High-Quality, Integrated, Full-Chain
Water Treatment Solutions

1. Cycles of concentration is not a dial

Cycles of concentration (CoC) is set by the balance between makeup water, evaporation, and blowdown. What actually decides whether it can rise is whether the water will scale, corrode, or grow biofilm at higher concentration. CoC is therefore a measure of your overall water-management capability — not a number you simply turn up on a controller.

2. Four common hidden ceilings

• Hard makeup water. Calcium hardness, alkalinity, and chloride set the baseline constraint — change the makeup source and the whole program must change with it.
• Mismatched chemical program. A generic scale inhibitor applied to hard water fails the moment critical pH is crossed — and actually accelerates deposition.
• Crude blowdown control. Bleeding down "when the water looks cloudy" instead of on conductivity or chloride means CoC can never hold steady.
• Undetected cross-leakage. Process media entering the circulating water skews everything. Until it is found, raising CoC is pointless.

3. A safe path upward

Step 1 — measure properly. Build a continuous two-to-four-week baseline: pH, conductivity, total and calcium hardness, total alkalinity, chloride, total iron, turbidity, and heterotrophic bacteria counts.

Step 2 — find the limiting factor. Use saturation indices (LSI/RSI) to identify which parameter crosses the line first if CoC rises another 0.5.

Step 3 — fix chemistry before operation. Choose a scale-and-corrosion program matched to your water, and move dosing from "rule of thumb" to calculated from makeup and blowdown volumes, then verified by online monitoring.

Step 4 — step up gradually. Raise CoC by no more than 0.3–0.5 at a time, hold one to two weeks, and only proceed when every parameter stays in range.

4. Supporting actions that make it stick

• Upgrade side-stream filtration — keeping suspended solids and biofilm low is what makes higher CoC worthwhile.
• Online instrumentation — conductivity plus pH is the minimum, with automatic blowdown valves interlocked to dosing pumps. Far more reliable than manual rounds.
• Scheduled cleaning — once scale has built up on heat-transfer surfaces, no chemical program will perform at its best.

How Aobang does it: two to four weeks of baseline data to locate the limiting factor, then a staged concentration plan — each step validated by data before the next one begins.

1. Perforation is a process, not an accident

A tube travels from healthy to perforated over months or years: surface deposits → oxygen depletion under the deposit forming a concentration cell → localised pitting → wall thinning → perforation. Catch any link in that chain and you still have time to intervene.

2. The six leading indicators to watch

• Total and dissolved iron. Total iron rising with a growing dissolved fraction means corrosion is accelerating — the earliest and most sensitive signal.
• Corrosion rate. Coupon or electrochemical probe monitoring — read the trend, not a single point.
• pH and alkalinity swings. Longer low-pH excursions multiply carbon-steel corrosion rates.
• Chloride and conductivity. Chloride enrichment drives pitting and stress corrosion — especially critical in stainless systems.
• Heterotrophic bacteria and biofilm. Microbiologically influenced corrosion (MIC) is often overlooked, yet accounts for a substantial share of field failures.
• Heat-transfer efficiency. Widening approach temperatures and rising fouling resistance usually accompany under-deposit corrosion.

3. A practical warning ladder

• Amber: a single parameter drifting upward for two consecutive weeks — increase testing frequency and re-check dosing.
• Orange: iron or corrosion rate clearly off baseline — adjust the inhibitor program and schedule an internal inspection at the next outage.
• Red: leakage indications or a step change in iron — locate the cross-leak immediately and prepare a retubing plan.

4. The order of response matters

First confirm the data is trustworthy (sampling point, reagents, instrument). Then identify the corrosion mode (uniform, pitting, galvanic, MIC). Only then change the chemical program. Reverse that order and you will often "change the chemistry without fixing the problem".

How Aobang does it: total iron, corrosion rate, and bacteria counts are charted as monthly trends. Decisions follow trends, not single readings — turning retubing from an emergency into a planned event.

1. Why buildings must take this seriously

Cooling towers offer the warm, wet, nutrient-rich environment Legionella thrives in. Once aerosolised and inhaled, the risk to the elderly, children, and immunocompromised is far higher than for the general population. Hospitals, hotels, schools, and care facilities are simultaneously the highest-exposure settings and the most tightly regulated.

2. When to test

• At least once before the season starts and once mid-season;
• Before restarting a system after prolonged shutdown;
• When a suspected case appears nearby, or when required by the health authority;
• To verify effectiveness after cleaning and disinfection.

3. How to sample

Sampling points should cover the cooling-tower basin, the main return header, and representative remote locations. Container type, transport conditions, and time-to-lab all directly affect validity. Alongside Legionella itself, track heterotrophic plate counts, biofilm volume, and turbidity — these are the preconditions for growth.

4. How to read the results

"Not detected" does not mean the system is safe — it means Legionella was not detected at that sampling point on that occasion. The reliable judgement comes from reading each result against historical data, cleaning records, and operating parameters as a trend. If Legionella is detected, assess concentration, system status, and occupant exposure together — do not simply shut down and move on.

5. Control and emergency response

• Routine: control CoC and turbidity, keep side-stream filtration effective, and alternate oxidising and non-oxidising biocide programs.
• Cleaning: physically clean fill media and basins on schedule — remove the biofilm that acts as a reservoir.
• Emergency: isolate the affected area first, then run high-concentration disinfection and re-test. Return to routine operation only after a clean re-test.
• Records: file test reports, cleaning logs, and dosing records completely — the strongest evidence you can hold in a health inspection.

How Aobang does it: Legionella testing is built into each building project's annual plan and filed together with monthly water-quality records and cleaning logs — turning compliance from an ad-hoc scramble into routine, documented practice.