Number

269-EN

Section

General Section

Use

Abstract

Controlled hydrodynamic cavitation may replace the use of hazardous chemicals for scale, bacteria and corrosion control in refrigerating and cooling systems. The method combines two side streams loops, one for cavitation the other for filtering and it has been applied in different sectors, including in a military facility where an allergy to biocides was reported for one of the maintenance employees.

Substituted substances

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Reason substitution

skin/respiratory sensitizing
ecotoxicity

Other type of alternative

Technological alternative using patented device for controlled hydrodynamic cavitation as active component and a filtration unit as auxiliary unit.

Hazard Assessment

Substances to be substituted: Strong acids are corrosives, EDTA is classified irritant. Nabam and glutaraldehyde are sensitisers. Glutaralaldehyde is fatal if inhaled, is toxic if swallowed, causes severe skin burns and eye damage, is very toxic to aquatic life, is toxic to aquatic life with long lasting effects, may cause an allergic skin reaction, may cause allergy or asthma symptoms or breathing difficulties if inhaled and may cause respiratory irritation. Nabam is very toxic to aquatic life, is very toxic to aquatic life with long lasting effects, is harmful if swallowed, may cause an allergic skin reaction and may cause respiratory irritation. Hydrogen chloride is toxic if inhaled and causes severe skin burns and eye damage. Orthophosphoric acid causes severe skin burns and eye damage. EDTA (ethylenediaminetetraacetic acid) causes serious eye irritation. 2,2-Dibromo-2-cyanoacetamide has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Bromochloro-5,5-dimethylimidazolidine-2,4-dione has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Alternative substance: The alternative does not use chemicals.

Description of Substitution

The technology involves a unit that uses controlled hydrodynamic cavitation (CHC) and a filtration unit to treat water in the refrigeration and cooling systems. CHC is generated in a specially designed chamber where the water to be treated is passed through patented nozzles and forms high speed jets that rotate in opposite directions. The jets emitted by facing, horizontal nozzles, collide inside the chamber initiating the cavitation process, which is the main treating principle for the method. Then the treated water is released into the system. Though happening at minute scale the cavitation process (implosion of tiny bubbles)develops high levels of energy, that has been known for its damaging effects on materials such as steel used for ship propellers. Controlled cavitation is used by this alternative technology to destroy the membrane of suspended bacteria and the biofilm. Obtaining biocidal effects without biocides has positive effects on corrosion, too, because it reduces the microbiological influenced corrosion (MIC) and eliminates the use of chemicals that are corrosive. The producer claims that the technology also reduces corrosion by raising the pH at a value of about 8.5, by stripping the carbon dioxide. The high energy of cavitation generates dissociation of water molecules resulting in the formation of hydrogen peroxide from unstable species like hydrogen ion and hydroxyl radical. These reactions also contribute to the biocidal effect. Moreover, cavitation contributes to scale control by converting dissolved bicarbonates into carbonate crystals that form a colloid that is afterwards filtered and separated from the treated water. The technology avoids using strong acids or EDTA as antiscaling agents or chemical biocides. A military base used chemicals for the maintenance of its centrifugal chiller and cooling tower. One of the members of the maintenance staff developed skin sensitivity, so the decision to use CHC was taken. The technology was applied successfully .Water quality has improved: bacteria and corrosive rates dropped and the base reported water savings of over 2000 metric cubes per year.

Case/substitution evaluation

The alternative uses an ingeniously designed device to substitute several types of chemicals, addressing simultaneously some important problems like scaling, corrosion, and microorganism proliferation. It eliminates the use of chemicals that are corrosive, sensitizing or toxic. It also prevents generating wastes that are hazardous to the environment. For example, EDTA though not classified as hazardous to the environment according to harmonised classification, may increase the bioavailability of metals in the environment, is resistant (in its chelated form) to biological treatment of waste waters. It needs adaptation of the overall scheme of the cooling or refrigerating system but it eliminates the problems related to chemical management.

State of implementation

In use

Availability ofAlternative

Alternative available on the market.

Producer/Provider

http://www.bpsburton.co.uk/vrtx.html

Type of information supplier

Producer / distributor

Type of publication and availability

Internet presentation from the producer.

Publication source: author, company, institute, year

http://www.bpsburton.co.uk/vrtx.html

Date, reviewed

November 26, 2021