LNG Terminal Wastewater Treatment: Amine Degradation Products, Oily Condensate and Hydrotest Water

LNG facilities are not large continuous wastewater producers, and that is precisely what makes their effluent awkward. Most of the load arrives in occasional slugs — amine system drainage, compressor condensate, tank hydrotest water and turnaround cleaning — rather than as a steady flow. A plant designed around an average daily flow will be undersized for the events that actually matter.

Intermittency Governs the Design

A liquefaction train produces relatively little water during normal operation. Then a hydrotest fills and drains a large tank, a compressor train is washed, or a turnaround generates thousands of cubic metres of cleaning water over a few days.

The practical response is holding capacity and controlled release rather than treatment capacity sized for the peak. Buffer tanks that let you meter a slug into the treatment plant over weeks convert an impossible hydraulic load into a modest continuous one. The same selection criteria reappear in Chemical Manufacturing Wastewater Treatment, which is worth opening alongside this one.

This is a case where equalisation does more than any treatment technology, and it is routinely under-specified because the average flow looks so small.

Amine-Bearing Water

Acid gas removal uses an amine solvent, and amine enters wastewater through pump seal leakage, sampling, filter changes, and periodic draining of the amine circuit. Concentrations in the drainage are high; in the mixed effluent they are diluted but still significant.

Amines matter for two reasons. They contribute nitrogen that converts to ammonia, and degraded amine products — heat-stable salts and organic acids from oxidative degradation — are poorly biodegradable and often inhibitory.

Where amine drainage is collected separately, treating it by oxidation or sending it to a dedicated treatment is far more effective than diluting it into the general sewer. It also keeps a recoverable chemical out of the waste stream.

Compressor systems contribute condensate containing lubricating oil, glycol from the dehydration unit and traces of heavier hydrocarbons. It is a classic oily water problem: free oil separates readily, emulsified oil does not.

Gravity separation followed by induced air or dissolved air flotation handles it. Where glycol concentration is high, note that glycols contribute a large biochemical oxygen demand while being readily biodegradable — treat them biologically rather than trying to separate them.

Reference Data from 42 Commissioned Plants

Across 42 commissioned plants where we hold complete COD records, influent COD ranged from 200 to 172,000 mg/L and treated effluent from 50 to 5,000 mg/L. Average removal across that set is 87.1% — not a marketing figure, but the measured mean.

That average is worth pausing on. It sits well below the 95%-plus numbers most suppliers quote, because the set includes genuinely difficult streams. On some electroplating and municipal duties the installed configuration only reaches about half the influent COD, and saying that up front is more use to you than a number the plant will never hold.

Keep refrigerant and seal oil drainage segregated where possible. Some refrigerants and their degradation products create treatment problems out of proportion to their volume.

Seawater and Cooling Side

Open rack vaporisers use seawater and return it cooled, and where biocides are dosed to control fouling, residual oxidant in the return stream needs managing. Dechlorination ahead of discharge is usually straightforward. Plants dealing with comparable loads face many of the same trade-offs covered in wood preservation and timber treatment wastewater.

The thermal effect of the cold discharge is an environmental matter handled by outfall design and dilution rather than by treatment, but it is worth confirming what your consent says about temperature.

Hydrotest and Commissioning Water

Hydrotesting tanks and pipework generates large volumes over a short period. The water itself is usually clean, but it picks up mill scale, welding residue and — where pipelines were chemically cleaned — residues of the cleaning agents used. The same selection criteria reappear in Carbon Fibre Manufacturing Wastewater system, which is worth opening alongside this one.

The mistake to avoid is discharging it all at once. Staged release with screening and settlement, and pH correction where chemical cleaning was involved, is normally sufficient. Where chromate-based passivation or oxygen scavengers were used in commissioning, check what was dosed before authorising discharge, because some commissioning chemicals are problematic in ways that general consent limits do not capture.

For new builds, agree the hydrotest discharge plan with the regulator before filling rather than after. It is a predictable event and the conversation is much easier in advance.

Combining Treatment Stages

We have written about the downstream implications separately in Zinc and Lead Smelting Wastewater system. Most facilities do not run a single clean stream, and a shared equalisation and biological stage is usually the economical answer once the streams are chemically compatible.

Why Choose Baihuipu as Your Manufacturer

Two decades in this industry teaches you that most treatment problems are procurement problems in disguise. Someone bought the cheapest skid, nobody checked the equalisation volume, and eighteen months on the plant cannot hold its consent limit. We build differently.

Manufacturing Base in Guangdong

Owned production lines mean we control tolerances, materials and delivery. Standard modular units and bespoke skids are both built by our own people, so schedule commitments are ours to keep.

Twenty-Plus Export Markets

We have shipped to the United States, Canada, Russia, Indonesia, India, Nigeria and Vietnam among others. Crating, export documentation and certificates are handled in-house, which keeps customs surprises to a minimum.

Experience Built the Hard Way

Since the early 2000s we have commissioned plants for food and beverage processors, chemical works, electroplaters, textile mills, mines and municipalities. The lessons that stick are scaling, fouling and sludge handling — those inform every design we issue.

Documentation You Can Actually Audit

Each system ships with as-built drawings, material certificates, welding records and a functional specification. If a client's own consultant wants to review the process calculation basis, we hand it over rather than treating it as proprietary.

Complete Units and Turnkey Plants

Whether you need a single package unit or a turnkey installation with civil works, we deliver the entire treatment scheme. Our engineering team covers process, mechanical, electrical and automation so one party owns the outcome.

After the Handover

Spares for everything we install are held in stock. Remote telemetry is available on most systems, and our service engineers commission, train your operators and turn out for emergencies.

Talk to Our Engineers

Send through your raw water data and we will advise on the viable process route and realistic operating cost before you commit to anything. We can be reached on WhatsApp: +86 13631765076 or through hkbhp.com.

WhatsApp: +86 13631765076

Frequently Asked Questions

What spare parts should we hold on site?

Critical spares are pumps, dosing valves, instrumentation sensors and any specialty media. We ship a recommended spares kit with the plant and hold stock for everything we supply, so lead times on replacements stay short.

Do you handle installation and operator training?

Every unit we supply is commissioned by our own engineers. Training happens on site with your actual operators, and the O&M manual covers routine work plus troubleshooting. Remote diagnostics through the control system are included for the first year.

Can you work with our existing equipment?

Often yes. We regularly integrate into existing civil structures where the concrete is sound, replacing internals and controls rather than starting over. We will tell you honestly when legacy kit is beyond economic repair.