pH adjustment in water treatment
What is water pH?
pH is a parameter that indicates the acidity or alkalinity of water. It influences the chemical reactivity and solubility of several contaminants and the behaviour of materials in contact with water.
In drinking water and process water projects, pH is a key input for the efficiency of treatment processes, including the removal of contaminants and the protection of systems from corrosion.
Why do we consider pH in water?
pH is taken into consideration when analyzing raw water, as it affects the performance of several treatment processes. Sometimes, during a project to discharge water into the effluent, the pH is the only variable addressed.
In drinking water treatment, the regulations in force as well as the treatability studies conducted by Magnor show that certain processes require pH adjustment to achieve treatment objectives. For example, a pH that is too low can reduce the effectiveness of a filter media and even have negative consequences for the media itself. On the other hand, raising the pH level limits the aggressiveness of the water and protects the distribution networks against corrosion in the long term. In addition, according to current regulations, the pH for drinking water should generally be between 6.5 and 8.5. The pH is therefore monitored, adjusted and controlled throughout the treatment chain according to the specific needs of the project.
In pH treatment for wastewater, during the design of a pH neutralization system, pH variations, their minimum and maximum, are key to choosing the treatment parameters and the type of components. In addition, current municipal and provincial wastewater standards are essential to ensure that treatment will meet these standards.
In summary, pH is a fundamental parameter that influences both the efficiency of treatment processes and the sustainability of infrastructure and equipment in contact with water.
Health and process issues related to pH
Drinking water
In drinking water, an inadequate pH can reduce the effectiveness of certain treatment processes or promote corrosion problems in distribution systems. For example, water with a pH that is too low is often associated with aggressive water, which can accentuate the corrosion of metals, including steel, cast iron, and, more risky for health, lead and copper. Conversely, a pH that is too high can exceed regulatory limits and create imbalances in the treatment.
Process water
In process water, pH directly influences the performance of equipment, the stability of chemical reactions and the compatibility of water with industrial materials and processes.
In wastewater, if wastewater is reused or sent to another process, an inadequate pH can cause problems with equipment, such as corrosion.
If it comes from a process to be discharged and the pH is out of standard according to the regulations in force, the authorities could impose fines, stop or limit production or ask for a corrective action plan.
What causes pH fluctuations?
Variations in pH are related to the natural characteristics of raw water, such as the presence of dissolved CO₂, low alkalinity or low hardness. Some waters that naturally have a low pH can result in aggressive water. In process waters, pH can also vary as water passes through different equipment or when chemicals are added, requiring precise pH control and adjustment to maintain process stability. Also, discarded cleaning products, such as those used in laboratories, pharmaceuticals or food manufacturing, can increase or decrease the pH of the water discharged.
Recommendations in Canada
In drinking water, Health Canada sets a recommended pH range of 6.5 to 8.5. However, provinces may have their own requirements.
In wastewater, the pH values generally range from 6.0 to 9.5. However, there are several circumstances that influence the pH of water discharges, such as the type of water discharged, where it is discharged, as well as provincial and municipal regulations.
How do we treat pH issues?
The pH treatment can be adjusted in different ways depending on the situation. In drinking water, if the pH is too low or too high, the addition of a basic or acid injection system, respecting drinking water standards, can be added.
In wastewater, while the water can sometimes be too acidic and sometimes too basic, a pH neutralization system will be required, including basins, base and acid injection systems, as well as probes and other instrumentation.
How can Magnor help you?
Magnor evaluates each situation and designs custom systems according to the particularities of each water and each customer, both industrial and municipal. Magnor specializes in basic or acid injection systems for drinking water, as well as in effluent pH neutralization systems.
Magnor supports its customers in the interpretation of water analyses, the performance of treatability tests for special cases, and the selection of the treatment process best suited to the water quality objectives.