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Pulp and Paper Industry
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Industry Issues

Characteristics of Pulp and Paper Mill Wastewater

High concentration of organic matter:

The wastewater contains a large amount of organic substances such as cellulose, hemicellulose, and lignin, resulting in high chemical oxygen demand (COD) and biochemical oxygen demand (BOD).

Abundance of Suspended and Particulate Matter:

Mechanical breakdown and agitation during pulp and paper manufacturing introduce a substantial amount of fibers, particles, and other solid impurities, resulting in a high content of suspended solids in the wastewater.

Fluctuating pH Levels:

The use of chemicals in pulp and paper processes and the degradation of organic compounds in wastewater can cause fluctuations in the water's pH, adding complexity to the wastewater treatment process.

High Coloration in Water:

Presence of color-causing substances such as lignin and phenolic compounds contributes to elevated color levels in the wastewater, necessitating specialized treatment to meet discharge standards.

Presence of Heavy Metals:

Certain pulp processing methods may introduce heavy metals like copper, manganese, chromium, etc., becoming pollutants in the wastewater, requiring effective treatment for these substances.

High-Temperature Wastewater:

Wastewater generated during pulping processes may have elevated temperatures, necessitating considerations for the impact of temperature on microbial activity and overall wastewater treatment efficiency.

Odor Issues:

The decomposition of organic compounds and the release of gases in wastewater may lead to unpleasant odors, necessitating comprehensive odor control measures.

Complex Wastewater Composition:

The wastewater is characterized by a complex mixture of organic compounds, inorganic substances, and solid particles, demanding a holistic approach to address the treatment of different components.

Based on the characteristics of Pulp and Paper Mill wastewater

MBBR Have the Following Advantages

1

Efficient Biological Degradation

The MBBR process provides a large surface area for attached biofilm, promoting microbial growth and facilitating the more effective degradation of complex organic compounds, thereby enhancing the biological treatment efficiency of wastewater.

2

Adaptability

MBBR systems demonstrate strong adaptability to fluctuations in water quality and changes in load, efficiently handling variations in water quality and load resulting from the production processes in pulp and paper mills.

3

Small Footprint

Compared to traditional wastewater treatment processes, MBBR systems typically require a smaller facility footprint, facilitating effective wastewater treatment within limited space.

4

Ease of Upgrading and Expansion

MBBR systems are designed with flexibility, making them easily upgradable and expandable to accommodate changes in the factory's production scale or to meet more stringent discharge requirements.

5

Simple Operation and Maintenance

Relative to some complex wastewater treatment processes, MBBR systems are simpler to operate and maintain, reducing operational costs and human resource requirements.

6

Low Energy Consumption

The MBBR process often achieves the same or higher wastewater treatment efficiency at lower air and electricity consumption compared to some traditional wastewater treatment methods.

7

Good Nitrogen and Phosphorus Removal

Through proper operational conditions, MBBR systems can achieve effective removal of nitrogen and phosphorus, aiding in compliance with discharge standards.

8

Stable Treatment Performance

Due to the use of suspended biofilm carriers, MBBR systems typically maintain stable treatment performance when facing shock loads and variations in water quality, enhancing system robustness.

Features

MBBR and Disc Diffuser Must have Performance

In the Pulp and Paper Mill 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 the water quality.

MBBR (Moving Bed Biofilm Reactor)

High Surface Area:Given the elevated organic concentration in the wastewater, opt for MBBR media with a high surface area. This facilitates increased biofilm attachment, promoting microbial growth and enhancing biodegradation efficiency.
Corrosion Resistance:Pulp and paper mill effluents may contain corrosive substances. Therefore, MBBR media should exhibit corrosion resistance to ensure structural stability and durability during wastewater treatment.
Anti-fouling Properties:Due to potential pollutants such as particles and colloids in the wastewater, choose MBBR media with excellent anti-fouling properties. This minimizes surface fouling and blockage, preserving the effectiveness of biofilm surface area.
Mechanical Strength:Given the possible presence of particulate matter in the wastewater, MBBR media should have sufficient mechanical strength to resist wear or breakage in stirring or flowing conditions, ensuring long-term effectiveness.
Lightweight Material:Opt for lightweight MBBR media to enhance suspension and movement in stirred water flow. This improves effective mass transfer of oxygen and pollutants, thereby enhancing biodegradation efficiency.
Large Pore Design:As the wastewater may contain larger particles, select MBBR media with a design featuring large pores. This reduces the risk of clogging, enhancing stability and long-term performance.

