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Characteristics of Municipal Wastewater

Diversity:

Municipal sewage comes from complex sources, including residential sewage, and commercial and industrial wastewater. This sewage may contain various organic and inorganic substances, such as food residues, grease, chemicals, heavy metals, microorganisms, etc.

Large scale:

The amount of municipal sewage generated is usually large because cities have large populations and contain many industrial and commercial activities. This makes wastewater treatment a large and complex task

Fluctuation:

The amount of sewage produced may fluctuate greatly at different times and locations, such as working days and weekends, day and night, holidays, etc. This requires a certain degree of flexibility and adaptability in the sewage treatment system.

Complexity:

Sewage contains various complex chemical components, including organic matter, nitrogen compounds, phosphates, microorganisms, etc. Treating municipal wastewater requires a multi-stage treatment process to remove or reduce the concentration of these pollutants.

Environmental impact:

If municipal sewage is not properly treated, it may have negative impacts on the surrounding environment, such as water pollution, and soil pollution, and impact on the ecosystem. Therefore, effective wastewater treatment measures must be taken to protect the environment.

Regulatory requirements:

The government usually formulates relevant regulations and standards to stipulate the treatment standards and discharge requirements of municipal sewage. Compliance with these regulations is critical to maintaining public health and environmental quality.

Technical requirements:

To effectively treat municipal sewage, advanced technologies, and equipment, such as biological treatment, chemical treatment, physical treatment, etc., need to be used to ensure that the discharged water quality meets the prescribed standards.

Based on the characteristics of municipal wastewater

MBBR Must Have the Following Properties

1

High attachment efficiency

The key to MBBR is to provide a large amount of surface area on the sliding biofilm to encourage microorganisms to grow and adsorb on the filler. Therefore, MBBR systems must be designed to provide sufficient attachment surface area to accommodate a large biological community, allowing for efficient biodegradation.

2

Strong load impact resistance

The water quality and flow rate of municipal sewage may fluctuate violently, and the MBBR system must have strong load impact resistance to adapt to these changes. This can be achieved by designing the system with buffering capacity to balance and adjust the biodegradation process.

3

Flexibility and adjustability

The MBBR system should have a certain degree of flexibility so that it can be adjusted according to different water quality and load conditions. This can be achieved by adjusting the mixing speed, increasing or decreasing the amount of filler, or using an adjustable gas distribution system.

4

Low maintenance requirements

Due to the large scale of municipal sewage treatment, the MBBR system must be designed with low maintenance requirements to reduce operating costs and system downtime. This may include packing designs that are easy to clean, automated control systems, and reliable equipment.

5

Adapt to different water quality and load

The water quality and load of municipal sewage may change at any time, and the MBBR system needs to be able to adapt to these changes to maintain stable performance. This may involve the optimization of operational control systems and the introduction of feedback mechanisms.

6

Efficient gas supply system

The biodegradation process requires oxygen, so the MBBR system must be equipped with an efficient gas supply system to ensure sufficient oxygen transfer and biodegradation process on the filler.

7

Anti-pollution performance

MBBR should have certain anti-pollution performance to deal with suspended solids, sediments, etc. that may exist in aquaculture wastewater and maintain the stability of the system.

8

Comply with regulatory standards

The MBBR system must comply with relevant regulations and emission standards during design and operation to ensure that the treated water quality meets environmental protection requirements.

Features

MBBR and Disc Diffuser Must have Performance

In the municipal wastewater treatment process, MBBR and aeration disks are usually key components of the biological treatment system. Through processes such as biodegradation and oxygen transfer, they help maintain good water quality.

MBBR (Moving Bed Biofilm Reactor)

High biofilm attachment efficiency: The key to MBBR is to provide sufficient surface area to encourage microorganisms to attach and form biofilms. High biofilm attachment efficiency helps improve biodegradability.
Good gas-liquid mass transfer performance: Sufficient oxygen is required to be transferred to the biofilm in MBBR, so the system must be designed with good gas-liquid mass transfer performance to support the respiration and degradation activities of microorganisms.
Impact resistance: The MBBR system has strong impact resistance in response to fluctuations in water quality and load to ensure stable operation of the system.
Corrosion resistance of filler materials: MBBR fillers must be corrosion-resistant to deal with corrosive substances that may exist in sewage and ensure long-term stable operation of the system.

