What Is Upflow Anaerobic Sludge Blanket Digestion?

What Is Upflow Anaerobic Sludge Blanket Digestion?

What Is Upflow Anaerobic Sludge Blanket Digestion?

The UASB process uses anaerobic microorganisms to degrade wastewater in a tank, with a blanket of granular sludge suspended by upward flow and gravity aided by flocculants.

After 3 months, the blanket matures and small granules with bacterial aggregations form. These aggregations grow into dense biofilms known as granules, and biogas with high methane concentration is produced as a byproduct that can be used as energy.

Monitoring is necessary to maintain the sludge blanket, and the heat produced from electricity generation can be reused to heat the tanks.

UASB is best suited for dilute wastewater streams (3% TSS with particle size >0.75mm) and enables both solid and hydraulic retention time, with solids able to stay in reactors for up to 90 days and liquid waste able to exit the system within a day.

What Is The Working Principle Of Upflow Anaerobic Sludge Blanket Reactor?

The UASB reactor processes waste by feeding it into the reactor in an upward direction with a hydraulic retention time of 8-10 hours.

No sedimentation is necessary and no specific medium is required as the flowing sewage creates small sludge granules in suspension which provide a surface for organic matter biodegradation.

The solid retention time in the reactor is 30-50 days or more, with no need for mixers or aerators. The produced gas can be utilized as biofuel.

Excess sludge is regularly removed and dried. The UASB reactor is suitable for bottling wastewater treatment, with low-rate installations available.

Sugar wastewater is easily processed, however, the reactor cannot treat pharmaceutical waste containing antibiotics and toxic chemicals, which is not suitable for anaerobic treatment and not cost-efficient.

What Is UASB Process In Water Treatment?

The UASB reactor is a type of anaerobic digester used in wastewater treatment and known for producing methane.

It works by suspending a blanket of granular sludge in the tank and having wastewater flow upward through it to be processed by anaerobic microorganisms.

Over time, small sludge granules form with a surface area covered in bacterial aggregations, leading to the formation of compact biofilms called granules.

This process is facilitated by the upward flow and gravity settling, as well as the selective environment created by the flow conditions.

What Is Meant By A UASB Reactor State An Advantage Of It?

UASB stands for Upflow-Anaerobic Sludge Blanket and is also known as the UASB reactor.

It is a type of anaerobic digester used in wastewater treatment, producing methane through anaerobic microorganisms processing granular sludge.

The UASB reactor is a single-tank process in centralized or decentralized anaerobic wastewater treatment, capable of removing high levels of organic pollutants.

The anaerobic process uses no air or oxygen and converts organic pollutants into biogas with methane and CO2.

The UASB reactor is effective in removing BOD, COD, and TSS but has minimal impact on wastewater nutrients. It can treat various wastewaters, including blackwater, greywater, industry effluent, and agriculture wastewater.

Advantages of using a UASB reactor:

·         Effective handling of organic shock loads

·         Low nutrient requirement

·         Can be shut down for extended periods without serious deterioration

·         Low energy and maintenance costs

·         Utilizable biogas production

·         Compact and space-efficient

·         Fewer bio-solids wastes due to energy conversion to gaseous form

What Are The Major Disadvantages Of UASB?

·         Trained and professional staff needed for monitoring plant’s internal condition.

·         Post-treatment necessary for anaerobic processes to reach surface water discharge standards.

·         Safe disposal of sulphur compounds important for safety, corrosion and odour.

·         Longer start-up required for UASB reactors.


·         Proper temperature range crucial for successful anaerobic process.

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