In a water treatment, it is important to see the overall picture of the treatment costs and not only the unit price of the coagulant...
If we only talk about price, conventional coagulants such as ferric chloride, ferric sulfate and alum (aluminum sulfate) which are standard coagulants (commodities) are going to be the cheapest in terms of purchase ($/kg).
In a water treatment, it is important to see the overall picture of the treatment costs and not only the unit price of the coagulant used.
Indeed, conventional coagulants such as ferric chloride, ferric sulfate and alum are acidic coagulants that will greatly reduce the pH of treated water. It will be necessary to adjust the pH of the water treated with caustic soda or other alkaline product in order to meet the discharge standards for pH.
Particles in water are negatively charged. Coagulation consists in destabilizing them. It is a question of neutralizing their electrostatic charges of repulsion to allow their meeting. When adding the inorganic coagulant, the metal ion (Al3+ or Fe 3+) is hydrolyzed to form a precipitate (floc or pinfloc) of aluminum hydroxide or iron hydroxide as well as hydrogen H+ ions. These released H+ hydrogen ions are responsible for the acidification of the treated water.
There are other aluminum-based coagulants on the market that are ‘pre-hydrolyzed’ such as AQ-8921, AQ-8925 or AQ-8929 to name a few;
This means that, due to the chemical nature of these coagulants, which already contains certain amount of aluminum hydroxides, these pre-hydrolyzed coagulants will consume less alkalinity in the water to be treated and will therefore affect the pH less. In some cases, no pH adjustment with an alkaline product will even be necessary.
These pre-hydrolyzed coagulants will be more expensive to purchase ($/kg) than commodity coagulants (ferric chloride, ferric sulfate, and alum), however they will have the following advantages:
Thus, looking at the total operating costs of water treatment, it is often wiser and more economical to use a pre-hydrolyzed coagulant versus a coagulant of amenities.
Trust the AQUASAN technical team. We have a very high technical expertise in wastewater treatment. Considering the characteristics of your effluent and your treatment chain, we will choose the most relevant coagulant for your treatment and the one that will allow you to have the lowest operating costs.
Our goal is to offer you an innovative and easy-to-use chemical program, efficient and corresponding to your performance objectives. We have unparalleled training and technical know-how, and we know how to provide creative solutions that ensure the maintenance of treated water quality.