Electrolysed water solutions as a disinfection option

Published: 6-Sep-2017

The EU Biocidal Products Regulation will see some disinfection products withdrawn soon from the market. Envirolyte argues that Anolyte ANK offers a cost-effective, efficient alternative

Every year people are injured or even killed due to chlorine gas-related accidents. This is mainly due to either a faulty chemical delivery system or to cleaning and disinfection chemicals being incorrectly mixed. Chlorine and its chemical compounds are extremely effective as disinfecting agents and the safety of our modern food and water supply chains depend heavily upon them.

The difficulty has been how to maintain the safety of the food and the water supply, while also protecting the health and lives of those working within these areas. The food, sanitising, disinfecting, agricultural and cleaning industries are currently using products and methodologies that have become increasingly environmentally burdensome. Envirolyte offers a patented membrane electrolysis technology, called Electro Chemical Activation (ECA), which produces a powerful disinfection liquid, that avoids the above scenarios.

The process uses a mixture of ordinary tap water that has been softened and a diluted saline solution. These are mixed together and then passed through a specially designed electrolytic cell, where the solution and its functional properties are electrically modified. This ECA process produces a powerful “free available chlorine (FAC)” sterilising and disinfection liquid – Anolyte ANK – at a concentration of 500–700ppm, within a neutral pH range of 6–7.5, making it ideal for use on equipment and surfaces within a cleanroom, for example.

Being non-toxic, it is suitable for wet or dry fogging as well as electrostatic spraying of surfaces and inaccessible areas. It can be manually applied to hard or soft surfaces as part of any daily disinfection and cleaning procedure.

Whereas some micro-organisms can develop a tolerance or resistance to conventional chemical sanitation products, it has been shown that micro-organisms cannot build up a tolerance to ECA technology, as the unique mechanism of biocidal action is distinct from that of conventional chemical products. Anolyte ANK conforms to the European Biocidal Products Regulation (BPR, Regulation (EU) No 528/2012) and is listed on the ECHA Article 95 database. The company’s products also meet the regulatory requirements of NSF/ANSI Standard 61 Certification for the US and Canada, and this standard can often meet or fulfil the testing requirements of many other countries.

In-situ machines at a customer’s site can form part of a bespoke system that incorporates one or more dosing pumps that are operated by either a FAC or Oxygen Reduction Potential (ORP) controller and sensor for serving a water system. The hypochlorous acid that the machines produce is stored in a suitably sized storage tank, from where it can be decanted or pumped to point of use outlets, to meet the disinfection requirements of customer applications. The company can also supply containers of Anolyte ANK to customers that do not require a machine.

Cost effective in use

The liquid solutions produced by Envirolyte’s standard range of generators help to save energy and water through some disinfection processes being carried out at ambient or even lower temperatures. It is also possible with some water processes to filter and disinfect the water so that it can be recycled for wash down applications or for other processes.

The water pressure to the machine is set by a pressure reducing valve, it then passes through a water filter and via a water softener, before branching off into a brine tank and passing directly into the machine (see Fig 1).

When using the standard machine, the cost in the UK to generate 1,000 litres of Anolyte ANK is about £3–£5, this price is dependent on the costs obtained by the customer for salt and the kWh electricity charge rate. One litre of anolyte can dose 1,000 litres of water at 0.5ppm of FAC, making it a cost-effective alternative to disinfection chemicals.

Electrolysed water solutions as a disinfection option

How the system works

Envirolyte standard machines produce two basic fluid types: anolyte and catholyte. They have the ability to destroy micro-organisms such as Legionella pneumophila, Pseudomonas, Botrytis fungus, Salmonella, E. coli, Listeria and Anthrax spores and biofilms.

Anolyte is a strong oxidising solution and can be made within a pH range of 2.5 and 8.5, but for most applications it is produced within a neutral pH band of 6.5 to 7. The Oxidation-Reduction Potential (ORP) is between +600 to +1200 mV. It is a highly potent bactericide that can be used as a broad spectrum germicidal agent to kill all types of micro-organisms including viruses, fungi and bacteria; it will achieve an log 8 reduction of E. coli within 10 seconds.

