Taking Hardness Out and Putting It Back In: pH Adjustment, Lime Softening, and Flue Gas Desulfurization Across San Diego County
Imported river water arriving hard, membrane permeate arriving aggressive, shipyard and laboratory effluent arriving acidic. RDP Technologies makes the equipment that prepares lime for all of it.
Talk Through an Application Our EquipmentA Water Market Unlike Any Other in This Batch
Every other city in this series sits on its own water. San Diego largely does not, importing most of its supply across hundreds of miles while building an increasingly large share locally through desalination and advanced purification. That produces an unusual situation where lime is used for two opposite purposes on opposite sides of the same county, stripping minerals out of one supply and adding them back into another. Municipal treatment across the county is covered on our San Diego municipal treatment equipment page.
Lime Softening on Imported Supply and Remineralization Behind Membranes
Colorado River water reaches this county carrying a mineral load and a total dissolved solids figure that industrial users have always had to manage, and any plant running cooling towers or generating steam on it deals with hardness before anything else. On the other side of the ledger sits everything coming off a membrane. Reverse osmosis strips water of essentially all its hardness and alkalinity, and what emerges is soft to the point of being aggressive, unstable and corrosive to the pipe carrying it. That water cannot go into distribution or into a plant loop untreated.
Lime does both jobs. Used to soften, it raises pH so that calcium settles out in carbonate form and magnesium exits behind it, and soda ash joins the reaction anywhere the noncarbonate portion also needs cutting. In the remineralization direction the same material is used to restore calcium and alkalinity to permeate, bringing a corrosive stream back into balance so it stops attacking whatever it touches downstream.
Both duties reward exactly the same thing, which is reagent whose concentration does not move. On Tekkem equipment the lime and the water go across load cells before anything reacts, the reaction is kept at the temperature it needs to run out fully, and strength is set for use after that. Remineralization in particular is unforgiving of drift, because the target is a narrow stability window rather than simply a number to exceed.
Look Inside the Tekkem
pH Adjustment for Ship Repair, Laboratory, and Light Industrial Effluent in San Diego
The working waterfront is where this county's most difficult industrial water sits. Ship repair and construction along the bay produce runoff and process water carrying copper, zinc and other metals from hull coatings and blasting operations, and copper loading in San Diego Bay has been under regulatory attention for years. Inland, the research and biotech corridor generates laboratory and process waste that leaves buildings acidic, and the county's unusually dense craft brewing industry contributes low pH, high strength effluent that regularly exceeds what a sewer agency will accept without pretreatment.
Lime handles these because one addition does more than one thing. Lifting pH satisfies the discharge requirement while dissolved metals convert to hydroxides and drop out for removal, which is precisely the combination a shipyard stream needs. The awkward part is that none of these sources runs steadily. A dry dock operation is episodic, a laboratory discharges in slugs, and a brewery's load follows its brewing schedule rather than a clock.
Feed that corrects itself is what copes with that. Dosing keys off whichever measurement the site prefers to drive it by, and the outcome stays put while conditions swing around it. Multiple treatment points come off one circulating loop with independent metering, and slurry kept in motion does not leave the deposit that eventually narrows a line.
Metering and Control
Flue Gas Desulfurization and Sorbent Feed for Southern California Combustion Sources
Worth saying plainly: this is not a sulfur market. California retired its coal generation years ago, and the plants serving this county burn natural gas, which carries almost no sulfur. Anyone claiming a thriving flue gas desulfurization business in San Diego is describing something that does not exist. The genuine demand within reach of here sits inland, at the cement operations in the Inland Empire and out in the high desert, where a kiln liberates sulfur from the fuel and from the rock alike, and at industrial boilers running heavier fuels.
Where that work does exist, the equipment sorts into two families. Wet systems wash the gas through a circulating suspension, and what leaves in the blowdown is sulfur bound up as a calcium solid. Dry and semi dry designs operate without any circulation, feeding powdered reagent into the duct ahead of particulate collection. Neither tolerates a reagent that varies, because the removal figure simply follows the reagent.
What we build is the preparation stage, and it is the same equipment whether the reagent goes to an absorber, a neutralization basin or a softener. That matters here more than in a heavy sulfur market, because a Southern California buyer is usually specifying for one of the other two duties and wants to know the platform is proven across all of them.
Powdered and Slurry Feed
Seismic Anchorage and Structural Requirements for Process Equipment in California
California asks questions about equipment that most of the country does not. A vessel holding several tons of slurry has to be anchored for ground motion, the calculation depends on where the site sits and what it sits on, and a water treatment facility frequently carries an importance factor that raises the requirement above what an ordinary industrial building would face. None of that is optional and none of it can be resolved after delivery.
The practical consequence is that anchorage details, mounting arrangements and structural calculations belong in the submittal package rather than in a conversation with the installing contractor. A supplier who has not done this work before tends to discover it during review, which costs schedule at the worst possible point.
Designing, fabricating and programming in house is what makes the response straightforward. When one organization owns the drawings and the fabrication, adjusting a mounting arrangement or producing the calculation a reviewer wants is an internal matter rather than a chain of requests through a supply chain. Tell us the site class and the governing code edition early and it stops being a problem at all.
Design Documentation
Specifying Equipment When the Water Source Itself Is Going to Change
Most plants can assume their influent will look roughly the same in ten years. Southern California cannot. This region is actively rebuilding its supply portfolio, shifting weight away from imported deliveries toward desalination, purified recycled water and local groundwater recovery, and the chemistry arriving at a given plant in 2035 may bear little resemblance to what arrives today. A treatment system specified tightly around current conditions is specified around an assumption with a known expiry date.
That argues for range rather than optimization. Slurry strength adjustable across a wide band, dosing that tracks measured conditions instead of a fixed setting, and enough turndown that the equipment stays accurate when the load is nothing like its design point are what let a system follow a moving source. Equipment tuned perfectly to one water is exactly the equipment that struggles when the water changes.
It also argues for asking about the plan rather than only the present. We would rather hear that a site expects to blend in permeate within five years, or that a groundwater project is in design, and size accordingly. That conversation costs nothing during scoping and is expensive to have afterward.
Four Decades of ProjectsStart With the Water Analysis
Send the current chemistry, whatever the plan says it becomes, and the duty you need covered. We will work from that.
Tell Us the Water