Processes in Raw Water Treatment

Introduction:

Treating raw water is a dynamic process. Implementing a raw water treatment system that is engineered to accommodate fluctuations in treatment thus goes a long way in avoiding costly replacements/upgrades down the line.

What is required in raw water treatment?

An efficient and well-designed raw water treatment system should be able to handle:

·        Periodical turbidity and flow variations

·        Fluctuations in water quality requirements

·        Updates in water chemistry requirements and chemical dosage quantities

A well-designed raw water treatment system would thus entail the following procedures:

pH Control:

Achieving a steady consumption of chemicals and forecasting chemical requirements accurately is achievable if the effluent to be treated maintains consistent chemical properties. pH control helps bring in this consistency. It is the process in which acidic or basic agents are added in order to neutralize the effluent or bring it to the pH ranges required.

Depending on the requirements, caustic soda (alkali) or sulphuric acid (acid) is used to bring the pH levels to the required range (Between 6 to 7). The set point for the pH value is determined based on the future utilization of the treated water. Adjustments in pH may also aid improve the coagulation of suspended particles.

Turbidity Control (Coagulation & Flocculation):

Murkiness in water caused by suspended organic and inorganic particles is denoted as its turbidity. This is caused by the suspension of light-weight particles in the water that repel each other due to the presence of like charges. The charged particles are neutralized by adding coagulants to the water, thus preventing the hindrance to assimilation caused by like-charge repellence.

Post coagulation, the water passes to the flocculation chamber, where it is dosed with long-chain polymers known as flocs that combine the coagulated particles, making them heavier. These particles settle to the bottom of the flocculation chamber on account of their weight and thus get separated from the water as sludge.

Microbial Control (Chlorination):

Along with suspended particles, contaminants in the form of water-borne bacteria also constitute pollutants. To curb their growth, we implement microbial control methods such as chlorination that not only exterminate the bacteria but also limit their repopulation.

Chlorination can be done before filtration or post-filtration, depending on plant requirements. Performing chlorination after filtration requires lesser amounts of disinfectant, whereas pre-chlorination of the effluent requires frequent filter washing. Thus chlorination, along with filter maintenance, depends upon the mill setup.

The chemical dosing in these processes can be optimized through the implementation of eLIXA®, a SaaS-incorporated device by Haber. The collection of real-time data at multiple touchpoints, followed by the identification of influencing parameters gives access to relevant data. Using this data, subsequent analysis through AI/ML algorithm is carried out, which ensures peak consistency in performance with minimum exhaustion of treating chemicals.