As a biocidal liquid, it provides the cleaning strengths and benefits of chlorine, but without many of the hazards. The anolyte will also remain stable and active in storage for up to 18 months, making it an ideal cold sterilisation tool that possess excellent sporicidal, fungicidal and bactericidal killing power.

Catholyte is a byproduct made during the production of anolyte on the standard machines. The liquid is an anti-oxidising, mild alkaline solution within a pH10.5–12.0 range and an ORP of – 600 to – 900 mV. Catholyte solutions potentially can be used as a degreaser, detergent, cleaning aid or flocculation product.

Use of the anolyte as a hard-surface disinfectant on a daily basis for more than a decade has demonstrated that micro-organisms do not develop an immunity to it. This makes it possible to use the equipment within many areas directly related to cleanrooms or for maintaining the personal health and safety of people.

The external view of the cell, with internal views of the cell showing the central membrane (shown on the right)

The external view of the cell, with internal views of the cell showing the central membrane (shown on the right)

At the core of the Envirolyte technology are the patented diaphragmatic cells that have been designed to effectively deliver electrolysed water (EW) solutions (anolyte and catholyte) using a 1–4% water solution of NaCl as the initial material.

Similar electrolysers have been used before: EW technology was first developed in the late 1970s in conjunction with the Russian Institute for Medical and Scientific Research and earlier models of EW products were sold throughout the former Soviet Union, generally for disinfecting water and sterilisation in hospitals, which significantly decreased the rates of infections that were being encountered.

Unlike other electrolytic cells, a diaphragm separates the anolyte and catholyte solutions that are generated respectively at the anode and cathode chambers of the cell. This prevents the two streams from mixing and inter-reacting to form a simple sodium hypochlorite solution, as happens in other commercially available electrolytic cells. The invention of the double-chamber diaphragmatic electrolyser marked a breakthrough in disinfection, sterilisation and water purification technology.

The Envirolyte cells are manufactured with variable anolyte output capacity that ranges from 20 to 6000 litres/hr from either a single or a multiple cell configuration. Anolyte is dosed into a water system from a storage tank at a rate that will provide constant disinfection by overcoming any biological load being encountered.

Scale prevention

Potable water systems tend to develop biofilms, which consist of a matrix of organic matter (polysaccharides, proteins, organic carbons, etc.), inorganics, waterborne debris, sessile micro-organisms and corrosion products adhering to metal, plastic, glass, wood and other surfaces.

Water systems also tend to develop mineral scales and other types of deposits. These mineral scale and organic deposit substrates vastly increase the available surface area or number of nucleation sites offering a breeding ground for sessile micro-organisms indigenous to water systems. Scale and deposits therefore accelerate microbial activity which aids biofilm development, this in turn, increases the potential for mineral scale development and accumulation by providing an organic matrix; effectively “cementing” mineral precipitates in place

Anolyte ANK disrupts the organic matrix of mineral scales and other deposition constituents in water systems, making on-line mineral scale and deposit removal fast, economical, non-corrosive and non-hazardous.

In conclusion, it is important to differentiate Anolyte ANK from other sources of chlorine (stabilised bleach, calcium hypochlorite, hydantoins and other chlorine donors) as the chemistry it possesses is unique. The disinfectant liquid is classed as non-toxic and biodegradable under EU guidelines and provides a powerful antimicrobial, sterilising and disinfecting solution.

The products help to meet the growing demand for safe foods and meet the EU’s BPR, ECHA and REACH requirements, which look to remove harmful products from the marketplace. Anolyte ANK can replace many other biocides that can no longer be used for disinfection purposes.

The benefits and potential cost savings from onsite production of Anolyte ANK make it safer and cheaper than using other traditional chlorine-based chemicals, such as chlorine dioxide or hydrogen peroxide systems.

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