RO – W23 AORA reverse osmosis filter (membrane)

A water ioniser is a device that changes the pH value of water and separates it into alkaline and acidic water. It does this by electrolysis: an electric current produces negatively and positively charged ions. The alkaline water is used as drinking water, the acidic water for cleaning. A water ioniser therefore mainly changes the pH value and the taste of the water.

A reverse osmosis system, by contrast, works on the principle of reverse osmosis. It forces the water through a semi-permeable membrane that holds back impurities such as salts, minerals, heavy metals, bacteria and viruses. The filtered water can be used for drinking, cooking or technical applications. A reverse osmosis system aims to remove as many substances from the water as possible.

The main difference is therefore the purpose: a water ioniser changes the pH value, a reverse osmosis system purifies the water thoroughly. Which device suits you depends on what matters more to you.

Osmosis membranes: how do they differ?

The heart of every reverse osmosis system is the membrane. In household systems you will mainly come across two types:

• TFC membrane (thin film composite, made of polyamide): fitted in most household systems today. It holds back dissolved substances very extensively but is sensitive to chlorine. That is why an activated carbon pre-filter sits in front of it.
• CTA membrane (cellulose triacetate): it tolerates chlorine better, but holds back fewer dissolved substances and only works within a narrower pH range. It is rarely found in new household devices.

Beyond that, membranes differ in three respects:

• Output: usually stated in GPD (gallons per day), it tells you how much filtered water is produced in a given time. It says nothing about filter quality.
• Design: replacement membranes only fit the housing and connections of the device they are made for. That is why the AORA GT600, the AORA GT800 and the W23 each have their own replacement membranes. A membrane from another device will usually not fit.
• Replacement interval: it depends on the local water quality and the amount used. On the W19 and the W23, the RO membrane should be replaced after 12 to 24 months. On the AORA GT800, we recommend replacing the membrane after about 18 months and the PPC pre-filter every 6 months.

Can an ioniser and reverse osmosis be combined?

Yes, the two methods are not mutually exclusive. An ioniser can be connected after a reverse osmosis system. There are also reverse osmosis devices with a built-in additional module, for example the W23 with hydrogen generator. If your main aim is to remove substances from tap water, reverse osmosis is what counts. If you care about pH value or taste, the ioniser is what counts.

Reverse osmosis is a water treatment process based on the principle of selective permeability. It is a widely used method for desalinating water and removing impurities. Reverse osmosis is used in various applications, including drinking water treatment, seawater desalination, wastewater treatment and process water purification.

The basic principle of reverse osmosis involves forcing water through a semi-permeable membrane under high pressure. The membrane is designed to retain certain molecules and ions, whilst allowing water molecules to pass through. This effectively removes salts, minerals, organic compounds, heavy metals and other contaminants from the water.

The reverse osmosis process consists of several components. First, the water to be treated is fed through a pre-filter to remove coarse impurities such as sediment, particles and rust. The water is then pumped into the reverse osmosis unit, where it flows through the semi-permeable membrane.

The high pressure generated by a pump forces the water to pass through the membrane. The membrane consists of a thin layer of semi-permeable material capable of allowing water molecules to pass through whilst retaining larger dissolved substances. This removes most impurities from the water.

The purified water that has passed through the membrane is known as permeate and can be used for various purposes, including drinking water, food processing or industrial processes. The water that has not passed through the membrane and contains the contaminants is known as concentrate and is usually disposed of or recirculated back into the reverse osmosis process to optimise water consumption.

The performance of a reverse osmosis unit is influenced by various factors, including pressure, the type of membrane, the temperature of the water, and the nature and concentration of the contaminants in the feed water. To ensure the efficiency and longevity of the system, it is important to carry out regular maintenance, such as cleaning and replacing the membranes.

Reverse osmosis offers an effective method of water treatment, particularly in areas with limited access to clean water or where high-purity water is required. It is a proven process for desalinating seawater and removing contaminants from various water sources. Continuous technological development has led to improved membranes and more efficient systems, enabling cost-effective and economical water treatment.

TheAORA W23is a reverse osmosis system that is particularly effective at removing contaminants from water. Here is an overview:

What is filtered out?

• Heavy metals: lead, copper, cadmium, chromium, nickel, etc.

• Chemical contaminants: chlorine, pesticides, herbicides, fungicides.

• Micro-organisms: bacteria, viruses (even more effective when combined with a UV filter).

• Salts and minerals: nitrates, sulphates, fluorides, arsenic.

• Particles: Sediment, rust, sand, suspended solids.

• Organic compounds: Medication residues, hormones.

What is not filtered out?

• Gases: Dissolved gases such as oxygen or carbon dioxide are not removed.

• Very small molecules: Some extremely small organic molecules can pass through the membrane.

• Taste and smell: Chlorine and other substances that affect the taste are removed, but the taste of pure water may be perceived as ‘flat’ due to the absence of minerals.

Note on minerals:

• Reverse osmosis also removeshealthy mineralssuch as calcium and magnesium. However, some models (including, where applicable, the AORA W23) have amineralisation filter which reintroduces important minerals into the water after filtration.

The installation of our reverse osmosis systems (such as the W12 or W23) can be carried out by anyone with some DIY experience, using the connection materials supplied and the illustrated installation instructions. The system is usually connected to the cold water supply under the sink and to a mains power supply. If you are unsure, we recommend having the installation carried out by a qualified plumber. Our customer service team will be happy to assist you with any questions regarding installation by telephone or email.