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Do You Know How Tertiary Wastewater Treatment Works?

In the wastewater industry, plants often focus on primary and secondary treatments, which do most of the work of preparing the wastewater that is released into the environment.

Tertiary treatment is also important in many cases. It provides peace of mind knowing that treated wastewater is clean, hygienic, compliant, and safe enough to drink or reuse.

Most wastewater treatment systems have at least two main treatment modalities: primary and secondary treatment, with some additional primary methods.

Primary treatment, which typically removes fifty to seventy percent of suspended solids in wastewater, uses physical processes such as filtration and sedimentation to remove grease, debris, oil, and some light solids.
Secondary treatment involves the application of additional biological processes, such as aeration and activated sludge treatment, to break down dissolved and suspended biosolids using beneficial bacteria.

Tertiary treatment adds a third level of more advanced and rigorous treatment. Primary and secondary treatments generally only clean the wastewater so it can be safely discharged into the environment.

However, with a , the water is purified to be reusable for water intensive processes and even drinkable.

However, not all wastewater treatment plants use tertiary treatment. Primary and secondary treatment is usually sufficient for a number of purposes.

People who use tertiary treatment achieve more stringent hygiene levels to meet the exact standards that govern water reuse, especially in public water supplies.

Tertiary treatments are also useful when facilities need to release water into sensitive aquatic ecosystems, such as water near beaches, shallow rivers, or coral reefs.

It is more effective than primary or secondary treatment in removing unwanted dyes from wastewater, making it essential in industrial pulp and paper applications and in textile manufacturing.

Tertiary wastewater treatment often works by combining physical and chemical processes to remove harmful microbiological contaminants from wastewater.

This process typically involves filtration followed by additional sanitizing treatment. In some cases, other special treatments may also be used in tertiary treatment, such as lagoon storage, biological nutrient removal, and nitrogen and phosphorus removal.

Tertiary filtration may contain a few different parts. Sand and activated carbon filters are common, and filters may contain finely woven fabrics. Filters also come in a few different types, including bag filters, drum filters, and disc filters:

Tertiary disinfection can take different forms such as:

Chlorine treatment

Chlorine is one of the most widely used disinfectants in wastewater treatment, especially in North America, because it is inexpensive, easy to use, and effective.

Sewage treatment plants can kill harmful microorganisms like bacteria and viruses by adding chlorine to wastewater. However, chlorine can harm the aquatic ecosystem, so chlorinated wastewater must be decontaminated before it can be released into the atmosphere.

Ultraviolet Light Treatment

Ultraviolet light treatment is a common disinfectant. Dirty water flows under the UV lights banks, and the light disinfects microorganisms by damaging their genetic makeup. UV light does not usually kill viruses and bacteria, but they are unable to infect humans and animals.

Ozone treatment

An alternative method is to use ozone, a compound that uses electrical energy to add a third oxygen atom to standard diatomic O2, as a disinfectant.

Ozone is highly reactive and can destroy most microorganisms it comes into contact with. It's safer than chlorine because plants can generate it on-site without the risk of long-term storage. It also won't create any dangerous by-products in the water.

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