile organics compounds (VOC's) or cause wastewater discharge problems at typical use levels.

• Iron and manganese reduction
• Trihalomethane and FAA control
• Color removal and tallow bleaching
• Algae and Biofilm control
• Zebra mussel control
• Microbial control of flumes, processing waters, retort waters, cooling waters, such as hydrocoolers, cooling canals, warmers, and coolers
• Fruit and vegetable rinses; uncut and unsealed, as well as cut and peeled
• Food Contact surface sanitizer for all processing equipment surfaces Cooling towers for slime and odor control Whole plant potable water treatment

TRIHALOMETHANE CONTROL

In 1998, the Stage One Disinfection ByProduct Rule (DBP) was signed into law. This rule reduces the level of DBP compounds allowed to be formed from the use of disinfectants. The objective of the DBP Rule is to minimize the adverse health effects associated with elevated levels of DBPs in the treated water.

The two classes of DBPs that impact most potable water facilities are total Trihalomethane (TTHM) and haloacetic acids FAA. Chlorination and bromination of naturally occuring humic substances in drinking water usually form these two classes. TTHMs & HAAs comprise 50% of the total organic halide (TOX) when water is chlorinated.

The Stage One Rule must be fully implemented in systems serving greater than 10,000 people by December 2001 and lowers the total allowable TTHMs to 0.08 mg/L and HAA's to 0.06 mg/L. Smaller systems serving less than 10,000 people must be fully implemented by December 2003. Stage Two of the DBP Rule, which will further reduce the allowable level of DBPs is scheduled for release 2003.

• Taste & odor control
• Iron & manganese control
• Improved disinfection credits
• Cryptosporidium & giardia control
• Color removal & algae control
• Zebra mussel control
• Biofilm removal

Compliance and Disinfection

In 1989, the Surface Water Treatment Rule (SWTR) required potable water utilities serving greater than 10,000 people to calculate their "CT" values. CT is the product of disinfectant residual concentration "C" in mg/L and contact time "T" in minutes to achieve a 3-log reduction of Giardia and 4-log reduction of viruses. This regulation set CT values on the four EPA approved disinfectants: ozone, chlorine dioxide, chlorine and chloramines to ensure a minimum inactivation of a particular pathogen in surface waters.

CRYPTOSPROIDIUM INACTIVATION

Disinfection of drinking water is one of the major public health advances in the 20' century. One hundred years ago, typhoid and cholera epidemics were common until disinfection was universally accepted. Today, we know there are specific microbila pathogens, such as Cryptosporidium, that are resistant to traditional disinfection practices. In 1993, Cryptosporidium caused 400,000 people in Milwaukee to experience intestinal illness. More than 4,000 were hospitalized and at least 50 deaths were attributed to the outbreak. There have also been outbreaks of Cryptosporidium in Nevada, Oregon and Georgia over the past several years. Amendments to the Safe Drinking Water Act (SWDA) in 1996 required the U.S.EPA to balance the risks between microbial pathogens and disinfection by-products (DBPs)

In 1998, the Stage One Disinfection ByProduct Rule (DBP) and the Interim Enhanced Surface Water Treatment Rule (IESWTR) were signed into law. These rules attempt to strengthen microbial protection, including provisions specifically to address Cryptosporidium, and to balance the risk with the level of DBPs that are allowed to form from the use of disinfectants. The objective of the IESWTR rule is to achieve a maximum contaminant level goal (MCLG) for Cryptosporidium of zero.

• Taste & odor control
• Iron and manganese control
• Improved disinfection credits
• Trihalomethane & HAA control
• Color removal & algae control
• Cryptosporidium and Giardia inactivation
• Zebra mussel control
• Biofilm removal

WASTEWATER ODOR ABATEMENT

A problem often associated with agricultural, industrial and municipal wastewater treatment is hydrogen sulfide formation during the treatment process. Odor is caused by bacterial degradation of compounds forming hydrogen sulfide (rotten egg odor) and other sulfur compounds such as mercaptans. Du Pont's chlorine dioxide products effectively eliminate these sulfur compounds, reduce odor and associated corrosion problems, help users comply with clean air regulations and reduce community complaints.