Disc Diffusers

High gas transfer efficiency: The disc diffuser needs to provide sufficient gas transfer to the water to meet the oxygen needs of microorganisms. High gas transfer efficiency helps improve biodegradation.
Uniform gas distribution: The disc diffuser should be able to ensure that the gas is evenly distributed throughout the entire treatment unit to avoid dead zones and ensure that all parts are adequately supplied with oxygen.
Anti-pollution ability: The disc diffuser needs to have a certain anti-pollution ability to prevent the gas transfer efficiency from being reduced due to clogging or covering.
Corrosion resistance: The material of the disc diffuser must be corrosion-resistant to adapt to different water quality conditions and extend its service life.
Low noise: Reduce the operating noise of the disc diffuser, which helps to improve the working environment of the treatment plant.

Municipal wastewater treatment

Precautions, Water Process and Parameter Table

Special points of municipal sewage process

Multi-stage treatment: Municipal sewage treatment usually requires the use of multi-stage water processes, including primary treatment, biological treatment (such as MBBR, activated sludge method), advanced treatment, etc., to ensure the effective removal of different types of pollutants.
Strong adaptability: Since municipal sewage water quality and load may fluctuate greatly, the water process system needs to have strong adaptability, be able to cope with changes in water quality and load, and maintain stable treatment effects.
Large-scale treatment: Municipal sewage treatment involves large-scale water volumes, so the design of water process systems needs to consider the scalability of treatment capacity to adapt to urban population growth and changes in industrial activities.
Efficient redox environment: The biodegradation process requires maintaining a suitable redox environment to ensure that microorganisms can effectively degrade organic matter. Therefore, water process design needs to focus on oxygen supply and mixing.
Low energy consumption and resource recovery: When designing water processes, consider minimizing energy consumption while paying attention to opportunities for recycling resources (such as nitrogen and phosphorus) that may be present in wastewater to improve sustainability.

Precautions for municipal sewage treatment The municipal wastewater treatment process has some unique characteristics, which are mainly related to the operation mode of the water treatment system, water circulation, water quality management, and wastewater treatment technology. The following are some characteristics of the municipal wastewater treatment process:

Water temperature: Pay attention to temperature changes in winter: The cold season may cause the water temperature to drop, affecting the activity of microorganisms, so measures need to be taken to ensure the stability of the biological treatment process.
pH value: Control within a suitable range: In the sewage treatment process, maintaining a suitable pH range is crucial for the activity of microorganisms. Usually, a range of 6.5 to 8.5 is more suitable.
Special pollutants: Identify and treat toxic substances: For special pollutants that may exist, corresponding processes and technologies need to be adopted to identify, decompose, or remove these toxic substances.
Regulations and discharge standards: Comply with local regulations: Strictly comply with local and national regulations and discharge standards to ensure that the treated water quality meets regulations.
Process adjustment: Adjust according to changes in water quality and load: Water quality and load may change due to factors such as seasons and population fluctuations, and the treatment process needs to be adjusted according to actual conditions.

Municipal wastewater treatment process

Preliminary Treatment: This initial phase removes large solids and debris from the wastewater through screening and grit removal. It prevents damage and clogging of downstream equipment.
Primary Treatment: In this stage, physical settling tanks (primary clarifiers) allow solids to settle out from the wastewater, significantly reducing the amount of suspended solids and organic load.
Secondary Treatment: This biological treatment phase uses microorganisms to consume organic matter in the wastewater. It typically involves processes like activated sludge, fixed-film reactors, or membrane bioreactors.
Tertiary Treatment: Tertiary or advanced treatment further cleans the wastewater by removing remaining suspended solids, nutrients (nitrogen and phosphorus), and other pollutants through filtration, chemical treatment, or additional biological processes.
Disinfection: Before the treated water is discharged or reused, it undergoes disinfection to kill any remaining pathogens. Common methods include chlorination, ultraviolet (UV) irradiation, or ozonation.
Sludge Treatment: The solids removed during primary and secondary treatment are treated separately in processes including thickening, digestion (aerobic or anaerobic), dewatering, and possibly composting or incineration.
Effluent Disposal or Reuse: The final treated water (effluent) can be discharged into local water bodies, and reused for irrigation, industrial processes, or even indirect potable use after further treatment if necessary.
Odor Control: Throughout the treatment process, measures are taken to manage odors through containment, chemical scrubbing, biofilters, or other technologies, ensuring the facility minimizes its impact on the surrounding community.