Disc diffusers

High Oxygen Transfer Efficiency:The aerator disc should be designed to efficiently transfer oxygen into the water to meet the microbial demand for degrading organic compounds in wastewater. High oxygen transfer efficiency helps maintain good biological activity.
Uniform Bubble Distribution:The aerator disc should ensure that bubbles are evenly distributed throughout the entire MBBR reactor. Uniform bubble distribution helps provide consistent conditions for biofilm attachment, enhancing the consistency of organic degradation.
Corrosion Resistance:Due to the possible presence of corrosive substances in wastewater, the aerator disc should be made of corrosion-resistant materials to ensure structural stability and durability during wastewater treatment.
Anti-Clogging Design:The aerator disc's design should consider anti-clogging features to prevent particles or pollutants in the wastewater from adhering to the disc, affecting bubble generation and transfer.
Adjustable Air Volume:The aerator disc should have adjustable air volume functionality to allow adjustments based on the needs of wastewater treatment. This helps optimize the use of oxygen, reducing energy consumption.
Long Lifespan:The materials and design of the aerator disc should have a long lifespan to minimize the frequency of replacement and repairs, thereby reducing operational costs.

Pulp and Paper Mill wastewater treatment

Precautions, Water Process and Parameter Table

Precautions for Pulp and Paper Mill wastewater treatment

Understand Wastewater Characteristics:Before developing a treatment plan, it is crucial to have a detailed understanding of the characteristics of the wastewater, including organic compounds, solid particles, chemicals, and other potential pollutants.
Comply with Regulations:Adhere to local and national environmental regulations and emission standards. Ensure that the design and operation of the wastewater treatment system comply with legally mandated environmental protection standards.
Implement Appropriate Pretreatment:Prior to entering the main treatment system, appropriate pretreatment steps may be necessary, such as screening, sedimentation, or pH adjustment, to reduce the content of solids and chemicals in the wastewater.
Select the Right Treatment Processes:Choose the appropriate treatment processes based on the nature of the wastewater, such as MBBR, biological reactors, advanced treatment, etc. The selection should consider efficiency, cost, and sustainability.
Optimize Biological Degradation:Encourage and optimize the biological degradation process. Maintain an appropriate biomass and favorable conditions for biofilm attachment to ensure effective removal of organic matter.
Regular Maintenance and Cleaning:Wastewater treatment equipment requires regular maintenance and cleaning to prevent the accumulation of pollutants and degradation of system performance.
Sludge Management:Manage the sludge generated during the wastewater treatment process. Appropriate solid-liquid separation and treatment methods may be necessary to ensure environmentally friendly disposal of the sludge.
Prevent External Contamination:Take measures to prevent pollutants from external sources, such as oil, chemicals, or other harmful substances, from entering the wastewater system.

Special features of handling pulp and paper mill wastewater treatment processes

Understand Wastewater Characteristics:Before developing a treatment plan, it is crucial to have a detailed understanding of the characteristics of the wastewater, including organic compounds, solid particles, chemicals, and other potential pollutants.
Comply with Regulations:Adhere to local and national environmental regulations and emission standards. Ensure that the design and operation of the wastewater treatment system comply with legally mandated environmental protection standards.
Implement Appropriate Pretreatment:Prior to entering the main treatment system, appropriate pretreatment steps may be necessary, such as screening, sedimentation, or pH adjustment, to reduce the content of solids and chemicals in the wastewater.
Select the Right Treatment Processes:Choose the appropriate treatment processes based on the nature of the wastewater, such as MBBR, biological reactors, advanced treatment, etc. The selection should consider efficiency, cost, and sustainability.
Optimize Biological Degradation: Encourage and optimize the biological degradation process. Maintain an appropriate biomass and favorable conditions for biofilm attachment to ensure effective removal of organic matter.
Regular Maintenance and Cleaning:Wastewater treatment equipment requires regular maintenance and cleaning to prevent the accumulation of pollutants and degradation of system performance.
Monitor Water Quality Parameters:Regularly monitor water quality parameters, including dissolved oxygen, ammonia nitrogen, pH, suspended solids, and chemical concentrations in the wastewater.
Sludge Management:Manage the sludge generated during the wastewater treatment process. Appropriate solid-liquid separation and treatment methods may be necessary to ensure environmentally friendly disposal of the sludge.
Prevent External Contamination:Take measures to prevent pollutants from external sources, such as oil, chemicals, or other harmful substances, from entering the wastewater system.
Continuous Improvement:Continuously seek and adopt new technologies and methods to improve treatment efficiency, reduce energy consumption, and achieve the goal of zero wastewater discharge.

