A Guide to Maintaining and Upgrading Industrial Water Treatment Systems

Industrial water treatment systems don't lose their performance suddenly. Rather, operators may be the first to see smaller changes, such as pressure beginning to rise, filter runs shortening, chemical usage increasing, or the quality of treated water decreasing.

Those changes can help differentiate between routine maintenance and a process starting to exceed its design capacity. A well-experienced water treatment system supplier can help determine the right equipment, though an experienced water treatment system manufacturer might be required for the redesign and integration of multiple treatment stages. A custom water treatment system can be a more feasible solution for a plant in some cases than constantly changing standard equipment.

The important point to remember is that decisions about equipment maintenance and upgrades should not be made purely based on equipment age.

Build a Reliable Performance Baseline First

A maintenance calendar is a schedule that indicates when maintenance is to be performed. A performance baseline indicates whether the system is performing as specified or not.

Document steady operating parameters, including feed flow, pump discharge pressure, filter differential pressure, membrane permeate flow, conductivity, chemical dosage, and energy consumption. These are then used as the baseline for future inspections.

Trend data is particularly helpful as many problems can develop over time. If the filter was operating for several days before reaching its pressure drop limit. It could mean that the solids loading is exceeding the filter, that the quality of the feed water has changed, or that the pretreatment is not as good.

Maintain Mechanical Equipment by Condition

Routine checks should be performed on pumps, valves, motors, seals, and piping, but should not just focus on leaks.

Listen for changes in pump noise, and check for vibration, bearing temperature, seal movement, and coupling alignment. Compare actual measurements to the expected operating range for flow and pressure. A pump with poor hydraulic performance can still be pumping.

Valves need to be given the same care. A partially closed, scaled or damaged valve can result in abnormal pressure losses, which can appear as pump deterioration. Prior to replacement of a pump, ensure the hydraulic path is free of obstructions around the pump.

Use Performance Data to Maintain Filters and Membranes

The main reason to conduct filter maintenance should be based on differential pressure and water quality, not on a fixed time basis.

If the pressure is going up at a rate that is greater than normal, check for changes and replace the media or cartridges if necessary. These may be caused by inadequate coagulation, excess suspended solids, biological growth, or changes in feedwater, which can result in unusual loading.

Similar monitoring is needed for reverse osmosis systems. The operators must monitor normalized permeate flow, salt rejection, feed pressure and differential pressure. These values can be used to differentiate between fouling, scaling, mechanical damage, temperature or feedwater quality changes of the membrane.

When contamination is reversible, cleaning can restore performance.

Check Dosing Equipment and Instrumentation Together

A problem with the pump is frequently thought to be the cause of chemical dosing problems, but the issue may actually be with the signal that controls the pump.

In a pH drift scenario, for instance, a pump may add too much or too little chemical even if it is operating properly.

In maintenance, check the entire control loop - sensor condition, sensor calibration, chemical concentration, dosing tubing, injection points, pump output and controller settings.

When Does Maintenance Stop Being Enough?

If individual components are brought back to acceptable levels with the treatment system, but acceptable process performance is not restored, an industrial water treatment system should be considered for upgrading.

One of the common triggers is production growth. The plant may have been designed for a capacity that was used only for a portion of the time, and the equipment may reach capacity levels fairly soon and for extended periods of time, giving minimal opportunity to accommodate peak demands and maintenance.

Feedwater may also vary. If the hardness, salinity, suspended solids, oils, organic loading or ammonia nitrogen increases, then the existing equipment may be operating outside its original design conditions.

Repeated intervention is another red flag. These situations may include regular membrane cleaning, frequent pump repairs, frequent sensor malfunctions, or high consumable use, and should be recognized as an annual operating cost. If corrective work becomes 'normal', an upgrade should be considered seriously.

How a Water Treatment System Supplier Should Approach an Upgrade

The first step in an upgrade isn't to start with a list of equipment replacements.

When membranes foul rapidly, it may be necessary to add membrane area, but it may be just as necessary to improve pretreatment. Improving the treatment process may mean getting better water quality instrumentation rather than replacing treatment equipment, if the operators do not know why the water quality changes.

QILEE provides combined water and wastewater treatment plants, involving membrane processes, modular solutions, containerised solutions, filtration and associated treatment solutions. The selection of the most appropriate solution must be done around the contaminant load and the treatment goal and not just because the equipment is new.

When a Custom Water Treatment System Makes Sense

A custom water treatment system can be beneficial when a facility requires a combination of flow, water quality, footprint, automation, and installation that the standard options do not provide.

Customization can include sizing membrane capacity, altering the number of pretreatment stages, incorporating chemical dosers, choosing appropriate construction materials, incorporating controls, and packaging it into skid-mounted or containerized modules.

For example, QILEE's containerized integrated membrane deamination equipment is intended for removal of ammonia nitrogen and can be configured for various capacities of treatment. Such a modular structure is helpful if transport or deployment time, site space or future expansion has an impact on system design.

Plan Upgrades Around the Existing Plant

Prior to ordering equipment, check the pipe size, space available, electrical power, control system capabilities, chemistry storage, drain access, lifting access, and shutdown time for installation.

Phased upgrades may be more feasible if a shutdown is not acceptable for the plant. Instrumentation and controls can be upgraded first, followed by the pumps, pretreatment equipment, or membrane stages later. These are all potential upgrades that can be scheduled during the maintenance window.

Conclusion

Proper maintenance is more than just about avoiding breakdowns. It generates operating history to determine where the lost performance is occurring and if upgrading makes sense.

Maintain equipment that continues to be used for its intended purpose. Don't enlarge the downstream equipment until you have addressed the issue of upstream problems. Upgrade when a real bottleneck occurs in individual stages as needed, and a custom water treatment system can be used when standard systems will not meet the application requirement.

If external engineering assistance is needed, then the qualified water treatment system supplier or water treatment system manufacturer should assess the system based on water quality, loading, and operating data; you optimize what is holding you back, and you spend your money where it's needed.