Reverse Osmosis (RO) is the process of reversing the natural act of osmosis by applying greater hydro-static pressure than the osmotic pressure through a semi-permeable membrane to generate pure water

Each application of a reverse osmosis machine needs to be evaluated to understand the return on investment opportunity.

All reverse osmosis applications are customizable – Your Aqua-Chem engineer will work with the facility personnel to determine the process flow and how each unit operation fits into the system. We are experienced in both retrofits and full new system installations.

Many factors need to be considered when estimating the life of a RO machine – typically a life of 20-30 years can be expected

Each application of water purification needs to be investigated to determine if a fit exists. Considerations for the use of a RO machine are numerous and need to be discussed with an Aqua-Chem engineer.

Reverse Osmosis machines remove impurities in water down to the ionic level. Crossflow filtration is based primarily on size differences (Molecular Weight Cut Off's), but also can be based on charges of ions, concentration of ions and density differences.
Microfiltration - 1.0 to 0.05 micron

Ultrafiltration - 0.1 to 0.005 micron
Nanofiltration - 0.008 to 0.001 micron
Reverse Osmosis - 0.001 to 0.0002 micron

Yes – there is a pump involved in reverse osmosis that is used to overcome the osmotic pressure and apply reverse osmosis to separate the impurities from the pure water.

There are many options for the design and construction of reverse osmosis machines – materials of construction, automatic or manual options, machine configuration based on permeate requirements. Our Aqua-Chem engineers are trained in these areas and will guide our clients through the selection process.

One can expect to be in the area of 75% when working with surface or well water, which means 100 gallons of feed water would translate into 75 gallons of pure water and 25 gallons of wastewater. There have been many advances with the application of antiscalant chemistry and concentrate recovery reverse osmosis machines that improve this water balance into the low 90% range. Your Aqua-Chem Engineer will model the raw water chemistry to determine what can be achieved and provide options to consider.

Most membrane manufacturers will advertise a 99.3 – 99.7% rejection rate. It is safe to use a 99.0% rejection for practical purposes.

Reverse Osmosis uses membrane separation using a thin film composite layer and high-pressure pumps to overcome the osmotic pressure of the feedwater.

Deionization employs ion exchange resin in vessels similar to multimedia filters – the ion exchange process has a strong acid cation resin for exchange of positively charged ion with H+ and strong base anion for exchange of anion OH-. The net result is HOH or H2O. Deionization requires a regeneration step with acid and caustic on a regular basis.

Distillation is a thermal process where the feed water is evaporated, re-condensed, passed through a deaerator to remove CO2 and cooled to generate pure H2O.

The cost of operation comprises 3 primary items – consumables associated with the pretreatment and RO machine, energy, and water. Your Aqua-Chem Engineer will work with you to generate a Total Cost of Operation statement for the system.

Consumables range from cartridge filters, media filters, chemistry, RO membranes, ultrafilter membranes. Each system has a different mix of consumables. Your Aqua-Chem Engineer will identify the required consumables based on the survey data collected from our client site.

Pre-treatment ahead of the RO machine conditions the water to achieve specific parameters required. Pre-treatment typically removes suspended solids, oxidants such as chlorine that can foul and damage membrane surfaces. It will also condition the water to help manage scaling minerals within the RO machine.

There are many membranes available on the market. The selection depends on the permeate specification and raw water source. The raw water needs to be modeled using computer software to investigate the appropriate membrane for a given situation. Your Aqua-Chem Engineer will conduct this evaluation as part of the discovery process.

The SDI – silt density index – is a measure of suspended solids in the water ahead of the RO machine. Suspended solids will foul the membranes diminishing its performance. Pre-treatment is required to remove the suspended solids and achieve an SDI value of <3.0.

The RO machine requires daily readings of the system parameters are recorded to monitor system performance. Aqua-Chem will provide a normalization spreadsheet to record the data and graphically trend the performance of the machine over time. This is used to predict such items as clean in place procedures

Some of the general maintenance items include filter changes, clean in place procedures, periodic membrane changes, instrumentation calibration, and high-pressure pump maintenance.

Yes, Aqua-Chem offers comprehensive service programs that encompass the consumables required for the RO machine, along with preventative maintenance service activities. We customize each service package according to our customers’ requirements

Chemicals used in the RO system are based upon the modeling of the water conducted by Aqua-Chem. The raw water chemistry will be entered into a computer modeling program, along with the process conditions of the facility. The modeling program will assess the mineral content of the water along with the process conditions and provide guidelines for the type and dosage of the chemistry required.

A full inorganic water analysis feeding the RO machine is preferred. Aqua-Chem can provide a template of the elements required for the water analysis.

Options range from extending recovery of the RO machine through the application of specialized antiscalants, processing the concentrate through a 2nd RO machine to generate more permeate, thus reducing the concentrate, or using the concentrate from the primary RO in other areas of the facility.

Yes, Aqua-Chem offers comprehensive training material for all aspects of a RO system.

A single-pass RO processes raw water into permeate and concentrate through a single RO machine. A double-pass RO takes the permeate from the single-pass RO and processes it again, further increasing the purity of the raw water.