Halland Instruments AS

pH analyzers for the wastewater treatment plants.

Applications in other industries:

The PH-1400 analyzer:

Sodium hydroxide process:

pH analyzer after ten years of operation. The pH measurement is used for automatic control of the NaOH valve.
Flow: 3 m³/h

“PH-1400”, the pH analyzer for the pH control of industrial wastewater and effluent treatment plants.

The “PH-1400” pH analyzer, delivers accurate pH measurement in the industrial wastewater treatment processes. The efficiency is increased and the overdosing of the pH reagents is eliminated. Our analyzers are in use in copper and zinc plants for wastewater treatment. The analyzer is excellent for the treatment of wastewater from electroplating plants and the treatment of wastewater from the alumina industry.
The problem is that other pH measuring systems have low accuracy and short lifetime of the electrodes. The nature of the lime, sodium hydroxide and sulfide processes causes build-up of a layer of precipitations on the pH electrode and the solutions poisons the reference electrode, this drastically decreases the accuracy of the pH measurements.
Our PH-1400 analyzer has high accuracy and the lifetime of the electrodes are very long, many months or even years. The reference electrode is never poisoned and the pH electrode surface is kept clean by an advanced cleaning system.  
Other systems require frequent calibrations, however, this only disguise the problem, the problem of low accuracy persists. A short lifetime of the electrodes or combination electrode is a symptom of low average accuracy, making process optimization impossible.

The following properties distinguish our analyzer from other known technology:
1. Most reliable, infrequent error with the analyzer or the electrodes, very low-maintenance.
2. High short-term and long-term accuracy.
3. Very long life of the electrodes, it is not possible to get high long-term accuracy without long electrode life.
4. Other systems require frequent calibration and still are not accurate. Our analyzer provides high accuracy even with weeks’ interval between calibrations.
5. It is fast and easy to calibrate the analyzer, there is no sample head which must be dismantled for calibration.
6. It is easy to install the analyzer and normally no encroachment in the process equipment is needed.

Other features:
1. Automatic cleaning of the electrodes by spraying the electrodes from below cleans the sensor surface mechanically and cleaning with chemicals prevents build-up of coating.
2. The analyzer is designed for harsh environments with high temperatures, acid, dust and gases. The analyzer is designed to tolerate electrical noise and fluctuations in the supply voltage. 
3. Easy to operate, logical menu structure, easy-to-use two point calibration procedure with calibration plausibility check.
4. The electrode system is designed in such a way that the reference electrode never can be poisoned.
5. The analyzer is designed for measuring the pH of solutions with high solid content.
6. The electrodes are in controlled pressure conditions and are protected against mechanical strains.
7. Large two-line LCD display with LED back-light.
8. Measuring range 0-14 pH.
9. Modbus port for data communication, 4-20 mA output and alarm output.

Calcium hydroxide/sulfide process for the treatment of wastewater from a zinc plant.

Process description:
The plant receives wastewater from the leaching plant and the cell house and from the wastewater from ponds. The currents enter a large collecting tank. The composition of the solution from this tank has a zinc content of 1-3 g/l. From this tank the wastewater is fed to the wastewater treatment plant where lime milk is added to neutralize the acid content and to precipitate the zinc. Sulphide is added to precipitate the cadmium. The process takes place in a string of four reaction tanks. The pH values are adjusted automatically with two regulators which controls two lime pumps which adds lime milk in the first two tanks. After the reaction tanks the solution flows to two thickeners. The pH value is also measured in the overflow of the thickeners.

Flow: 200 m³/h. pH range: 4-9 pH. Zinc content: 1-3 g/l. Temperature: 10-30 ° C. Number of pH analyzers: 6. Tanks: 4 tanks each with a capacity of 150-200 m³. Number of thickeners: 2

Reaction tanks

Thickeners

Analyzer room