Municipal wastewater treatment

Typical Parameter

The following is a parameter table of a typical Recirculating aquaculture wastewater treatment process. The specific values can be adjusted according to the actual situation:

Satge	Processing unit	Typical parameters	Unit
Solid-liquid separation	Sedimentation tank	TSS	50 - 500 mg/L
Biological treatment	MBBR	COD	30 - 200 mg/L
		NH3-N	2 - 10 mg/L
		NO2-N	< 1 mg/L
		NO3-N	< 10 mg/L
		TN	5 - 30 mg/L
Aeration system	Aeration tank	DO	3 - 8 mg/L
Physical treatment	Filter	TSS	10 - 50 mg/L
Ammonia nitrogen removal	Ammonia nitrogen removal unit	NH3-N	< 1 mg/L
Sterilize	Sterilization equipment	Sterilant concentration	0.5 - 5 mg/L
Water quality monitoring	Monitoring equipment	PH	6.5 - 8.5
		Conductivity	500 - 2000 μS/cm
		Temperature	20 - 30 ℃

For Municipal wastewater treatment

A Unique MBBR Model is Recommended

Based on the characteristics of sewage treatment and the experience of previous cooperative customers, the recommendation is our MBBR64 or MBBR7

MBBR37

Size: Φ25*12mm

Hole Numbers: 37

Material: 100% White Virgin HDPE

Densilty: 0.96-0.98g/cm³

Surface Area: >800m2/m³

Dosing Ratio: 15-65%

Membrane-Forming Time: 3-15days

Nitrification Efficiency: 400-1200gNH₄ N/M³.d

BOD₅, Efficiency: 2000-10000g BOD₅/M³.d

COD₅ Efficiency: 2000-15000g COD₅/M³.d

Applicable Temperature: 5-60℃

Life-Span: >20year

MBBR19

Size: Φ25*12mm

Hole Numbers: 19

Material: 100% White Virgin HDPE

Densilty: 0.96-0.98g/cm³

Surface Area: >650m²/m³

Dosing Ratio: 15-65%

Membrane-Forming Time: 3-15days

Nitrification Efficiency: 400-1200gNH₄N/M³.d

BOD₅, Efficiency: 2000-10000g BOD₅/M³.d

COD₅ Efficiency: 2000-15000g COD₅/M³.d

Applicable Temperature: 5-60℃

Life-Span: >20year

Municipal wastewater treatment

AquaSust Customer Case

Use of MBBR in Brazilian municipal renovation projects

Facing limited space and a UASB reactor not meeting BOD removal goals, the client selected Aquasust's MBBR and aeration system for its efficiency and low cost. The MBBR system, enhancing removal rates to >92% BOD, includes reactors, a settling tank, and hypochlorination before river discharge. Early results show over 92% BOD and 87% COD removal, with plans for future expansion based on these positive outcomes.

Harestua-Intl town reconstruction project MBBR use

Harestua STP, constrained by space, needed an upgrade to handle more load and better BOD/COD removal. They chose Aquasust's MBBR system for effective use of existing tanks, meeting treatment goals with potential for expansion. The system integrated primary settling tanks into the MBBR stage and included a multifunctional final clarifier for phosphorus removal and sludge storage. The comprehensive solution was divided into mechanical installations (M1), the MBBR biological stage (M2), and phosphorus removal with Lamella DAF (M3).

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