Biological transformations involved in the sulfur cycle are tremendously complex. It is commonly known that sulfate-reducing bacteria are the principal odor-causing problem. Although the biological production of hydrogen sulfide requires anaerobic conditions, problems can also occur in aerobic systems. Hydrogen sulfide is particularly troublesome as its odor is offensive at levels as low as 0.05 ppm and a threshold limit of 0.00047 ppm.

• Lift station deodorization
• Lagoon deodorization
• Wet scrubber deodorization
• Sludge press deodorization
• Waste water disinfection
• Land fills

• Trihalomethane and HAA control
• Iron and manganese reduction
• Color removal and tallow bleaching
• Algae and biofilm. control
• Zebra mussel control
• Microbial control of flumes; processing waters; retort waters; cooling waters, such as hydrocoolers; cooling canals; warmers, and coolers
• Fruit and vegetable rinses, uncut and unpeeled, as well as cut and peeled
• Food contact surface sanitizer for all processing equipment surfaces
• Cooling towers for slime and odor control
• Plant potable water treatment
• Rendering plant odor control
• Waste lagoons
• Portable toilets
• Landfills
• Odor scrubbers
• Municipal collection systems
• Heating and ventilation systems
• Institutional
• Commercial aircraft

SODIUM CHLORITE

COOLING TOWERS

Due to the warm temperatures and continual scrubbing of nutrients, cooling towers are a prime environment for the buildup of microorganisms. They cause serious problems in the system through which the cooling water circulates. Among them are:

1. Buildup of odors and slime, caused by an increased microorganism population.
2. Loss of heat transfer, due to the low thermal conductivity of the biofilm and inorganic deposition.
3. Increased corrosion rates, due to electrochemical cell formation in the biofilm and blocking of the contact of any corrosion inhibitor with the metal.
4. Increased-pumping energy required to circulate the cooling water in the presence of a biofilm which has a high friction factor.

1. Chlorine dioxide has 2.6 times the oxidizing power of chlorine.
2. It will kill blue-green algae; chlorine cannot.
3. It does not chlorinate organic molecules (no chlorophenols or trihalomethanes), meaning no toxic pollutants, nor does it form chloramines with NH3, Providing a lower demand for chlorine dioxide.
4. Its biocidal activity is constant over a wide pH range.
5. The organisms cannot find metabolic pathways around its biocidal activity.
6. It is a wide spectrum biocide, killing bacteria, fungi and viruses.
7. The safety considerations in storing chlorine gas are eliminated.
8. The discharge limits are reduced.
9. No dechlorination is required.
10. Chlorine dioxide is less corrosive to cooling tower equipment.
11. There is no noticeable delignification of the cooling tower wood.

1. Standard aerobic and anaerobic plate counts incubated at 30-35' for 48 hours.
2. Pseudomonas s. with a Chondromata agar incubated at 30-35' for 48 hours.
3. Sulfate reducing bacteria with a sulfate-reducing agar incubated anaerobically for 6 days at 30-350.
4. Phenol oxidizing bacteria with a Temple/Richardson medium MS200 at 30-35' for 72 hours.
5. Easicult® or other dip sticks for fieldwork.

ZEBRA MUSSEL CONTROL

Fresh Surface Waters - Inlet Pipes

Continuous Feed - Use 1 -0 PPM Of ClO₂ in the inlet water to the prechlorination section of the water purification plant.

Shock Feed - If possible to interrupt the water flow to the plant, then add 25 ppm to the entering water and block in the inlet system when ORP indicates breakthrough. Allow to stand for 12 hours and backflush the inlet pipe. Then add ClO₂ as above in continuous feed.

Sea Water

Continuous Feed - Add 3.0 ppm C102 to the inlet water until all signs of zebra mussel infestation in the inlet lines disappear. Then reduce treatment to 1.0 ppm to maintain the inlet system free of zebra mussels.

Shock Feed - Add 50 ppm ClO₂ to the feed water and maintain that concentration until ORP indicates breakthrough and block in inlet line for 12 hours. Backflush vigorously and then reverse flow and continue addition of ClO₂ at 1.0 ppm level to prevent reinfestation.

Feed Points

Add the ClO₂ at the inlet of the feed system to the water plant or cooling tower. This is the area where infestation will begin and eventually choke off the feed to the water plant or cooling tower.

SODIUM BROMIDE