What Is Biological Wastewater Treatment System and How Does It Work?

Wastewater treatment is a process of removing contaminants from wastewater and returning it to the water cycle. Among the various treatments, biological wastewater treatment stands out as a natural and effective approach to treating wastewater. It harnesses the power of microorganisms to dissolve the organic contamination of wastewater.

In this comprehensive guide, we will learn the various methods and technologies used in the biological treatment of wastewater while covering the basic definition and working of the same.

A] What Is Biological Wastewater Treatment?

Biological wastewater treatment uses sewage treatment microorganisms such as bacteria, nematodes, algae, fungi, protozoa and rotifers for purifying the water. These microbes decompose the organic substances and suspend the solids before releasing them back into the environment. 

This process is designed to dissolve the water pollutants naturally to improve water quality and make it safe to drink. It is a secondary wastewater treatment which treats the water left over by the primary treatment. Biological treatment for wastewater is the most efficient and modern treatment process which claims to remove 98% of organic contaminants from wastewater.

B] How Does the Biological Wastewater Treatment System Work?

In biological wastewater treatment, pre-treated wastewater enters into a biological reactor such as activated sludge tanks or trickling filters. Aerobic or anaerobic bacteria and other microorganisms break down organic pollutants into less harmful substances through biochemical reactions. 

In an aerobic system, the air is introduced to promote microbial growth and enhance treatment efficiency. In anaerobic systems, organic matter is converted into methane and carbon dioxide gasses to form biogas. 

C] Aerobic Wastewater Treatment & Technologies

1. Activated Sludge

Activated sludge refers to developing organism culture inside the aeration tanks in a controlled manner to degrade the pollutant in wastewater. Activated sludge appears brown and is also known as waste-activated solids or waste-activated biosolids. They are made with aerobic bacteria and fungi, protozoa and other forms of invertebrates.

Activated sludge uses multi-chamber reactors with highly concentrated microbes to degrade the wastewater pollutants. In this process, a timely supply of oxygen is needed to maintain the aerobic condition. This process is generally used in the treatment of municipal wastewater and industrial wastewater.

2. Fixed Bed Bioreactors (FBBRs)

It is an advanced biological treatment in wastewater treatment which uses a series of tanks containing multiple chambers. These chambers are usually made from porous materials such as plastic, foam or ceramics. This serial alignment of tanks efficiently dissolves the highly contaminated wastewater pollutants. This aerobic water treatment process treats wastewater produced in petrochemical, food and meat processing industries.  

3. Moving Bed Bioreactors (MBBRs)

Moving Bed Bioreactors consist of a series of aeration tanks that contain free-to-move polyethene biofilms in cylindrical or cubical formations. Biofilm-covered plastic carriers tend to break down the organic contamination using aerobic bacteria. These carriers increase the performance of the MBBR system through their free movement within the biological reactors. This process is frequently used in wastewater treatment processes.  

4. Biological Trickling Filters

It is a secondary wastewater treatment process that is used to remove organic contamination from the wastewater. In this biological treatment, trickling filter vessels are filled with solid materials such as gravel, rock, coke, ceramic or plastic. Sprinkles of wastewater trickle over the solid materials. The continuous stream of wastewater sprinkles creates biological biofilms over the solid materials. These biofilms absorb the dissolved organic pollutants from wastewater for their growth. This cost-effective and effortless process is used in MSMEs for high filtration needs. However, the Trickling filter process fosters a high rate of sludge and clogging, creating a major concern for industries. 

D] Anaerobic Wastewater Treatment & Technologies

1. Upflow Anaerobic Sludge Blanket Reactor (UASB)

An anaerobic sludge blanket reactor is an anaerobic digester of wastewater. It uses microorganisms to convert organic pollutants into biogas. In this process, wastewater enters from the bottom of the reactor and flows in the upward direction. A blanket formed by the granular sludge treats the wastewater as it flows through it.

The upward flow of wastewater passes the zone of blanket and sludge to separate solid, liquid and gas from the contaminated water. This process treats seasonal industrial wastewater such as food processing industries. It requires low energy and produces methane and biogas gas as a by-product of treatment.  

2. Anaerobic Filter Reactors

Anaerobic filter reactors use the fixed bed to form a bacteria biofilm. The fixed bed area consists of solid materials such as pumice, gravel, crushed rock, and pumice stones. When the wastewater goes through the fixed bed, the organic contamination of water is decomposed by the microorganisms grown on the fixed bed.

The upflow operation mode of Anaerobic filters significantly removes the contamination from wastewater using the fixed bed microbes biofilms. This process is best suited for treating such wastewater that has non-settle and dissolved solids.

E] Why Choose PureBact For Your Biological Wastewater Treatment

Here are some of the top reasons to choose PureBact for your Biological wastewater treatment:

• Significant BOD/COD Reduction: PureBact’s PureBact10 significantly removes biochemical oxygen demands (BOD) and chemical oxygen demand (COD) to improve the efficiency of waste plants.
• Excellent MLSS/MLVSS Formation: Pure Bact provides excellent mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) to enhance the mixture of total solids, which improves the number of microorganisms in wastewater.
• Degradation of Tough-Treat Organics: Our products are designed to degrade tough organic contamination such as pesticides, solvents, surfactants, dyes, and chemical intermediates.
• Odour Control: Our products are efficient enough to control the odour of wastewater by increasing the oxygen supply to aerobic bacteria which further slows down the anaerobic digestion to control the odour. 
• Enhanced Colour Reduction: PureBact uses inorganic coagulants such as alum, lime, ferric or ferrous sulfate and polyaluminium chloride (PAC) for effective reduction of wastewater colour. 
• Versatile- Works In All Types Of Treatment Plants: PureBact’s are made to support all kinds of wastewater treatment plants such as activated sludge plants (ASP), submerged aerated filter systems, and sequencing batch reactors and are compatible with approx all aerobic and anaerobic wastewater treatment & technologies.

Conclusion

Various industries are now adopting biological wastewater treatment and its various technologies as a sustainable approach to wastewater treatment. These biological wastewater technologies have a long history; continuously improving and evolving to provide more efficient and cost-effective ways of treating and reusing wastewater. However, it is crucial to choose those biological wastewater treatment methods that comply with your requirements and operational flexibility. You can contact PureBact to solve your specific water challenges. Our experts will listen and understand your specific challenges or needs and deliver a solution that caters to your specific needs and requirements. Contact us today!