Tank-Farm Wastewater with 100,000 mg/L Oil — Two Units Turn It Into Clear Water? A Look at This Sichuan Petrochemical Project

You might think industrial wastewater treatment is just the usual dosing, settling and filtration?

But there is one kind of water that is really hard to handle——the oily wastewater from crude-oil storage tanks.

Simply put, when tanks store, transfer and are cleaned, water and oil mix together, and with pumps and valves in the loop, the oil gets"broken"into micron-scale droplets evenly dispersed in the water. Expect them to separate on their own? Impossible.

At a domestic petrochemical enterprise's crude-oil storage, the influent oil content can reach 100000mg/L. What does that mean? In one liter of water,100 grams is oil. Pour out a bottle of mineral water and one tenth is crude oil ———roughly that ratio.

So how is this water treated?

On this project SINOKLE used two"'high-tech' units:"——a coalescing pressure oil separatorleading,CDFU and cyclonic dissolved-air flotationfinishing.

First, the coalescing pressure oil separator. Think of it as a"'make-oil-droplets-clump-and-grow'"accelerator. It is packed with a special material; as water passes through, those micron droplets collide on the material surface, stick together and grow. Once droplets grow, buoyancy soars——like a grain of sand sitting still underwater, but stick it into a ping-pong ball and it floats up by itself. Plus the pressurized operation breaks the"emulsion film"between oil and water, maxing out separation efficiency.

After this stage, some low-concentration oil and suspended solids remain. Now it is the turn of CDFU——which you can picture as"'giving the wastewater a bubbleSPA"'. It releases vast numbers of ultra-fine bubbles — how small? An order of magnitude finer than conventional flotation bubbles. The micro-bubbles adsorb onto residual oil droplets and suspended particles like magnets, then carry them quickly to the surface to be skimmed off. AndCDFU it uses cyclonic water distribution, the flow spiraling upward to ensure bubbles contact every point fully, leaving no"slacking"corners.

Now let's look at the results:——

· Influent: oil content ≤100000mg/L

· Effluent: oil content <100mg/L

· Oil-removal rate:>99.9%

· Treatment capacity:50m³/h，2026 Monthly delivery:

From 10 ten-thousand to under, a three-orders-of-magnitude gap. In plain words: one liter of water originally hadgrams of oil; after treatment less than0.1 gram remains.

Where is the value of this?

It is not theoretical data from a lab, but figures from CNPC's actual production line. And this project sets a benchmark for similar tank-farm oily-wastewater treatment in the Southwest petrochemical industry——telling peers: this duty, this process route — it works, and works beautifully.