Pulp and Paper Mill wastewater treatment process

Influent Screening:The influent wastewater undergoes an initial screening process to remove larger solids, such as wood fibers and debris, preventing them from entering the MBBR system.
Equalization Tank:The pre-screened wastewater is directed to an equalization tank to balance flow rates and load fluctuations, ensuring a consistent feed to the MBBR.
MBBR Reactor:The wastewater is then introduced into the MBBR reactor, where plastic biofilm carriers with attached microorganisms provide a surface for the growth of beneficial bacteria.Microorganisms on the biofilm carriers actively biodegrade organic pollutants, breaking them down into simpler, more stable compounds.
Aeration and Mixing:The MBBR system employs aeration devices to provide oxygen for the aerobic microbial activity on the biofilm carriers.Continuous mixing within the reactor ensures optimal contact between the wastewater and biofilm, promoting efficient treatment.
Effluent Clarification:After the MBBR process, the treated water passes through a clarification unit to separate suspended solids and biofilm carriers from the treated effluent.
Secondary Clarifier:The clarified effluent undergoes further settling in a secondary clarifier, allowing any remaining solids to settle, resulting in a clearer supernatant.
Disinfection:To meet regulatory standards, the clarified and treated effluent is subjected to a disinfection process, commonly using chlorine or UV radiation, to eliminate any remaining pathogens.
pH Adjustment:pH levels of the treated water are adjusted as necessary to meet discharge requirements, ensuring compliance with environmental standards.
Monitoring and Control:Continuous monitoring of key parameters such as dissolved oxygen, pH, and microbial activity allows for real-time adjustments to optimize treatment efficiency.
Environmental Compliance Reporting:Comprehensive documentation of the entire MBBR process and effluent quality is maintained for regulatory reporting, demonstrating adherence to environmental standards.

Pulp and Paper Mill wastewater treatment

Typical Parameter

The following is a parameter table of a typical Pulp and Paper Mill 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 Pulp and Paper Mill 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

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: 400-1200gNH N/M3d

BOD, Efficiency: 2000-10000g BOD,/M3d

COD5 Efficiency: 2000-15000 gCOD/Md

Applicable Temperature: 5-60C

Life-Span: >20year

MBBR37

Size: Φ25*12mm

Hole Numbers: 37

Material: 100% White Virgin HDPE

Densilty: 0.96-0.98g/cm3

Surface Area: >800m2/m3

Dosing Ratio: 85%

Membrane-Forming Time: 15-65%

Nitrification Efficiency: 3-15days

BOD, Efficiency: 400-1200gNH4 N/M3.d

COD5 Efficiency: 2000-10000g BOD/M3d

Applicable Temperature: 2000-15000 gCOD5/M3d

Life-Span: 5-60C

Pulp and Paper Mill wastewater treatment

AquaSust Customer Case

Case 1: Application of MBBR Media in Pulp and Paper Mill Wastewater Treatment

Faced with high organic loads and complex wastewater composition issues, a large pulp and paper mill in Canada used MBBR technology to optimize its wastewater treatment process.The MBBR system used HDPE MBBR Media manufactured by Aquasust, which has a high surface area and provides enough space for microorganisms to attach and grow.

With a capacity to treat 10,000 m3 of wastewater per day, the MBBR system successfully reduced the Chemical Oxygen Demand (COD) from an initial 1,200 mg/L to less than 200 mg/L and the Biochemical Oxygen Demand (BOD) from 800 mg/L to less than 30 mg/L. This treatment effect significantly improves the effluent water quality and meets the local environmental discharge standards.

In addition, the energy consumption of the system is relatively low, and the operating cost is about 25% lower than that of the traditional activated sludge method, which saves a lot of operating costs for the plant.

Case 2: Aeration Diffusers in Pulp and Paper Mill Wastewater Treatment

Due to the need to efficiently treat wastewater containing high concentrations of suspended solids and lignin in a Finnish pulp mill, the mill installed Aquasust's Disc Diffuser in its activated sludge system. These Disc Diffusers produce fine, uniform bubbles that enhance the metabolic activity of microorganisms by improving the efficiency of oxygen dissolution in the water.

Post-installation data showed that the new aeration system improved oxygen delivery efficiency by 50% and increased overall treatment efficiency by approximately 30%. Suspended solids in the treated wastewater were reduced from 500 mg/L to 50 mg/L, and COD was reduced from 1,500 mg/L to 250 mg/L, greatly improving effluent quality.

This system improvement increases the efficiency of wastewater treatment and reduces energy consumption from 0.9 kWh per cubic meter to 0.65 kWh per cubic meter, further optimizing production costs and environmental impact.

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